Lull 944E-42, Service Manual

Page: 272 / 844

Hydraulic System
8.22 Model 644E-42/944E-42 Rev. 6/04
TEST
SEQUENCE
TEST
LOCATION
Valve
Port
ADJUST.
LOCATION
COMPONENT
DESCRIPTION
PRESSURE
READINGS
PRESSURE TEST PROCEDURES
8
—
Auxiliary
Hydraulics
2,900-3,100 psi
(200-214 bar)
With engine at high idle, use the auxiliary hydraulic control lever
to check pressure to both male and female connectors. Hold
over relief and check pressure. If pressure is incorrect, adjust or
replace cartridge located in the auxiliary section of the main
control valve.
9
— N/A
Main Valve Port
Relief
Attachment Tilt
Backward
3,400-3,600 psi
(234-248 bar)
CONSULT FACTORY
10
— N/A
Main Valve Port
Relief
Attachment Tilt
Forward
3,400-3,600 psi
(234-248 bar)
CONSULT FACTORY
11
—
Main Valve Port
Relief Boom
Extend
2,900-3,100 psi
(200-214 bar)
With engine at high idle, use the boom extend lever to fully
extend the boom. Hold over relief and check pressure. If
pressure is incorrect, check the main system pressure using
test sequence 7.
12
— N/A
Main Valve Port
Relief Transfer
Carriage
Forward
3,400-3,600 psi
(234-248 bar)
With engine at high idle, use the transfer carriage lever to fully
extend the transfer carriage. Hold over relief and check
pressure. If pressure is incorrect, check the main system
pressure using test sequence 7.
13
—
Main Valve Port
Relief Transfer
Carriage Back
See
2,400-2,600 psi
(165-179 bar)
With engine at high idle, use the transfer carriage lever to fully
retract the transfer carriage. Hold over relief and check
pressure. If pressure is incorrect, adjust or replace cartridge
located in the transfer section of the main control valve.
14
— N/A
Brake Valve
(Service Brake
Pressure)
See
450-550 psi
(31-38 bar)
With engine at idle, depress and hold brake pedal. Check
pressure for the front axle. If pressure is incorrect, check
accumulator pressure using test sequence 6.
15
— N/A
Brake Valve
(Service Brake
Pressure)
See
450-550 psi
(31-38 bar)
With engine at idle, depress and hold brake pedal. Check
pressure for the rear axle. If pressure is incorrect, check
accumulator pressure using test sequence 6.
16
— N/A
Brake Valve
(Service Brake
Accumulator
Pressure)
See
450-550 psi
(31-38 bar)
With engine OFF, depress and hold brake pedal. Check
pressure for the front axle. If pressure is incorrect, check for
external leaks. If no leaks are found, check accumulator
pressure using test sequence 6.
17
— N/A
Brake Valve
(Service Brake
Accumulator
Pressure)
See
450-550 psi
(31-38 bar)
With engine OFF, depress and hold brake pedal. Check
pressure for the rear axle. If pressure is incorrect, check for
external leaks. If no leaks are found, check accumulator
pressure using test sequence 6.
18
G1
Stabilizer
Cylinder
See
75-150 psi
(5,2-10,3 bar)
With the engine at idle, check the pressure on the cylinder. If the
pressure is not correct, adjust or replace the cartridge located
on the stabilizer cylinder block.
19
G1
Stabilizer
Cylinder
See
50 psi min.
(3,4 bar) min.
With the engine at idle and boom below 40°, frame sway all the
way to the right, check the pressure on the cylinder. If the
pressure is not correct, adjust or replace the cartridge located
on the stabilizer cylinder block.
20
G1
Stabilizer
Cylinder
See
200 psi max.
(13,8 bar) max.
With the engine at idle and boom below 40°, frame sway all the
way to the left, check the pressure on the cylinder. If the
pressure is not correct, adjust or replace the cartridge located
on the stabilizer cylinder block.
—
A
— —
Load Sense
(Steering)
—
Consult with JLG Technical Service Department for additional
testing information.
—
B
— —
Load Sense
(Implement)
—
Consult with JLG Technical Service Department for additional
testing information.
2
4
2
2
2
5
2
2
6
7
8
7
8
9
7
9
7
9
7
CAUTION:
GAUGE DAMAGE may occur. Malfunctioning hydraulic system circuits may have
excessive pressure and can cause hydraulic pressure spikes. Test circuit with the highest reading
pressure gauge first. If this gauge cannot record an accurate pressure reading, use the next lower
pressure gauge.