Lull 944E-42 Service Manual - Manual (Page 120)

Hydraulic System
8-4 944E-42
8.3 HYDRAULIC PRESSURE DIAGNOSIS
Two kits are available to use for hydraulic system
maintenance and troubleshooting. The kit is contained in
a durable polyethylene carrying case for demanding field
service conditions.
Pressure Test Kit
The hydraulic pressure test kit is used to pressure test the
various hydraulic components in the hydraulic system.
The kit includes:
• Gauges for testing high and low pressure circuits
• Fittings, couplers and hoses
• Durable carrying case
Flowmeter Kit
A flowmeter test kit is used to pinpoint hydraulic system
faults. It includes a flowmeter with load valve, magnetic
base, photo tachometer head and flex arm. The kit
features:
• Bi-directional for unrestricted connection and
simplified testing
• Internal by-pass to protect system and tester from
over-pressure
• Measures up to 60 GPM and 6000 psi
• Durable carrying case
Contact your local authorized distributor for ordering
information.
8.3.1 Pressure Checks and Adjustments
When diagnosing trouble in the hydraulic system, use the
hydraulic testing information in Section 8.4.1, “Hydraulic
Pressures.”
In general, follow the steps below whenever conducting
pressure checks and performing adjustments:
1. Park the machine on a firm, level surface. Engage
the park brake, place the travel select lever in (N)
NEUTRAL, level the boom and turn the engine OFF.
2. Remove the access plate from the cab floor to gain
access to the test ports.
3. Pressure test ports are located under the cab floor
and are for each hydraulic circuit being tested. A
decal (1) showing each test port and function being
tested is located on the underside of the access
plate (2). Install a pressure gauge capable of
measuring at least 10% more pressure than that
which the circuit being checked operates under.
4. Start the engine. Operate machine functions several
times to allow hydraulic oil to reach operating
temperature. The hydraulic oil temperature should
be between 100-120°F (38-49° C). If a temperature
gauge or thermometer is unavailable, the hydraulic oil
reservoir should be warm to the touch.
5. Refer to Section 8.4.1, “Hydraulic Pressures,” for
testing procedures.
6. Fully depress the accelerator pedal if required. Place
and hold the joystick in the position needed to
operate the particular machine function being
checked. Continue holding the joystick in position
until pressure readings are taken.
Part
Number
Description Approximate
Weight
Price and
Availability
80904003 Hydraulic Pressure Test Kit 10 lbs. Consult Factory
1321107 Hydraulic Flowmeter Kit 28 lbs. Consult Factory
4110392
1
6 5
4
3 2
Location Function Tested
1 Main Valve Pressure
2 Pilot Pressure
3 Park Brake
4 Pump #1
5 Accumulator Pressure
6 Load Sense (Steering)
7 Load Sense (Implement)
7
MU3921
1
2