Operation & Maintenance Manual
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LG968 /969Wheel Loader
104
3.1 Driving Brake System
This system is double brake pedal, air pushing oil and four wheels caliper disk brake system. 8 brake
clamps with 2 rear clamps and 2 front clamps are used to improve the safety of the whole machine.
When the left brake pedal is stepped on during driving, the compressed air of air tank 4 flows through
air brake valve 3 and shuttle valve 2 into the air chamber of air booster valve 1 and pushes the piston
of booster pump to change oil pressure (oil pressure is about 14MPa). Brake fluid pushes the piston of
caliper disk brake and makes the friction disk contact the brake plate and brake the wheels to achieve
the purpose of decelerating or parking. And the air pressure signal is send out to cut off the power of
gearbox.
When the right brake pedal is stepped on during driving, the braking theory is the same as left pedal is
stepped, but the power of gearbox is not cut off.
Release the brake pedal, the compressed air of booster pump bleeds from brake valve to atmosphere
and the brake state relieves.
3.3 Emergency and Parking Brake System
This system employs the electronic control air driving inner expand hoof type brake system. During
running, gently rotate the operation button of the brake electromagnetic valve 7, the button will
rebound later automatically, the compressed air of air tank 4 flows through brake electromagnetic
valve 7 into the parking brake air room 8, pushing the spring to open the piston, release the disk brake
to release braking status; when stopping,
push
the operation button of brake electromagnetic valve 7,
the compressed air in brake air room 8 will be drained to the environment through the air drain outlet
of brake electromagnetic valve, the brake unit will be pulled up due to the spring force to brake the
machine, and at the meanwhile, air pressure signal will be send and the break indicator lamp will be
ON
and the power of gearbox is cut off.
When the system pressure is lower than 0.4MPa, the brake electromagnetic valve will power off
automatically, so that to achieve emergency brake, so that the compressed air in parking brake air
room 8 will be drained to the environment through manual control brake valve to achieve emergency
brake, to ensure the safety of machine and the people.
