The 'Nimble' T-6

A ''Nimble ''International T-6? Applying a Lifetime of Experience/ One Man Shows it can be Done

| August/September 2003

  • Dick and Ann Holcombe and the T-6

  • Air Cylinders
    A belt-driven automotive air-conditioning compressor provides compressed air for the air cylinders.
  • Dick's Air-assisted Steering

  • Dick's T-6
    A belt-driven automotive air-conditioning compressor provides compressed air for the air cylinders.

  • Dick and Ann Holcombe and the T-6
  • Air Cylinders
  • Dick's Air-assisted Steering
  • Dick's T-6

Dick and Ann Holcombe and the T-6. After 66 years of marriage, Ann still puts up with Dick's mechanical experiments. The T-6, serial number 39517, is of circa 1952 vintage.

With the seat folded up the air tank, air cylinders, control valves and plumbing for Dick's air-assisted steering are clearly visible. Dick's biggest challenge was making air valves that would pull the levers back quickly while also allowing the levers to return to their normal position rapidly.

One day in 1924 I watched a red hit-and-miss engine being unloaded from a Lehigh Valley freight car at the Dushore (Pa.) railroad station. From that time on I had an almost uncontrollable desire to acquaint myself with anything that had wheels and ran on gas.

Crawlers have played an important role in my life, and over the years I've had a number of different units. My first bulldozer was a Caterpillar D2, followed by a Caterpillar RD7, an OC3 Oliver, a TD-14 International and then a T-4 International.

I had some land in Sullivan County, Pa., that had the promise of a lake site. With the help of our county agent we laid out a dam and started construction. I hired a man with a new D4 Cat to do the main breastwork, and after finishing the drainpipe and spillway we filled the lake. The 16 acres the water would cover was swamp, brush and trees. After a winter of extreme cold, with ice 24 inches thick, we drained the lake and the job of clearing and grading began.

The D2 was the first bulldozer to be put to work, and after a short time I decided a larger tractor would be necessary. My financial situation at the time precluded a more modern tractor and I had to settle for the ancient RD7 Cat, a model designation introduced in 1936. For the next three years clearing and grading took place on a schedule of convenience, with the RD7 being retired and the TD-14 doing the heavy work. I then acquired the T-4 International, and with the engine overhauled and new pins and bushings installed the T-4 became my only crawler tractor.

The Next Chapter

The small pedals now control steering on Dick's T-6. Close examination reveals cables running through pulleys from the hand-clutch lever to the brake pedal. A light touch on either pedal makes an air cylinder pull on its respective lever, which in turn pulls on its respective brake, making the T-6 turn.

Fifty years passed. The lake had been sold, but the T-4 was still in my possession. At the age of 85 I decided that the gymnastics of getting on and off the T-4 were getting to be a chore, and after a fellow offered me a price I couldn't turn down I sold it. For the first time in nearly 50 years, I was without a crawler.

About two years ago a casual friend of mine asked if I would take a look at a tractor he had acquired, as he needed some advice on making it work. It was a T-6 International with a Drott bucket and bulldozer blade. The engine was stuck and the steering clutch cavities were full of water. The street grousers were smooth and the track pins and bushings were worn through. I told him it would be a very expensive job to put it in shape and he decided to just let it sit.

Time passed, and my friend passed away. One morning his widow called, and she offered me the T-6 if I would take it away. The starting of the engine and the refurbishing of the steering clutches is a story in itself, but we managed to get it on a lowboy and delivered to my place.

A common method of steering a crawler tractor at the time was to pull back the hand steering clutch lever and apply the foot steering brake, thus making the tractor pivot on the disengaged track. Now, these levers are unassisted, mechanical devices requiring a fair amount of pull to engage. The T-6 book calls for a maximum pull of 35 pounds on the steering clutch hand lever. Now, that was okay when the machine was used for plowing, but when it was used as a bulldozer or loader, it took a lot of pulling - a lot more than an overweight, underpowered 87-year-old could muster. 'There has got to be a better way,' 1 thought to myself.

My T-4 had linkage between the hand clutch levers and the steering brakes for turning, so why not rig a cable from the steering hand lever to the brake pedal of the T-6 and achieve the same results? I tried it and it worked, but the pull on the levers was more than 1 could manage.

I have some experience with air cylinders, and recognizing the universal use of air in braking systems on trucks I thought why not steer the tractor with air. With considerable trial and error I came up with the following scenario.

The tractor's original gas tank was rusted, so I discarded it and mounted a smaller gas tank to the right of the operator's seat. I then mounted a used air-conditioning compressor on the left side of the engine, and via v-belts and an electric clutch I had compressed air. I used a three-gallon tank for air storage and mounted two 6-inch diameter pull-type air cylinders under the seat, attached via cables to the steering clutch handles. 1 then made two air valves from 3/8-inch air quick-couplers and connected these to two small foot pedals convenient to the operator. Sounds simple, but it took a lot of bench testing and valve size manipulation to finally achieve quick operating response.

The day of testing was wet and the tracks were soon a mass of mud, but the response was great. Light pressure on the foot pedals swung the machine right or left, and, if such a term could be applied, the T-6 was actually 'nimble.'

The T-6 now rests on some land near my house. The worn out tracks are covered with mud, and the machine's generally shabby paint and dents present a forlorn picture. The gas engine and the drive train are in serviceable condition, but at my age ingress and egress to the operator's seat is a nightmare.

It is doubtful that my power steering experiment was unique. My long life has been associated with many mechanical adventures, but making a T-6 to be 'nimble' was worth the while.

Contact engine enthusiast Dick Holcombe at: P.O. Box 247, Dushore, PA 18614; e-mail:


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