Secondary pressure regulating valve

SECONDARY PRESSURE REGULATING VALVE

1. Sliding bearing ring (Primary pulley)
2. Ratio between the pulleys: high (low speed)
3. Ratio between the pulleys: low (top speed)
4. Pitot pressure
5. Spring
6. Pressure control solenoid valve
7. Circuit pressure
8. Secondary pulley
9. Lubricating oil pressure
10. Oil pump
11. Transmission control valve
12. X: Outlet

The regulator valve ensures that the correct quantity of pressurised oil is sent to the secondary pulley when the pulley is forced to rotate by the belt. Oil supply to the primary pulley is controlled by the transmission control valve.

The oil exiting the pump is directed into circuits (A) and (B) in such a way that the circuits and spring (5) pressure remain in equilibrium.

The circuit oil pressure varies as a function of the transmission ratio and the primary pulley speed, as follows:

The position of the primary pulley slide ring is read from the sliding sensor and provokes a change in the imposed length of the pressure regulating valve spring.

In pratrice, when the pulley ratio is high (low speed) the pressure regulating spring is pushed towards the left, reducing the outlet size.

In this way the pressure remains high and the pulley is forced to increase diameter.

When the transmission ratio is low (Overdrive), the circuit pressure is held low, so the secondary pulley decreases in diameter.

The oil pressure (Pitot pressure) is proportional to the primary pulley RPM and acts on the circuit at (X) on the opposite side to spring (5).

The pressure regulating valve is consequently pushed towards the right, which limits the oil pressure increase (circuit pressure) provoked by the increased engine speed.