jcb ROBOT 150 - Pressure Reducing Solenoid Valve

6 - 2
Pressure Reducing Solenoid Valve
(machines without sequencing E.C.U.)
This valve controls the Safety Restraint Bar circuit, the door
latch circuit, brake circuit, and pressure reduction circuit.
It contains a reducing valve cartridge and a 3 position, 3 port
cartridge solenoid valve.
The relevant sections of the hydraulic and electrical circuits
are shown on the opposite page. Refer to the left hand
electrical schematic.
When first entering the machine the solenoid valve should be
in position X i.e. with the parking brake ON, the Safety
Restraint Bar in the access position (hence switch 19 open)
and the door open (switch 18 open). In this condition,
pressure from the auxiliary pump is dumped to the tank
(brake ON).
Closing the door correctly, moving the Safety Restraint Bar to
the operation position and starting the engine will energise
solenoid 16 and move the solenoid valve to position Y.
In this position the valve directs hydraulic power via the
loader joystick to the loader valve and other circuits, but the
brake pressure is still dumped to the tank.
Operation of the Parking Brake switch 15 energises solenoid
17 and de-energises solenoid 16. This causes the solenoid
valve to move to position Z, directing hydraulic power via the
loader joystick as before, but also pressurising the brake
circuit (Brake OFF).
Key to L. H. Electrical Schematic
1 Reducing Valve Assembly
2 Reducing Valve
3 Solenoid Valve
4 Restrictor
14 Interlock Relay
15 Parking Brake Switch
16 Brake Solenoid
17 Operational Solenoid
18 Door Switch
19 Restraint Switch
29 Diode
78 Brake Switch Illumination
112 Fuse
Pressure Reducing Solenoid Valve
(machines with sequencing E.C.U.)
Note: The sequencing E.C.U. was fitted to machines from
serial number 675358 but was not fitted to machines
manufactured after May 1996.
This valve controls the Safety Restraint Bar circuit, the door
latch circuit, brake circuit, and pressure reduction circuit.
It contains a reducing valve cartridge and a 3 position, 3 port
cartridge solenoid valve.
The sequencing E.C.U. inhibits the selection of the
operational and brake solenoids until firstly the door switch is
closed followed by the restraint switch. Unless the switches
are closed in the correct sequence the E.C.U. will not
operate.
The relevant sections of the hydraulic and electrical circuits
are shown on the opposite page. Refer to the right hand
electrical schematic.
When first entering the machine the solenoid valve should be
in position X i.e. with the parking brake ON, the Safety
Restraint Bar in the access position (hence switch 16 open)
and the door open (switch 17 open). In this condition,
pressure from the auxiliary pump is dumped to the tank
(brake ON).
Closing the door correctly and moving the Safety Restraint
Bar to the operation position triggers the sequencing E.C.U.
to close the interlock relay 11. When the engine is started,
solenoid 14 is energised and the solenoid valve is moved to
position Y.
In this position the valve directs hydraulic power via the
loader joystick to the loader valve and other circuits, but the
brake pressure is still dumped to the tank.
Operation of the Parking Brake switch 12 energises solenoid
13 and de-energises solenoid 14. This causes the solenoid
valve to move to position Z, directing hydraulic power via the
loader joystick as before, but also pressurising the brake
circuit (Brake OFF).
Key to R. H. Electrical Schematic
1 Reducing Valve Assembly
2 Reducing Valve
3 Solenoid Valve
4 Restrictor
11 Interlock Relay
12 Parking Brake Switch
13 Brake Solenoid
14 Operational Solenoid
15 Diode
16 Restraint Switch
17 Door Switch
18 Sequencing E.C.U.
81 Brake Switch Illumination
113 Fuse
114 Fuse
Section E
Hydraulics
9803/8500
Section E
6 - 2
Issue 5
Descriptions