Hydraulic unit

Its functions are:

to operate the clutch control lever;

to operate the gear control shaft (selection and engagement manoeuvres;

maintain a reserve of energy/hydraulic power for efficient actuator operation.

The hydraulic unit consists of:

a cast body 1 fastened directly to the gearbox;

a single-acting actuator 2 for operating the clutch lever;

two proportional pressure valves EV1 3 and EV2 4 controlling the engagement actuator;

two on-off solenoids EV3 5 and EV4 6

proportional flow solenoid EV0 7 for controlling the clutch actuator;

hydraulic gas accumulator 8;

pressure sensor 9;

sensor 10 for detecting clutch actuator position;

sensor 11 for detecting engagement actuator position;

sensor 12 for detecting selection actuator position;

bleed valve 13.

• A - Gear selection
• B - Gear engagement
• C - Clutch engagement/release

The diagram below illustrates the internal mechanisms for:

gear selection and engagement controls;

clutch control;

• 1 Reservoir
• 2 Electric pump
• 3 Single-acting valve
• 4 Engagement/release actuator (with three mechanically-defined positions)
• 5 Engagement actuator position potentiometer
• 6 Selection actuator (with two fixed positions, the third selection position is defined by the inner gearbox springs)
• 7 Selection actuator position potentiometer
• 8 Clutch actuator (single-acting)
• 9 Clutch actuator position potentiometer
• 10 Proportional pressure solenoid EV2 controlling the engagement actuator
• 11 Proportional pressure solenoid EV1 controlling engagement actuator
• 12 Proportional flow solenoid EV0 controlling clutch actuator
• 13 On-off solenoid EV3 controlling selection actuator
• 14 On-off solenoid EV4 controlling selection actuator
• 15 Pressure sensor
• 16 Hydraulic gas accumulator

HYDRAULIC DIAGRAM