Hydraulic Operation - jcb 214e Service Manual

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Section D
45 - 3
Basic System Operation

Hydraulic Operation

Oil at system pressure flows to the servo pressure supply
valve C via a hose connected at the excavator valve J. An
integral pressure regulating valve F maintains the oil at
'servo' pressure.
When the operator actuates the system by locking the seat
in the forward or reverse facing position and raising forward
the arm rests, the isolation valve solenoids D are energised
and oil is directed to the joystick controllers A and B.
Each joystick controller contains four spool valve 'capsules',
numbered 1 to 4 on each valve. The valves are operated by
moving the associated joystick. With the joystick in the
neutral position the valves vent the oil from the excavator
valve servo pilot ports to tank K.
Example Operation:
When the operator moves the right hand joystick B forward
this pushes spool 3 down. Oil at servo pressure is directed to
port S5b at the excavator valve J. This causes the boom
spool to move and operate the boom ram. As the boom
spool moves, oil is vented from port S5a via spool 1 and port
T to tank.
The valve 'capsules' feature proportional control. This
enables backhoe precision control. Each valve capsule
regulates the oil pressure supplied to the associated
excavator valve pilot line in proportion to the joystick
position. The further the joystick is moved the greater the
servo pressure and the further the associated excavator
valve spool moves.
Accumulator E maintains servo pressure for several
operations of the excavator spools with the engine stopped.
This allows venting of pressure from the backhoe hydraulic
rams, or lowering of a load in the event of engine failure.
Note: The diagram opposite shows the servo pilot hoses
connected to give the ISO + control pattern. For SAE +
control pattern the servo pilot hoses are connected
differently at the excavator valve as shown at Z.
9803/3280
Precision Control (Servo)
Purchased from www.WorkshopManuals.co.uk
Controls
Component Key:
A Left hand joystick controller
B Right hand joystick controller
C Servo pressure supply valve
D Isolation valve solenoids
E Accumulator
F Servo pressure regulating valve
G Servo pressure relief valve
H Loader valve block
J Excavator valve block
K Hydraulic tank
L Stabiliser controls
M Auxiliary footpedal
S1a Servo pilot port - Slew ram spool
S1b Servo pilot port - Slew ram spool
S2a Servo pilot port - Dipper ram spool
S2b Servo pilot port - Dipper ram spool
S3a Servo pilot port - R.H. stabiliser ram spool
S3b Servo pilot port - R.H. stabiliser ram spool
S4a Servo pilot port - L.H. stabiliser ram spool
S4b Servo pilot port - L.H. stabiliser ram spool
S5a Servo pilot port - Boom ram spool
S5b Servo pilot port - Boom ram spool
S6a Servo pilot port - Bucket ram spool
S6b Servo pilot port - Bucket ram spool
S7a Servo pilot port - Auxiliary spool (Extending Dipper)
S7b Servo pilot port - Auxiliary spool (Extending Dipper)
Section D
45 - 3
Issue 1