Tadano TR-800XXL4, Service Manual

Page: 96 / 402

2 WD02-0211E
D - 1 . D - 1 .
Swing System
2. The maximum pressure in the swing circuit is
regulated by the relief valve. In case of sudden
stoppage of swing movement, the overload relief
valve (high pressure) in the circuit with unusually
high pressure operates to protect the hydraulic
motor for swing operation.
3. Circuit for free swing
In this hydraulic circuit, the solenoid valve (swing
free) and the swing relief proportional control
valve control the vent ports of the two overload
relief valves (high pressure). As the set pressure
of the swing relief proportional control valve is low,
the overload relief valve (high pressure) in the
circuit with internal pressure higher than the set
pressure is activated at low pressure. The
overload relief valve (high pressure) is activated at
low pressure only when the swing control lever is
located at the neutral position.
4. Circuit for swing automatic stop
The right swing proportional control valve, the left
swing proportional control valve and the swing
relief proportional control valve serve to
automatically stop the swing movement. These
valves control the swing operation according to
the output from the AML. The swing relief
proportional control valve automatically stops the
swing movement only when the swing free/lock
selector switch is set to “FREE” side.
5. Circuit for swing brake release
In this hydraulic circuit, the solenoid valve (swing
brake release) controls the pilot pressure to the
brake release port of the hydraulic motor for swing
operation.
6. Circuit for remote control pressure vent
In this hydraulic circuit, the solenoid valve (remote
control pressure vent) controls the pilot pressure
to the remote control valve.