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jdemaris
08-18-2003 06:04:39
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Re: JD350 crawler loader in reply to John L, 08-16-2003 11:44:28
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That's a typical problem with the John Deere(Twin Disk) hydraulic reversers. There are many things that can cause the problem. First of all, you are sure it's the reverser slipping and not the steering clutches? And . . . you've got a 350B or older, i.e. a machine with dry steering clutches and not a 350C or later with hydraulic steering clutches powered by the reverser? If you ARE sure it's the reverser, find out if it slips in both directions; e.g. put the trans. in 1st gear and reverser in forward - check for slipping, then put the trans. in reverse and reverser in reverse (machine will still go forward) and again check for slipping. If it does indeed slip in both directions, pull the floor-cover off to expose the clutch pedal linkage and return spring. Sometimes a combination of a weak return spring along with dirt and/or brush stuck in the linkage keeps it from returning to "full pressure" position. Other than that you ought to get pressure gauges plugged into the reverser and check your lube/clutch return pressure and your clutch operating pressure. Lube should be 10 - 30 p.s.i. and clutch pressure around 125 p.s.i. (for an older machine). There are a number of components inside the reverser that wear out over time. The only remedies I can suggest that you can try, without pulling the reverser apart are #1 checking the clutch-control linkage as aforementioned, #2 open up the "rate of shift" screw by turning it counter-clockwise, or #3 shim up the main pressure control valve. These can all be done with major dissassembly. Other than that, there are a few things inside the control valve assembly that could possible cause the problem - and it can be removed with the reverser in place - but it's difficult. There's mechanical linkage inside of it that wears, there's a shift accumulator spring and stop that can malfunction, etc. Some of these items can be manipulated to compensate for internal wear, but you have to know what you're doing. Other than that, all else requires removing the reverser. The internals aren't complicated, but parts are expensive. If you have an early 350, the repair can become even more expensive because some major parts that normally wouldn't require replacment have been updated.
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