Lull 944E-42 Service Manual - Manual (Page 456)

Hydraulic System
8.204 Model 644E-42/944E-42 Rev. 6/04
8.12.13 Accumulator Charge/Secondary
Function Valve
Hydraulic oil from the front pump flows into the
accumulator charge/secondary function valve and then is
directed to the power steering unit, the two accumulators
which direct pressure to the service brakes. Oil also flows
from the accumulator charge/secondary function valve to
the main control valve, the park brakes in the front axle
and also provides pilot pressure to the joysticks.
The accumulator charge/secondary function valve (1) is a
machined block with ports for various valves, cartridges
and other fittings. The accumulator charge valve/
secondary function is located on the valve plate (2) which
is located under the cab floor.
a. Accumulator Charge/Secondary Function Valve
Replacement
1. Park the vehicle on a firm, level surface, fully retract
all hydraulic cylinders, ground the attachment (if
any), place the travel select lever in the [N]
NEUTRAL DETENT position, engage the park brake
switch and shut the engine OFF.
2. Place an Accident Prevention Tag on both the
ignition switch and the steering wheel, stating that
the vehicle should not be operated. Refer to Section
1.5, “Accident Prevention Tag Usage.”
3. Unlatch and open the engine cover. Allow the
hydraulic fluid to cool.
4. With the engine OFF, relieve the hydraulic pressure
from the accumulators. Apply the service brake
pedal and then release. Do this several times until all
hydraulic pressure has been relieved from the
accumulators.
5. Remove the access plate from the floor of the cab.
6. Label or otherwise mark the hydraulic hoses in
relation to the accumulator charge/secondary
function valve. Disconnect and cap all hoses and
fittings. Label or mark any wire harness connectors,
as they relate to the accumulator charge/secondary
function valve.
7. Swing the valve plate down. See “Sub Plate w/Valve
Plate Lowering” on page 8.176.
8. Remove the accumulator charge/secondary function
valve from the valve plate. The accumulator charge/
secondary function valve (3) is held to the valve plate
(4) with two carriage bolts (5) and two hex nuts (6).
The carriage bolts will remain in the slots in the valve
plate. Wipe up any hydraulic fluid spillage in, on,
near and around the vehicle.
b. Accumulator Charge/Secondary Function Valve
Disassembly, Cleaning, Inspection and
Assembly
1. Secure the accumulator charge/secondary function
valve (7) in a suitable bench vise if possible.
2. Tag and remove all hydraulic fittings, and diagnostic
test nipples, from the accumulator charge/secondary
function valve.
WARNING:
Hot hydraulic fluid can
cause severe burns. Wait for hydraulic fluid to
cool before servicing any hydraulic component.
B
A
MU5950
1
2
WARNING:
Escaping hydraulic fluid
under pressure can penetrate the skin, causing
death or serious injury. Relieve hydraulic
pressure before servicing any hydraulic
component.
MU1940
3
4 5
6