Load Propelling Trolley Design Report

EMD112 CONCEPTUAL DESIGN AND CAD

LOAD PROPELING TROLLEYGroup B4

Group members:

Wong Pooi Mun 120430

Mark Selvan a/l Anthony Rogers Louis 120385

Faiz bin Mohamad 120367

Muhammad Azizi bin Yahaya 120397

Jerome Lee Jie Jen 120375

Lecturers:

Dr. Abdullah Aziz

Dr Muhammad Iftishah Ramdan

En. Azizul Abd Karim

Dr. Mohd Azmi Ismail

Date of submission:

20 MAY 2014

EMD 112 GROUP B4 2014

ABSTRACTUbiquitous wheelbarrows require force to be lifted up when wheeled around and

unloading. This simple action takes out energy of construction workers and tires them out. Another sub-problem for wheelbarrows is the limited volume of their carrying receptacle due to the inclined surface. Limited volume sets a higher number of travelling back and forth to move the same amount of load compared to a spacious receptacle.

To those problems, we propose our design “Load Propelling Trolley”.

Load Propelling Trolley mainly targets society of construction workers as replacement for wheelbarrow. This trolley eases load-removing process by using lesser physical strength. This design combines the concept of a wheelbarrow with a door installed in front for load to be removed. The floor of receptacle shall be inclined for unloading process and returns to horizontal after that. This horizontal floor allows larger volume in the trolley so that more loads can be contented, saving time and energy during transportation.

According to the functional decomposition diagram we have constructed, the main function of a wheelbarrow is to carry load for near-distance transportation. Revolving about the efficiency of this function, we have inserted certain sub functions for this improvement. One of them is to enable steering system so that this Load Propelling Trolley can move load in more directions and with smaller turning radius. Next, we have increased the load capacity of the carrying receptacle allowing more load to be carried in one time. Another sub-function that we have focused on is to reduce physical energy consumption in moving and unloading the trolley. Innovatively, we have eliminated the lifting action that is normally needed in moving and unloading a wheelbarrow. Load can be propelled off the vehicle instead of being poured out. And then, for the comfort of the users, we have improved the gripping of the handle. Slipping effect shall be prevented when it is used to push heavy load.

Several alternatives are available in designing this vehicle. Our team chooses a latching system to open and close the front door while the floor of the trolley will be inclined using pivot mechanism. With that, the load will be propelled out of the carrying receptacle induced by gravitation pull. In this project, we investigate the geometry of the system and the calculations needed for these mechanisms.

In conclusion, Load Propelling Trolley will benefit workers in construction field by negating the problem posed by high physical strength required in lifting. With this design, lesser physical energy can be used for higher workload and efficiency of the workers can be improved by the increased volume of the carrying receptacle.

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CONTENTSABSTRACT..............................................................................................................................................2

Contents................................................................................................................................................3

1.0 INTRODUCTION.........................................................................................................................5

2.1 DESIGN PROBLEM..................................................................................................................5

2.2 PROBLEM STATEMENT...........................................................................................................6

2.3 OBJECTIVE..............................................................................................................................6

2.0 METHODOLOGY.........................................................................................................................7

3.0 FORMULATING DESIGN PROBLEM.............................................................................................8

3.1 FUNCTIONAL DECOMPOSITION DIAGRAM............................................................................8

3.2 FUNCTIONAL REQUIREMENTS...............................................................................................9

3.3 ALTERNATIVES.....................................................................................................................10

3.3.1 PATENT SEARCH..........................................................................................................10

3.3.2 MORPHOLOGY CHART................................................................................................12

3.2.3 MORPHOLOGY MATRIX................................................................................................12

3.2.4 ALTERNATIVE DESIGN SKETCH.....................................................................................13

3.3 MATERIAL SELECTION..........................................................................................................14

3.3.1 SCREENING METHOD...................................................................................................14

3.3.2 RANKING/RATING METHOD........................................................................................14

3.3.3 COMPONENTS..............................................................................................................14

3.4 CONFIGURATION DESIGN....................................................................................................17

3.4.1 PRODUCT ARCHITECTURE............................................................................................17

3.4.2 PART CONFIGURATION................................................................................................18

3.4.3 ANALYSING AND REFINING CONFIGURATION ALTERNATIVES.....................................19

3.4.4 REFINING ALTERNATIVE CONFIGURATION...................................................................21

3.4.5 EVALUATING ALTERNATIVES........................................................................................21

3.5 PARAMETRIC DESIGN..........................................................................................................21

3.5.1 DESIGN VARIABLE VALUES...........................................................................................21

3.5.2 MANUFACTURING PROCESSES.....................................................................................22

3.5.3 PERFORMANCE PREDICTION........................................................................................22

3.5.4 DIMENSIONS................................................................................................................23

4.0 SELECTED DESIGN....................................................................................................................23

4.1 OVERVIEW...........................................................................................................................23

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4.2 DETAIL DESIGN.....................................................................................................................23

4.3 PRODUCT SPECIFICATIONS..................................................................................................24

4.4 DETAIL DESIGN CONSIDERATIONS......................................................................................24

5.0 CONCLUSION...........................................................................................................................25

6.0 REFERENCE..............................................................................................................................25

7.0 APPENDIX.................................................................................................................................27

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1.0 INTRODUCTIONWheelbarrows were first invented by the Chinese to transport supplies to war. The

design initially only took advantage of a wheel and lever system, sometimes includes a sail to reduce original force needed to transport the load.

Being a second-class lever, carrying the load still require an amount of energy in lifting. This technology is only effective when the load is being put in the right spot. If the load is placed too far behind, lifting the wheelbarrow to move might be back-breaking. And so, a wheelbarrow fails to support heavy load. To make it worst, most wheelbarrows only have a single wheel that makes balancing difficult when handled.

In our project, the team aims to design a trolley to overcome this lifting action. Although with the current development of load-carrying hand vehicles, ways to lift the load off the receptacle has been greatly eased by mechanisms, the lifting action still exists. With the idea of a door at the receptacle and an inclinable receptacle floor, our team has brainstormed a few alternatives to be evaluated after predicting performance of each concept design. By following the overall design process as below, we finally select the best design alternative to proceed with our idea.

2.1 DESIGN PROBLEM

Figure 1 Product ASteelSteel Wheelbarrow

Figure 2 Product BPlasticPoly Wheelbarrow with Dual Wheels

Figure 3 Product CHeavy Duty Poly Dump Cart

Problem faced by product A:

Single wheel of left product makes balancing difficult when handled. Wheels located at the front require balancing of load when pushing. Lifting action consume excessive energy in unloading. Inclined floor of receptacle limits the shape of load (ie: brick-shaped loads).

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Formulation Concept Design

Configuration Design

Parametric Design Detail Design


Smooth floor of receptacle combined with the inclined shape concentrates the load to the front of the wheelbarrow causes load to spill easily.

Handle is fixed at a certain angle which might not fit all users’ comfortability.

Problem faced by product B:

Single wheel of left product makes balancing difficult when handled. Wheels located at the front require balancing of load when pushing. Need large turning radius in steering. Lifting action consume excessive energy in unloading. Small angle of inclination of receptacle requires large degree of lifting to unload from

carrying receptacle.

Problem faced by product B:

The carrying receptacle is shallow which can only hold limited load. Need large turning radius in steering. Wheels are not rotate sideways. Lifting action consume excessive energy in unloading. Small angle of inclination of receptacle requires large degree of lifting to unload from

carrying receptacle.

2.2 PROBLEM STATEMENTWheelbarrows are used to ease transporting loads in short distance and are most widely used by construction workers. However, the ubiquitous wheelbarrows require to be lifted off the rear wheel support using force during pushing and unloading process and tires out workers. When that happens, work efficiency of construction will drop. While the period of completion is delayed, construction companies will have to face higher expenses which will in the end effect housing prices.

Therefore, a wheelbarrow which increases work efficiency will be designed.

The project team will design a trolley to replace the function of wheelbarrow. This trolley will unload by sliding off the receptacle without lifting action; and have a carrying receptacle with larger volume that comes in a geometry which allows more load capacity.

2.3 OBJECTIVE To shorten period of construction. To increase safety factor when transporting load. To design an inclinable carrying receptacle.

Unloading will be by sliding motion. By that, construction site workers can conserve energy from the eliminated lifting action to do more work.

To increase volume content of carrying receptacle.When the construction site worker can transport more loads at a time, time to complete transporting a large amount of load is decreased.

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To improve steering motion.Construction sites are full of obstacles. An improved steering system can reduce chances of colliding with obstacles.

2.0 METHODOLOGYOur team has implemented the basic design concept:

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FunctionCollect and analyze costumer functional requirements and engineering characteristics.From current products of wheelbarrows used in construction sites, our team analyzed its strenghs and weakneses as a benchmark for further improvement in our product.

DesignOriginal concept of ubiquitous wheelbarrow is used as reference. From there we created alternatives of modifications for each aspect of components and transform our trolley to make its functions that terms with our objectives. Alternative designs were drafted and the best selected based on the 'Decision Making Process'.

FormOur product, Load Propelling Trolley takes a modified shape of a wheelbarrow to meet the objectives.The final configuration of our product will be more complicated but allow higher efficiency proving its worth.The dimension of the trolley shall remain almost the same as a ubiquitous wheelbarrow.The materials used shall be choosen for higher strength, higher maintainance durability and have reasonable cost.


In the engineering design process, our team follows the decision making process:

3.0 FORMULATING DESIGN PROBLEM

3.1 FUNCTIONAL DECOMPOSITION DIAGRAM

Figure 4 Functional Decomposition Diagram for Load Propelling Trolley

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T h e d e s i g n c o n s t r a i n s w e r e a l s o i d e n ti fi e d a n d b r a i n s t o r m e d u s i n g t h e H o u s e o f Q u a l i t y .

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A l t e r n a ti v e d e s i g n s w e r e c o m p a r e d u s i n g t h e P u g h ' s M o d i fi e d M e t h o d a n d W e i g h t e d R a ti n g M e t h o d .

B e s t a l t e r n a ti v e d e s i g n w a s s e l e c t e d .

CARRY LOAD

MOVE LOAD

ENABLE STEERING

INCREASE LOAD CAPACITY

PROVIDE MORE SPACE FOR LOAD

CARRY HEAVY LOAD

REDUCE ENERGY CONSUMPTION

ELIMINATE LIFTING

PROPEL LOAD EASILY

IMPROVE GRIP


3.2 FUNCTIONAL REQUIREMENTSCustomer Requirements - Easy to move

- Easy to remove load- Handle is not slippery- Able to carry large volume of load- Able to carry heavy load- Cost efficient- Maintenance- Safety- No slipping effect on wheels- Strong materials

Engineering Characteristics - Weight- Centre of gravity- Degree of inclination- Moment- Force required for inclination- Friction factor of carrying receptacle- Volume of carrying receptacle- Friction factor of wheels- Corrosion resistance- Strength of material

Figure 5 House of Quality

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On referral to the HOQ, the relationships between customer requirements and engineering characteristics are detailed. For example, a heavy wheelbarrow increases the friction factor of the wheels which makes it less likely to slide, easier to move, provided the shaft of the wheels are not pressed more tightly onto the tires.

3.3 ALTERNATIVES

3.3.1 PATENT SEARCHPatent search can be carried out before designing alternatives to study the weakness

and strength of similar product. Understanding the design selected for patents helps narrowing the possible alternatives in our design concept. This stage also minimizes impact of patent infringement.

1) US PATENT NO: US6193319 B1

US PATENT NAME: Handle-propelled, load-carrying land vehicle

DRAWING : DESCRIPTION:A handle-propelled, load-carrying land vehicle comprises a frame having two parts, one having wheels and ground-engaging pedestals forward of the wheels, and the other being pivoted to the front of the first part and having a load-carrying receptacle mounted on it and having a telescoping handle.

STRENGTH:Dumping hand cart for granular loads, since the forward edge of the receptacle is spaced from the ground at least at the completion of the dumping operation.

WEAKNESS:The force required to tip the receptacle forward is somewhat larger than the force required to raise the pedestals off the ground.

2) US PATENT NO: US4789171 A

US PATENT NAME: MULTIPURPOSE BARROW VEHICLES

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DRAWING : DESCRIPTION:Two-wheeled convertible barrow vehicle used as a trailer hitched to a power-operated vehicle.

STRENGTH:Can be easily stored and unloading process more faster

WEAKNESS:Heavy weight, small amount of load, not efficient in rough surface

3) US PATENT NO: US5149116 A

US PATENT NAME: BALANCED MULTI-WHEEL WHEELBARROW

DRAWING:

DESCRIPTION:A wheelbarrow comprising a frame having two arms defining handles, supporting legs, a load container and double wheel support structure. The center of gravity of the container is located substantially in vertical alignment with the axle in the operative position of the wheelbarrow.

STRENGTH:Adaptable to all kinds of ground or terrain since it may be equipped with different wheel arrangements with the wheels positioned for easy discharge, light weight.

WEAKNESS:Hard to carry and move because the handle is not ergonomic towards hand shape.

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3.3.2 MORPHOLOGY CHART

3.2.3 MORPHOLOGY MATRIX72 alternative designs were formed by all possible combinations of the alternatives in Morphological Chart.

In the end, 3 alternative designs are chosen, namely alternative 1, alternative 36 and alternative 69.

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Sub-function Alternative Concepts

1 2 3

Inclination system of receptacle

LeverHydraulic cylinder

PulleyHandle type

Continuous T-shaped Projected two arms

Receptacle Floor Orientation

Horizontal Tray Slanted Tray

Wheel type

Trolley WheelsTreaded Wheels

Unloading path With door No door


ALTERNATIVE INCLINATION SYSTEM OF

RECEPTACLE

HANDLE TYPE

RECEPTACLE FLOOR

ORIENTATION

WHEEL TYPE

UNLOADING PATH

1 LEVER CONTINUOUS

HORIZONTAL TRAY

TROLLEY WHEELS

WITH DOOR

36 HYDRAULICCYCLINDER

T-SHAPED HORIZONTAL TRAY

THREADED WHEELS

NO DOOR

69 PULLEY PROJECTED TWO ARMS

SLANTED TRAY

TROLLEY WHEELS

WITH DOOR

3.2.3.1 WEIGHTED RATING EVALUATIONConcept Alternatives

Alternative 1 Alternative 36 Alternative 69Criteria Importance

Weight (%)Rating Weighted

RatingRating Weighted

RatingRating Weighted

RatingHigh Efficiency 40 4 160 2 80 1 40High reliability 20 3 60 3 60 3 60Low Maintenance 10 2 20 1 10 3 30Low Cost 10 3 30 0 0 2 20Low Energy Consumption

20 4 80 4 80 1 20

Total 100 16 350 10 230 10 170

NoteRating ValueUnsatisfactory 0Just tolerate 1Adequate 2Good 3Very Good 4

3.2.4 ALTERNATIVE DESIGN SKETCH

Alternative 1 Alternative 36

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Alternative 69

3.3 MATERIAL SELECTION

3.3.1 SCREENING METHOD Firstly, we screen out materials that are not required in material selection. Furthermore, we also figure out whether the materials are functional or non-functional and manufacturable or not. We use two aspects for this case:

• Material-first approach• Process-first approach

3.3.2 RANKING/RATING METHODFor this project, our group decided to use ranking method together with material first approach.

We screen out materials that will not satisfy the functional requirements of the part. We will include the criteria regarding the nature of the applied loads and the operating environment. This screening will eliminate a number of infeasible material classes. Then we rate the material before we apply it that is we select the best material among those materials which we have screened out component

3.3.3 COMPONENTSHandle Operating Environment

Gripped. Provide support and skin-friendly to user under high load. Ergonomically shaped.

Suggested Materials

High Density Polyethylene (HDPE) - HDPE commonly have tensile strengths of between 21.3 and 37.9 MPa. No corrosion. Easy manufacturing. Flexible.

Bright Oak – Bright oak wood has high compressive strength between 47 to 61.2 MPa and bending strength of 100 to 130 MPa. It has low density 660 kg/m3. And this type of wood has relatively high tensile strength 163 MPa.

Material of choice

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Bright Oak

Justification for choice

• Bright oak has lower density than HDPE. Easy to be manufactured by bending. Able to withstand high stress.

Carrying receptacle

Floor

Floor Stand

Door

Operating Environment

Shifting materials such as: rocks, bricks, sand, tiles, pavers and concrete.

Suggested Materials

High Density Polyethylene (HDPE) - HDPE commonly have tensile strengths of between 21.3 and 37.9 MPa. No corrosion. Easy manufacturing. Flexible.

Medium carbon-steel - Harder than iron. Case hardened steel is also considered since it makes the steel more water resistant making it more rust resistant. It is also ductile which is suitable for the environment the load-propelling trolley will be used.

Material of choice

High Density Polyethylene (HDPE)


• HDPE is cheaper than steel. Tensile strength is high enough to avoid fracture within maximum load capacity. Lower density than steel, making the product lighter, easier to be handled. Low static and kinematic friction coefficient.

Lock

Stopper

Shaft

Bracket


Shifting materials such as: rocks, bricks, sand, tiles, pavers and concrete.

Suggested Materials

Aluminium - Aluminium alloys commonly have tensile strengths of between 70 and 700 MPa. Unlike most steel grades, aluminium does not become brittle at low temperatures. Excellent corrosion resistance. Easy jointing. Aluminium’s superior malleability is essential for extrusion.

Medium carbon-steel - Harder than iron. Case hardened steel is also considered since it makes the steel more water resistant making it more rust resistant. It is also ductile which is suitable for the environment the load-propelling trolley will be used.

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Material of choice

Medium carbon-steel


• Steel is affordable, do not resemble its component elements of carbon and iron, low in weight, durable, good impact strength, the ability to cool down quickly from a high temperature when exposed to water or oil, steel does not rust very easily on exposure to water and moisture.

Bolts

Nuts


Wet, muddy, constant force subjection, poor maintenance

Suggested Materials

Brass - Higher malleability than bronze or zinc.. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.Aluminium makes brass stronger and more corrosion resistant.Aluminium makes brass stronger and more corrosion resistant.

Iron - Hard, wear-resistant, ductile, malleable, corrosion can be prevented from powdered coating

Material of choice

Iron


Iron is suitable for the environment the wheelbarrow will be used in because it has a high wear and tear resistance, its harder than brass which make it last longer, it is not as ductile and malleable compared to brass so it will maintain its function as a bolt and also nut for an extended period of time.

Hinges Operating Environment

Promotes corrosion, sandy, high wear and tear

Suggested Materials

Stainless-steel - does not corrode, tough, high tensile strength, ductile

Brass - Higher malleability than bronze or zinc.. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.Aluminium makes brass

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stronger and more corrosion resistant.Aluminium makes brass stronger and more corrosion resistant.

Material of choice

Stainless- steel

Justification of choice

Stainless-steel is perfect for the wet condition the wheelbarrow will be used in. Furthermore, the high tensile strength possesed by stainless-steel makes it an ideal candidate to be used compared to brass which has a lower tensile strength.

Wheels Operating Environment

Sharp objects scattered on the ground, promotes corrosion

Suggested Materials

Plastic centered pneumatics wheel

Steel centered pneumatics wheel

Material of choice

Steel centered pneumatics wheel


Steel centered pneumatics wheel is harder than of plastic. Hence, the steel centered pneumatics wheel suits perfectly for the operating environment when compared to plastics centered pneumatics wheel.

3.4 CONFIGURATION DESIGN

3.4.1 PRODUCT ARCHITECTURE

Figure 6: Functional Structure

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PART FUNCTIONAL ELEMENTSBOLT Hold the tyre and bracketBRACKET Hold tyreNUT Lock and unlock with the bolt to hold tyre and bracketWHEEL Move and reduce force during moving of the wheelbarrowDOOR HINGE Act as axis of rotation which allow rotation between door and baseDOOR Open and close during loading and unloading processFLOOR Acts as support for the load that being putFLOOR STAND

Support the floor

HANDLE Act as a grip to move the wheelbarrowRECEPTACLE Support the structure of wheelbarrow from handle to tyreSTOPPER Acts as elevator to the floor which allows floor to rise and fallLOCK Lock the door and stopper in place when loaded

Table 1: One-to-one mapping

The product architecture diagram above shows the function of each part and the interaction between them.

As shown in the diagram, the connections between parts enable all parts to be functional. For instance, the function of the handle shaft extended from the lock is to enable control over machine during operation by counteracting the moments and forces produces during moves the trolley. When shaft is turned 90 degrees, the extended lock rotates and unlock the door and the stopper. The door and the stopper will then be free from static motion during unloading process. Connection between stopper and floor allows the floor to incline when the stopper inclines downwards from its static position. Now, as gravitational force pulls the load to slide off the floor (downward), the load hit the door open to get off the trolley.

3.4.2 PART CONFIGURATION

Figure 7: Product architecture-geometric layout

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Rotation- Reaction force

removedLOCK

Rotation- Exerts force on

floorSTOPPER

Rotation- Allow sliding motion of load

FLOORRotation

by momentum of load

DOOR


Figure 8: Configuration requirement sketch

As shown as above, the basic concept is the floor of receptacle supported by a stopper. The forces acting on floor when it is not unloading (floor horizontal) is sown at an end. The rough scale dotted line shown represents the receptacle and the floor stand which supports the floor. Then, we connect the stopper in various alternatives as noncontiguous part configuration.

3.4.3 ANALYSING AND REFINING CONFIGURATION ALTERNATIVESFrom here, the configuration alternatives are analyzed and refined.

A configuration check-list by categories:

Design for function Design for assembly Design for manufacture

3.4.3.1 DESIGN FOR FUNCTION The wheel shaft should made by corrosion resistant metal such as stainless steel, for it is strong enough to sustain the pressure and is resistant to corrosion, proving it long-lasting.

Stopper which supports the floor and the lock which block the stopper from inclining during loaded period also receive very high reaction force at the joints. Internal force is also high giving a chance to bend. Therefore, steel should be used here to prove maintainance and reliability of the system.

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User-friendliness can be achieved by having an ergonomic handle and rotatable trolley wheels. These allow users to steer the trolley with ease.

Mechanism-wise, our product has to be easy to use. With just a simple rotation of the shaft extended from the lock, a full unloading mechanism will be able to perform. To restore the system, the user only has to step on the pedal extended from the stopper and then return the lock into vertical position. According to the estimated calculations, accompanied by a few assumptions, energy needed to activate unloading system is low compared to lifting the whole cart.

Having only the floor inclined, users actually have their body parts protected from being clamped in between components when restoring the system (i.e.: unlike dump cart system which tilts the whole receptacle when unloaded.

The four-wheeled system solves the balancing problem which is commonly found when using wheelbarrows. This again proves safety, user-friendliness, and stability.

3.4.3.2 DESIGN FOR ASSEMBLY (DFA)By merging parts, for example, directly extending pedal from stopper and extending a handle shaft from lock, these minimize part counts. Standard parts, bolts and nuts; hinges; and wheels, are used. Self-locating features are found throughout the receptacle to fix floor, floor stand, stopper, and lock in place.

3.4.3.3 DESIGN FOR MANUFACTUREDON’T DO

Minimize variation of standard part sizes.

DON’T DO

Minimize part count by incorporating multiple functions into single parts.

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3.4.4 REFINING ALTERNATIVE CONFIGURATION Use hollow tube instead of rod to reduce weight. Avoid changes in thickness when possible. Avoid sharp corners as they produce stress concentration. Fillet corners. Do not use narrow web. Narrow web causes bulging which will eventually tear.

3.4.5 EVALUATING ALTERNATIVES For each criteria, marks is given whether the concept is better (+), worse (-) or more or less the same (S) as the datum. Each of other unit of knowledge is similarly rated, by using similar marking system. On the other hand, Weighted Rating Method is used which is similarly to matrix layout as the modified Pugh’s method.

PUGH’S MODIFIED CONCEPT SELECTION METHODLEVER

Criteria Importance Wt. (%)

Concept Alternatives

Bent at single edge

lever

Straight Lever Curved Lever

Production Cost

20 D + -

Effectiveness 30 A + +

Reliability 30 T + +

Life Span 20 U + -

100 M

∑ + 0 100 60

∑ - 0 0 40

∑ S 100 0 0

3.5 PARAMETRIC DESIGN

3.5.1 DESIGN VARIABLE VALUESThe main aim of the design is to unload the trolley without any lifting action. To achieve this, the angle of inclination without lifting action.

To find the angle of inclination: Target for theta: θ>10 °

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b = position of floor before inclined – diameter of stopper = 10.8 – 2 = 8.8 cm

Simply setting the position of the pivot,Let c = 49.5 cm

When the floor drops, c is repositioned as hypotenuse.

Now, θ = sin-1 bcθ = sin-1

8.849.5

θ = 10.24o > 10o ; Therefore, target angle achieved.

3.5.2 MANUFACTURING PROCESSESSpecial Parts Manufacturing ProcessReceptacle Injection MouldingFloor Injection MouldingFloor Stand Injection MouldingDoor Injection MouldingHandle Wood BendingLock Rolling and WeldingStopper Rolling and Welding

Table 2 Manufacturing processes chosen for each part

3.5.3 PERFORMANCE PREDICTIONTo find the angle of inclination: Now, we’ve set

Diameter of slot = 2 cme = 1.5 cmα = 21o

a = e sin αa = 1.5 sin 21o

a = 0.5376

b = 8.8 cmc = 49.5 cm

When the floor drops, c is repositioned as hypotenuse.

Now, θ = sin-1 a+bcθ = sin-1

0.5376+8.849.5

θ = 11o

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3.5.4 DIMENSIONSTo minimize possibility of fracture at parts, a safety factor of 2 is recommended.

At weakest joint B on Floor, r x t > 2.10 E -5

Safety factor = (0.008 x 0.008) /(2.10 E -5) = 3 > 2

4.0 SELECTED DESIGN

4.1 OVERVIEWWith all the above results, Load Propelling Trolley is proven to be better in industrial areas because:

The floor remaining horizontal when loaded allows loads of rectangular shapes (i.e. bricks).

Lever system used can reduce force needed to incline the floor of receptacle when unloading is pulled by gravitational force.

Only the floor is inclined and not the whole receptacle, reducing the chances of clamping hazard. Safety feature is increased.

Four-wheeled is proved to be more stable and easier to be handled. Hind wheels are rotatable which allows steering. Trolley can be directed with ease. Ergonomic continuous handle provides comfort and working capability of user. Material used has high tensile strength, namely HDPE and steel. Parts are either coated with corrosion resistant materials or manufactured from no

corrosion materials. Modular system of the trolley keeps maintenance convenient.

4.2 DETAIL DESIGNThe following is the assembly view of the final product:

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4.3 PRODUCT SPECIFICATIONSFunctional Depth 32 cmFunctional Width 58 cmFunctional Length (Upper) 98 cmFunctional Length (Lower) 85 cmWater Capacity 170 LMaximum Load Capacity 500 kgProduct Height 78 cmProduct Width 61 cmProduct Length 105 cmAngle of Floor Inclination (before unloading) 0o

Angle of Floor Inclination (after unloading) 11o

Approximate estimated Force needed to restore system 0.06 NTable 3: Load Propelling Trolley Specification

4.4 DETAIL DESIGN CONSIDERATIONS Economic

Materials chosen for our product are affordable and durable. For example, we avoid choosing aluminium because it is too expensive. Instead, we chose the low cost steel which also has very high tensile strength. Our product has high marketing potential especially when its result is proven to increase production at industrial sites,

Environmental

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Long lasting HDPE can be well maintained for a long period of time. Product can be reused for multiple industrial project with care and not renew the trolley. When the trolley is no longer in use, HDPE can be recycled into other products. Steel is found redundant on Earth. Steel can be extremely reliable and has long life, and on the plus point, steel is environmental friendly to Earth.

Health and Safety

Handle manufactured from bright oak. It is skin-friendly, no allergy causes, and has allowable friction between the handle and users hand. Only the floor is inclined, which is out of user’s reach. Clamping hazard is reduced. No lifting action is required. This saves muscle aches from supporting the weight of load during unloading.

Manufacturability

Parts can be manufactured using current technology. Mass production can be obtained within short period of time with precision and accuracy.

5.0 CONCLUSIONAfter months of hard work and sacrifices, we have finally produced our final design

product – Load Propelling Trolley. We have applied the knowledge we learned from lecture in our project design process. It is impossible to reach this point without proper coordination, ethics, and teamwork among our team members. From this project, we had acquired skills as mentioned above required for a good engineer.

We have learned that proper procedures are needed in any design project. We also learned that decision making is very important. In order to make the most optimal decision, we needed to input the correct information. We have done lots of research by browsing the internet, searching for information from the books in the library as well as obtaining advice from other group and also experienced seniors. We have organized group meetings several times to discuss about our ideas and opinions, and finally make the best decision of all.

We have encountered a lot of hardships throughout our design project. Through our teamwork and sacrifices from our team members, we have finally to overcome those obstacles and problems coming in our way. Through this design project we have strengthened our mastery on the conceptual design theories and knowledge such as formulation of problems, design concept, configuration design as well as parametric design.

The skills and knowledge acquired from this design project will surely benefits us a lot in our future career as an engineer.

6.0 REFERENCETrolley Wheelhttp://www.electrictrolleyspares.com/powakaddy_legend_p4.htm#

25

http://www.electrictrolleyspares.com/powakaddy_legend_p4.htm


Wheelbarrowhttp://www.letstalkscience.ca/hands-on-activities/engineering-technology/how-does-a-wheelbarrow-help-you-to-carry-heavy-loads.html

Patent Searchhttp://www.google.com/patents/US6193319

History of wheelbarrows

http://www.uh.edu/engines/epi377.htm

Wheelbarrows Specifications

http://www.alibaba.com/product-detail/wheelbarrows-WB6209-wheelbarrow-specifications-standard_988143096.html?s=p

http://www.homedepot.com/p/Jackson-6-cu-ft-Steel-Wheelbarrow-M6KBUT11/100325962

http://www.homedepot.com/p/True-Temper-6-cu-ft-Poly-Wheelbarrow-with-Dual-Wheels-CP6DWUT8/202616068?N=5yc1vZc5qk

http://www.homedepot.com/p/Unbranded-4-cu-ft-Gorilla-Carts-Plastic-Garden-Dump-Cart-GOR200B/202353037?N=5yc1vZbx50

Customer’s Requirement

http://www.wikihow.com/Buy-a-Wheelbarrow

Product Architecture

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.183.3175&rep=rep1&type=pdf

Friction Coefficient

http://www.tribology-abc.com/abc/cof.htm

http://www.finesoftware.eu/help/geo5/en/table-of-ultimate-friction-factors-for-dissimilar-materials-01/

Wood Manufacturing Process

http://www.tai-workshop.com/english/tech-2(b)-e.html

Wood Specification

http://www.matbase.com/material-categories/composites/polymer-matrix-composites-pmc/wood/class-4-wood-slightly-durable/material-properties-of-red-oak-wood.html#properties

Steel Specification

http://www.azom.com/article.aspx?ArticleID=6130

Polyethylene Specification

http://www.sdplastics.com/polyeth.html

Text

26

http://www.sdplastics.com/polyeth.html

http://www.azom.com/article.aspx?ArticleID=6130



http://www.tai-workshop.com/english/tech-2(b)-e.html



http://www.tribology-abc.com/abc/cof.htm

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.183.3175&rep=rep1&type=pdf

http://www.wikihow.com/Buy-a-Wheelbarrow





http://www.homedepot.com/p/Jackson-6-cu-ft-Steel-Wheelbarrow-M6KBUT11/100325962



http://www.uh.edu/engines/epi377.htm

http://www.google.com/patents/US6193319

http://www.letstalkscience.ca/hands-on-activities/engineering-technology/how-does-a-wheelbarrow-help-you-to-carry-heavy-loads.html

http://www.letstalkscience.ca/hands-on-activities/engineering-technology/how-does-a-wheelbarrow-help-you-to-carry-heavy-loads.html


Engineering Design, Rudolph J. Eggert, Boise State University, Pearson, Prentice Hall, ISBN 9780131433588

7.0 APPENDIX

ALTERNATIVE

INCLINATION SYSTEM OF

RECEPTACLE

HANDLE TYPE

RECEPTACLE FLOOR

ORIENTATION

WHEEL TYPE

UNLOADING PATH

1 Lever Continuous Horizontal Tray

Trolley Wheels

With door


Trolley Wheels

No door


Threaded wheels

With door


Threaded wheels

No door

5 Lever Continuous Slanted tray Trolley Wheels

With door

6 Lever Continuous Slanted tray Trolley Wheels

No door

7 Lever Continuous Slanted tray Threaded Wheels

With door

8 Lever Continuous Slanted tray Threaded Wheels

No door

9 Lever T-shaped Horizontal Tray

Trolley Wheels

With door


Trolley Wheels

No door


Threaded wheels

With door


Threaded wheels

No door

13 Lever T-shaped Slanted tray Trolley Wheels

With door


No door

15 Lever T-shaped Slanted tray Threaded Wheels

With door


No door

17 Lever Projected two arms

Horizontal Tray

Trolley Wheels

With door


Horizontal Tray

Trolley Wheels

No door

27

http://www.amazon.com/Engineering-Design-Rudolph-J-Eggert/dp/013143358X



Horizontal Tray

Threaded wheels

With door


Horizontal Tray

Threaded wheels

No door


Slanted tray Trolley Wheels

With door



No door


Slanted tray Threaded Wheels

With door



No door

25 Hydraulic cylinder

Continuous Horizontal Tray

Trolley Wheels

With door



Trolley Wheels

No door



Threaded wheels

With door



Threaded wheels

No door


Continuous Slanted tray Trolley Wheels

With door


Continuous Slanted tray Trolley Wheels

No door


Continuous Slanted tray Threaded Wheels

With door


Continuous Slanted tray Threaded Wheels

No door


T-shaped Horizontal Tray

Trolley Wheels

With door



Trolley Wheels

No door



Threaded wheels

With door



Threaded wheels

No door


T-shaped Slanted tray Trolley Wheels

With door


T-shaped Slanted tray Trolley Wheels

No door


T-shaped Slanted tray Threaded Wheels

With door


T-shaped Slanted tray Threaded Wheels

No door


Projected two arms

Horizontal Tray

Trolley Wheels

With door


Projected two arms

Horizontal Tray

Trolley Wheels

No door

28



Projected two arms

Horizontal Tray

Threaded wheels

With door


Projected two arms

Horizontal Tray

Threaded wheels

No door


Projected two arms


With door


Projected two arms


No door


Projected two arms


With door


Projected two arms


No door

49 Pulley Continuous Horizontal Tray

Trolley Wheels

With door


Trolley Wheels

No door


Threaded wheels

With door


Threaded wheels

No door

53 Pulley Continuous Slanted tray Trolley Wheels

With door

54 Pulley Continuous Slanted tray Trolley Wheels

No door

55 Pulley Continuous Slanted tray Threaded Wheels

With door

56 Pulley Continuous Slanted tray Threaded Wheels

No door

57 Pulley T-shaped Horizontal Tray

Trolley Wheels

With door


Trolley Wheels

No door


Threaded wheels

With door


Threaded wheels

No door


With door


No door


With door

64 Pulley T-shaped Slanted tray Threaded Wheels

No door

65 Pulley Projected two arms

Horizontal Tray

Trolley Wheels

With door


Horizontal Tray

Trolley Wheels

No door

29



Horizontal Tray

Threaded wheels

With door


Horizontal Tray

Threaded wheels

No door



With door



No door



With door



No door

Coefficient of friction for a range of material combinationscombination Static Dynamic

dry lubricated dry lubricatedsteel-steel 0.5...0.6 0.15 0.4...0.6 0.15copper-steel - - 0.5...0.8 0.15steel-cast iron 0.2 0.1 0.2 0.05cast iron - cast iron 0.25 0.15 0.2 0.15friction material - steel - - 0.5-0.6 -steel-ice 0.03 - 0.015 -steel-wood 0.5-0.6 0.1 0.2-0.5 0.05wood-wood 0.4-0.6 0.15...0.2 0.2...0.4 0.15leather-metal 0.6 0.2 0.2...0.25 0.12rubber-metal 1 - 0.5plastic-metal 0.25...0.4 - 0.1...0.3 0.04...0.1plastic-plastic 0.3-0.4 - 0.2...0.4 0.04...0.1

CALCULATION

To find force required to unload MAXIMUM LOAD CAPACITY: LOAD = 500 kg

Using figure (c),

30


∑ Fx=0, Hx = Dx

∑ Fy=0, Dy = 0.93 (9.81) = 9.1233 = 9.12 N

∑MH=0, -(0.10 cos 20o)(9.1233) – (0.20 cos 20o)Dx + (0.20 sin 20o)(9.1233) = 0

Dx = -1.095867 = -1.10 N

Using figure (b),

∑ Fx=0, Dx = - Bx

Bx = 1.095867

∑MB=0, 0.43445(506.534)(9.81) – 0.495 Cy + 0.8689 Dy = 0

Cy = 2166.75210 = 2167 N

∑ Fy=0, By + Cy – Dy – 506.534(9.81) = 0

By = 2811.46974 = 2811 N

Using figure (a),

∑MA=0, -(0.0405 cos 5.6o)(0.968)(9.81) + (0.1225)Q + (0.3925 cos 5.6o + 0.05)(0.174)(9.81) –(0.4735 cos 5.6o)By + (0.4735 sin 5.6o) Bx = 0

Q = 1324.55373 = 1325 N

Users only have to overcome Q and static friction between lock and stopper to unload.

For single-wheeled wheelbarrow, force needed for lifting action, Z, let’s say, not considering its capability, 500 kg is:

Distance between rotation axis and load center of gravity = 0.46 m

Distance between rotation axis and point of exertion of force = 1.22 m

Z = 0.46 x 500(9.81) / 1.22

Z = 1849 N

Therefore, our target for designed product is to unload the trolley with force > 1849 N.

To find force required to restore system:

LOAD = 0 kg

Remove Q. Add in P at the end of pedal.

Using figure (c),

31


∑ Fx=0, Hx = Dx

∑ Fy=0, Dy = 0.93 (9.81) = 9.1233 = 9.12 N

∑MH=0, -(0.10 cos 20o)(9.1233) – (0.20 cos 20o)Dx + (0.20 sin 20o)(9.1233) = 0

Dx = -1.095867 = -1.10 N

Using figure (b),

∑ Fx=0, Dx = - Bx

Bx = 1.095867

∑MB=0, 0.43445(6.534)(9.81) – 0.495 Cy + 0.8689 Dy = 0

Cy = 72.27262 = 72.3 N

∑ Fy=0, By + Cy – Dy – 6.534(9.81) = 0

By = 0.94942 = 0.95 N

Using figure (a),

∑MA=0, -(0.0405 cos 5.6o)(0.968)(9.81) + (0.3925 cos 5.6o + 0.1) P + (0.3925 cos 5.6o + 0.05)(0.174)(9.81) –(0.4735 cos 5.6o)By + (0.4735 sin 5.6o) Bx = 0

P = 0.05585 = 0.06 N

All joints : A, B, C, D, Q

When loaded with MAXIMUM LOAD:

StopperBx = 1.10 NBy = 2811 NQ = 1325 N

Calculate Ax and Ay.Using figure (a),∑ Fy=0, Ay – P – 0.174(9.81) – 0.968(9.81) – By = 0Ay = 17.2145 = 17.2 N∑ Fx=0, - Ax – Bx = 0Ax = -1.09587 = - 1.10 N

FloorBx = 1.10 NBy = 2811 NCy = 2167 NDx = -1.10 NDy = 9.12 N

Highest shear force detected: Axial B

32


For Floor, material chosen is HDPE.

Shear stress < 21.3 MPa

Shear stress = F/ (2∏r x t)

21.3M > By / (2∏r x t)

21.3 M> 2811 / (2∏r x t)

r x t > 2.10 E -5 m

At Axial B, material chosen is steel.

Shear stress < 570 MPa

Shear stress = F/ (∏r2)

570 M > By / (∏r2)

570 M > 2811 / (∏r2)

r > 1.57 E -6 m

There are certain joints which experience high tensile strength and may face fracture if the cross-sectional area of these portions is not taken care.

To minimize possibility of fracture at parts, a safety factor of 2 is recommended.

At weakest joint B on Floor, r x t > 2.10 E -5

Safety factor = (0.008 x 0.008) /(2.10 E -5) = 3

33


2D DRAWING

34


35


36


37


38


39


40


41


42


43


44

Documents

Load Propelling Trolley Design Report