TM 5-3895-382-24
Checks During Operation
The checks during operation can be used to find leakage in the
system. They can also be used to find a bad valve, pump or
motor. Travel speed can be used to check the condition of the
propel motors and the pump.
Drive the machine backwards and forwards several times.
Operate the propel controls in all speed ranges.
1.
Watch the drive drum and wheels. Starting and
stopping operations should be progressive. Drum and
wheel rotation should be smooth and regular at all
times.
2.
Check for noise from the pump and drive motors.
3.
Check for the sound of the relief valves opening. The
opening pressures of the relief valves are given in the
relief valve pressure tests located in the Testing And
Adjusting section of this module.
4.
After selecting the travel speed of the compactor, the
forward and reverse motion should be identical.
Problem: Propel system engages very slowly when
making a shift.
Probable Cause to Low Charge Pressure:
1.
Low charge pressure.
2.
Low oil level in the hydraulic tank.
3.
Plugged filter element.
4.
Inadequate flow from steering pump.
5.
Plugged stroking orifices in the propel pumps.
6.
Plugged orifice out of brake shift valve.
Problem: Propel system engages very suddenly when
making a shift.
Probable Cause:
1.
Stroking orifices missing from propel pumps.
2.
Broken or weak propel pump servo valve springs.
Problem: Propel system operates in forward speeds only.
Probable Cause:
1.
Failure of the pump servo piston.
2.
Failure of the pump servo valve.
3.
Failure of the rocker arm section of the pump
swashplate assembly.
4.
Main relief valve damaged or incorrectly adjusted in the
reverse line of loop circuit.
5.
Propel shuttle valve spool is stuck in one position.
Problem: Propel system operates in reverse speeds only.
Probable Cause:
1.
Failure of the pump servo piston.
2.
Failure of the pump servo valve.
3.
Failure of the rocker arm section of the pump
swashplate assembly.
4.
Main relief valve damaged or incorrectly adjusted in the
forward line of loop circuit.
5.
Propel shuttle valve spool is stuck in one position.
Problem: Propel system does not disengage (zero oil flow)
when propel control lever is returned to neutral.
Probable Cause:
1.
Failure of the propel pump servo piston.
2.
Failure of the propel pump servo valve.
3.
Failure of the rocker arm section of the pump
swashplate assembly.
4.
Incorrect neutral adjustment of the swashplate.
5.
Incorrect linkage rod adjustment between drum and axle
pump controls.
6.
Incorrect neutral adjustment of the manual displacement
control lever.
11-35
