GONZAGA UNIVERSITY School of Engineering - ASMEfiles.asme.org/Divisions/SERAD/15941.pdf · GONZAGA...

GONZAGA UNIVERSITY

School of Engineering

FINAL REPORT

For

TOOL DESIGNS FOR THE SAFE REMOVAL AND INSTALLATION OF HEAVY EQUIPMENT BUCKET TEETH

Engineering Design Team: Rudy Lauth, Brian Gaither, Luis Real

Faculty Project Advisor: Tom Zysk

Liaison Engineer: Grant King

Sponsored by: National Institute of Occupational Safety and Health (NIOSH), Spokane Research Lab

Center for Engineering Design Project ME-05

April 22, 2004

GONZAGA UNIVERSITY

School of Engineering

PROJECT PROPOSAL

For

BUCKET TOOTH REMOVAL/INSTALLATION SYSTEM

Center for Engineering Design Project ME-05

Prepared By:

____________________ ____________________ ____________________ Rudy Lauth Brian Gaither Luis Real

Reviewed By:

____________________ Tom Zysk

____________________ Grant King

April 22, 2004

Project 2003 ME-05 Bucket Tooth Removal System 2

TABLE OF CONTENTS

Review Page

List of Figures

1.0 Introduction

1.1 Abstract

1.2 Overview

1.3 Background

1.3.1 Injury Data Analysis

1.3.2 Bucket Tooth Configurations

1.3.3 Tooth Removal Methods

2.0 Proposal Statement

3.0 Project Scope

3.1 Customer Requirements

3.2 Project Deliverables

4.0 System Decomposition

5.0 Concept Development

5.1 Concept Development Process

5.1.1 Leverage Bar

5.1.2 Brake Piston

5.1.3 Bullet Piston

5.1.4 Spring System

5.1.5 Tooth Hugger

5.1.6 Screw Clamp

5.1.7 Pneumatic Hand Nailer

5.1.8 Hand Held Punch

5.1.9 Slide Hammer

5.1.10 Super Sucker

5.2 Concept Selection Criteria

5.3 Final Design Selection

6.0 Project Direction

6.1 Hand Tool Design, Fabrication, and Testing


6.2 Hydraulic Cylinder System Design

6.2.1 Scaling the System

6.2.2 Hydraulic Cylinder System Design

6.2.2.1 Cylinder Selection and Modification

6.2.2.2 Jack Selection and Modification

6.2.2.3 Hydraulic Cylinder System Modification

and Testing

7.0 Conclusion

8.0 Acknowledgements

Appendix A – Explanation of Customer Requirements

Appendix B – Hydraulic System Set-up and Warnings

Appendix C _ Detailed Drawings


LIST OF FIGURES

Figure 1: Injuries by Type

Figure 2: Injuries by Machine Type

Figure 3: Horizontal Pin

Figure 4: Angled Pin

Figure 5: Pin with Rubber Center

Figure 6: Horseshoe Retainer

Figure 7: Punch and Hammer Tools

Figure 8: Punch and Hammer Method

Figure 9: Pin Removal Tool

Figure 10: Leverage Bar

Figure 11: Brake Piston

Figure 12: Bullet Piston

Figure 13: Spring System

Figure 14: Tooth Hugger

Figure 15: Screw Clamp

Figure 16: Pneumatic Hand Nailer

Figure 17: Hand Held Punch

Figure 18: Slide Hammer

Figure 19: Super Sucker

Figure 20: Large Bucket

Figure 21: Hand Held Punch (First Generation)

Figure 22: Slide Hammer (First Generation)

Figure 23: Interchangeable tool attachments

Figure 24: Various types of tip finishes

Figure 25: Hand Held Punch (Second Generation)

Figure 26: Slide Hammer (Second Generation)

Figure 27: Hand Held Punch Test

Figure 28: Slide Hammer Test

Figure 29: Bucket from NORCAN

Figure 30: Hydraulic Cylinder System (front)

Figure 31: Hydraulic Cylinder System (rear)


Figure 32: Cylinder Adapter

Figure 33: Hydraulic Cylinder System in working position

Figure 34: Side View of Cylinder System Assembly

Figure 35: Isometric View of Cylinder System Assembly

Figure 36: Set Up of Hydraulic Cylinder System

Figure 37: Team Photo

Table 1: Conceptual Design

Table 2: Decision Matrix


1.0 Introduction 1.1 Abstract

The purpose of this project is to design, manufacture and test tools that are capable of safely removing teeth from heavy equipment buckets. Bucket teeth are secured to the bucket utilizing a pin that must be removed by force. Current removal methods typically utilize a sledgehammer and hand held punch. This method frequently results in shards of metal from the punch imbedding in the worker’s skin as well impact injuries when workers strike their hand or finger with the hammer or punch. This project has created several solutions for the safe removal of bucket teeth. For small teeth, two different hand tools have been designed to accommodate a wide range of tooth geometries. These hand tools were tested and modified based upon their performance to safely and effectively remove small teeth. For large teeth that require removal forces in excess of the capabilities of our hand tools, a removal system that consists of a hydraulic cylinder coupled with an adjustable jack stand has been produced. This method of mechanical intervention has been validated through testing and the equipment design is such that may be scaled accordingly to match a wide range of bucket geometries and field conditions. This report presents background injury date, customer requirements, conceptual designs, detailed drawings, and prototype fabrication and testing information. 1.2 Overview Earthmovers and other construction equipment often have teeth on the buckets they use to increase their operational efficiency. The buckets range in volumetric capacity, tooth size, and tooth spacing. The bucket teeth wear out over time, sometimes break, and thus must be changed. This project deals with the tooth replacement process.

The purpose of this project is to design, manufacture, and test a device that safely removes and installs bucket teeth on construction equipment. Bucket teeth are worn out as a result of the friction and impact forces associated with digging and scooping dirt and rocks. They must be replaced for the machines to operate at maximum efficiency. When changing teeth, most workers currently use a punch and hammer. The size of both these tools depends on the size of the tooth that needs to be changed. Each tooth is connected to the bucket by means of a pin and clevis. The pin must be removed in order to change the tooth. A significant number of workers are injured during this process as shown in injury data provided by the National Institute of Occupational Safety and Health (NIOSH). This design team is collaborating with NIOSH to develop tools that will remove and install teeth, both big and small, in a safer but equally efficient way as the current methods provided.


1.3 Background 1.3.1 Injury Data Analysis In order to design a solution to avoid injuries resulting from bucket tooth removal, an understanding of the source of the injuries was required. The Mine Safety and Health Administration (MSHA) maintains a database that compiles accident and injury data from mines and construction sites across the United States. From the period of 1998 to 2002, MHSA reported 93,223 accidents.

In order to extract data specific to accidents resulting from the removal of bucket teeth, search parameters of the database were set to inquire using the following key words.

• Punch

• Tooth

• Shard

• Pin

• Hammer

• Sledgehammer

This database search yielded 1726 accidents during the 5 year period.

The injury data that MSHA receives is not always clear regarding the nature and circumstances of an injury. Therefore, the information that MSHA compiles is indeed valuable but not all inclusive. See Figures 1 and 2 for a summary of the injury data.

Injuries associated with bucket tooth removal may be categorized into three major types:

• Ergonomic o Injuries such as back strains from lifting and shoulder and elbow strains

from swinging. All injuries that resulted from the pin removal and installation process that did not involve impact or shards are in this grouping.

• Impact o Injuries that resulted from the impact of a sledgehammer to the body,

whether self inflicted or by another person. • Shard

o Injuries that resulted from a shard of metal flying off either the punch or sledgehammer.

To summarize, analysis of MSHA injury data verifies the need for a safer means

of bucket tooth removal to replace the conventional method utilizing a sledgehammer and punch.


Injuries by Type

20

50

136

0

20

40

60

80

100

120

140

160

Ergonomics Impact Shard

Num

ber o

f Inj

urie

s 19

98-2

002

Figure 1 - Injuries by Type

Injuries by Machine Type

92 1

16

36

1 1

140

0

20

40

60

80

100

120

140

160

Bulldozer CarriageMounted Drills

on Track

ContinuousMiner

Dragline, shovel Front Loader Ore HaulageTruck

Roof BoltingMachine

Not Reported

Num

ber o

f Inj

urie

s 19

98-2

002

Figure 2 - Injuries by Machine Type


1.3.2 Bucket Tooth Configurations

In order to gain a better understanding of the equipment around which we would have to design a solution for tooth removal and installation, our design team performed a field survey of various equipment manufacturers’ bucket teeth. Our survey found that there are a wide variety of tooth geometries currently in use. The specific tooth configuration depends upon the manufacturer. Teeth range in size from approximately 4” to over 30”. The attachment methods also vary, however the majority of teeth are attached with a pin in some orientation. Below are examples of common tooth geometries and attachment methods.

Figure 3 - Horizontal Pin

The alignment of the pin in this configuration is parallel to the ground. This is the most common pin configuration and the hammer and punch method is widely implemented.

Figure 4 - Angled Pin

The alignment of the pin in this configuration is at a 45 degree angle to the ground. This configuration is commonly used on smaller teeth where the distance between teeth is small.

Figure 5 - Pin with Rubber Center

The alignment of this pin is 90 degrees to the ground. The pin twists onto the bucket and locks into place with the pin. The pin keeps the tooth from twisting off.

Figure 6 - Horseshoe Retainer

The retainer in this configuration is similar to a “C” type retaining ring and is not reused when teeth are changed. The retainer is generally cut off with a torch when it is removed.


1.3.3 Tooth Removal Methods

To understand the tooth removal and installation methods, our design team met with various equipment maintenance personnel to witness the practice firsthand. It was discovered that the removal method used depends greatly upon the pin size and configuration. The horseshoe retainers are generally cut out with a torch, while the straight pin configurations are removed using a hammer and punch. The hammer and punch method of pin removal (a pin must be removed whenever a new tooth is put on a bucket) requires a person to hold a punch (cylindrical piece of metal) against the pin with one hand and hit it with a 3 to 15 lb. sledge hammer in order to drive the pin out. Hazards involved with this current method include lacerations from shards of metal flying off the punch or hammer and impact injuries from the sledgehammer itself.

Figure 7 - Punch and Hammer Tools

Figure 8 – Punch and Hammer Method

During a tour of an equipment maintenance facility, we had the chance to watch a mechanic remove a pin using a punch and sledgehammer (see Figure 8). Although equipment manufacturers have developed a tool to make this process safer (see Figure 9), the worker did not use it since the old method (punch and a hammer) is quicker and readily available. We also learned that shards are more likely to fly off a punch (from brittle fracture) when the punch is made of a harder material then the hammer and pin. If a softer metal is used for the punch, the material will “mushroom” or expand out as a result of the impact force. Fracture is also possible if the punch is allowed to remain “mushroomed” and not filed back to a cylindrical cross-section on a regular basis.

Figure 9 – Pin Removal Tool


2.0 Proposal Statement Our design team proposes to design, build and test a means of safely removing and installing bucket teeth from heavy construction equipment. This new method or device will replace the existing hazardous “punch and hammer” method of bucket tooth removal and installation.


3.0 Project Scope 3.1 Customer Requirements In order to establish the requirements that would control our design and overall direction of this project, discussion with the project sponsor, NIOSH, took place to understand the customer’s functional, operational and financial constraints. This discussion generated a set of customer requirements, defined as:

• 1 person can operate the tool • The final cost of the “system” is under $100 • Minimal amount of fabrication required • Use as many off the shelf components as possible • Minimal training required to use the tool • Durable and reliable • No damage to bucket or tooth during operation • Short cycle time to remove tooth • Operate in a hostile environment • Capable of working with multiple teeth geometries and fastening schemes • Replaces existing punch and hammer method • Minimal number of pinch points

3.2 Project Deliverables In addition to the project requirements, a set of deliverables was also negotiated:

• Working prototype • Drawings of prototype • Field testing and results • Promotional material on CD, DVD and/or poster board.


4.0 System Decomposition

The bucket tooth removal system that we plan to design will have three basic subsystems which will be expounded on and explored as we move further along in the design process. The three basic subsystems are as follows:

Anchoring • If required to be stationary for operation, the pin removal system that we create

will have to be secured to the bucket or tooth in order to remove the pin. Pin removal/insertion • Our design will have some means for removing and installing the pin from the

tooth/clevis assembly. External power supply • Our design will require some sort of power in order to drive the pin from or into

the tooth.


5.0 Concept Development 5.1 Concept Development Process In order to develop our concepts, we first looked at each of the basic subsystems for the tooth removal process. Ideas were brainstormed for each subsystem individually. A list of brainstormed conceptual methods for anchoring, pin removal and external power supplies are listed in table 1.

Anchoring Pin Removal External power Human Shot Gun Bullet Human

Magnetic Shock Wave Leverage

Weld Air Pressure Pneumatic

Adhesive Ratchet/Jack Hydraulic

Clamp Push Liquid Nitrogen

Spring Clamp Pull - Magnet Electric DC

Hand Vacuum Air

Screw Water to Push Out Explosive

Cam Clamp Impact Electromagnetic

Bolt Air Hammer Impact Torch

Braze Screw Jack - Push it Out Steam

Solder Pneumatic Jack Gravity

Hook Scissor Jack Battery Pack

Chain Freeze it Out Stored Energy

Gravity Clay Hydraulic Jack Springs

Duct Tape Lubricant Under Pressure CO2/Nitrogen

Strap Hand Hammer

Zip Ties Spring

Vacuum Melt Rubber

Gear Pulled

Table 1 - Conceptual Methods


Based on the list of concepts identified in Table 1 and group analysis and discussion of these concepts, preliminary concept sketches were created. These preliminary concepts were revised to increase feasibility, clarity, and reflect as many of the customer requirements as possible. The final 10 concepts selected for further exploration were identified as follows:

• Leverage Bar • Brake Piston • Bullet Piston • Spring System • Tooth Hugger • Screw Clamp • Pneumatic Hand Nailer • Hand Held Punch • Slide Hammer • Super Sucker


5.1.1 Leverage Bar

Figure 10 - Leverage Bar

Description: The tool is operated in the following manner: The worker secures the clamps around the tooth. He then lines up the punch with the pin that is to be driven out. He finally pulls on the lever which applies a horizontal pressure to the punch, which in turns drives out the pin.

Pros:

• Requires little training • Can use on wide variety of horizontal pin teeth • Could be used to push pins in • Easy to use • 1 person can operate it • Minimal training • It does not damage bucket, tooth and pin

Cons:

• Not capable of working with different geometries • Cam system necessary to push pins out could get complex • Durability • It may not be operable in a hostile environment


5.1.2 Brake Piston

Figure 11 - Brake Piston

Description: The tool is operated in the following manner: The worker secures the clamps around the tooth. He then lines up the piston with the pin that is to be driven out. He finally applies pressure to the brake pad. The force travels through the hydraulic fluid in the tube and applies a greater force on the piston, which in turn drives out the pin.

Pros:

• Durable • Easy to use • Requires little training • One worker could operate it • It does not damage the bucket, tooth and pin • Very safe

Cons:

• Requires hydraulic fluid of some kind • Need to investigate adjustable clamps for different teeth size • Could only be used on horizontal pins • Need to investigate some sort of device to catch pin • Repairs could get complex • Long time of operation


5.1.3 Bullet Piston

Figure 12 - Bullet Piston

Description: The tool is operated in the following manner: The worker holds the tool in his hand and lines up the piston flush with the pin to be driven out. He then inserts a charge into the tool and pushes a button detonating the charge. The explosion applies a force on the piston, which in turn drives out the desired pin.

Pros:

• Fun to use • Could work on horizontal and diagonal pin geometries • Easy to use • Durable • The time of operation is short

Cons:

• Requires shotgun shell type of charge • Cost could be an issue • Could require some mechanism to catch pin • Could damage teeth • Repairs could be complex • Recoil may cause safety issues


5.1.4 Spring System

Figure 13 - Spring System

Description: This tool does not require any anchoring system because it can be held and operated by only one person. In order to use the tool one has to pull to compress the spring inside. The spring will stay compressed until the operator presses the release button. Then the spring will push the punch against the pin creating an impact to drive out the pin from the bucket tooth.

Pros:

• Easy to use • Inexpensive • Capable of working with multiple tooth geometries • Safe • One person is able to use it

Cons:

• High impact against the pin • Loss of spring tension • May not generate sufficient force to extract pin


5.1.5 Tooth Hugger

Figure 14 - Tooth Hugger

Description: This system works for different sizes of teeth since one can adjust its length. This system does not require an impact to release the pin. It uses a screw to push the pin out. At the same time one can use the same system to install the pins.

Pros:

• Easy to use • No impact against the pin • Inexpensive • Durable

Cons:

• Unknown performance for 45° pins • It only works for small sizes of pins • Deflection or deformation of frame


5.1.6 Screw Clamp

Figure 15 - Screw Clamp

Description: The tool is used in the following manner: The worker attaches the clamp to the tooth, lining up the screw with the pin to be punched out. He then turns the screw which in turn pushes out the pin.

Pros:

• It requires minimal training • No impact on the pin • Inexpensive • Easy to manufacture

Cons:

• Unknown performance for 45° pins • Stability and rigidity of clamp frame


5.1.7 Pneumatic Hand Nailer

Figure 16 - Pneumatic Hand Nailer

Description: Powered by air, this unit fits in your hand and has attachments to accommodate a wide variety of pin diameters. The unit strikes the pin at up to 1000 strokes/minute.

Pros: • Compact • Safe • Accommodates a wide variety of pin diameter • Quick to remove/install pin • Can be used on multiple pin orientations/geometries • May have other uses beyond pins

Cons: • Requires a compressed air source • Expensive • Reparability may be an issue


5.1.8 Hand Held Punch

Figure 17 - Hand Held Punch

Description: The punch is held with your hand and struck with a sledge hammer. The head of the punch is removable so it can be replaced when it wears. The punch has interchangeable attachments to accommodate a variety of punch diameters and punch insertion fittings.

Pros: • Inexpensive • Easy to manufacture • Easy to create prototype • Only requires a sledge hammer to operate • Quick to remove/install pin • Accommodates a wide variety of pin diameters • Can be used on multiple pin orientations/geometries • Compact • May have other uses beyond pins

Cons: • Still uses a sledge which has some danger


5.1.9 Slide Hammer

Figure 18 - Slide Hammer

Description: The stationary portion is held with your hand while the sliding weight is grabbed with the other and slid down the track to create the impact for pin removal and installation. The punch has interchangeable attachments to accommodate a variety of punch diameters and punch insertion fittings.

Pros: • Human powered • Easy to manufacture • Easy to create prototype • Safe • Accommodates a wide variety of pin diameter • Quick to remove/install pin • Can be used on multiple pin orientations/geometries • May have other uses beyond pins

Cons: • Small danger of smashing fingers • Fairly long at 30”


5.1.10 Super Sucker

Figure 19 - Super Sucker

Description: The pin will be removed by placing a cylinder over the exit point and applying a sudden vacuum which will suck the pin out. The procedure may be able to be reversed by using compressed air and a backstop to drive the pin in without driving it too far.

Pros: • The cylinder will catch the pin during the removal process • Safe • Easy to fabricate (excluding the power supplies) • It only requires one person to operate it

Cons: • Needs an external vacuum source and possible an external compressed air source • The vacuum may not be strong enough to dislodge pin • Needs a relatively flat surface to create seal • Durability • It may be dangerous for workers


5.2 Concept Selection Process

Following the generation of this project’s conceptual designs, an objective means of evaluating these designs was required. In order to accomplish this, a decision matrix was created that would combine the relative importance of each customer requirement and the concept’s ability to meet that requirement. A full explanation of customer requirements is shown in Appendix A.

Utilizing input from NIOSH, weighting factors from 1 (low) to 10 (high) were assigned to each design requirement. Each unique concept was evaluated by the design team and the customer to determinate the concept’s ability to satisfy that requirement and was then assigned a score in the same manner from 1 – 10.

The weighting and the score for each requirement were then multiplied and summed for a total score and concept ranking. This depicted in the Decision Matrix shown in Table 2.


Leve

rage

Bar

Brak

e Pi

ston

Bulle

t Pist

onSp

ring

Syst

emTo

oth

Hugg

erSc

rew

Clam

pPn

eum

atic

Han

d Na

iler

Hand

Hel

d Pu

nch

Slid

e Ha

mm

erSu

per S

ucke

r

Requirements Weight 1 2 3 4 5 6 7 8 9 10One person operation 9 8 8 10 10 8 8 10 10 10 10

Product Cost less than $100

8 5 5 4 7 7 7 3 9 8 5

Reparability\ Maintenance 5 4 6 2 7 7 7 5 9 8 3

Minimal Training 8 8 8 6 7 8 8 8 10 9 6

Durable 10 5 7 8 8 7 7 7 10 9 4

Patentable 7 10 10 10 10 10 10 10 10 10 10

No damage to bucket, tooth and pin

10 9 9 5 5 9 9 8 7 8 9

Short time for operation 9 5 5 8 8 4 4 7 9 9 4

Operable in a hostile environment

9 4 7 4 7 6 6 6 9 8 4

Capable of working with different geometries 8 4 5 8 8 4 4 9 9 8 5

Safety use 10 7 8 3 7 8 8 8 7 9 4

Total Score 589 664 582 706 659 659 692 831 813 545

Ranking Points1 Leverage bar 8 5892 Brake Piston 5 6643 Bullet piston 9 5824 Spring system 3 7065 Tooth Hugger 6.5 6596 Screw Clamp 6.5 6597 Pneumatic Hand Nailer 4 6928 Hand Held Punch 1 8319 Slide Hammer 2 813

10 Super Sucker/Blower 10 545

Project 2003 ME-05 Bucket T
Table 2 - Decision Matrix
ooth Removal System 28


5.3 Final Design Selection

Upon completion of this project’s decision matrix, our design team further analyzed the results in order to select a final design to pursue. The low scores of (3) designs – Leverage Bar, Bullet Piston and Super Sucker resulted in the immediate disqualification of those concepts.

Considerable discussion within the team took place over the issue of the wide range in equipment designs and sizes. Large bucket teeth may weigh 60 lbs or more (see Figure 20) while small teeth weigh approximately 5 lbs. This range made a single solution very difficult because no one design could deliver the necessary force to push the bucket tooth pins out of the large teeth while still fulfilling the size constraints required for the use with small teeth.

Following further coordination with the customer, it was decided that multiple solutions were required – a tool that was suitable for small teeth and a separate tool that was capable of overcoming the larger required for a large tooth removal.

The lower forces required for small tooth removal reinforced the decision matrix results that showed that (2) hand tool designs – the Hand Held Punch and the Slide Hammer best met the design requirements. Both of there designs will be fully developed by this design team.

Figure 20 - Large Bucket

Five designs remained for large teeth. The Pneumatic Hand Nailer was eliminated

because the force it can generate is determined largely by the force applied by the operator and is small relative to the force delivered by a 15 pound sledgehammer. The Spring System was eliminated next because working with a spring strong enough to generate the necessary force would not be feasible and may be quite dangerous. The Tooth Hugger and Screw Clamp were eliminated because of the ability to generate a force large enough depends largely on the strength of the operator and the amount of mechanical advantage that can be gained using leverage, which would result in an unacceptably slow cycle time. The Brake Piston uses hydraulics, a superior way of translating operator strength into mechanical power and also allows the flexible positioning of the operator in various removal applications.

To summarize, multiple designs will be designed, fabricated and tested as follows. Small tooth removal = Hand tool concepts – both Hand Held Punch and Slide Hammer. Large tooth removal = Variation of the Brake Piston “system” concept.


6.0 Final Design, Fabrication and Testing 6.1 Hand Tool Design, Fabrication, and Testing

Having selected the Hand Held Punch and Slide Hammer as our tools of choice for removing small teeth, our design team created a more thorough design of each tool. These preliminary designs were provided to NIOSH for initial prototype fabrication at their facility. First generation prototypes are shown in figures 21 and 22.

Figure 21 - Hand Held Punch (First Generation) Figure 22 - Slide Hammer (First Generation)

Since the effectiveness of the tools depended on their ability to transfer a load to

the pin, the tool’s interface with the pin became a concern (see Figure 23 below). To accommodate this concern, several interchangeable attachments were designed making the tools applicable to all pin sizes and geometries. The tips of the attachments were also modified to strengthen the interface with the pin (see Figure 24 below). The different finishes on the attachments include:

• Waffle finish, to increase the attachment’s grip on the face of the pin • Concave finish, to cup the pin for better alignment • Tapered finish, to accommodate pins with small diameters

Any attachment can be used on any tool and attaches in the same way a socket

attaches to a ratchet.


Figure 23 – Interchangeable tool attachments

Figure 24 – Various types of tip finishes

Our initial prototype hand tools were subjected to testing that would replicate

their use for the removal of small teeth in simulated environments encountered in the field. The initial prototypes performed at an acceptable level, but our testing showed that some changes would enhance their performance. These changes follow:

• Slide Hammer

Change Reason Increased the mass of weight To generate more force per impact Increased diameter of slide rail To accommodate a larger weight Increased the triangular hand grip To accommodate larger hands with gloves

Added on the adjustable socket head To put on punch attachments of different lengths

Waffle the end of the tool To increase grip with pin surface


• Hand Held Punch

Change Reason

Diameter of the hand guard From 6 inches to 8 inches, to increase user comfort

Added a lip on the shield To prevent the hammer from deflecting off the shield and into the operator

Increased the length of the grip To increase user comfort

Put a rubber sleeve on the grip To reduce the impact force transferred to the operator

Changed impact head material from brass to steel To increase the strength and life of the tool

These improvements were incorporated into a final set of design drawings. In order to gain a full appreciation of the effect on a design on product manufacturability, the student members of the design team took on the task of fabrication of the final hand tool prototypes in the Gonzaga University machine shop. The final prototypes may be seen in the Figures 25 and 26, and design drawings are shown in Appendix C and D.

Figure 25 - Hand Held Punch (Second Generation) Figure 26 - Slide Hammer (Second Generation)

Upon completion of the prototypes, final testing was conducted on a Komatsu bucket donated by NORCAN Parts and Equipment of Spokane, WA. Pictures of the testing can be shown of Figures 27 and 28.


Figure 27 - Hand Held Punch Test Figure 28 - Slide Hammer Test

It was found that both the Hand Held Punch and the Slide Hammer provided a higher level of safety than the current removal methods without imposing higher levels of complexity on the user.

6.2 Hydraulic Cylinder System Design

6.2.1 Scaling the System

Having completed the Slide Hammer and Brake Piston, the team turned its attention to making the Brake Piston concept a reality. Since this design depended a great deal on the bucket and tooth geometry, we did extensive research on large buckets and large teeth and worked with local heavy equipment suppliers to secure a large bucket with teeth for design and testing purposes. Unfortunately, we found that the large-scale bucket and tooth sizes we needed are only used in limited parts of the United States where large open pit mining operations are still going on.

Budget constraints prevented us from having a rented bucket shipped to Spokane and the individual parts themselves were too expensive to build a full scale mock-up. After some deliberation, our team obtained a smaller bucket (95 inch) with teeth and horizontal pins from NORCAN Parts and Equipment (see Figure 29 below). The idea behind a smaller bucket was to produce a smaller scale variation of a Hydraulic Cylinder system that would be capable of being scaled up to match the sizing requirements of large buckets typically used for open pit mining operations.


Figure 29 - Bucket from NORCAN

6.2.2 Hydraulic Cylinder System Design

The hydraulic cylinder system the team came up with (See Figures 30 and 31 below) includes the following components:

• Hydraulic cylinder capable of generating enough force to push the pin out

• A hand pump which attaches to the cylinder and allows the worker to extend or retract the cylinder as required

• A jack which supports and positions the hydraulic cylinder

• Various attachments with go on the plunger of the cylinder in order to compensate for various pin diameters and pin lengths

• A plate that goes between the end of the hydraulic jack and the opposing tooth in order to prevent damage to the hydraulic cylinder

Figure 30 - Hydraulic Cylinder System (Front) Figure 31 - Hydraulic Cylinder System (Rear)


In order to use this system to remove a pin from a tooth, a worker would go through the following procedure:

• Position the cylinder on the jack such that the pin would be pushed out in the correct direction (pushed out such that the minimum amount of pin must go through the retainer)

• Elevate the jack such that the plunger of the cylinder is lined up with the pin

• Secure a suitable length attachment to the end of the plunger

• Put the plate between the hydraulic cylinder and the adjacent tooth to prevent damage to the cylinder

• Attach the hand pump to the jack and begin extending the plunger

• Push the pin out of the retainer

• Retract the plunger

The advantages of this system are as follows:

• Increases worker safety by eliminating danger from “impact forces”

• Does not rely on physical strength of operator

• Can be used for multiple tooth and pin sizes

• System is portable and can be used both in the field and in the shop

6.2.2.1 Cylinder Selection and Modification

Having acquired a bucket for testing, our team began designing the Brake Piston. We started by choosing an appropriate cylinder from the ENERPAC catalog. We had 2 physical constraints when choosing a cylinder:

• Length between teeth (7 to 7.5 inches)

• Distance between the lip of the bucket and the pin (2 inches)

Using these geometric constraints, the design team selected the ENERPAC RCS201 cylinder which has the following features:

• Collapsed height of 3.88 inches

• Stroke length of 1.75 inches

• Overall diameter of 3.63 inches

• Inner cylinder diameter of 2.38 inches

• Weight of 11 pounds

In order to make the inner cylinder compatible with the smaller diameter of the tooth pin, a cylinder adapter was designed (see Figure 32). This adapter includes a socket adapter, which is welded to the base, to accommodate various lengths of extensions to


remove and install the pins. The adapter is secured to the inner cylinder using a pair of recessed screws.

Figure 32 – Cylinder Adapter

6.2.2.2 Jack Selection and Modification

To support and provide positional location to the hydraulic cylinder, the design team chose to utilize the means of a simple floor jack. A used car jack was modified by welding on two plates to fore a “V” cradle for the cylinder to rest in. In addition, a 3/8 inch bolt was welded to the jack actuator in order to allow extension and retraction of the jack by a ratchet (see Figure 33). Finally, a 1/8 inch backing plate was fabricated to match the cradle geometry. This plate is inserted between the base of the hydraulic cylinder and the adjacent tooth to prevent damage to the cylinder due to pin protrusion or uneven too surfaces.

Figure 33 – Hydraulic Cylinder System in working position


6.2.2.3 Hydraulic Cylinder System Modification and Testing

With all necessary components now fabricated, final assembly of the completed system was performed at the NIOSH test facility (see Figures 34 and 35).

Figure 34 - Side View of Cylinder System Assembly

Figure 35 - Isometric View of Cylinder System Assembly

Alignment of the cylinder parallel to the pin to be removed or inserted was easily accomplished by the flexibility allowed by the jack. As hydraulic pressure was applied to the cylinder, the extension of the cylinder securely lodged it between adjacent bucket teeth (see Figure 36). Utilizing a pressure gauge on the hydraulic hand pump, it was determined that the pin was pressed from the retainer washer with 100 lbs of applied force.

Figure 36 - Set Up of Hydraulic Cylinder System


7.0 Conclusion

In conclusion, this project successfully designed, produced and tested several alternative tools to be utilized for the safe removal of heavy equipment bucket teeth. These tools have proven to be simple to use, effective and affordable, therefore making their use practical for the mining and construction environments. The availability of multiple choices in tools allows the user to select the tool that is appropriate for the size of equipment being worked upon, thereby improving both efficiency and safety.


8.0 Acknowledgements

Our team would like that acknowledge and thank the following individuals and companies for their support during the duration of this project:

• Western States Equipment Company • Modern Machinery Company, Inc • NORCAN Parts and Equipment Company • Ed Martz, Gonzaga University Machine Shop Technician

Figure 37 – Team Photo

(L to R, Grant King, Rudy Lauth, Brian Gaither, Luis Real, and Tom Zysk)


APPENDIX A

EXPLANATION OF CUSTOMER REQUIREMENTS


Requirement Detailed Explanation

One Person Operation

The ability of a single person to setup and use the device. The easier a device is to use, the better the score. Extra support equipment, such as an external air supply, do not affect scores unless an additional person is required to operate it during use.

Product Costs Less than $100 Final product cost (i.e. MSRP). Lower cost results in a better score.

Reparability/Maintenance

The ability to fix the device out in the field should something break. The tendency for the device to break is not included in this requirement (see “Durable” below). The easier to fix the better the score.

Minimal Training The amount of training needed to operate the device as it is designed to be used. The less training required the better the score.

Durable The ability of the device to withstand abuse during operation and anticipatable field hazards such as being dropped or run over. The more durable the better the score.

Patentable While this remains as a customer requirement, it is not weighted in our decision matrix.

No damage to bucket, tooth, or pin

The device should not cause damage to the bucket, tooth, or pin during normal operation or foreseeable device misuse. The less prone to damage the higher the score.

Short time for operation

The amount of time it takes to extract or insert a pin relative to the current punch and hammer method. Any setup time, such as a required external air source, is factored into the score. The shorter the cycle time, the higher the score.

Operable in a hostile environment

The ability of the device to operate in extreme environments such as dust, dirt, water, mud, hot, cold, or spark sensitive areas. The more versatile the device is to operate in these conditions, the higher the score. Alternate designs, such as using a different metal to prevent sparks, is allowed without jeopardizing the score.

Capable of working with different tooth geometries

The ability of the device to work with different tooth geometries and pin configurations. This includes horizontal, vertical, and angled pins of varying cross sections, as well as tooth geometry restrictions such as spacing between teeth and overall tooth dimensions. The more versatile the device, the higher the score.

Safe to use

The overall safety of the device during normal use and foreseeable misuse. The less likely the operator is to be injured by the device or the process of using the device, the higher the score.


APPENDIX B

HYDRAULIC SYSTEM SET-UP AND WARNINGS



The following is a list of warning and precautions that should be adhered to when using the Slider Hammer, Hand Held Punch, and Hydraulic Cylinder System:

• Always wear personal protective equipment when using the tools (i.e. safety glasses, gloves, ear plugs, etc)

• Always make sure the hydraulic cylinder is lined up parallel to the pin to avoid eccentric loading

• Always read the operator’s manual (from ENERPAC) before using the cylinder

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