LR3/Disco 3
The rotational motion of the ring gear and the impeller collects fluid from the intake port in the spaces between the teeth.
When the teeth reach the crescent spacer, the oil is trapped in the spaces between the teeth and is carried with the
rotation of the gears. The spacer tapers near the outlet port. This reduces the space between the gear teeth causing a
build up of fluid pressure as the oil reaches the outlet port. When the teeth pass the end of the spacer the pressurised
fluid is passed to the outlet port.
The fluid emerging from the outlet port is passed through the fluid pressure control valve. At high operating speeds the
pressure control valve maintains the output pressure to the gearbox at a predetermined maximum level. Excess fluid is
relieved from the pressure control valve and is directed, via the main pressure valve in the valve block, back to the pump
inlet port. This provides a pressurised feed to the pump inlet which prevents cavitation and reduces pump noise.
MECHATRONIC VALVE BLOCK
The Mechatronic valve block is located in the bottom of the transmission and is covered by the fluid pan. The valve block
houses the TCM, electrical actuators, speed sensors and control valves which provide all electro-hydraulic control for all
transmission functions. The Mechatronic valve block comprises the following components:
TCM
Six pressure regulator solenoids
One shift control solenoid
One damper
Twenty one hydraulic spool valves
Manually operated selector valve
Temperature sensor
Turbine speed sensor
Output shaft speed sensor.
A radio interference suppressor is located on a bracket on the right hand side of the transmission, forward of the selector
shaft lever. The suppressor is connected into the transmission wiring harness and prevents solenoid operating noise
affecting the audio system.
ZF 6HP26 Automatic Transmission – Mechatronic Valve Block
