WORKSHOP MANUAL
PARK
Chapter
EDITION
2020
PAGE
88 /
124
8.2 OPERATION OF THE HYDRAULIC SYSTEM
8.2.1 Components description and functioning
The engine drives the loading pump (1d) which feeds the main pump (1b) at a constant speed.
The oil, introduced into the main pump during operation, replaces the oil leaking from the rear (1)
and front (5) axle transmissions.
The loading pump takes the oil from the volume present in the rear axle, through the filter (1d). The
rear axle transmission is fed with oil from the tank (2).
The flow and direction of the oil flow through the main pump is controlled by the speed pedal (10),
mechanically connected to the main pump (1b) in the rear axle (1). The main pump pressure de-
pends on the power required from the wheel axles and is limited by the engine power.
In the 4WD machines, the hydraulic motors are connected in series, with the rear motor (1e)
slightly ahead of the front one (5a). This fact is not noticed by the operator, since the machine is
driven with its four wheels.
Components legend
1. Rear axle
1a Loading pump (35-45 bar)
1b Main pump
1c Pressure limiter of the loading pump
1d Oil filter
1e Rear hydraulic motor
2. Oil tank
3. Connection with the hydraulic steering valve
4. Rear by-pass valve
5. Front axle (4WD)
5a Front hydraulic motor
6. Front by-pass valve (4WD)
7. Main line (4WD)
8. Main line (4WD)
9. Drainage line (4WD)
10. Drive pedal
▶▶
only 4WD
