11 - 0
Section E Hydraulics
9803/8550
Section E
11 - 0
Issue 1
Pumps
Hydrostatic Transmission Problem Solving
The purpose of this page is to help you trace transmission problems to a faulty unit (pump, motor, joystick etc). Once you have
traced the faulty unit, refer to the appropriate dismantling, inspecting and test instructions given elsewhere in the manual.
*
Before you begin problem solving, read the Safety Information at the beginning of this manual.
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Make simple checks before say, stripping a major component.
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Make sure that the hydraulic fluid is at correct working temperature (50 °C, 122 °F).
*
Whatever the fault, check the condition of the hydraulic fluid. Drain and replace if necessary.
*
Be sure to remove ALL contamination and if possible identify its origin. It may be part of a component from elsewhere in
the circuit.
PROBLEM CAUSE
No drive in any direction 1, 3, 4, 9, 16
No drive in either forward or reverse 1, 4, 6, 8, 10, 11
No spin turn either left or right 2, 3, 10, 11, 14
No drive on one side 4, 5, 6, 8, 10, 11, 14, 15
Machine will not travel in a straight line 2, 7, 8, 10, 11, 12, 13, 14
Poor drive performance, no tractive effort 3, 5, 6
Machine creeps in neutral 7
Machine will not move at idle but
moves at max. revs. 3
Hydraulic fluid is overheating 1, 17, 18
Noise in transmission 15
KEY TO CAUSE REMEDY PAGE REF.
1 No oil in hydrostatic system or oil level too low Top-up as necessary. 3/8-1
2 Tyres worn or pressure incorrect Check tyre pressures and condition. 3/9-3
3 Charge pressure low Adjust charge pressure at transmission pump. E12-3 & E12-11
4 Brake release pressure incorrect Check brake valve.
5 No or low pump output Check pump - carry out wheel speed check. E12-8 & E12-13
If one pump suspect, swop motor feed hoses and notice E12-14
if problem changes sides - if ‘yes’, pump related fault;
if ‘no’, motor related fault.
6 High pressure ‘loop’ relief valve/tow valve Check that valves have been re-tightened after towing. E12-2 &
open/set incorrectly Replace relief valve and re-check. E12-10
7 Pump neutral position set incorrectly Adjust servo neutral position. E12-8 & E12-12
8 Feed hose failure Check motor feed hoses.
9 No hydraulic feed to joystick Check for feed to joystick. E12-16
..... continued
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