Esteem GLX Sedan Plus L4-1.8L (1999)
When Running at Low Speed
As the engine speed rises, the pump discharge rate increases and causes a pressure difference to occur between both ends of the orifice (P1 - P2). Thus
the pressure exceeding the flow control spring force pushes the flow control valve to the right in figure shown, making the opening in the orifice
narrower through which only a necessary amount of fluid is fed to the gear box and the excess fluid is returned to the pump.
When Running at High Speed
As the engine speed rises higher, opening in the orifice is made narrower and fluid flow to the gear box reduces. As a result, hydraulic pressure
application is slow at the start of the steering wheel turn. This provides straight-ahead stability to suit the driving condition with the steering wheel
operated near its neutral position.
RELIEF VALVE
The relief valve located in the flow control valve controls the maximum hydraulic pressure.
The steel ball in the relief valve is under the hydraulic pressure in the circuit coming through orifice A2. When the steering wheel is turned and the
hydraulic pressure increases higher than 8000 kPa (80 kg/cm2, 1137 psi), it compresses the relief spring to push the steel ball which then allows the
fluid to flow to the P/S pump.
Such relief valve operation causes a pressure difference to occur between chambers A and B.
Then the flow control valve moves to the right to make opening in orifice A1 narrower, maintaining the hydraulic pressure constant.