jcb JCB305, Service Manual

Page: 40 / 51

03 - Attachments, Couplings and Load Handling
10 - Excavator Arm Quickhitch
06 - Hydraulic Quickhitch
03 - 8 9813/6700-1 03 - 8
Component Identification
Figure 10.
A
A Solenoid valve (located in the hydraulic
compartment above the hydraulic pump)
Figure 11. Solenoid connectors (C155, C156)
Figure 12. Harness switch connector (C121)
Figure 13. Joystick connector C095-X2 (green)
Operation
Quickhitch Unlock
The quickhitch switch is a momentary two position
type. When the switch is not pressed it sets to the
unlock position. Power is connected to the quickhitch
pressure switch and quickhitch relay.
The quickhitch will not unlock unless the pressure
switch and quickhitch button in the right joystick are
closed at the same time. The system operates as
follows.
When the operator closes the bucket fully the
pressure switch contacts close and power is
connected to the quickhitch button in the right
joystick.
When the operator presses the quickhitch button at
the same time, the quickhitch relay energises. The
relay contacts close and power is connected to the
quickhitch solenoid which energises. The quickhitch
latch cylinder moves to the unlatch position. At the
same time the quickhitch buzzer and red LED (Light
Emitting Diode) in the quickhitch switch energise.
When the quickhitch relay energises it latches via
the quickhitch diode. This means the relay remains
energised and the quickhitch remains unlatched.
The operator can release the quickhitch button and
move the excavator controls to hitch or unhitch the
attachments. The quickhitch buzzer and red LED in
the quickhitch switch remain active.
Quickhitch Lock
The quickhitch switch is a momentary two position
type. When the switch is pressed momentarily the
system is set to the lock position as follows.
The power supply to the quickhitch relay is isolated
momentarily. The relay unlatches and the contacts
open. The quickhitch buzzer and red LED in the
quickhitch switch de-activate.
The quickhitch solenoid de-energises and the latch
cylinder moves to the lock position, due to force from
its internal spring.
For information about the quickhitch pressure switch
refer to PIL (33-90).