Does anyone have or know where I might be able to get a diagram , picture or an exploded view picture out of a repair manual that shows the drive system on one of these older buldozers? like from the engine back so I can see how the power gets to each track.
Really apprieciate it.
Jim K

Jim,

Be specific as to make and model.

thx

D-6 International
Any model actually I just want to know how the basic drive system works.
I don't have a dozer yet but am curious as to how they work. I am interested in getting a small machine.

Try these for starters:

Just so you know what you're supposed to be seeing,,,,,,,,,,,,,,

Most old crawler tractors (and wheel tractors as well) had a hand clutch not too different from the ones still used today on PTO equipped power units. This clutch "snaps in" and stays engaged until it is pulled or pushed back "over center" to disengage it.

Then there is a transmission of some description and the output shaft of the transmission is to the pinion of a bevel gear set that gives speed reduction and a 90 degree change in orientation so the output (the bevel gear shaft) is cross ways at the rear of the tractor.

The bevel gear shaft drives a steering clutch on each side so that each track can be disengaged to allow a turn to be made. Note that this is not a differential arrangement though that was a feature of a very few old tractors and now some new ones. A differential allows power to flow to both sides throughout a turn, while the steering clutch arrangement disconnects power to the "inside" track so traction is cut by half. Power will not be cut in half if surface conditions are good enough that the powered track can absorb more engine power without spinning.

Each steering clutch outputs power to the pinion of a spur gear reduction final drive on each side. This may be a single reduction or a double reduction depending on the tractor.

The output of the final drive is the sprocket that drives the tractor along it's tracks.

Jim - On all the "direct drive" Cats from the 1940's, 1950's and 1960's .. the power goes from the clutch, via a short jackshaft with double universal joints, to the sliding gear or countershaft-type transmission.

From the transmission, power then travels via the transmission output shaft, to a straight pinion and bevel gear.
There is no differential in most crawlers .. apart from a few oddball machines, such as some Cletrac/Oliver, some European machines, and some Massey Ferguson crawler models.

The bevel gear is bolted to a solid cross-shaft, which transfers power crosswise, to the steering clutches, and thence to the final drives.
The steering clutches are operated via levers and crank mechanism, most times power-assisted in some way.
Around the steering clutch drums are mounted foot operated brakes.
Disengaging a steering clutch, disables power to that track .. and applying the brake stops the track for a sharper turn.

Early machines of the 1930's, 1940's, and early 1950's used dry steering clutches and main clutches. These are prone to heat build-up and rapid wear under heavy working conditions.
Around the early to mid 1950's, oil main clutches were introduced, and in the early 1960's, oil-immersed steering clutches were introduced.
Both of these features, are very worthy improvements to any tractor you buy, if you wish to do some serious work. The dry clutches are adequate for hobby work.

The power goes from the steering clutches, to a gear reduction called the final drive, which drives the big sprocket that propels the tractor along the track.
Most larger machines have double-reduction final drives (a pinion drives an intermediate gear, which then drives a bull gear, which is bolted to a hub that the sprocket is splined onto).
Most smaller machines, or cheaper models, have only a single reduction final drive (a pinion driving directly onto a bull gear).

Caterpillars have a 'dead axle' .. a large diameter shaft, tapered both ends, that is pressed into the final drive/steering clutch case, and which supports the track frame.
The sprocket and bull gear are attached to a tubular 'sprocket shaft', which fits neatly over, and which rotates around, the dead axle.

Vintage International crawlers of the 1930's used a different drivetrain setup, with steering clutches turned 90° so they were parallel to the transmission. These were accessible from the rear housing.
Later Internatiional crawlers used planetary gearsets in the final drives, and the track frame was supported by, and pivoted on, a large shaft that ran across the full width of the tractor, in front of the final drives.

The Caterpillar D2 also used this track frame pivot shaft arrangement .. the only Cat to do so.

Here's a couple of exploded views of a D6 drive train, that may assist you. The details listed are more selling points, than a drivetrain precise parts description .. but I'm sure you'll get the idea.

img339.imageshack.us/img339/7064/d6drivetrain1gk4.jpg

img182.imageshack.us/img182/7066/d6drivetrain2do8.jpg

Jim K,

Here is a scan out of "Moving the Earth" It is of an International Diesel. I couldn't how big of a file we could submit so I stayed on the smaller side when I resized the scan. If you want the larger scan, I can email it to you.

Hope this helps.