Worldwide Tractor Test & Development History

William Schubert

December 12, 2015  

 

I was appointed Product Test & Development Engineer in 1967 to lead the development and test group for the Worldwide tractor program at the International Harvester Engineering Center located at 7 South 600, County Line Rd, Hinsdale, IL (the address is now Burr Ridge, IL). I have a BS degree in Agricultural Engineering (1960) with emphasis on Power and Machinery from the University of Illinois. I also completed all the course work for a MS degree in Ag Engineering, but unfortunately I never did complete my thesis. I grew up on a farm located near Trenton, Illinois which is about 30 miles east of St. Louis, and had always liked working with agricultural machinery, especially tractors. I started with International Harvester in Dec 1961. The Worldwide Test & Development Group consisted of four to ten employees that varied as the program progressed. Several had Engineering degrees, but most had learned their trade working on other tractor projects through the years.

 

The major emphasis for the Tractor Engineering Group at that time were the Farmall Plant, Rock Island, IL products, so I had to do some creative things to get the development and test work done here at the Engineering Center. Considerable development work was done in the Engineering Center labs before and during the testing phase of the project. Some of these development activities were very detailed and extensive in order to meet the performance and durability requirements set for the Worldwide tractor models. Note that a lot of the development work was applicable to all three models: 454, 574 and 674, although there were obvious differences to accommodate the differences in horsepower and vehicle mass. The various areas of emphasis are detailed below:

 

Vehicle development testing:

Power train development

               Rear axle planetary gear sets and bearings

               Rear axle shafts

               Bevel gear set / rear frame deflection evaluation

               Range transmission gear sets and shaft

               Speed transmission gear sets and shafts

               PTO driveline and clutch

               Master clutch

               Differential gear set and diff lock mechanism

               Speed transmission synchronizers

               Wheel brake function, performance to OECD braking requirements and durability

               Park brake function performance to OECD braking requirements and durability

               Lubrication oil management to insure proper lubrication at all potential vehicle operating angles

               Torque amplifier function and control system

               Hydrostatic drive performance, noise reduction and control functionality

Cooling

               Engine   

               Hydraulic system

Hydraulic system

               Power steering

               Three point hitch

               Auxiliary valves

               Hydraulic wheel brake system

               Torque amplifier control and lubrication

               Transmission lubrication distribution

                            Evaluate at vehicle operating angle of 30 degrees of all combinations of nose up or down and side to side

                            Full load at high and low ambient temperatures

               Hydrostatic transmission lubrication

Three point hitch

               Linkage

               Draft control

               Control levers

Cold temperature function and performance to -30 degree F

               Engine start

               Hydraulic system

               Hydraulic brake system

Chassis

               Complete chassis structure stress coat and strain gage analysis

                             Rear frame and speed housing

                             Engine block

                             Front axle bolster

                             Complete front axle (three different designs of front axles offered)

                             Three point hitch linkage

                             Three point hitch

                             Swinging drawbar and drawbar support and front pivot bracket

                             Sheet metal

               Vibration and noise reduction

                             Hydrostatic transmission

                             Sheet metal

                             Operator foot rests

               Vehicle lighting (Doncaster Engineering did the work on European lighting)

               Miscellaneous

                             Cooling fan blast attenuation

                             Operator control function

                             Serviceability rating

 

Vehicle endurance testing conducted at Engineering Center:

Specific endurance tests were completed on the following areas of the vehicle prior to releasing the Worldwide tractor series for production:

               Chassis/Frame/Front and rear axles/Front weight bracket/Sheet metal/Three point hitch

                             Torture track

                             Jerk test

                             Sway test

               Power train

                             Speed transmission gearing, shafts and bearings

                             Range transmission gearing, shafts and bearings

                             Bevel gear set and differential gearing, shafts and bearings

                             Planetary final drives gearing, shafts and bearings

                              Master clutch

                              Wheel brakes—Internal wet oil cooled single disc each side

                              Park Brake—Internal wet oil cooled band brake

                              Synchronizer

                              PTO—Internal wet oil cooled multi disc

               Three point hitch/Swinging drawbar

                             Draft sensing torsion bar

                             Hitch linkage

                             Draft, position and raise rate control lever linkage and friction disks

                             Swinging drawbar anchor, rear support and bar

                             (Doncaster completed testing on various trailer hitches for Europe)

 

Vehicle performance and endurance field testing:

The prototype tractors were also tested in the field in various areas of the US and UK prior to releasing the Worldwide tractor series for production. In the US, field testing was completed in the area of the country where sales were expected to be highest. That included the states of Texas, Alabama, North and South Carolina, Kentucky, Tennessee and Georgia as well as some farms around the Engineering Center. UK testing was done in the farming area surrounding the Doncaster plant. (Possibly Graham Dixon could provide more detail on the field testing done in the UK.  He left the company in the early 1980’s. I think he lived in the Sheffield area at that time. I do not have a phone number for him but his address may be “Cooks Wood Road, Sheffield, South Yorkshire, S3”).

 

Early on performance testing was completed on the following areas:

               General vehicle performance in a variety of field conditions with a variety of different implements

               Draft control performance

               Operator comfort – engine heat, fan blast/dust stirring/transmission case heat impingement on operator

 

A lot of detailed information could be supplied on each of the above items if needed, but I would first just like to highlight a few of the more interesting developments that occurred during the project. 

 

One interesting aspect was the way we did powertrain endurance testing during this project. In this time frame, IH tractors were normally tested on the 1-1/8 mile paved test track located at the Engineering Center where 24 hour/day operators drove the tractors around the track pulling ”load  machines” made from previous prototype tractors. The exhaust on the load machines was restricted to provide a load on the test vehicle. Each test vehicle followed a prescribed test plan so that each gear speed was tested at full load. As indicated above, the Farmall line of tractors had priority and was consuming all of the resources for the test track. In order to test the WW tractors, we developed a treadmill setup where the load tractor was set up in pit and equipped with smooth steel wheels/rims. The test tractor was anchored above the load tractor so that the rear wheels, equipped with smooth rubber tires, were positioned on the steel wheels. A fuel supply was connected and additional safety controls were added so the test setup could be operated unattended 24 hrs/day.  Again, the test plan required testing of each gear selection at full load, and a technician would make the necessary gear changes and adjust the load as necessary. He would also periodically monitor the setup. In fact, we had two of these setups so we could cover the variations on the models and more efficiently endurance test the powertrain than was possible on the test track.  This system worked so well that the powertrain endurance testing moved in this direction and so now powertrains are tested in a test cell that is equipped with wet disc type load absorbers attached to each axle, including MFD if equipped, and everything is computer monitored and controlled and operates unattended 24 hrs/day. I was deeply involved with the design and development of this test setup. The test track operators where happy to see this development, as they had to be on the track driving in the rain, snow, and cold weather on tractors without cabs!

 

I had started my career at IH working in the Hitch T & D group, so I was very familiar with the problems and shortcomings of the draft control systems on the tractor. I was determined that we would overcome some of these problems – one in particular was the hysteresis of the torsion bar system which caused poor draft regulation. Working with the design group, we developed a top link torsion bar system that had no hysteresis because it had no pivot bearings at all. The ends of the torsion bar were welded to a bracket, while the top link anchor was splined to the center of the shaft. The twisting or movement of the torsion bar could occur without any hysteresis, which means the draft control system could sense very small load changes which significantly improved the draft control function of the 3-point hitch. Another addition to the draft control that I championed was the ability to independently set the hitch raise rate, which I pushed so hard on that it almost got me fired, but in the end it was incorporated and again enhanced the draft control performance. The open center hydraulic system on this tractor had what was called an unloading valve that would open after demand was satisfied. The problem with the valve was that it made a snapping sound each time it closed on hydraulic demand. When draft control was operating, this opening and closing could occur three times a second, which resulted in an annoying sound for the operator—especially since the valve was located right under the operator’s seat. Again working with the design group, we developed a spool-type valve that overcame the problem.

 

This was the first farm tractor in the industry that utilized synchronizers on the speed transmission gear selection.  This was a significant advancement, and greatly improved the functioning of the tractor. Unfortunately, IH had no test procedures of test requirements established for synchronizers, so I had to develop the test procedures, criteria and a test stand for these units. The test stand was unique in that it consisted of a speed transmission with a stripped down rear frame that only contained the bevel pinion shaft. An engine was attached to the bevel pinion shaft so the setup was driven from the rear. A master clutch driven plate was attached to the speed transmission input shaft as this represented the inertia element along with gearing and shafting that would be accelerated or decelerated during each gear change. This setup represented the situation that occurs during a gear change in that the under roading conditions, the vehicle inertia keeps the bevel pinion shaft rotating at a constant speed while the synchronizer accelerates the master clutch plate and speed trans gearing during a gear change. The test setup realistically tested the synchronizers under real world conditions. Sufficient controls and safety equipment allowed the test stand to operate unattended 24 hr/day, again providing very efficient endurance testing of the synchronizers.

 

The planetary final drive was also new to IH, so we spent considerable development time insuring that the components had sufficient life to meet the IH powertrain criteria. Planet gear bearing progressed from a simple shaft support through bronze bearings to needle bearing and finally to tapered roller bearing which satisfied the life criteria and went into production. We also had to do considerable sun gear tooth profile development to optimize the tooth load pattern for the various load conditions that the vehicle would encounter. The endurance test rig, discussed previously, was invaluable in allowing us to quickly test the various iterations of the planetary gear set and then proving that the final design had sufficient life to meet the vehicle life objectives.

 

I believe the WW tractor models were adequately developed to meet the customer’s demands/requirements and that all the endurance testing proved that the vehicles had acceptable service life. In general, production tractors performed well and service life was acceptable, although there were a few minor glitches that needed to be and were resolved early in the production run.

 

The WW powertrain was also used in later production Industrial (yellow paint) Model 2400 backhoe/loader tractors. Even though the wheel brakes had satisfactorily completed all the current IH brake performance and endurance tests, this application developed wheel brake disk wear out problems that took considerable investigation to determine the cause. Some thought that panic brake application to cause rapid vehicle deceleration of the heavier Industrial tractor was the cause of the problem. Because of that assumption, the Doncaster Test Group tested several fully equipped 2400 tractors for one million cycles of the following procedure. The vehicle was accelerated to maximum ground speed and then a panic application of the wheel brakes was applied bringing the vehicle to a rapid stop. After the test was completed, inspection of the paper brake discs showed absolutely no damage to the brake material. At the same time, I was running all types of brake tests in the lab at the Engineering Center trying to duplicate the results that we saw on failed parts. Nothing successfully duplicated those results. I finally made a trip to a tractor located in Exeter, UK that had suffered repeat brake failures and finally discovered the cause of the brake failures! As you probably know, the Exeter area in southeast England has some pretty steep slope on the roadways. What I found was that the operator would let the tractor coast down the steep slopes reaching speeds of nearly 30 mph (normal max speed is ~20 mph) which was not a problem until he would lightly tap the brakes when he happened to see a car poke it’s nose out of the driveway hidden by hedgerows. Even though he did not necessarily slow the vehicle, just that short application instantaneously dissipated the equivalent of 300 hp per wheel brake. There was not sufficient lube oil in the interface between the paper disc and the stationary steel disc, and the result was that the paper was burned or charred, which eventually resulted in complete wear out of the paper facing. Lab testing with various modification of paper material and oil flow patterns eventually developed a brake system that could adequately handle that kind of energy dissipation without failure, and our brake problems were resolved! As a side note, at the same time the same type of brake problems developed on Ag tractors in South Africa. The study of that problem found that the operators were hauling sugar cane and were working on piece rates, so the more loads they could haul, the more money they could make. These were diesel tractors that had external high idle stops on the injection pumps. We found that the operators were bending the stops to allow higher engine speeds, resulting in travel speeds near the 30 mph found in Exeter. Stopping the fully-loaded cane wagons resulted in the same condition—high energy dissipation in the brakes and resultant brake failure.

 

Those are just some of the interesting tests and developments that were encountered during the development of the WW tractors.

© 2016 by Harvester Heritage. Proudly created with Wix.com