JLG 1850SJ Service Manual - Manual (Page 273)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-103
5.8 DRIVE & FUNCTION PUMP START UP
PROCEDURES
Start-Up Procedure
The Boom Lift uses a Triple Combination Pump coupled to the
Deutz diesel engine. The pumps are connected in-line to each
other as follows:
1. 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.
2. Middle hydrostatic transmission pump, or drive pump, is
coupled to back of the front pump and provides oil flow
to operate machine's left side wheels.
3. Third or rear pump is the function pump. It is coupled to
the back of the middle pump and provides oil flow to
operate boom, axle, steer and platform functions.
Transmission pumps share some common connections. Each
pump charge oil suction ports are connected by steel tubing.
Charge pumps discharge oil flows are connected and flow to a
common charge pump in-line oil filter. Cleaned and filtered oil
flows back to the transmission pumps "G" ports. Pump case
drain ports are connected (T1 & T2).
Oil flow from middle pumps T1 port flows to the oil cooler.
Charge pump 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 ensures only
one valve controls charge pressure and provides an amount of
charge oil flow to the front pump's case for flushing & removal
of hot oil.
Each pump has a separate electrical proportional directional
control valve to control oil flow and direction. Signals or com-
mand values to each pump are similar except when steering.
During steering and moving, the pump supplying oil to
"inside turning radius" has a command less than pump supply-
ing oil flow to "outside turning radius" pump.
"Posi-Traction" control, front to rear on each side of machine is
accomplished by a flow divider/combiner cartridge installed
in the Traction Control Manifold. There is a flow divider/com-
biner for each side. Each flow divider/combiner also has a
"bleed orifice" to limit 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 brake release oil pressure.
BRAKE RELEASE OIL PRESSURE MUST BE SET 25 PSI (1.7 BAR) BELOW BOOST
OIL PRESSURE RELIEF VALVE. IF BRAKE RELEASE PRESSURE IS SET TOO LOW,
BRAKE DRAG AND PUMP CONTROL WILL BE AFFECTED. IF SET TOO HIGH,
DAMAGE TO WHEEL DRIVE PARKING BRAKES COULD RESULT. CONNECT
APPROPRIATE PRESSURE GAUGES TO THE UNIT BEFORE STARTING.
Brake release pressure is controlled by a pressure relief valve
cartridge # 130 and a solenoid operated brake release direc-
tional control cartridge, #170, also located in the Traction Con-
trol Manifold.
START-UP OF NEW OR OVERHAULED INSTALLATIONS:
1. Ensure all electrical checks have been performed and
machine is set up correctly using JLG Analyzer.
2. Ensure machine has all four wheels jacked & blocked off
the ground per JLG procedures.
3. Ensure triple pump assembly is installed and connected
correctly per hydraulic circuit diagram.
4. Disconnect electrical connector from diesel throttle
actuator to prevent engine start.
5. Crank the engine until charge pressure reaches 50 psi or
more.
6. 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 hydrostatic system to fill.
7. Listen for any abnormal noises.
8. Check for oil leaks.
9. 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 charge oil filter inlet.
Charge pressure is checked with the joystick 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].)
10. Operate drive system in "turtle mode" forward and
reverse.
11. De-aerate system by bleeding fluid from Ma & Mb ports.