T Tank
2 Loader Valve
2X Pressure Test Points
4 Check Valve (2 bar)
8 Drive Control Joystick
8a Joystick Control Spool
8b Joystick Control Spool
8c Joystick Control Spool
8d Joystick Control Spool
8e Shuttle Valves
9 Pressure Reducing Solenoid Valve
10 Filter By-pass & Cooler Relief Valve
Hydraulics
9803/8500
Issue 1
Key
C Cooler
F1 Filter
P1 Main Pump
P2 Main Pump
P3 Auxiliary Gear Pump
Pa Charge Valve
Pb Pressure Relief Valve
Pc Pressure Relief Valve
Pd Pressure Relief Valve
Pe Pressure Relief Valve
M1 Right Hand Drive Motor
M2 Left Hand Drive Motor
S1 Suction Strainer
8 - 1
8 - 1
Descriptions
Section E Section E
S242300
TRANSMISSION OPERATION - NEUTRAL
With the engine running but no drive selected, oil
from pump P3 is fed through the loader valve 2 and
filter F1 to main pumps P1 and P2. A small amount
of oil flows through the chargel valve Pa, enters the
pump casing and is returned via line z and through
check valve 4 to the suction side of pump P3.
Oil is also fed from pump P3 to the transmission
servo joystick 8 but, because the joystick is not
operated, the oil is blocked by the spools 8a, 8b, 8c
and 8d and therefore no servo pressure is applied
to operate the swash plates of pumps P1 and P2.
As the pump swash plates are spring loaded to the
neutral position there is no delivery from either
pump and the machine remains stationary.
The motor brakes x and y are released whenever
the engine is running by oil fed through the pressure
reducing valve 9. However the machine is prevent-
ed from moving by oil locked up in the pump/motor
circuit.
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