Secondary Function Manifold - JLG sky trak mmv Service Manual

Note: Check for leaks and repair as required before
continuing. Add hydraulic fluid to the reservoir as
needed.
8. Wipe up any hydraulic fluid spillage in, on, near and
around the vehicle, work area and tools.
d. Pilot Select Manifold Test
Conduct a function test of the boom operation.
9.12.5

Secondary Function Manifold

The secondary function manifold (11) is a directional control
valve. Hydraulic oil from the main pump flows into the accu-
mulator charge valve where the pressure is directed to the
secondary function manifold which directs pressure to the
park brake or pilot pressure to the joystick.
The secondary function manifold is a machined block with
ports for a pressure reducing valve, a pressure relief valve,
two park brake solenoid valves (one normally open and one
normally closed), a check valve and diagnostic test nipples.
The secondary function manifold is secured to a bracket
(12) at the hydraulic fluid reservoir/engine mount with cap-
screws, lockwashers and nuts.
12 Front
Verify the correct operation of the solenoids before con-
sidering replacement of the secondary function manifold.
Refer to Section 10, Electrical System. The manifold itself
is not serviceable and must be replaced if defective.
Model MMV Rev. 12/04
11
Front
MM4210
DO NOT loosen, disassemble or attempt to adjust any of
the pressure valves unless specifically instructed by JLG
to do so! Tampering with a pressure valve will irrevocably
alter pressure in the affected circuits.
a. Secondary Function Manifold 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 [N] NEUTRAL,
place the neutral lock lever in the [N] NEUTRAL
LOCK 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 .
WARNING:
cause severe burns. Wait for hydraulic fluid to
cool before servicing any hydraulic component.
3. Unlatch and open the engine cover. Allow the
hydraulic fluid to cool.
WARNING:
under pressure can penetrate the skin, causing
death or serious injury. Relieve hydraulic pres-
sure before servicing any hydraulic component.
4. Label or otherwise mark the hydraulic hoses in
relation to the secondary function manifold.
Disconnect and cap all hoses, fittings, solenoid wire
terminal leads, etc.
5. Remove the secondary function manifold from the
vehicle. Wipe up any hydraulic fluid spillage in, on,
near and around the vehicle.
Hydraulic System
Hot hydraulic fluid can
Escaping hydraulic fluid
9.117