When the safety lever is pulled to the brake OFF
position, pressure air goes through port (5) to air
compartment (3). The pressure air moves piston (2),
sleeve (4) and rod (7) back to the left. Rod (7) then
moves the parking brake lever to release the parking
CONTROL VALVE FOR DIFFERENTIAL LOCK
The electric differential control switch (18) controls a
solenoid activated hydraulic valve located on the
differential carrier. When switch (18) is in the off (LOCK)
position, the indicator light (17) is off. No current flows to
the solenoid coil connector (16) and the valve is held
open by spring force.
P1 pressure oil from the
transmission relief valve group flows through a hose to
opening (15). The internal passages of the solenoid
valve act as an orifice.
ELECTRIC SOLENOID VALVE
11. Opening to reservoir. 12. Opening to clutch. 14.
Pressure check test port. 15. Inlet opening. 16.
Solenoid coil connector.
P1 oil goes into opening (15) and out opening (12) to the
differential lock clutch. The oil goes into the differential
through the differential cage assembly to cavity (2) in the
differential housing. The P1 oil pushes piston (1) against
clutch plates (3) which cause side gear (9) to turn with
bevel gear (4). Pinions (7) do not turn on spider (5) but
turn with side gears (8) and (9).
The speed of the wheels will be equal, even if the
traction under each tandem becomes different.
When the differential control switch (18) is in the on
(UNLOCKED) position, the indicator light (17) is on and
current flows to the solenoid coil connector (16). The
solenoid force then moves the valve spool against its
spring force. The pressure oil in cavity (2) goes through
opening (11) to the reservoir. Pinions (7) and side gears
(8) and (9) are now free to turn when traction under each
tandem is different.
The differential with the electric control can be locked
1. Piston. 2. Cavity. 3. Clutch plates. 4. Bevel gear.
in any speed since the P1 pressure source is taken
5. Spider shaft for pinions. 6. Bevel pinion. 7.
direct from the transmission relief valve.
Pinions (four). 8. Side gear. 9. Side gear.
On some machines with the electric control, an
adapter plate is used between the solenoid valve and the
differential carrier. This plate blocks the flow of oil from
the No. 6 transmission clutch on machines that used the
air control. On other machines with electric control, the
plate is not used and the hole to the No. 6 clutch is
tapped and blocked with a plug.