L322 Range Rover System Description and Operation
AUTOMATIC TRANSMISSION – ZF 5HP24
DESCRIPTION AND OPERATION 44-2-15
In the unlocked condition, the oil pressure supplied to the piston chamber and the turbine chamber is equal.
Pressurised fluid flows through a drilling in the turbine shaft and through the piston chamber to the turbine chamber.
In this condition the clutch plate is held away from the torque converter body and torque converter slip is permitted.
In the locked condition, the TCC spool valves are actuated by the electronic pressure regulating solenoid (EPRS4).
The fluid flow in the unlocked condition is reversed and the piston chamber is vented. Pressurised fluid is directed into
the turbine chamber and is applied to the clutch piston. The piston moves with the pressure and pushes the clutch
plate against the torque converter body. As the pressure increases, the friction between the clutch plate and the body
increases, finally resulting in full lock-up of the clutch plate with the body. In this condition there is direct mechanical
drive from the engine crankshaft to the transmission planetary gear train.
Fluid Pump
The fluid pump is an integral part of the transmission. The fluid pump is used to supply hydraulic pressure for the
operation of the control valves and clutches and also to pass the fluid through the transmission cooler.
The 5HP24 fluid pump is a crescent type pump and is located between the intermediate plate and the torque
converter. The pump has a delivery rate of 16cm
3
per revolution.
1 Securing ring
2 Shaft oil seal
3 O-ring seal
4 Pump housing
5 Ring gear
6 Crescent spacer
7 Roller bearing
8 Impeller
9 Centring pin
10 Spring washer
11 Outlet port (high pressure)
12 Inlet port (low pressure)
The pump is driven by a positive coupling with the torque converter impeller, therefore the pump is driven at engine
crankshaft speed.
The pump comprises a housing, a crescent spacer, an impeller and a ring gear. The housing has inlet and outlet ports
to direct flow and is located in the intermediate plate by a centring pin. The pump action is achieved by the impeller,
ring gear and crescent spacer.
M44 1823
10
4
6
5
8
9
3
1
7
2
12
5
6
11
8
