Developing a remote controlled leveling lifting yoke in the 2-5 ton range

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Developing a remote controlled leveling

lifting yoke in the 2-5 ton range

Utveckling av ett radiostyrt nivellerande lyftok i 2-5 tons omr ˚adet

Johannes Westh

Faculty of Health, Science and Technology

Degree Project for Master of Science in Engineering, Mechanical Engineering 30 hp

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Abstract

When lifting unbalanced objects with a crane or other lifting equipment it can be hard to get the object leveled. This is dealt with in ways which often rely on experienced workers and can be dangerous as well as time consuming. A remote leveling lifting yoke (LLY) can be a solution to this problem, there are currently only one such product available capable of lifting up to 20 tonnes called L20. The L20 is however rather large and not practical for smaller lifts or lifting equipment. This report investigates weather a smaller version of L20 is needed and how it should function. By using modern product development techniques a few concepts to a new LLY was presented. The concepts are based on the fundamental working principles of the existing L20, that is being battery powered and leveling the load by a chain with its two ends connected to the lifted object driven by a chain wheel. The main challenge during the concept development was to figure out a brake function which would prevent the driving mechanism from being overloaded in the event of an unexpected load shift. Another challenge was to try to implement a freewheel function which would enable the chain wheel to spin freely making it possible to adjust the chains by hand. From the prestudy it was seen that in order to make this new LLY unique, the remote controlled function would be the main thing setting it apart from alternatives on the market. The freewheel ability was also not seen amongst the competitor products.

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Sammanfattning

Vid lyft av obalanserade object med kran kan det vara sv˚art att f˚a det balanserat. Idag hanteras

detta p˚a lite olika sätt, oftast s˚a löses det genom att använda en kombination av olika lyftredskap

eller genom erfarenhet hos operatörerna, detta kan vara tidskrävande och ibland en säkerhetsrisk.

Ett tr˚adl¨ost nivellerande lyftok (LLY) kan l¨osa m˚anga av dessa problem, idag finns bara en s˚adan

produkt som kan lyfta upp till 20 ton och detta kallas d¨arav f¨or L20.

L20 ¨ar dock ganska stor och inte praktisk f¨or mindre lyft eller lyftutrustning. Denna rapport

undersöker om en mindre version av L20 behövs och hur den ska fungera. Genom att använda

moderna produktutvecklingstekniker presenteras n˚agra koncept till en ny LLY. Koncepten ¨ar baserade

p˚a de grundläggande arbetsprinciperna för den befintliga L20, det vill säga batteridriven och jämna ut

lasten med en kedja vars tv˚a ¨andar ¨ar anslutna till det lyftade objektet som drivs av ett kothjul. Den

huvudsakliga utmaningen under konceptutvecklingen var att implementera en bromsfunktion som

skulle förhindra att drivmekanismen överbelastas vid oväntad lastförskjutning. En annan utmaning

var att försöka implementera en frihjulsfunktion som skulle göra det möjligt för kedjehjulet att snurra

fritt vilket gör det möjligt att justera kedjorna för hand. Fr˚an förstudien s˚ags det att för att göra

denna nya LLY unik skulle den fj¨arrstyrda funktionen vara det viktigaste att skilja den fr˚an alternativ

p˚a marknaden. Frihjulets f¨orm˚aga s˚ags inte heller bland de konkurrerande produkterna.

Det mest lovande konceptet var ett snäckväxelbaserat system eftersom det i sig är själ-vhemande

och därmed löser bromsproblemet och eliminerar mycket av växellreduktionen. Emellertid hittades

inget enkelt sätt att lägga till en frihjulsförm˚aga med detta system men detta är löst genom att lägga

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1 Introduction

1.1 Background

Today there is no product on the market that provides and easy way of leveling a hanging load in the range of 2-5 tonnes suspended by a crane. There is however an existing leveling lifting yoke (LLY) capable of handling 20 tonnes available today. This 20 ton LLY is shown in figure 1, the unit consists of a chain wheel that drives a chain which ends are connected to the object that is lifted. Driving the chain wheel results in a rotation of the hanging object around the center of mass enabling more control of the object when handling it. The 20 ton LLY is mainly used in construction where larger and heavier objects are being handled, but because of its large size it is not suitable for smaller operations such as those performed in workshops etc. A smaller remotely controlled LLY based on the same principle as the 20 ton LLY would fill this vacancy on the current market.

Figure 1: Existing 20 ton LLY

1.2 Aim

The aim of this project is to construct a new smaller LLY capable of handling 2-5 tonnes by using modern product development techniques. The final result is set to be one or more concepts with performance, cost and strength analysis that can be further worked on or inspired by if this product should be further developed and manufactured.

1.3 Limitations

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1.4 Invencon AB and Ganterud AB

This projects commissioners are Invencon and Ganterud. Ganterud AB is a company which sells lifting equipment of different types. The 20 ton LLY previously mentioned is a product from Ganterud called L20, it is to expand this product line that they are now looking into developing this smaller LLY. Invencon AB is an engineering company which has helped Ganterud develop the L20 and it is also via Invencon that this project is conducted.

2 Method and theory

A project is a specific task with specific goals, a defined start and ending, an assigned team and a budget. This product development task was performed in the form of a project.

Going back in time about 70 years the view on product development was quite a bit different from now. Back then it was considered more of an art form than science, the ability to come up with and develop products and machines was seen more of as a gift and something that some people were born with. As a result of this there was no real research conducted in this field. It wasn’t until about 1960 that this view changed and theories and research started to take form. A lot of inspiration for this came from Japan when their new products came and proved to be better than the traditional ones used for centuries in the Western world. The Japanese product developers had a much more strict focus on the customer and their needs and a much more systematic way of working. This new competition forced the engineers of to start researching the ”art” of product development and this has continued on ever since [1]. Today there are many theories and ideas on the subject and during this work some of the most common methods will be applied and discussed.

2.1 Product specification

With the given background and an initial idea of what the new product should look like and its features it is necessary to specify the details and together with the project’s stakeholders agree on these details so that it can be easily determined if the result is what they ordered. Often, the necessary information to fully specify the product is not available at the start of a project and so the first phase will then be to conduct a prestudy[1].

2.1.1 Prestudy

The general idea of a smaller LLY unit was proposed a while back and a preliminary prestudy was conducted resulting in the decision to move on with the development.

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should the product do, look like, cost, feel like and so on. The result of the prestudy should be a better understanding of what the stakeholders are actually interested in. This information is then processed and formulated in the product specification[1].

For this projects specification the most crucial information to obtain will be: • Maximum lifting capacity

• Maximum uneven load • Maximum unit weight • Appropriate selling Price

The first step was to take part of and summarize the previously comprised prestudy. Using this previous study as a starting point the next step was to further investigate the market to pinpoint more exactly what product is needed. More interviews with companies who may be potential customers needed to be conducted as well as information about existing solutions that partly or completely solve the same problem needs to be researched via the internet, but also interviews with people who work with similar situations. Patents where examined to make sure that no patent infringements occur but also to find inspiration for the new product. Laws and regulations that applies where followed to make sure the product will be safe and sellable. Selling volumes and a Swot analysis were also conducted.

2.1.2 Prototype 0

Since the idea of this type of LLY is new to many of the people interviewed a ”prototype 0” was built to simply help persuade the concept. Because no matter how well the principle is explained the risk of the interviewed having their own perception of the functionality is always present. Having a small working prototype that shows how the chain moves and the load tilts ensures better communication and increases the reliability of the interviews. This prototype gives an illustration of the final concept and its soul purpose is to aid the interviewing process.

2.1.3 Specification and QFD

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To help visualize relations between a criterion and function a quality function deployment (QFD) is a useful tool. A QFD is a way of combining functions and product specifications in a matrix and sums up correlation to give a better sense of the challenges ahead and where to assign resources. A QFD can also help visualize the competitiveness of the product by comparing competitors product to the intended new product for each function and criteria[1]. More details about the QFD parts can be read in the results chapter.

The product specification can be changed at any time during the development and may be necessary after new information emerges that was not available at the beginning of the work. However since these changes may cost much more at a later stage in the project it is often very beneficial to be thorough in the beginning and make sure that the specifications are as complete as possible with the available information.

2.2 Concepts

With a complete product specification it is possible to start exploring solutions to solve the functions of the new product. There are many different methods to help aid this process of coming up with a complete solution. Modern product development theory categorizes these methods into two categories, creative and systematic. The creative methods are based on environments and strategies to help one or many people come up with solutions based on their own knowledge and creativity. Examples of creative methods are: Brainstorming, analogies and Gordon method. The systematic methods are based more on research and by systematically examining existing solutions of similar problems or functions to try to find ways of implementing these into solving the problem at hand. Biomimicking is a form of strategic method, by looking at how nature solves problems and find inspiration [1].Having a good system for naming the solutions can be helpful to navigate amongst them.

During this Project both systematic and creative methods where used and evaluated, the systematic in the from of researching similar systems and technologies and creative in the form of brainstorming sessions with slight variations.

The problem was also broken down into smaller pieces in order to simplify it but also because it is easier to come up with solutions to some smaller problems rather than one bigger. The main problem was divided into Braking, driving and measuring torque. Driving focuses only on solutions to drive the chain wheel while braking only focuses on solutions to brake the rotation of the chain wheel. The torque measuring is different ways of measuring the applied torque on the chain wheel in order to provide information to warning system and brake system which rely on a signal of some sort.

Brainstorming is widely used in the industry as a way of generating ideas but can have other positive effects as well. Brainstorming is sometimes incorrectly used as a general way of referring to just coming up with ideas, it is however a defined process with specific rules [1].

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• No criticisms is allowed.

• Quantity is more important than quality

• Use ideas as stepping stones to build and combine into additional ideas • Wild ideas are welcomed.

It can however still be performed in slightly different ways, one thing that can vary is how interactive the group is during the brainstorming session. It has been shown that the quality of ideas and concepts is higher when every person initially works more by them selves instead of having a face to face discussion and coming up with ideas. However many companies still practice the more interactive group method despite this knowledge because it contributes with other beneficial social effects. It is also very hard to judge the quality of the results and also choose an appropriate time frame of evaluation (just the result after the session or the whole project result) which is one of the reasons that different opinions about the best practice exists. [2].

The result can be a few or sometimes thousands solutions to the whole or some parts of the problem. Sorting amongst these can oftentimes be difficult and a system for sorting can be necessary.

With many solutions formulated it is time to start sorting. By combining and discussing solutions many can be immediately discarded. The ones that remain can further be eliminated using a method by Eppinger and Ulrich where an elimination matrix is set up with all solutions and criteria. The criteria are usually if the solution fulfills the main requirements and all the specifications, if it is realizable, within budget, safety and if enough information is available. And by evaluating all the solutions only the ones which pass all of these criteria pass on to further steps [1].

The result of the elimination of concepts can be only a few or many, but all of these could be a final solution which all fulfill the product specification and this next step is to determine which one will be the best. A popular way of ranking solutions is a Pugh matrix. Based on the product specification some abilities or criteria are chosen as base for ranking, they can also be weighted to emphasize if some are more important. One concept is then set as a reference and all other are compared to this one resulting in a score and rank

It is important to have in mind that these results are not perfect and these methods are only aids, the result needs to be evaluated and sometimes repeated. A product that consists of many components can sometimes need many concept generating and selecting sessions for different parts of the construction, this can result in many concept evaluation sessions even during the layout construction phase[1].

2.3 Layout construction and verification

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During this project and due to the limitations mentioned in section 1.3 this phase will only be to somewhat verify the concept, solving the bigger problems and packaging the whole product not going all the way to drawings ready for manufacturing.

After a concept is chosen there may be further problems within the concept which can be solved in numerous ways, this can be tackled in the exact same way as the original concept was generated and chosen. This can result in many concept selections depending on the complexity of the system [1].

Calculations in the form of performance and structural strength will also be performed in this phase as well as selecting a suitable material.

3 Results

3.1 Product specification

3.1.1 Prestudy

The prestudy contains all the information obtained from research and interviews with companies and people involved used as a basis to form the product specification. The product specification contains both information about the technical bits of the product as well as abilities affecting the marketing side of the LLY as a product.

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Figure 2: Prototype 0

3.1.1.2 Interview conclusions The full interviews from each company can be found in appendix A as well as the competitor products. Following is a conclusion from all interviews and research about the different aspects of a new smaller LLY. The companies and people interviewed ranged from small workshops to larger boat yards, managers as well as crane operators.

How is the problem solved today?

Depending on the line of business and the specific lift, uneven loads are handled in different ways. Often times it is overcome by experienced workers but can still be time consuming and sometimes pose a risk to safety. This can also be a problem when hiring new personnel and having to invest time to teach them the techniques. If precision is required the use of chain pulleys and winches can be used in different combinations, this works well but can take some time to set up and can’t be operated from a distance. A remote controlled leveling yoke could help speed up and bring down risk to some of these applications.

Maximum lifting capacity?

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both. The compromise here will be against unit weight and cost. About 3 tonnes would seen to satisfy most demands, this also fits the common 3,2 ton traverse often seen in smaller workshops.

Maximum uneven load

The general answer here was as much as possible, but this will also be a compromise between cost and weight. The L20 can only drive an uneven load of up to 3 tonnes, 15 percent of the total load and this works for the construction applications where it is used. The application of a smaller L20 will be somewhat different and the uneven loads may be higher. About one fourth the total lifting capacity is probably be sufficient

Unit weight

The design of this smaller version of the L20 unit will have to take the unit weight into account in a different way since it is intended to be handled manually to some extent. The Swedish work environment agency states that lifts of 25 kg can be performed if the lift is controlled and close to the body and does not occur frequently. Lift above 25 kg should be avoided [3].

Since existing manual chain pulleys capable of lifting 3 tons weigh about 20 kg it will be difficult to construct a similar unit with the additional features of being remotely electrically driven. If a realistic goal of 35 kg is set the way it is manually transported may be limited to only smaller distances and height differences.

3.1.1.3 Manufacturing methods and material The biggest factor regarding the manufacturing methods and material will be the production volume. Wenmec AB is the company which currently builds the L20 and will probably also be part of producing the smaller version as well. A lot of components in the L20 are standardized which helps bring the cost down for the smaller volumes. The estimated volumes for the smaller L20 are more but not enough to set up production for custom parts. Trying to keep the main structure simple enough to laser cut from s355 steel sheets is a good way to keep costs down in both smaller and larger volumes. The casing could be made from plastic to make it easy to replace and light weight, it would require a bit larger volume to be feasible but probably not impossible. Further analysis regarding material and manufacturing will be made after the concept phase.

3.1.1.4 Price Most companies in construction and manufacturing know how expensive lifting equip-ment can be and are often willing to pay. Recommended selling price from precious prestudy was 100 to a maximum of 175 thousand Sek. The Humlan and other competitor products can be found in the competitor products appendix D

3.1.1.5 Patent A patent search was conducted by searching in databases from Sweden and Europe. Search words that was used were; nivellerande ok, nivellering, vinkla, rotera, h¨angande last, lyft, leveling, lifting and yoke. The result was two expired patents which included some type of leveling functionality [4] [5].

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their work. To avoid being copied by a larger company the product needs to be sold at a competitive cost from the start and good relations with customers be established.

Table 1: SWOT analysis

Strength The product is unique

Weaknesses Expensive

The product is not yet recognized by the industry

Opportunities Create a new way of working with uneven loads, a “disruptive innovation Threats Some may not realize they need a leveling lifting yoke.

The concept is copied by bigger companies and sold cheaper.

Table 2: Conflicts of objectives

Low weight High dynamic uneven load

Low weight High static uneven load

Low weight High total lifting capacity Simple to operate Many additional functions Low price/cost Durability and safety

3.1.1.7 Conflicts of objectives To help emphasize the different construction challenges ahead table 2 states the main conflicts. Weight being the main obstacle working against almost every desired func-tionality requested from potential costumers, in order for the unit to lift and handle high loads the unit needs to be bulkier as well. Adding additional features such as different operation modes, sync options between more units etc. will increase the complexity and the time it takes for a new operator to learn the system. The price is a bit more complex though, in order to increase the durability of the unit the initial cost of the unit will probably increase but if this increases the life of the product it may be cheaper in the long run. further information about the relationships between abilities are illustrated in the QFD found in appendix B.

3.1.2 Competitor products

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3.1.3 Specification and QFD

One of the main goals of the prestudy was to put together a product specification from the LLY. Table 4 shows the whole specification as well as the different relations to the Olsson matrix in table 3 and stating if it is a limitation of a function.

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QFD: Quality function deployment Function Economi Product _Attributes "L " L N G 30 "K " C la ss ic l ev el ing sc rew "M " N ew L L Y Specifications 1 2 3 4 5 1 6 K L M 2 6 K L M 3 6 M K _L 4 6 x KL M 5 6 KL M 6 6 x M K L 7 6 x M K L 9 6 K M _L 10 6 K L M 12 6 xK_L M 13 6 K_L M Competitors 1 1-5, 5 being he best 2 "L" LNG30 3 "K" Classic leveling screw 4

"M" New LLY 5 K K

Freewheel, or high speed gear

(USP) 6 3 9 3 M K K M L M C omp eti tor s KL K L L 9 9 6 3 3 3 180 180 180 72 -+ + -x M 3 3 9 6 + -x 50m 1 per son < 0. 5m _Ja Previous problem x Ja Target value _>1/4 ma xl as t >3 ton ma xl as t Ja <5 0 kg >1 0mi n ja 2 3 3 2 2 4 3 3 2 >1 50 tk r <1 00 tk r 342 162 162 288 342 360 Technicality score 198 270 360 90 252 L K M K L Difficulty 3 2 4 1 3 1 L M M M L M L L M L K M K L M L K M M KLM K K L K Battery rechargeable ₉ ₉ ₆ 3 6 3

Endure sun, wind and water 3

6 6 6 Endure temperatures of -20 to 70 c 3 6 9 3 6 3 3 6 9 9 6 6 6 6 6 6 9

Maximum selling price of 100-175

thousand Sek 3 3 9 3 3 3 3 Max unit weight so that one

person can move it around 6 9 3 3 9 6

3 3 9 3 6 6 9 9

Operated wireless via hand

controller (USP) 6 6 6

9 3 9

Statically hold max load in one

chain end 6 9 6 3

6 6 6 9 9 9 6

Handle an uneven load of at least

a quarter of max load 9 9 9 9 3 Handle a mass of 2-5 tons ₉ ₉ ₉ ₉

6 6

3 9 9 3 9 6 6 9

Previous proble

ms

Fulfill EU’s Laws and

regulations, CE-marking 9 9 Materia l Remotely control led Be handled b y a singl e

person _{Unit size}

Give a robust impres

sion

Battery capa

city

Endure outside enviroment Free wheel Selling pr

ice Manufact uring cos t 6 6 Row # Weight Ability t o level ability to l ift ability to br ake

Rechargeble Unit weight

Target ◇ ◇ ◇ ◇ ▼ ◇ ◇ ◇ ▲ ▼ ◇ ▲ ▼ ▲

Category Usage Other

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3.1.4 Product specification Table 3: Olsson Development 1.1 1.2 1.3 1.4 Production 2.1 2.2 2.3 2.4 Distribution 3.1 3.2 3.3 3.4 Use 4.1 4.2 4.3 4.4 Elimination 5.1 5.2 5.3 5.4

Table 4: Product specification

nr. Cell Criteria Function / limitation

1 1.1 Fulfill EU’s Laws and regulations, CE-marking Limitation

2 4.1 Handle a mass of 2-5 tons Function

3 4.1 Handle an uneven load of at least a quarter of max load Function

4 4.1 Statically hold max load in one chain end Function

5 4.1 Operated wireless via hand controller Function

6 4.3 Max unit weight so that one person can move it around Limitation

7 3.4 Maximum selling price of 100-175 thousand Sek Limitation

8 4.2 Endure sun, wind and water Limitation

9 4.2 Endure temperatures of -20 to 70 c Limitation

10 4.1 Freewheel, or high speed gear Function

11 4.1 Battery rechargeable Function

3.1.4.1 Explanation of product specification

1. Fulfill EU’s Laws and regulations, CE-marking. The product has to fulfil the laws and regulations which concern it.

2. Handle a mass of 2-5 tons. The total weight which the Lifting yoke needs to be able to handle has to be between 2 to 5 tonnes. The maximum load of the yoke will be referred to as maxload. 3. Handle an uneven load of at least a quarter of max load The minimum load difference between the

couplers that the leveling system can drive needs to be at least a quarter of the maxload of the yoke. This uneven load will be referred to as leveling capability.

4. Statically hold max load in one chain end. When the load difference between the couplers exceeds that which the leveling system can drive, either when driving the leveling mechanism to the limit or in the event of sudden loadshift the chain sprocket has to remains stationary until the uneven load returns to the leveling capability.

5. Operated wireless via hand controller. The leveling function should be wirelessly managed by a hand control. Details about this system will not be part of this project. Only the space for receiver box will be looked into.

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7. Maximum selling price of 100-175 thousand Sek. In order to compete and be able to sell the product it cannot cost more than 100 000 sek but if not possible the absolute limit is not more than 175 000 sek.

8. Endure sun, wind and water. The unit needs to be able to endure outside weather of the Europe climate.

9. Endure temperatures of -20 to 70c. The unit needs to be able to endure Mean temperatures of -20 to 70 degrees Celsius

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3.2 Concepts

The concept generation took place during a few sessions. At first by my self using a more systematic approach and looking at similar products solving similar problems. For example on fishing boats they have large winches which can be driven and held under enormous loads, the drive of these are hydraulic so this would be hard to apply but the brake system is operated by a lamella type brake which could be a solution to a brake on the LLY. After looking at similar solutions a group of 4 people met and did a brain storm session on complete solutions as well as sub solutions such as braking, driving and measuring torque. The concept process actually continued after this in the form of casually discussing solutions with other people from different backgrounds adding some new ideas and variations on existing ones. All concept sketches can be found in appendix C.

The following concepts are the resulting ones after initial eliminations.

L20 working principle In order to help understand some of the new concepts here is a quick explanation of the working principle of L20 since some of the new ones are based on the L20. The L20 drive mechanism consists of a motor unit that has a brake and a planetary gearbox build in. This drive unit drives the chain wheel via one par of spur gears as illustrated in figure 4.

Mot or B rak e G earbo x Cha in whee l

Final gear pair

Main axle

Figure 4: Working principle of existing L20

Concept 1.0 Small L20 with additional features: The base system consists of a drive unit with integrated gearbox and brake driving the chain wheel via two spur gears like the L20. Depending on the brake system this concept provides a free wheel ability. If the brake system needs information about when to engage/disengage a torque sensing system could be needed.

Brake systems alternatives:

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• Lamella friction plates brake

• Centripetal locking bars as in car seat belt • Axial engaging plate with driving dogs Additional torque Sensing alternatives:

• Measure twist in main axle

• Helical spur gears or helical splines and measure induced axial forces • Monitor motor current and voltage.

Following are some combinations of the different brake systems and torque sensing solutions, they are named 1.X as different combinations of concept 1.0.

Concept 1.1 small L20, Sylv´en stop with helical splines Using the same principle and layout as L20 adding the flipping stop under the chain wheel as from S´ylvens report about L20 brake system [6]. To obtain information about the torque applied and thus knowing when to apply the brake the splines connecting the smaller gear driving the main axle are helical and thus inducing an axial force when torque is applied. This will sense torque weather the system is in motion or stationary and can therefore always apply the brake if necessary.

Concept 1.2 small L20, axial dog brake with helical splines Using the same principle and layout as L20 adding but with a plate which is hindered from rotation but can slide in the axial direction. The plate is equipped with drive dogs that engage in the main gear and stops it from rotating. To obtain information about the torque applied and thus knowing when to apply the brake the splines connecting the smaller gear driving the main axle are helical and thus inducing an axial force when torque is applied. This will sense torque weather the system is in motion or stationary and can therefore always apply the brake if necessary.

Concept 1.3 Lamella brake plates with torque sensors along basket rim Using the same principle and layout as L20 but adding a brake system composed of friction lamella plates in a basket equipped with force sensors to measure the applied brake torque. The brake is activated in the unaffected state and releases when power is applied. Actuated via a solenoid pushing a lever for fast disengagement. Concept 1.4 Same as L20 but relatively stronger gearbox and brake The current L20 has the weakness of only being capable of braking the same load as it can level. If however the brake and gearbox were strong enough to hold the maximum lift capacity as an uneven load it would work here as well.

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freely an extra high speed gear is added to the drive system adding the ability to manipulate the chains before a load is attached at a much faster rate than the normal high torque leveling operating mode.

Concept 2.2 Worm gear drive, main axle weight engaged By letting the main axle and chain sprocket move up and down by the load itself and in the loaded position be engaged with the driving screw an automatic free wheel function is obtained. When the chains are not loaded the main wheel can spin freely with the force applied by a person being enough to change the chain lengths. Concept 2.3 Worm gear drive, lift axle weight engaged The top lifting point mechanically disconnects the worm drive when the yoke is not carrying any load. Ether by a tilting or a sliding, spring loaded mechanism which when the hanging load is less than a decided value it disengages the worm screw from the driving gear letting the chain sprocket spin freely. The

Concept 2.4 Worm gear drive, manual disengagement A manually actuated lever which disengages the drive screw.

3.2.1 Ulrich and eppinger elimination

Eliminating concepts which do not fulfill the basic requirements using Ulrich and Eppinger elimination matrix shown in figure 5. Only the concepts which pass all criteria will pass this stage and be further evaluated and/or developed.After elimination the concepts to move forward with are 1.1, 1.2, 2.1. The next step will be to rank them.

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3.2.2 PUGH

Figure 6: PUGH

Figure 6 shows the PUGH diagram used to rank the solutions that passed the elimination stages. Concept 1.2 was selected as a reference since the concept is simple and therefore well understood and easy to compare with. Comparing the other concepts against 1.2 by the stated criteria and their associated weights the 2.1 concept scored the highest and was chosen to move forward with.

3.2.3 Preliminary calculations for concept 2.1

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3.3 Layout construction

3.3.1 Concepts motor drive

The worm gear concept is decided to be moved forward with but the next question will be how the worm screw will be driven. These concepts were too difficult to illustrate by sketch or words so they were done with Cad. The different drive concepts can be seen in figure 8.

1.0

1.2

2.1

3.1 _4.1

4.2

Figure 8: Drive concepts

3.3.1.1 Drive concept 1.1 Bevel gear on worm and motor parallel with main axle A bevel gear set mounted directly on the worm resulting in the motor being able to be mounted parallel with the main axle. High efficiency of bevel gears but they need to be relatively large to handle the torque.

3.3.1.2 Drive concept 1.2 Bevel gear on worm and motor perpendicular to main axle A bevel gear set mounted directly on the worm resulting in the motor being able to be mounted perpen-dicular with the main axle. The bevel gear major diameter needs to be about 90mm which makes this concept a somewhat large installation.

3.3.1.3 Drive concept 2.1 Direct drive Motor unit directly connected on the same axis as worm. This is the most direct approach but the main disadvantage being the packaging, it may be hard to package in a neat and efficient way.

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requires for leveling 2.6 tonnes. Alternatively move the motor closer and replace chain with spur gears. This is probably the best solution when it comes to packaging but it adds more components which adds on the weight, cost and reliability.

3.3.1.5 Drive concept 4.1 Double worm drive driven directly with electric motor, main axle parallel Adding an additional worm gear set on the main worm the angle of the input is again shifted 90 degrees enabling the motor to be mounted parallel or perpendicular to the main axle. The added gear reduction eliminates the need for a gearbox unit on the motor. The second worm gear set can be lubricated by the same oil as the main set. Size approximately as shown in picture.

3.3.2 Drive concepts PUGH

A PUGH matrix was used again to rank the drive concepts shown in figure 9. In this case the 2.1 solution with the direct drive was chosen as a reference since it is very simple and easy to compare with. Here it was the reference which scored the highest, all the other ones scored negative compared to the direct drive. Two concepts where chosen to move forward with here, 2.1 and 3.1 to further develop and examine them.

Figure 9: PUGH matrix drive concepts

3.3.3 Reevaluating a custom worm gear

Further research about worm drives concluded that lubrication is of high importance, in previous stages the assumption about lubrication was that grease and maintenance would solve this but that will not be the case. After contacting a supplier of worm gears about a quotation and technical specification it became clear that the worm drive will need constant lubrication in order to function properly. Since a sealed system with liquid lubrication makes this 2.1 concept more complex and expensive this new information lead to a re-evaluation of the concept. It should be noted that a custom integrated worn gear has the potential of making the packaging of the whole unit better and thus the overall aesthetics as well as making it harder to copy.

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The result of this meeting was to look into implying a complete standard worm gearbox unit like the one in figure 10 instead of constructing a custom drive system to get around the problems and costs that will probably occur when constructing a custom gearbox.

Figure 10: Standard worm gear unit [7]

3.3.4 Standard Gearbox

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Wormgear drive

Custom gearbox 4.2 tonnes

Standard gearbox 2.5 tonnes

Figure 11: layout construction work flow

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Figure 12: Standard worm gear concept

3.4 Material selection and structural verification

The concept is at this point not very complete but it is still possible to verify the main load bearing components shown in figure 13 which will most likely not change during further construction.

3.4.1 Material selection

Price, safety and regulations are the main deciding factors here. However since the regulations needs to be full filled and they specify certain materials to use the easiest way to go is to just pick the materials specified in the standard. The Materials specified are the following steels; S235, S275 and S355 [8]. All of these steels are low alloy general purpose construction steels. The low alloy content results in a very high weldability and ductility, which are desired in a lifting unit since failures should be slow and predictable [9]. The highest strength S355 grade was selected to minimize weight and thereby minimizing environmental impact and maximize lifting capacity. Hence, the S355 grade properties are introduced in the design calculations below.

3.4.2 Structural verification

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experience stresses of up to 355MPa in tensile and compression and 205MPa in shear [8].Figure 13 was put together using Cad and shows the different components refereed to in this section.

Main axle Side plates Top axle Chain wheel Bearing seat Sliding bearings

Figure 13: Component explanation

Table 5: Acronyms

Description Acronym Unit

Length between plates L mm

Maximum allowed stress σs MPa

Safety factor n

Force applied F N

Moment applied M Nmm

Bending resistance Wb mm3

Twistning recistance Wt mm3

Shear stresses τ MPa

3.4.2.1 Top axle Starting with the top axle and finding the thickness required. The loading is seen as a 3 point bend shown in figure 14. Using s355 steel with a safety factor of 2 [8].

L = 63mm σs= 355M pa n = 2 F = 25000N

M = F L

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σ = M Wb (2) Wb= πd3 1 32 (3)

L

F

d

1

Figure 14: bending of top axle

Combining eq. 1 , 2 and 3 from [10] the resulting minimum diameter d1 is then 28mm

3.4.2.2 Top axle hole The hole or seat for the top axle is also of importance, finding the smallest plate thickness t allowed.

σ n =

F d1∗ t

(4) Using the previous top axle diameter the resulting minimum plate thickness is 2.5mm fron eq.5 Too reduce the chance of warping during welding of the main bearing houses this is too thin however, a plate of 5mm will be used instead.

3.4.2.3 Lifitng ear After knowing the top axle diameter and the plate thickness it is possible to calculate the upper outer diameter D1shown in figure 15. The resulting minimum outer diameter of the top ear using precious d1=28mm and a thickness t=5mm is 57mm. Before calculating the bottom part of the plate the main axle and bearing houses need to be properly dimensioned.

σ n =

F (D1− d1)2t

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D

d

₁ 1

t

Figure 15: upper plate ear

3.4.2.4 Main axle analytical Since the chain wheel is a standard product the middle size of the main axle cannot be changed, it will be of diameter 50mm and a length of 60mm with a key way along the axle. Since the middle part between the bearings is almost as thick as it is long i will skip the bending analysis and only look at the shear stresses at the edge of the bearings instead, eq 8. However the hanging load will not be the only thing causing stresses in the main axle, there is twisting from the driving mechanism which also results in shear stresses along the perimeter of the axle, eq 6. Since These to shear stresses act in the same plane and in the same position they can simply be summarized and compared to the allowed maximum shear stress. An approximate of the axle diameter will be derived by combining eq 6 and eq 8 and then verified further in FEA. The resulting minimum diameter from these equations is d2=42mm τ n = Mv Wv (6) Wt= π ∗ d3₂ 16 (7) τ n = F d2 2 2 ∗ π (8)

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force are so small compared to the those from the twisting and are in this picture hidden by the color scale. It is worth mentioning here that the radius at the diameter change creates a singularity at the radius where the meshes go from coarse to fine and the stresses there are not valid. However the stresses at the perimeter of the right side of the bar agree with the analytical results pretty well. More details on how this analysis was performed can be found in the appendix. The overall results from the numerical do not agree with the analytical at the diameter transition, further analysis could be performed during the development of this concept. One solution could be to have a diameter of 50mm all the way and eliminate diameter changes which induce local stresses, and also add a hole though the length of the axle to save weight since very little stress is seen here.

Figure 16: Combined loading of main axle in FEA

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Figure 17: BMF-LMB sliding bearing [11]

When it comes to the bearing dimension the deciding factor is the contact pressure. The maximum allowed contact pressure is 140N/MM static and 60N/mm dynamic [lagermetall]. Using eq 9 with an axle diameter of 42mm the minimum bearing length l is 10mm. To increase service life even further the 15mm wide could be used here.

σ n =

F 2 ∗ d2∗ l

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4 Discussion

The prestudy performed can be even further improved but may not be worth the effort, during the three weeks of finding information and talking to people the results was still a bit spread out and there was not a definitive answer to the main questions. The reasons for this could be that it may be impossible to get definitive answers concerning new product releases as no one can have the right answers and is therefore at this stage not worth the effort to spend even more time hoping it will yield a better result. Instead focus on a first prototype and have it tested by potential customers could be much more efficient since this feedback will be more valuable and it is perhaps only then more definitive answers will emerge and this is why a prototype should be of high priority during further development of this product. The Prototype 0 worked well by capturing the interest and immediately explaining the functionality of the product and is something i think should be used in all product development processes when possible.

In this development process the QFD helped to point out the challenges and really show where the competitor product stood in comparison with the expected new product. The realization that the biggest unique selling points where the wireless controller and the freewheel ability, this would have not been as clear at this stage without the QFD.

The newer view on product development as more of a science has developed many good aids for the creative process, but it is still important to keep this in mind and treat them as this, aids. In the end all of the ideas and criteria are made up by the people involved. This becomes even more evident during the selection and ranking phase, the criteria and ranking will always be heavily affected by the people. The ranking process performed in this work could be optimized by including more people and discussing the weights and criteria, a group which are at the stage where they feel comfortable amongst each other so that group thinking does not affect the results as well as all being well informed about the project at hand.

Regarding the creative and systematic strategies of coming up with solutions they are very similar in practice. Being creative with experience is just an effective systematic way of finding a solution using previous similar solutions from your own head instead of research. The ”pure” creative part of construction that is not inspired by anything based on previous experience is tricky to systematize and could actually be a personal attribute in some sens.

The different ways of coming up with concept ideas, individual or more in collaboration with others can play a big part depending on the task. For this project which was more about finding a direct technical solution it worked well by initially researching and individually generate concepts until no more seemed possible and after this meet in a group and together boost each others creativity and concepts. This reduces the risk of missing something obvious that could emerge after just a group brainstorming session where known simple technologies may be looked passed while trying to be innovative. Using the group to try and build upon ideas and doing research individually beforehand could be a more efficient way than to start with a group as a first step and risk setting everyone on the same path of solutions.

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solution the concepts could have been kept longer in the selection process and developed in parallel and not discarded until it was clear that it was not the right way. Working with more concepts in parallel would have taken more time but since the concept stage is still an early stage time and changes do not cost anything in comparison to a concept change later in the process, it would still be part of the front loading.

Choosing concepts in the beginning proved to be a challenge since very little info about them exist as became evident when the new information about worm drives lubrication and tolerances emerged and the decision to instead look into buying a complete gearbox unit was taken and some of the previous work was ”discarded”. It can feel like a bit like a wasted work but this can be a danger to many development processes, to continue on a path because work has already been put down along with personal preferences for different solutions.

The custom worm gear solution is however not deemed impossible, it is clear that it adds complexity and initial expenses and risks. But a working custom system would improve packaging and aesthetics as well as making the product harder to copy and therefor be more resilient against future competitor products as is an actual threat previously discussed in the SWOT analysis.

The performance calculations for the first concept 2.1 found in appendix 22 were the foundation for further work concerning worm gear solutions. These calculations were very promising as they basically resulted in the drive would be almost as strong as the maximum load of 4.2 tonnes. These results however changed during further development of the concept, the two main changes leading to worse performance than the initial 2.1 calculations where the change of motor and switching to a standard gearbox. The choice to involve OEM motors was based on the previous collaboration with them in the L20. Since OEM have a good reputation and can deliver a whole drive train including a worm gear and motor it was natural for them to be one of the first companies to contact regarding these components. The worm gear and motor however differed quite significant from previous calculations because they turned out to be bigger and weaker. The motor performance used in the initial calculations are based on a battery powered drill because the idea was that it would be a good comparison but as shown from supplier suggestion this is probably not the case for the more industrial grade motors and it may even be worth looking into implementing a similar system as from the drill when further developing this concept. The standard worm gear found from industrial supplier and proposed here did not match the previous calculations, being bigger and not holding nearly as much torque as the custom system which used a worm gear from another manufacturer. This part needs further investigation of available standard components to reach an optimum solution.

The selection of material for the main load bearing structure was rather straight forward since the regulations where pretty clear and reasonable. However there are still many components left which are not determined such as the cover panels, these could be manufactured from many different materials such as polymers, composite or metal depending on the volume and manufacturing methods. So there is still work to be done regarding the different components materials and the reason that this is not included in this work is simply because the concept did not reach this phase.

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the sense of simply verifying the general idea of the structure. No calculations regarding welds were performed since they would not carry any of the major loads.

5 Conclusion

The aim of this project has been to develop a concept for a smaller LLY with working principle similar to the existing L20 unit.

The prestudy concluded that there is indeed a need for such a unit. The product specification resulted in mainly a wireless LLY system capable of lifting 2-5 tonnes, and be able to hold this load in one end of the chain and the unit itself should be light enough for a single person to lift.

The most critical part of this development was to integrate a braking function capable of handling the maximum uneven load without adding a too much weight and power consumption to the unit. The resulting best concept was to use a Worm drive principle for driving the chain wheel. The worm drive possesses the somewhat unique property of being self locking as well as adding lots of gear reduction.

A standard worm drive gearbox is probably more suited for this product due to the relatively small volumes expected the development and manufacturing costs of a custom gearbox unit. This concept will need further work until it will be ready for testing. An integrated custom worm gear concept was also investigated but comes with added complexity such as lubrication and tight manufacturing tolerances, it could however improve design and make the product harder to copy.

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References

[1] _{Dennis Pettersson Hans Johannesson Jan-Gunnar Persson. Produktutveckling. Liber AB, 2013. isbn:} 978-91-47-10582-3.

[2] CORINNE FAURE. “Beyond Brainstorming: Effects of Different Group Procedures on Selection of Ideas and Satisfaction with the Process”. In: The Journal of Creative Behavior 38.1 (2004), pp. 13– 34. doi: 10.1002/j.2162-6057.2004.tb01229.x. eprint: https://onlinelibrary.wiley.com/ doi/pdf/10.1002/j.2162- 6057.2004.tb01229.x. url: https://onlinelibrary.wiley.com/ doi/abs/10.1002/j.2162-6057.2004.tb01229.x.

[3] Arbetsmilj¨_{overket. Manuell hantering. 2020. url: https://www.av.se/halsa- och- sakerhet/} arbetsstallning-och-belastning---ergonomi/manuell-hantering/ (visited on 04/17/2020). [4] U Heikkinen. “Lyftokanordning vid en kran”. SE395261 B. 1973.

[5] B H. Holmqvist S ˚A. Johansson. “L˚angsträckt horisontellt manövrerat lyftok”. SE439766. 1981. [6] Anton Sýlven. “Bromsfunktion till nivellerande lyftok”. MA thesis. Karlstad University, 2019. [7] OEM motors. OEM motors snäckv¨_{axel. 2020. url: https://www.oemmotor.se/produkter/v%C3%}

A4xlar/snackvaxel (visited on 07/05/2020).

[8] _{Swedish standards institute. Svensk standard SS-EN 13155+A2:2009. 1. 2013. isbn: 14.250; 53.020.30.} [9] Donald R. Wright Wendelin J Askeland. the science and engineering of materials. 2. Cengage

learning, 2015. isbn: 9781305077102.

[10] Karl Björk. Formler och tabeller för mekanisk konstruktion. 7. Karl björks f¨_{orlag HB, 2016. isbn:} ...

[11] _{Lagermetall AB. BMF-LMB. 2020. url: https : / / www . lagermetall . se / produkt / bmf - lmb/} (visited on 06/21/2020).

[12] _{vettercranes. Manuell hantering. 2020. url: https://vettercranes.com/en/industry-solutions/} foundry-industry/ (visited on 04/21/2020).

[13] _{Grainger. Chain Sling, 2000 lb. Lifting Capacity. 2020. url: https : / / www . grainger . com /} product/HEIN-WERNER-Chain-Sling-12G736 (visited on 04/21/2020).

[14] LNG30. Lastutj¨_{amningsblock 3000 kg LNG30 L=2 mR. 2020. url:} http://shop.carlstahl.se/E-handel/Utjamningsblock/Lastutjamningsblock_3000_kg_LNG30_L_2_m?id=25105500035003 (visited on 04/21/2020).

[15] _{timars. TIMARS GRAVITY CENTRALIZER. 2020. url: http : / / buffersusa . com / files /} CENTRALIZER_TIMARS.pdf (visited on 04/21/2020).

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A.0.0.1 previous study conclusion Area of work: assembling and transportation within workshops and construction sites, steel constructions. Some assemblies may see benefits using a smaller more agile leveling yoke. They propose a product which is capable of handling 1-5 tonnes, preferably one smaller model capable of only a single ton accompanied by a larger one capable of handling around 5 tonnes. The reason for wanting more variants is to make it a lot easier to handle the lifting unit when not assembling larger pieces, and also the price can be lower. For a unit capable of lifting 5 tonnes they are willing to pay about 175-200 thousand sek and for a 1 ton unit about 100-150 thousand sek. The current process when lifting can be slow and dangerous and they agree on that this can be improved by a remote controlled leveling yoke system.

A.0.0.2 Havator (previous study conclusion Havator mostly lifts heavy balconies, not really in the need of a smaller L20 but more in the line of a bigger model. 7.1.3 Deromes facility in annedal (previous study conclusion): Area of work: Constructing house modules. The modules constantly need to be moved and tilted for the different operations. This is currently performed by skilled and experienced workers which are good at estimating center of mass and how to lift. Problems still occur though, it can still take time and be somewhat dangerous but the biggest issue is the learning period for a new employe. A small L20 unit could be a solution here and also help bring down assembly costs. The weights handled are about 500-1500 kg and the maximum lifting capacity of the facility crane is 2.5 tonnes. The modules are about 11m long.

A.0.0.3 Wenmec Wenmec is the company that today manufactures the L20 unit as well as doing many other manufacturing and assembly work. For a smaller version of the L20 they think that it at least has to be able to handle at least 5 tonnes and as much uneven load as possible because loads lighter that this can be managed using current methods. Unit weight is irrelevant because it will be hanging from a crane. Maximum price about 150 thousand Sek. manufacturing methods need to be easy and cheap, laser cut sheet metal as much as possible. 7.1.5 Viebekke (previous study conclusion): Viebekke does assembling of house modules and plan to start building houses in sweden in the year 2020. There can be a need for a leveling yoke capable of about 1500 kg. The precision is not as critical for the wooden structures as fro the concrete ones. the gains they see with a smaller L20 are shorter assembling times and safer workplace.

A.0.0.4 L20 users (previous study conclusion In workshops it is too big and heavy, it is very useful on larger construction sites but a need for a smaller unit does not seem to exist.

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yoke is present, however the situations where one can be used are somewhat limited. Most of the time the weights being handled range from 0-5 tonnes. When installing units inside of a ship the space is often time extremely limited in both height (0,2-1m) and the access to lifting points in the sealing. but since all installations are somewhat unique the access to an extra tool can be useful and when mounting units outside the ship such as winches, propeller blades a leveling unit could be useful. I see the possibility of them needing one or two units capable of about 3 tonnes. The unit also needs to be small and light enough to be handled by one person.

A.0.0.6 R¨osbo haulage This company focuses on special and unique lifts and the need for an extra tool to extend their services could be useful. A leveling unit capable of a few tonnes could be of interests since uneven loads do occur. Today this is solved by experienced crane operators and adjusting the lifting cables. If the crane is equipped with a winch system this can be used to balance the load but not all cranes have this.

A.0.0.7 Bergs mekaniska Bergs mekaniska do mostly sheet metal production, cutting and bending sheets up to 6m. Tough the pieces weighs several hundreds of kilograms the problem of uneven weight distribution has not been experienced as a problem. however they thought that some of their customers which assemble their pieces may be interested in such a lifting yoke.

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B

QFD

QFD: Quality function deployment

Function Economi P rod u ct A tt ribu tes " L " L NG 30 "K " C las sic lev elin g sc rew "M " New L L Y Specifications 1 2 3 4 5 1 6 K L M 2 6 K L M 3 6 M K _L 4 6 x KL M 5 6 LK M 6 6 x M K_L 7 6 x M K L 9 6 KM L 10 6 K L M 12 6 xK_L M 13 6 KL M Competitors 1 1-5, 5 being he best 2 "L" LNG30 3 "K" Classic leveling screw 4 "M" New LLY 5 + Correlation Positive + Negative _{_} No correlation Relations + -average ₆ + Strong 9 -Target + - + -Strong 3 - + + Maximize ▲ + - + value ◇ + + -Minimize ▼ - - + + + + + - - - -- - - -- + + - - + + - + + - - - +

Category Usage Other

12 13 14 15 16 17 6 7 9 10 11 column # 1 2 3 4 5 ◇ ▲ ▼ ▲ ◇ ◇ ◇ ▲ ▼ R ow # W eig h t A bilit y to lev el ab ilit y to lif t ab ilit y to br ak e R ec h ar geb le Un it w eig h t Target _◇ _◇ _◇ _{◇ ▼} P rev iou s pr ob lem s

Fulfill EU’s Laws and regulations, CE-marking ₉ ₉

M at er ial R em ot ely c on tr olled B e h an dled b y a sin gle per son Un it s iz e G iv e a rob u st im pr es sion B at ter y ca pa cit y E n du re ou ts id e en vir om en t F ree w h eel Sell in g pr ic e M an u fa ct u rin g cos t 6 6 6 6 3 9 9 3 9 6 6 9

Handle an uneven load of at least a quarter of

max load 9 9 9 9 3

Handle a mass of 2-5 tons ₉ ₉ ₉ ₉

6 6 6 9 9 9 6

Operated wireless via hand controller (USP) ₆ ₆ ₆

9 3 9

Statically hold max load in one chain end ₆ ₉ ₆ ₃

9 3 6 6 9 9

6 6 6 6 9

Maximum selling price of 100-175 thousand Sek ₃ ₃ ₉ ₃ ₃ ₃ ₃ Max unit weight so that one person can move it

around 6 9 3 3 9 6

3 3 3 3 6 9 9 6

6

Endure sun, wind and water ₃

6 6 6 Endure temperatures of -20 to 70 c ₃ 6 9 3 6 3 Battery rechargeable ₉ ₉ ₆ ₆ ₃ K K L L M L K M K L M L K M M KLM L M M M L M K L K M K L Difficulty 3 2 4 1 3 1 342 162 162 288 342 360 Technicality score 198 270 360 90 252 L >1 0m in ja 2 3 3 2 2 4 3 3 2 Previous problem x Ja >1 50 tk r <1 00 tk r Target value >1 /4 m ax las t >3 t on m ax las t Ja <5 0 k g x 50m 1 per son < 0. 5m Ja -+ + -x M 3 3 9 6 + -C om pet it or s KL K L L 9 9 6 3 3 3 180 180 180 72 K K

Freewheel, or high speed gear (USP) ₆ ₃ ₉ ₃

M K K M

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D.0.0.1 Humlan Humlan is actually Ganteruds first product but is now sold by another company and is thus a competitor product. It operates using hydraulics and is capable of handling loads up to 18 tonnes. The downsides of this system is that it is heavy and lack of reversibility, it requires a minimum load to pull the hydraulic pistons back out.

D.0.0.2 Nord greif Nord greif is a company which does special lifting equipment for unique tasks, some of which seem to have some form of leveling capability.

D.0.0.3 Vetter Krantechnik Vetter Krantechnik manufacture a system which seems similar to the L20 and thus a smaller version of the L20, however it is much larger than the L20 and is capable of lifting up to 50 tonnes. remote controlled but not battery powered [12].

D.0.0.4 Grainger 2000lb chain sling Grainger 2000lb chain sling is a simple, light and cheap product sold only in the us. The drawbacks of this system compared to a small L20 is the need to reach the adjustment knob which makes is not as versatile. its costs around 11500 Sek and can lift up to 900 Kg [13].

D.0.0.5 Classic style engine leveling system The classic style lifting bar with adjustable lifting point often seen in engine mounting operations shown in figure 20. It’s sold by manny different companies and is very cheap, down to just a few hundred Sek. Lifting capacity often ranges between 500-700 kg. one drawback can be the lack of precision.

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D.0.0.6 Carlstahl LNG30 The LNG30 is a manual leveling lifting yoke capable of 3000kg. It is perhaps the most similar system to a small L20 unit, the only thing setting them apart would be the remote operation. This unit weighs 45 Kg and costs about 60 000 Sek [14].

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E

time plan

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F

Concept 2.1 calculations

Koncept 2.1, high speed worm gear. 4.3t

tot vikt (kg) tot kostnad (kr)

33,8 33300

component volume mm3 material density kg/m3 mass, grams est unit cost(kr) accuracy

motor and battery 1800 3800 good

plate, drive side 373379 steel 7800 2912 500 medium

plate, motor side 316143 steel 7800 2466 500 medium

worm drive and screw 563990 steel 7800 4399 3100 good(quotation)

screw axle 71278 steel 7800 556 500 medium

chain wheel, RUD tec43 654970 steel 7800 5109 5000 good(quotation)

main axle 374984 steel 7800 2925 1200 medium

2x conical bearing skf 33205 steel 7800 360 2000 medium

chain (108cm) 30 länkar 51930 steel 7800 3600 1500 medium

top bolt, lift bar 70685 steel 7800 551 200 medium

main solid bearing x2 82008 steel 7800 640 1500 medium

drive plate, between worm ring and main axle 188495 1500 bad

electronics, radio, cables.. 500 5000 bad

+ covers, screws etc. 8000 5000 bad

assembly - 2000 bad

DRIVE good

chain sprocket dia 152 mm medium

worm dia 200 mm bad

worm reduction 47

worm+bevel gear efficiency 0,612

MOTOR

motor torque LOW 70 Nm

motor torque HIGH est. 17,5

power

max speed 2000 rpm

low speed 500 rpm

low speed @ 70nm estimation 250 rpm

RESULTS

chain speed HIGH 338 mm/s

chain speed LOW 42mm/s

chain force LOW 26493 N

chain force HIGH 6623 N

estimation with uncertainties whole drill machine

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The numerical calculations where performed is Abaqus modelling the main axle as an axisymmet-ric part with minor diameter of 42mm, major diameter 50 and a 1mm radius in the transition, these dimensions are based on the analytical results.

At first only the twisting moment was applied with medium mesh size shown in figure 23. As seen the stresses where very high at the diameter transition so another analysis was run with a finer mesh to investigate weather it was a singularity point.

Figure 23: Combined loading of main axle in FEA

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Figure 24: Only twist with very fine mesh

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Developing a remote controlled leveling lifting yoke in the 2-5 ton range