Rd6 pinion

Which pinion shaft is it? Starting clutch pinion, bevel gear pinion, final drive pinion? May need a bit more info, then we can give you a good idea what to expect. 😖mile:

I took the inspection plate off the rear of dozer. It is the ring and pinion that drives both tracks. I pulled the tractor and watched it turn, it looks like the shaft is broke. thanks Dave

Is the broken shaft, the pinion shaft in the transmission, or the cross-shaft that the ring gear is bolted to?

If the pinion shaft is broken, you need to remove seat, fuel tank, floor plates and everything bolted above the transmission and rear case.
Then you will find a huge cast cover bolted to the top of the transmission and rear case.
This cover has to be unbolted, and then removal of it exposes all the transmission gears, ring gear and pinion, cross-shaft and steering clutches.

You have to dis-assemble the transmission to remove the pinion shaft, but nothing in the cross-shaft area or steering clutch area needs to be touched.
However, if the ring gear is damaged or the cross-shaft broken, the steering clutches, cross-shaft and ring gear all have to be removed.
In short, you're looking at major dis-assembly to repair damage to either.

Regards, Ron.

Don,t know if I want tackle it or not. Nice old looking dozer and has a hydraulic blade on it. I think this is the first year for hydraulics 1936 > thanks Dave

Hydraulics were available from about 1923 for some items of equipment. LaPlant Choate was an early hydraulics adopter. Early hydraulics were low pressure, and the seals were poor design and low quality.
Leather was about the only seal material available. Gaskets leaked continually, and pumps were low output, making hydraulic operation slow.

The first hydraulic blade for a bulldozer was fitted by LaPlant Choate to a Cat in 1925. By 1932, LaPlant Choate produced a range of 11 hydraulic bulldozer blades, called the "Roadbuilder" range.
The Roadbuilder range fitted Cats from Twenty Two to the Seventy, Seventy Five and RD-8. The model R-6X fitted the wide track Thirty Five, the Forty, the R-5 and the RD-6.

The amount of repair hours required in replacing the broken shaft is certainly substantial. If the rest of the tractor is in good shape, it's well worth the effort to repair it.
The pinion shaft is also referred to as the "lower transmission shaft" - so therefore, all transmission gears have to be removed to take it out.
The cross-shaft and ring gear is removed complete with steering clutches.
The outer clutch flanges are unbolted, the center bearing caps are unbolted, and the entire unit is lifted out in one piece, then dismantled on the shop floor.

[quote="OzDozer"]Hydraulics were available from about 1923 for some items of equipment. LaPlant Choate was an early hydraulics adopter. Early hydraulics were low pressure, and the seals were poor design and low quality.
Leather was about the only seal material available. Gaskets leaked continually, and pumps were low output, making hydraulic operation slow.

The first hydraulic blade for a bulldozer was fitted by LaPlant Choate to a Cat in 1925. By 1932, LaPlant Choate produced a range of 11 hydraulic bulldozer blades, called the "Roadbuilder" range.
The Roadbuilder range fitted Cats from Twenty Two to the Seventy, Seventy Five and RD-8. The model R-6X fitted the wide track Thirty Five, the Forty, the R-5 and the RD-6.

The amount of repair hours required in replacing the broken shaft is certainly substantial. If the rest of the tractor is in good shape, it's well worth the effort to repair it.
The pinion shaft is also referred to as the "lower transmission shaft" - so therefore, all transmission gears have to be removed to take it out.
The cross-shaft and ring gear is removed complete with steering clutches.
The outer clutch flanges are unbolted, the center bearing caps are unbolted, and the entire unit is lifted out in one piece, then dismantled on the shop floor.[/quote]

Do you think I could replace the shaft and not the ring gear, it looks ok. I have always heard to replace as a unit. Would also be less work. Dozer has not been run in 8 years, was being used to build a pond when shaft broke. Undercarriage is about 20%

only high speed sets need replacing as sets. If the Ring Gear isn't worn down or chewed up, then replace the broken parts only. A machine that old isn't going to get worked hard all the time, hence it shouldn't cause any issues.
IMO

The pinion can be replaced as a separate part. The pinion and ring gear were always available as separate parts, they are not a matched set.
If they were a matched set, you would only be able to acquire them as a matched set.
As drujinin says, if the ring gear isn't chewed up too bad, you will be O.K. to re-use it.