JLG 18RS Service Manual - Manual (Page 128)

SECTION 5 - HYDRAULICS
5-38 – JLG Lift – 3121284
Engaging the Bypass Function
Use this procedure to bypass the pump to allow moving the
vehicle/machine short distances when you cannot start the
prime mover.
1. 1. To open the HPRVs (L150), rotate three revolutions
counter clockwise using a 22mm hex wrench. Do not
rotate more than 3 revolutions, leakage will result.
2. To close the HPRVs, rotate them clockwise until seated.
Torque to 70 N•m [52 lbf•lb].
3. If machine is towable with HPRVs opened three turns
and if wheels are locked (not towable) with HPRV valves
closed, bypass function is working correctly.
IT IS POSSIBLE TO DAMAGE THE DRIVE MOTOR(S) BY OPERATING IN BYPASS
MODE WITHOUT CHARGE PRESSURE. MOVE THE VEHICLE/MACHINE AT A
SPEED NOT MORE THAN 20% OF MAXIMUM FOR A DURATION NOT EXCEEDING
3 MINUTES.
Displacement Limiter Adjustment
BEFORE ADJUSTING THE DISPLACEMENT LIMITER, MARK THE POSITION OF
THE SERVO CYLINDER. BE SURE THE SERVO CYLINDER DOES NOT TURN WHEN
SETTING THE DISPLACEMENT LIMITER LOCKNUT.
If your pump has displacement limiters, you will find them on
either servo cover. You can limit forward and reverse displace-
ment independently.
NOTE: Displacement limiters are not pre-set by the factory. We
install them as far as possible without contacting the servo
piston. Limiting displacement requires clockwise adjust-
ment of the limiting screw.
1. Loosen the locking nut.
2. Rotate the adjusting screw to achieve the desired maxi-
mum displacement. Set the adjusting screw against the
servo piston by feel before counting turns. Refer to the
table below for change per turn. Clockwise rotation
decreases displacement, counter clockwise rotation
increases it. Adjustment is possible from zero to maxi-
mum.
3. After establishing the desired maximum displacement
setting, hold the adjusting screw while torquing the
locknut to the value in the table below.
4. Test operation of the vehicle/machine to verify proper
maximum speed of vehicle/work function.
Figure 5-41. Engaging the Bypass Function
Table 5-10. Displacement limiter adjustment data
Displacement
Locknut Wrench
Size and Torque
Adjusting
Screw Size
Approximate
Displacement
Change Per
Revolution of
Adjusting Screw
45 13 mm 23 N•m
[17 lbf•ft]
4 mm
internal hex
5.1 cm3
[0.31 in3]
53 13 mm 23 N•m
[17 lbf•ft]
4 mm
internal hex
6.0 cm3
[0.37 in3]
60 13 mm 23 N•m
[17 lbf•ft]
4 mm
internal hex
6.8 cm3
[0.41 in3]
68 13 mm 23 N•m
[17 lbf•ft]
4 mm
internal hex
7.7 cm3
[0.47 in3]
Figure 5-42. Displacement Limiter Adjustment