Hydraulic Lines Connections; Proportional Pressure Relief Valve; Air Bleeding - JLG TOUCAN 8E Service And Maintenance Manual

SECTION 7 - HYDRAULICS
Port 1: Mast and Jib Lift Up/Down
Port 2: Pressure Plug
Port 3: Swing Right
Port 4: Swing Left
Port 5: Steer Left
Port 6: Steer Right

Hydraulic Lines Connections

Figure 7-7. Hydraulic Lines Connections

Proportional Pressure Relief Valve

This two stage spool type proportional relief valve (9)
(Refer to Figure 7-5.) is controlled by a PWM signal deliv-
ered by the master controller. As a function of the electri-
cal control signal, the pressure relief value changes. When
7-4
a machine function is performed, the valve is controlled
with a signal corresponding to the appropriate relief pres-
sure.
THE COIL OF THE PROPORTIONAL RELIEF VALVE IS SPECIALLY
DESIGNED FOR PROPORTIONAL CONTROLS APPLICATIONS. DO
NOT INVERT THIS COIL WITH ANOTHER DIRECTIONAL VALVE
COIL. THE VOLTAGE INDICATION ON THE PROPORTIONAL COIL
IS 24 "VADC" AND ITS RESISTANCE VALUE IS 8.8 OHMS.
AFTER REPLACEMENT OF THE PROPORTIONAL RELIEF VALVE
AND/OR THE PROPORTIONAL COIL, ALL PRESSURE RELIEF
VALUES MUST BE CHECKED AND ADJUSTED ACCORDINGLY.
Refer to Section 9.4 for proper proportional relief valve
adjustment procedure.

Air Bleeding

Air entrapped in the valve pole tube can cause noisy oper-
ation of the valve when relieving the pressure. This can be
due to an insufficient fluid level in the hydraulic reservoir.
Check oil level as previously indicated. This can also
appears after the hydraulic circuit has been serviced.
1. From ground controls, operate a jib lift up movement
till the jib is fully raised.
2. Unscrew and remove the valve coil nut (1).
3. Using a screw driver of appropriate dimension,
loosen the bleeding screw (2) from about 3 turns
(Do not remove the screw).
4. Continue jib operation (with the jib cylinder fully
extended). Once a continuous and regular oil flow
comes out from the valve bleeding orifice, tighten
the bleeding screw to 1 N.m.
5. Install coil nut (1).
– JLG Lift –
NOTICE
NOTICE
Figure 7-8. Air Bleeding
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