Wacker Neuson 28Z3, Service Manual

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5-22
SHB 28Z3 EN – Edition 2.0 * 28z3s510.fm
Hydraulic system
Function
Driving:
If high pressure is applied to a drive, the brake piston is slowly actuated via the throttle ori-
fice. Brake piston control causes high pressure to be applied to the motor, which starts
turning. There is no pressure on the return line.
Stopping:
The oil flows from both ports to the tank upon releasing the joystick. The brake piston
slowly returns to its base position via the throttle. The slow return of the brake piston pre-
vents the hydraulic motor from coming to an abrupt standstill. With the brake piston in neu-
tral position, the ports are no longer connected to the motor, which can no longer turn.
2 speed range functions
Speed range 1
• “High speed” switch switched off
The solenoid valve on the pilot oil supply unit is de-energised, and the oil flows through the
control line to the tank. The swash plate of the hydraulic motor is fully swivelled in this posi-
tion, i.e. the motor is at maximum capacity.
➥
The engine runs at slow speed but at maximum tractive power.
Speed range 2
• “High speed” switch switched on
The solenoid valve is energised, and the swash plate of the hydraulic motor returns to
base position, i.e. the motor is at minimum capacity.
➥
The engine runs at high speed but at low tractive power.