DRIVER-CONTROLLED LOCKING DIFFERENTIAL Dallas Moore A

DRIVER-CONTROLLED LOCKING DIFFERENTIAL

w Dallas Moore II

A project

submitted in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Industrial Arts and Technology

California State University, Fresno August 1975 TABLE OF CONTENTS

Page LIST OF FIGURES ...... v

INTRODUCTION 1 STATEMENT OF PROBLEM 1

IMPORTANCE OF STUDY ...... 2

LIMITATIONS OF STUDY ...... 3 SOURCE OF DATA . 3

DEFINITION OF TERMS ...... 3 REPORT OF THE STUDY ...... 5 CONCLUSION AND RECOMMENDATIONS ...... 1^

APPENDIXES !5 A. Letters of Inquiry ...... 16 B, Illustrations; True—Trac Limited Torque Bias

ing Differential 24 BIBLIOGRAPHY LIST OP FIGURES

Figure Page 1. Torque Bias - View A ...... 8

2. Torque Bias - View B...... 9 3. Torque Bias - View C ...... 10 Driver-Controlled. Locking Differential . . 11 5. Spicer Model^4 Differential with Axle "Tubes Removed and Modified Shifting Linkage Mounted in Cover ...... 12

6. Locking Block Assembly and Shifting Ring As Used in Proto-Type Driver-Controlled Locking Differential ...... 12 7. Locking Block Assembly and Shifting Ring Mounted in the Differential Case .... 13 INTRODUCTION

The last decade has ushered in a period of sales mania for the recreational vehicle field, to the extent of being almost unbelievable."'"

Boats (Outboard Motors) $204 million 1957 $473 million 1974 i Boat Trailers 148,000 units 19&3 325,000 units 1974 Motorcycles (Reg, California) 1,700,000 1966 3,293.^00 1971 Motorhomes (Executive Indus- Two hundred $20,000 tries mass production) units May, 1975 With all the various types of recreations available, each seeks to offer the chance for the participant to get away. As a result of this writer's observations of people using these "get away vehicles" in out-of-the-way places, he began to investigate the feasibility 01 a low-cost driver-controlled locking differential.

Statement of Problem It was the purpose of this project to design and construct a device that would aid a driver in freeing his vehicle from its mired position by flipping a switch

1..EVR/DMS Reports!_Exee«tire Officers' Stocks," Recreat1 onal— — — 1975). 15. 2 on the dashboard arid driving out.

The project centered around a device that would be simple and low cost, with installation necessitating use of hand tools only, and no modification machining on the vehicle's differential. The device was primarily designed for installation on vehicles which would rarely be used off the more travelled roads. It was not intended to be used on vehicles traversing difficult terrain regularly. The owners of today's recreational vehicles do

have many options to help them cope with the problems of getting mired down, but they are certainly expensive com

pared- to the "under fifty dollar" device to be developed in this project. The approximate costs of the following

options are as follows: Winch (Warn #8200) j>25.80 Positrac Differential (Warn WP-4) 2^-5.50 Four Wheel Drive (Optional) 1,000.00 Approx. General Motors-West Coast

Importance of Study This study was necessary to provide the writer

with pertinent Information regarding the feasibility of marketing such a device for today's recreational vehicle

The alternatives a recreational vehicle purchaser would

have all seem to be rather expensive, thus the decision

to make this study. Limitations of Study

This study deals exclusively with American-made vehicles, components, and their sales statistics.

Source of Data Information concerning the various types of avail able limited slip axle units was obtained from many dif ferent manuals and references. Sources include materials received during correspondence with Eaton Manufacturing

Company. Materials were also obtained from Detroit Auto motive, as well as numerous interviews with people in related fields, one of the persons being Mr, Victor Hickey of Rickey Enterprises, Ventura, California,

Definition of Terms Backlash: The amount of free play between the ring gear and drive pinion. Bearing Preload: The amount of side pressure

placed on bearing, through adjustment, that carries heavy loads. Differential Case, A ease that contains both the

differential pinion gears and side gears. Differential Cover: .A cover that is removable for inspection and maintenance of the differential. Differential Pinion Gears: The gears which pro

vide torque between the differential case and side gears. k Drive Pinion Gear: The drive gear for the differ ential in an automobile.

Pinion Depth: The relative position of the pinion drive gear in the differential housing.

Recreational Vehicle (R.V.): Vehicles designed primarily for recreational use, such as Motorhomes, Off-

Road Vehicles (O.R.V.) and dual purpose vehicles such as a Utility Pickup Truck that is equipped with a slide-in

camper or a Four-Wheel Drive IJtility/R.V. Jeep, Motorcycle,

etc. Ring Gear: The driven gear that conveys the power

to the axle side gear in an automobile differential. Side Gear: A gear which receives torque from the

differential pinion gear and transfers it to the axle.

Thrust: To push forcibly. Toraue: That which produces or tends to produce

torsion or rotation. Torque Bias; A particular tendency of one wheel

to absorb the torque produced by the engine of a vehicle. Traction: The adhesive friction of a body, as

of a wheel on a rail. REPORT OP THE STUDY

It is necessary at this point to discuss some of the drawbacks to the regular limited slip units that make them undesirable for the vehicle that is used infrequently where more traction is needed. As discussed earlier, these units are expensive, not only upon initial purchase but in increased operational costs of the vehicle. Due to their design, the units work, regardless of need; therefore, rear tire life is greatly reduced. The units emit an annoying noise, and axle breakage is much more common in vehicles using these units. Some of these designs revert back to a standard differential s,fot>.r ap proximately 30,000 miles because by then the clutches are worn out. In addition, many complaints have been regis tered about the characteristic hard turning. For the project a Spicer Model m differential, commonly found in automobile and pickup trucks was chosen. This model was used because it represented a wide range of vehicle applications and is a very strong unit. Photographs of components designed and fabricated are found on pages 12 and 13- A piece of mild steel was milled and drilled to the proper dimensions for this appli cation to make up the locking block, cam, and cam follower units. 6 The next unit to be constructed was a shifting ring and its necessary linkage needed for the constant con trol of the unit whether engaged or disengaged.

Considered next was the differential cover selector and linkage which could be either cable or electric solenoid operated. Having a device that could be driver-controlled would be much more desirable for most drivers since it would only be engaged when needed, thus reducing the cost. For most drivers it would be the occasional muddy stream crossing or unnoticed mudhola that would give the problem. With this situation, the driver could engage the differential, and in most cases could drive out of his predicament with just the added traction the other wneel

would afford.

The Driver-Controlled Differential was designed

to be engaged only after the vehicle has been stopped.

This is to keep the cam followers from damaging the dif ferential pinion gears upon engagement. To eliminate the

possibility of accidental engagement, the spring-loaded

toggle switch could be mounted under the dash, and fch- driver would have to keep his finger on the switch to keep

it engaged. A warning light could also show when the unit

is engaged. The looking block Is designed in such a manner

as to restrict the differential pinion gears from turning when the unit is engaged, (See Figures 1, 2, and 3.) The torque is then cancelled out in a self-energizing manner because each gear rotates in opposite directions. Any residual thrust would be conveyed to the differential pinion gear shaft by the locking block, and thus eliminated.

Cam followers and cams contained within the lock ing block would be responsible for the engagement of the device. These units are operated from the outside of the differential housing by a shifting ring and its necessary linkages. The original specifications pertaining to backlash, pinion depth, and bearing preload would be used. 8

Figure 3.

TORQUE BIAS View A 9

Figure 2 TORQUE BIAS

View B 10

Figure 3 TORQUE BIAS V lew G

Figure 5 SPICER MODEL DIFFERENTIAL WITH AXLE TUBES REMOVED AMD MODIFIED SHIFTING LINKAGE MOUNTED IN COVER

Figiire 6 LOCKING BLOCK ASSEMBLY AND SHIFTING RING

PHOTO-TYPE DRIVER-CONTROLLED LOCKING DIFFERENTIAL 13

Figure 7 OCKING BLOCK ASSEMBLY AND SHIFTING RING MOUNTED IN THE DIFFERENTIAL CASE CONCLUSION AND RECOMMENDATIONS

The following conclusions were formulated from this project:

1. This unit is nob as easily adapted to other model differentials as it was originally thought to be.

2. The processes involved are more detailed, thus raising the projected price much higher than anticipated and resulting in its being above the competitive price range of

$50 or less. 3. A far superior design was discovered to be ready for marketing by Detroit Automotive under the name of

True-Trac (Appendix, pages 21-23* ) While the differential specifications would

remain the same, it is unknown just what the wear factor

would be when used under extremely difficult circumstances.

5. A very simple unit utilizing silicone is now

in the experimental stages. The simplicity and performance

of this unit is remarkable, according to Mr. Vic Hickey of

Hickey Enterprises, who has witnessed experimental tests.

Any further study in this area would probably be

relatively fruitless as there have been several attempts a ornprimental vehicle by both large auto manufacturers an.

companies to develop such a device. APPENDIXES APPENDIX A Letters of Inquiry 189 Eugenia Drive Ventura, Ca. 93003 February 6, 1975

Warn Industries 9050 Empire V/ay S. Seattle, Wash. 98118

Gentlemen: I would appreciate any information you would be able to supply me concerning a driver- controlled locking differential. Presently I am working on a driver-controlled solenoid operated unit for passenger vehicles for a master's degree project.

Any information regarding design, feasibilit, of such a unit, or anyone manuiactaring a unit would certainly be appreciate »

Sincerely

Dallas B. Moore I89 Eugenia Drive Ventura, Ca. 93003 February 6, 1975

Eaton Corporation Truck Components 26101 Northwestern Highway Southfield, Mi. 48076

Gentlemen: I would appreciate any information you would be aole bo supply me corcerning a driver-controlled locking differential. Presently I am working on a driver- controlled solenoid operated unit for passenger ve hicles for a master's degree project.

iainly be appreciated.

Dallas B. Moore DETROIT AUTOMOTIVE Ditision of ASPRO. INC. P.O. Box 882 11445 Stephens Dnve Warren. M'Chigan 48090 (513! 759-3850 Telex 23-0109

June 17. 1975

Mr. Dallas Moore 189 Eugenia Drive Ventura, California 93003

Dear Mr. Moore:

Thank you for your letter of June 9. Mr. Jeffers is no longer with Detroit Automotive.

I am sending you brochures on our True-Trac Difierential and NoSPIN. I hope these will be of use to you.

Sincerely,

Kathy Wojas, Secretary Advance Products Group

/kw Encs APPENDIX B

True-Trac Limited Torque Biasing Differential TORQUE BIAS OF THE TRUE-TRAC DIFFERENTIAL

2 6 h™ < cc 5 CO < S3

3/4 TON TRUCK

0 200 400 600 800 1 000 0 200 400 600 800 1000

COMBINED TORQUE TO AXLES, LB-FT COMBINED TORQUE TO WHEELS, LB-FT

200 400 600 800 1000 3000 6000 SOOO 12000 COMBINED TORQUE TO WHEELS, LB-FT COMBINED TORQUE TO WHEELS, LB-F7 BIBLIOGRAPHY 25 Automotive Editorial Department. Chilton's Repair and Tune-up Gulde-»Blazer Jimmy. Radnor, Pennsylvania: Chilton Book Company, 19W7

Chilton's Auto Repair Manual--1971» New York: Chilton Book Company, 1971. Crouse, William H. Automotive Chassis and Body. 3d ed. New York: Webster Division McGraw-Hill Book Company, 1966.

. Automotive Mechanics. 6th ed, New York: McGraw- Hill Book Company, 1970, . The Auto Book. New York: McGraw-Hill Book Company"^ 197^. / Eaton Truck Aries--Service Manual Ea-10^. Southfield, Michigan: Eaton Corporation, 1972. Porier, Louis C., S.A.E., and others (eds.). Motor's Auto Repair Manual. 35th ed. New York: Motor, The Auto motive Business Magazine, 1971. Kelm, Paul W., and others. National Service Data Domestic. San Diego: Mitchell Manuals, Inc., 1973. 1959 Pontiac Shop Manual. Pontiac, Michigan; General Motors Corporation, 1959. 1973 Car Shop Manual—Chassis. Volume 1, Dearborn, Michigan: Ford Marketing Corporation, 1973. Rosen, Erwin M. (ed.). Petersen's Complete Book of Four- Wheel Drive. Los Angeles: Petersen Publishing Com pany, 1975» "RVR/DMS Reports: Executive Industries Buys Back Officers' Stocks," Recreational Vehicle Retailer, July, 1975. p. 15. Service Manual—Jeep Universal Series. Toledo: Jeep Cor- poration, 1970. Stockel, Martin W. Auto_Segrtoe

Toboldt, William K., and Larry Johnson (eds.). Motor Service's Automotive Encyclopedia. Homewood, Illinois. The Good.heart-v/ilicox Co., Inc ., 19°« « True-Trac: A 'T^rpie neslgn for Traction, Warren, Michigan: Detroit Automotive, 1975 •