output of the final planetary reduction is transmitted di-
rectly to the swing pinion.
The swing system consists of a swing reducer, or a hydraulic
The disc brake is connected to the sun gear of the primary
motor and swing transmission, a stewing ring, and a disc
planetary reduction, and is a spring applied - hydraulically
type brake. The swing brake control valves are also included
released brake. The brake is in the released position during
in this system.
normal crane operations, and is applied when the brake
pedal is depressed, or when the brake lock is in the applied
The swing transmission provided two gear reductions be-
tween the hydraulic motor and the swing shaft. The swing
shaft pinion to slewing ring ratio provides a third reduction.
Table 6A-1 contains a list of possible troubles, along with
probable causes and remedies for each. It is recommended
The hydraulic motor drives the sun gear of the primary
that you study the schematics in Section 4A prior to
planetary reduction. The output of this reduction is trans-
troubleshooting the swing circuit.
mitted to the sun gear of the final planetary reduction. The
S W I N G CIRCUIT TROUBLESHOOTING
Lift swing brake lock knob.
Swing lock in applied position.
1. Swing completely inoperative.
Swing brake not releasing due to
Disassemble and reseal swing brake.
excessive internal leakage.
Swing brake pedal stuck in
Check swing brake valve spool for
Remove & clean main relief valve.
Main relief valve stuck in
Replace or re-seal the motor.
Swing motor leaks excessively
Repair swing reducer or replace
Mechanical fault in swing reducer
or slewing ring.
Repair or replace swing pump.
G. Faulty swing pump.