JLG 1850SJ Service And Maintenance Manual Download

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SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS

5-170

3121619

5.10 DRIVE & FUNCTION PUMP START UP

PROCEDURES

Start-Up Procedure

The Boom Lift utilizes a Triple Combination Pump coupled to
the Deutz diesel engine. The pumps are connected in-line to
each other as follows:

The front hydrostatic transmission pump, or drive pump,
is coupled directly to the diesel engine and provides oil
flow to operate the machine's right side wheels.

The middle hydrostatic transmission pump, or drive
pump, is coupled to the back of the front pump and pro-
vides oil flow to operate the machine's left side wheels.

The third or rear pump is the function pump. It is cou-
pled to the back of the middle pump and provides oil
flow to operate the boom, axle, steer and platform func-
tions.

The transmission pumps share some common connections.
Each pumps charge oil suction ports are connected by steel
tubing, the charge pumps discharge oil flows are connected
and flow to a common charge pump inline oil filter, cleaned &
filtered oil flows back to the transmission pumps "G" ports. The
pumps case drain ports are connected (T1 & T2), oil flow from
the middle pumps T1 port also provides flows to the oil cooler.
The charge pumps oil pressure is regulated by a single boost
oil pressure relief valve installed in the middle pump. The front
pump has an orifice cartridge (0.047" diameter) installed in
place of a charge oil pressure relief cartridge. This insures that
only one valve controls charge pressure & provides an amount
of charge oil flow to the front pump's case to insure flushing &
removal of hot oil.

Each pump has its own separate electrical proportional direc-
tional control valve to control oil flow and direction. The sig-
nals or command values to each pump are similar except
when steering. During steering and propel of the machine the
pump supplying oil to the "inside turning radius" has a com-
mand less than the pump supplying oil flow to the "outside
turning radius" pump.

"Posi-Traction" control, front to rear on a given side of the
machine, is accomplished by a flow divider/combiner car-
tridge installed in the Traction Control Manifold. There is a flow
divider/combiner for each side. Each flow divider/combiner
also has a "bleed orifice" to limit the amount of flow splitting
or combining.

The middle transmission pump also supplies oil to a hot oil
flushing valve cartridge, #120, in the Traction Control Mani-
fold. This cartridge provides a means to obtain brake release
oil pressure. The brake release pressure is controlled by a pres-
sure relief valve cartridge # 130 and a solenoid operated brake
release directional control cartridge, #170, also located in the
Traction Control Manifold. This is important to note as the
brake release oil pressure must be set 25 psi (1.7 bar) below
the boost oil pressure relief valve. If the brake release pressure
is set too low, brake drag and pump control will be affected. If
set too high, damage to the wheel drive parking brakes could
result. Prior to start, connect appropriate pressure gauges to
the unit.

FOR THE START-UP OF NEW OR OVERHAULED INSTALLA-
TIONS:

Insure all electrical checks have been performed & the
machine is set up correctly with the JLG Analyzer.

Insure the machine has all four wheels jacked & blocked
off the ground per JLG procedures.

Insure the triple pump assembly is installed and con-
nected correctly per the hydraulic circuit diagram.

Disconnect the electrical connector from the diesel's
throttle actuator, to prevent engine start.

Crank the engine until charge pressure reaches 50 psi or
more.

Re-connect throttle actuator electrical connector and
start engine. Allow engine to run at idle speed only for at
least 5 minutes. This will allow the hydrostatic system to
filled.

Listen for any abnormal noises.

Check for oil leaks.

Check charge pressure (500 psi +50psi, - 0 psi [34.4 bar
+3.4 bar, - 0 bar]). Pressure can be measured a pump
ports Ma & Mb or by "teeing" into the inlet for the
charge oil filter. Charge pressure is checked with the joy-
stick in neutral. A 0-1000 psi (0-70 bar) pressure gauge
must be used. (If pressure gauges were installed in Ma &
Mb to check charge pressure, disconnect the gauges
installed in Ma & Mb, as they will be damaged if loop
pressure rises above 1000 psi [34.4 bar].)

JLG 1850SJ, Service And Maintenance Manual

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