350B reverser issue

eidolon · Post by **eidolon** » Mon Jun 20, 2016 4:55 pm

350B crawler, 6 way. Dozer doesn't want to push in forward or reverse. Moves on flat ground and small incline, but will not pull its own weight if the incline is very steep - even in lowest gear. I changed the reverser filter (it was really dirty) and have adjusted the rate of shift screw out 1/4, then 1/2 turn. No noticeable effect. It just started doing this all of a sudden, and No, the manual clutch is not sticking. Would the reverser pump go out this quickly, or is it more likely dirt in some of the reverser control orifices? I'm pretty sure the clutches wouldn't both go at same time. any additional advice appreciated.

jtb51b · Post by **jtb51b** » Mon Jun 20, 2016 6:16 pm

Slipping coupler? Does the engine load up at all?

eidolon · Post by **eidolon** » Tue Jun 21, 2016 6:24 am

Engine does NOT load up. Increasing RPM has no effect - only if I reduce it to an idle and repeatedly pull/release steering levers can I get the machine to "inch" back up an incline. Slipping coupler? Where is that, and how common an issue? I have all the manuals, but am still relatively new to this machine. Thanks for reply. I greatly appreciate any ideas or help.

Stan Disbrow · Post by **Stan Disbrow** » Tue Jun 21, 2016 6:48 am

Hi,

A reverser equipped 350 has no engine clutch. There is an isolator where the clutch would be in a non-reverser machine to dampen vibrations from the engine. They are known to fail with great loudness, so it probably isn't that.

The clutch pedal works a valve to dump hydraulic pressure inside the reverser. There are clutch packs inside for forward and reverse which are operated by hydraulic pressure. Usually only one quits at a time, and if both are out I would be looking at the dump valve the clutch pedal works.

You need to check reverser hydraulic pressures first. And, the reverser hydraulic pump is inside the reverser. It has nothing to do with the attachment hydraulic pump.

The coupler is in between the output shaft of the reverser and the input shaft of the transmission. They are known to strip out and lose drive. This would also cause both forward and reverse to quit. There might be a little bit of drive right as you try and move, then it quits as the stripped splines lose what little grip they have left.

In any event, getting to these things to repair them requires disassembly of the machine from the front to the back.

Stan

eidolon · Post by **eidolon** » Tue Jun 21, 2016 5:11 pm

Thanks for the very useful insights. I would suspect a problem in the control valve (including the clutch valve) first. I will likely need help from a JD professional with the right pressure gauges first. I looked up the shaft coupling. Could be that - I have stripped splines before on hydraulic pumps, but that would not be my first place to look. Thank you very much for the ideas. It helps me to keep narrowing down the areas to investigate.

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