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BSE 509 Senior Design Student Project "Hand Controls for Utility Vehicles"

Abstract

A hand control modification product was designed and installed on several of the leading utility vehicles on the market today. This product was designed to help people who are unable to use the speed and brake pedals. There are no available products made specifically for utility vehicles. Any type of modification that has been done was a custom application. There are many different areas in which a utility vehicle can be utilized such as: farming, ranching, hunting, construction, and athletics. Without full use of the legs, the operation of a utility vehicle becomes difficult. Our goal was to make an option available to solve this problem so that everyday activities can be done without assistance.

Project Introduction

A utility vehicle can be very useful for working around the farm, however people with disabilities such as arthritis, amputations, or paralysis are virtually unable to use or operate a utility vehicle because they cannot operate the foot pedals. "The USDA estimates that as many as 20 percent of the nation's agricultural workers have disabilities that interfere with their work." (Virginia Cooperative Extension, 2002) Spinal cord injuries as well as amputations make it impossible to use the foot controls to operate the utility vehicle. (PE Central, 2005) This means that a hand control modification that replaces the foot controls is required in order for the vehicle to be operable. Arthritis can also make it very painful and virtually impossible to use the foot pedals. These disabilities may also limit hand and arm movement which means that to be most beneficial the hand controls must be both easy to grip and easy to move. Hand controls with thicker, longer handles as well as a cushioned surface require less force and provide more comfort (AgrAbility Project, 2003), which may make it possible for someone with arthritis to operate the vehicle for a longer period of time and with less pain than would be possible using the foot pedals.

Design Goal and Specifications

The goal of this design was to create a low cost, easily operated, quickly installed, and unrestricting set of hand controls that can be fit to most of the utility vehicles available today. Developing a set of design specifications was important for guiding the design process. Original design specifications are as follows:

1. The target price for a purely mechanical system is less than $400; of course the addition of any electronic, pneumatic, or hydraulic components will require a revision of this amount.
2. Installation time of 2 hours or less on all leading models
3. Use of the controls is to be designed with a force between 3 and 8 pounds (AgrAbility)
4. Control handles should be round and 1.5" to 2" in diameter (AgrAbility)
5. Handgrip should be at least 3" long (AgrAbility)
6. Control handles should be covered in a padded non-slip material such as rubber (AgrAbility)
7. The presence of the modified controls will not alter the normal use/operation of the machines (AgrAbility)
8. Any part of the hand control system that may come into contact with the operators legs should be padded. (AgrAbility)
9. The modified controls will have less than a $100 devaluing effect on the vehicle.
10. The controls are to universally fit most of the markets leading utility vehicles.
11. Design will include a safety factor of 3 or higher
12. Design will follow all applicable ASABE, SAE, ISO, and ADA standards and restrictions including: SAE J1138 , SAE J1139 , SAE HS24 , SAE J386 , SAE J833 , ASAE S335 , ASAE EP443 , ASAE S318 , ASAE S304 , ISO 5349 , and more.

Design Production

After a design was chosen from the initial six ideas, research was conducted to obtain measurements from utility vehicles within the industry. The design team came up with a series of sixteen measurements needed to develop a design. Focusing on four of the major manufacturers (Polaris, Kawasaki, Yamaha, and John Deere), measurements were taken from the following 2005 models: Polaris Ranger 4X4 EFI, the John Deere Gator TX, the Kawasaki Mule 3010 4X4 Diesel, and the Yamaha Rhino 660 4X4.

The models and the measurements retrieved from these vehicles were analyzed to evaluate for similarities. A similar mounting position would be needed to attach the hand control on each of the models. After consideration for interfering with standard operation, a mounting position underneath the dash was selected. Similar on all models was a steel cross-member support extending across the width of the vehicle, just underneath the dash. These members were chosen for the mounting positions because they would keep a mounting bracket "out of the way," as well as provide a structurally sound anchoring position for the attachment of any mechanical system.

Final Product and Specifications

• Weight is approximately 10 pounds
• Average handle diameter with accelerator fully depressed is 1.5 inches
• Material cost of approximately 65 dollars
• Labor cost to manufacture equals about 100 dollars
• Installation time with 2 people is less than 30 minutes
• Maximum force required to apply hand brake is 5 pounds
• Maximum force required to change speed is 7 pounds
• Length of hand grip is 6 inches
• Hand grip and speed lever are coated with non-slip, cushioned, vibration-dampening material
• Areas near the legs are padded to prevent injury
• Presence of the hand controls will not hinder the use of the foot controls
• The modification will not devalue the utility vehicle
• The safety factor is 1.5 times the design goal of 3 using 1020 steel
• The controls were painted black for appearance and protection

Pictures

• View of the complete Hand Control sitting on the rear of the Utility Vehicle
• Close up view under the dash of mounting Hand Control on Polaris Utility Vehicle
• Close up view under the dash of throttle connection of the Hand Control on Polaris Utility Vehicle
• Close up view of handle of Hand Control as mounted on Polaris Utility Vehicle

Parts

Fabrication Procedure

All pieces/fasteners can be fabricated according to the design drawings or obtained from the given part numbers or specifications. Assembly drawings should be followed when fabricating all parts.

Main Mounting Bracket

1. Weld the strip with the six holes in it (Part MB-1) to the back side of the main mounting bracket according to the assembly drawing.
2. Now weld the ½ in NC nut to the front side of the bracket 1.5 inches from the center of the nut to the right side of the bracket. The top of the nut should be flush with the top of the bracket.

Main Handle/Lever with Main Mounting Bracket Assembly

** All angles needed for this assembly can be found in the Assembly H drawing**

1. Weld the brake cam to part H-1 according to the assembly drawings.
2. Insert this piece into the main mounting bracket MB holes so that the brake cam is on the left side.
3. Once the pipe is all the way through both holes, weld part H-1.1 to the end of the pipe opposite the brake cam. This prevents the pipe from moving laterally.
4. Next pull the pipe as far to the left as possible so that part H-1.1 is touching the right side of the main mounting bracket. Now weld on part H-1.2 to the pipe on the inside of the bracket closest to part H-1.1. Leave about 1/8 inch space between this part and the mounting bracket. This now secures the pipe in its lateral position.
5. Now weld part H-2.1 to part H-2 according to the assembly drawing.
6. With the main mounting bracket clamped to a level surface, weld part H-2 to part H-1 according to the assembly drawing.
7. Now weld part H-3 to part H-2.
8. Next weld part H-4 to part H-3.
9. Next weld part H-5 to part H-4.
10. Part H-6 needs a plastic coating on the final 6 inches of its length. This can be done now or later during assembly.
11. Weld part H-6.1 to part H-6.
12. Finally weld part H-6 to part H-5 according to the assembly drawing.

Throttle Lever Assembly

1. Place throttle lever over handle aligning it with the mounting hole.
2. Slide in bushings and spacers between the throttle lever and handle. Make sure the spring is also slid in on the side with the cable attachment post.
3. Now guide the bolt through the hole making sure it goes through all bushings and spacers and tighten down nut on other side.
4. Slide the spring ends into position and test to make sure the lever operates correctly.
5. Now the throttle cable can be attached to the post on the throttle lever and secured in place with the retaining washer.
6. Part 12 can now be installed into the hole on part H-6.1 and tightened down around the throttle cable.
7. The other end of the cable can be slid through part 1 and loosely bolted on.

*These cable attachments will need to be adjusted during vehicle mounting.

Handle Attachment Procedure

Read all directions before beginning assembly.

1. On all models, excluding Polaris Ranger, attach model specific bracket to handle bracket. Align all four holes and attach with provided fasteners.
2. Locate and mark desired mounting position on vehicles main frame member(s), just underneath dashboard. Position should not compromise standard operating procedures. Brake cam should be located directly over brake pedal in the left/right oriented direction and as close to brake pedal as possible in the front/back oriented direction.
3. With help, hold assembly in marked position and insert provided U-bolt fasteners. Tighten all lock nuts simultaneously, making sure that assembly stays in desired location.
4. With the handle in place, adjust the handle stopping bolt to the desired position to keep the handle from contacting the dash. Caution, if this adjustment causes the brake cam to engage the brake pedal, then the mounting position must be adjusted to account for this movement!
5. Choose a mounting position for the Throttle Cable Mounting Bracket that best aligns the throttle cable and the gas pedal in the left/right oriented position. Tighten this nut in place.
6. Mount the gas pedal mounting brackets on the gas pedal.
   • Choose a position "in line" with the throttle cable.
   • With one bracket on each side of the pedal lever arm, tighten the bracket bolts until bracket can no longer move.
7. Adjust the nuts on the threaded end of the throttle cable until a gap of approximately 3 inches is achieved.
8. At this time, double check to make sure the brake handle engages the brake system of the machine.
9. Measure the distance from the peg on the gas pedal mounting brackets to the end of the throttle cable sheath. Adjust the loop at the end of the throttle cable to this length, making sure to leave the soft metal clamp at least 1 ½ inches away from the end of the sheath to allow for cable travel. Apply enough force on the soft metal clamp to completely lock the loop into place (use of a vice-grips is recommended). Snip and dispose of extra cable.
10. Place cable loop over the clamp peg and then place lock washer on peg to hold loop in place.
11. Test throttle before use. Adjustments can be made on the threaded end of the throttle cable to tighten or loosen the cable tension.

Acknowledgements

We would like to acknowledge our advisors for this project, Prof. Ron Schuler and Mark Novak. A special thanks also goes to Middleton Power Center and Mid-State Power and Equipment for their cooperation throughout this project. A very special thanks to Brian Hitt and Polaris Industries for lending us a Polaris Ranger over the length of the project.

References

Virginia Cooperative Extension. (2002) AgrAbility Program Offers Assistance to Farmers with Disabilities. (www.ext.vt.edu) This article talked about the Virginia Agrability Project as well as how many people physical disabilities causing them to need up with their agricultural work.

PE Central. (2005) Spinal Cord Injury: Fact Sheet. (www.pecentral.org) This article discussed the make-up of the spinal cord as well as what abilities one might have depending on where along the spinal cord the injury occurs.

AgrAbility Project. (2003) What to look for when selecting or modifying hand tools to provide a better fit with the user. (www.agrabilityproject.org) This article discussed what someone should look for when purchasing a hand control system. It also talked about some of the ergonomic factors to look at when designing a hand control system.