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December 2019W11/W12/W13 | Operation manual
6. DISCHARGING RESIDUAL PRESSURE IN HYDRAULIC
SYSTEM
Caution, risk of injury!
A fine hydraulic jet under high pressure can penetrate the skin! See a doctor immediately if oil gets in the eyes or
skin. Open only depressurized hydraulic systems! Even when a wheel loader with the lifting frame completely
lowered and the engine stopped is parked on a horizontal surface, there may be considerable residual pressure in
parts of the hydraulic system. Residual pressure discharges gradually. If a hydraulic system needs to be opened
immediately after shutdown, you must first depressurize the system.
Opening the lowering brake valves
The lowering brake valves may only be opened by trained specialist personnel.
Following servicing/repair, the lowering brake valves must be closed again or returned to their original condition!
For wheel loaders with lowering brake valves on lifting and tilting rams, the valves must be opened.
1. Undo the nut.
2. Unscrew the screw until the lifting frame lowers slowly. If the lifting frame cannot be lowered afterwards due
to friction or insufficient mass, you must assist the process using a cable winch or lashing straps.
3. Refit the screw as soon as the lifting frame is fully lowered and retighten the nut. In the case of machines with
electrically operated lowering brake valves on the lifting and tilting rams, the ignition must be switched on in
the event of engine or hydraulic failure and the unlocking switch must be activated so that the working
equipment can be lowered to the ground.
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