940 L4-2.3L SOHC VIN 88 B230F (1992)
disengaged). The downshift valve remains in this position until the solenoid valve is deenergized.
In a kickdown shift, on the other hand, the valve is held in the bottom position only as long as the kickdown pressure is greater than the
governor pressure. The latter acts in opposition to the kickdown pressure through shift valve 3-4.
Downshift D-2 Control Valve, Manual (19)
The valve controls the point at which 2nd gear is engaged when downshifting manually from position D to position 2, ensuring that this takes
place in stages from 4th to 3rd and then to 2nd.
Line pressure (throttled) acts on one end of the valve and the operating pressure for clutch C0 on the other.
A port in the middle of the valve controls the flow of fluid to downshift valve 3-2.
The flow to downshift valve 3-2 is a function of the balance between the line pressure and clutch C0 operating pressure on the valve spool.
Control Valve, Rear Clutch, Reverse (20)
Clutch C2 is provided with two piston surfaces. While the smaller surface is sufficient to enter reverse when 3rd gear is engaged, both must be
used to prevent the clutch from slipping when in position R. The function of the control valve is to ensure gentle engagement of reverse by
application of the rear clutch in stages.
Control Valve, Rear Brake, Reverse (21)
The function of the valve is to ensure gentle engagement of reverse. This is achieved by application of brake B3 in stages. The brake is
equipped with two hydraulic pistons, each with individual ports.
Consisting essentially of a restriction in the supply to the pistons, the valve distributes the oil flow between the ports. Since the front piston
receives a higher flow than the rear piston, it receives full operating pressure before the latter, prolonging the operation of B3.
Lock-up Signal Valve (22)
Line pressure is supplied to one end of the valve and governor pressure to the other. Two line pressure inlets are provided, one for selector
positions 1-3 and one for selector position 4. When 4th gear is engaged and the governor pressure (i.e. the speed of the car) increases, oil flows
at line pressure from the control valve to the changeover valve (23).
Lock-up Changeover Valve (23)
The valve is actuated by oil at line pressure from the signal valve. Opening of the valve reverses the fluid flow from the torque converter,
operating the lock-up clutch plate and activating the lock-up function.
Accumulator Pistons (3 Off) (24)
Each of the circuits serving the front clutch, rear clutch and brake B2 incorporates an accumulator piston.
The pistons are installed in parallel with the C1, C2 and B2 circuits.
When supplying operating pressure to B2, for example, the fluid flow is divided between the brake piston and the accumulator piston. As a
result, braking takes place gently when the brake is first applied and full operating pressure is developed only when the accumulator piston is
full. This ensures a smooth increase in operating pressure, resulting in gentler shifting.
Solenoid Valve (25)
Disengagement of 4th gear (overdrive) is controlled by the solenoid valve. Disengagement is performed manually using the switch on the gear
selector lever.
When the switch is operated, the solenoid valve (which is supplied at constant line pressure) relieves the pressure to downshift valve 4-3,
moving shift valve 3-4 to its bottom position and disengaging overdrive.
The valve does not return to its idle position until another signal is received from the switch on the gear selector or the ignition is switched off.
Oil pressure switch, kickdown inhibitor (26), (Europe only)
The oil pressure switch is actuated by the throttle/kickdown pressure. The signals supplied by the switch to the overdrive relay are delivered to
the solenoid valve (25), which operates downshift valve 4-3 (18). In this manner, the pressure switch indirectly controls downshifting from 4th
to 3rd.
