Swing Gear Brake - Fig. WH 218
(1) Double variable displacement pump
(2) Hydraulic oil reservoir
(3) Pressure filter in the pilot hydraulic system
(4) 2/2-way valve (access and exit protection)
(5) Connection for miniature gauge coupling
(6) Swing brake pedal - pressure relief valve
(7) Swing brake cylinder
(8) Swing gear brake
(9) Swing gear hydraulic motor
(10) Shuttle valve (211 only)
(11) Control piston (211 only)
The swing brake is spring applied and oil released. The pilot pump integrated into the double variable displacement pump (1) produces the pilot pressure of 30+3 bar (3000+300 kPa). Through the pressure filter (3) with bypass and the 2/2-way valve (4), the oil flows to the pressure reducing valve (6) on the swing brake pedal. In the pressure reducing valve of the swing brake pedal (6), the pressure is reduced to 16+1 bar (1600+100 kPa). If the pedal has not been depressed, this pressure is applied to the swing brake cylinder (7), and the swing gear brake (8) is released. When the pedal is actuated, the applied pressure is reduced to a partial pressure. The swing gear brake (8) produces a braking torque corresponding to the pedal travel (movement). The completely depressed pedal will latch, and the swing gear brake is permanently locked under the depressurized swing brake cylinder (permanent locking).
Measure the stroke of the cylinder from the engaged to the released brake position. When the movement is greater than 35 mm (1.38 in.), an adjustment or new brake shoes are needed.
If during a braking process, the system pressure on the swing gear motor is higher than 140 bar (14 000 kPa), the control piston (11) will limit the pedal travel of the swing brake pedal as well as the braking torque. Depending on the increasing driving torque from 140 to 210 bar (14 000 to 21 000 kPa), the possible pedal travel is reduced in such a way that the total driving and braking torque will not exceed an admissible value. See the test instructions on page 31.
Swing Lock Pin
Engage the pin only when the upper structure is aligned with the lower carriage.
Do not attempt to engage the pin when the upper structure is rotating.
Pin Engaged - Turn the knob and push down. The upper structure will not swing when the control lever is down and the pin is engaged.
Pin Disengaged - The upper structure can swing when the lever is up and in the detent.
Brake - Push the pedal (1) down to slow, or further down to stop the upper structure from rotating.
Do not use the swing brake pedal and the swing control lever at the same time.
Brake Lock Detent - Push the brake pedal (1) down past the normal braking position and the pedal will be held down by a detent.