Alfa Romeo Selespeed system
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SYSTEM COMPONENTS - SOLENOID VALVES AND ACTUATORS
  The solenoid valves manage the oil flow to the actuator chambers.
All the valves are the three-way type, they are normally discharged when not controlled.

Proportional pressure solenoid valves (EV1 and EV2)
These control the oil pressure at the two chambers of the gear engagement-disengagement double-action actuator that has three set mechanical positions according to the control combination (even number gear, idling, odd number gear). The maximum flow rate is 7 l/min with pressure differential of 10 bar. The control current ranges from 0 to 2.5 A directly controlled by control unit CFC 208F. Electrical resistance of the winding is 2.5 Ohm +/- 6% at 20°C.
   
   

Position of solenoid valves and current pressure diagram

  
    The electro-hydraulic group consists of:
 1. A casting casing fastened on the gearbox
2. Single action actuator to activate the clutch lever
3. Proportional pressure solenoid valve EV1 to control the engagement of the odd gears 1-3-5
4. Proportional pressure solenoid valve EV2 to control the engagement of the even gears 2-4-R
5. On-off solenoid valve EV4 to control 5-R gear selection
6. On-off solenoid valve EV3 to control 1-2 gear selection
7. Proportional flow-rate solenoid valve EV0 to control the clutch actuator
8. Hydraulic gas accumulator
1. Hydraulic circuit pressure sensor
2. Sensor to detect clutch actuator position
3. Sensor to detect engagement actuator position
4. Sensor to detect selector actuator position
5. Bleed valve
6. Access to gear shaft actuators connecting screw
7. Union for oil delivery pipe
8. Union for oil return pipe
9. Connector for gearbox speed sensor
10. Selespeed wiring harness connector

The following are also installed in the electro-hydraulic group:
• a check valve
• an oil inlet filter
• screws fastening the engagement / selection actuator to the gearbox gear shaft.

  
   
  ON/OFF solenoid valves ( EV3 and EV4)
These feed the oil flow to the two chambers of the double action gear selection actuator that has only two set mechanical positions (1-2 and 5-R). The maximum flow rate is 1.4l/min with pressure differential of 10 bar. They are controlled with a voltage of 12V directly from control unit CFC 208F and absorb approx. 2A.
Electrical resistance of the winding is 5.1 Ohm +/-6% at 20°C.
   
   

On-Off solenoid valve position

  
   
  Solenoid valves and actuators
 The solenoid valves manage the oil flow to the actuator chambers.
All the valves are three-way; they are normally discharged if not controlled.

Proportional flow-rate solenoid valve (EV0)
It controls the oil inlet and outlet flow of the clutch stroke actuator chamber (single action).
The maximum flow rate is 10l/min with pressure differential of 10 bar. The control current ranges from 0 to 2A directly controlled by control unit CFC 208F. Electrical resistance of the winding is 2.5 Ohm +/- 6% at 20°C.
   
   

Solenoid valve position and flow rate/current diagram