Section E - Hydraulics
Problem Solving
Hydrostatic Transmission
E-63 E-63
9803-9340-8
Checking Motor Speed - Series 1
Machines
The pump output and general efficiency of the drive
system may be checked by raising the machine off the
ground and checking the motor speed.
!MWARNING
The following procedure requires the machine to be
disabled (wheels raised off the ground, attachment
disconnected etc.) while the work is carried out.
HYD-8-1_2
1 Place the machine safely onto blocks, so that the rear
wheels are clear of the ground. Ensure that the
machine is stable.
2 Remove the rear wheels.
3 Stick a piece of reflective tape on one of the wheel
flanges.
Note: It is not possible to achieve maximum pump swash
simply by operating the control pedal.
4 Remove the front floor plate.
5 Disconnect the control cable A from the swash plate
lever on the pump and remove the lever from the
swash plate shaft.
6 Make sure that the engine is thoroughly warm and the
hydraulic fluid is at its correct working temperature
(50 ºC, 122 ºF).
7 Start the engine and run at maximum speed then,
using a spanner, turn the swash plate shaft B fully in
both directions. Using a stroboscopic meter, measure
the speed of the hub rotation in each direction which
should be about 100 rev/min.
Note: The machine is fitted with a limited slip differential.
Because of this both wheel hubs will turn at the same
speed and in the same direction.
Note that excessive motor speed may result in cooling
problems due to overheating of the hydraulic oil.
If the correct motor speed cannot be achieved, the pump
or motor could be faulty. Proceed as follows:
8 Insert a flow meter, load valve and pressure gauge
into a motor feed line.
9 With the load valve off, start the engine and operate
the pump swash plate in the appropriate direction.
10 Whilst maintaining pump flow, slowly increase the
load valve to achieve the setting of the main relief
valves.
Check the flow and pressure readings
K Technical
Data ( T E-1).
732910-1
Fig 3.
If the correct pressure cannot be achieved, disconnect the
hoses from the motor and connect the flow meter and load
valve across the motor lines.
Repeat steps 7 to 9. If the flow and pressure readings are
now correct, the motor is probably faulty. Carry out a motor
leakage test (see following page).
If the flow and pressure readings are still incorrect, the
pump is probably faulty.
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