Pressure Relief Valves Adjustment; Mast Power Unit Pressure Relief Valve - JLG TOUCAN DUO Service Manual

IV-5
4.5 Pressure
adjustment
Pressure relief valves are used to protect the hydraulic
system from excessive pressures. They return the oil
to the reservoir when the pressure setting is reached,
relieving pressure within the circuit in which they are
used.
The pressure relief valves are checked and adjusted
by bringing the circuit to reach its prescribed pressure
limit. At this point, the relief valve opens, returning oil
to the reservoir. The cylinder circuit can be adjusted
by extending the cylinder to its limit of travel.
The values indicated correspond to the settings to be
obtained with the pressure gauge connected to the
pressure point on the power unit. Connecting the gauge
to another point of the circuit presents risks of setting
the relief valve too high and could result in serious
injuries and equipment damage.
A correct setting of the relief valve is mandatory for
the hydraulic circuit to function correctly. Settings must
be performed by qualified technicians only using
correct equipment, within tolerances and only after
the need for adjustment has been established.
Setting values of the relief valves are indicated in
chapters 4.5.1 and 4.5.2. If the setting of a relief
valve is not within ± 5% of the indicated setting, adjust
it to its correct value.
Do not exceed indicated torque values.
Do not leave the relief valve open for more
than one minute.
NOTE
To adjust a relief valve, turn the setting screw
until the correct setting is reached (pressure
increase by tightening the setting screw).
! CAUTION
Do not adjust the pressure of the system
above its prescribed value. Increasing the
pressure could damage the hydraulic
components.
40
ADJUSTMENTS
relief valves
DANGER
DANGER
Do not attempt to loosen hydraulic fittings in
pressurized lines or when the pump motor
assembly is running. Failure to do so may
result in death or serious injuries.

4.5.1 Mast power unit pressure relief valve

1- Place the rated load increased by 10% in the
platform (approximately 220 kg).
2- Connect a 0-400 bar pressure gauge on the
pressure plug (mini-mess type) of the power
unit.
3- Remove the plug.
4- Loosen the locknut.
5- From the emergency control panel, fully raise
the mast.
6- Adjust the setting to 15 MPa using the setting
screw.
7- Tighten the locknut while holding the setting
screw to preserve the setting. Torque to
16 ± 1 N.m.
8- Install the seal
9- Torque the plug to 11 ± 1 N.m.
TOUCAN Duo
IV-5
DANGER
Locknut
Setting screw
Seal
Plug
Fig. 4.2 Power
unit
models
Updated 06-2015