Emergency Circuit (Emergency Lowering Circuit) - Toyota 7FBEF 15 Service Manual

4. Emergency circuit (emergency lowering circuit)

(1) The emergency circuit is provided in consideration of a circumstance where for some electrical
reason the solenoid valve fails to function. This refers to bypassing the hydraulic circuit that links
the lift logic valve lower side to the lift spool. This bypass circuit is provided with a needle valve,
which is normally shut off with the needle pushed in with a bolt. This bolt is locked with a lock nut.
(2) The lowering operation is as follows:
1) Loosen the lock nut.
2) Turn the hexagonal bolt to loosen it. (A turn is sufficient.)
3) Operate the lift lever toward the lowering side to lower the fork. The lowering speed is set at
approximately the same rate as for normal lowering.
4) When the lowering is completed, tighten the bolt and the nut according to the instructions given
in the repair manual.
(3) When the lift is manually lowered, hydraulic oil in the lower part of the cylinder, which is led to the
lower side of the lift logic valve, is also led to the needle valve on the emergency circuit. When the
lowering is manually operated, the hydraulic oil led to the needle valve is now led to the tank port,
generating a differential pressure between C1 port and the logic valve lower side same as in
normal circumstance. This causes the logic valve to open. It also opens the main circuit from C1 to
the tank port, allowing the hydraulic oil in the lower part of the cylinder to flow to the tank port.
Needle valve
Lift spool
Bolt
Nut
Emergency circuit
Pump port
Solenoid valve
C1
Logic valve
Tank port
7-15
Lift cylinder