JLG 45e Service Manual - Manual (Page 30)

SECTION -
-4 – JLG Lift – 3120861
Pressure relief valves limit the pressure in the swing circuit
and the rod end of each lift cylinder. When the pressure in
one of those circuits reaches the set point of the valve, the
valve opens, allowing enough flow to return to the reser-
voir so that the set pressure is not exceeded. An adjusting
screw on each cartridge relief valve allows the set pres-
sure to be adjusted.
The aluminum manifold provides the passages through
which the hydraulic oil is diverted to provide the desired
movement of the actuators. No moving parts of the valves
slide against the manifold and so it is not subject to wear.
Steer Valve 4640726.
(30/35/n35/40/n40/45 electric)
This valve controls the STEER function. It consists of
screw-in cartridge type valves in an anodized aluminum
manifold. The cartridge valves provide for control of direc-
tion of flow and pressure in the STEER hydraulic circuit.
The directional control valve is a solenoid operated, three
position, 4-way sliding spool type valve. Energizing one of
the electrical coils on the valve will divert the supply of
hydraulic oil to provide steering in one direction. Energiz-
ing the other coil will divert the oil for steering in the other
direction. When neither coil is energized, the supply of
hydraulic oil is blocked.
A pressure relief valve limits the pressure in the steer cir-
cuit. When the pressure reaches the set point of the valve,
the valve opens, allowing enough flow to return to the res-
ervoir so that pressure is not exceeded. An adjusting
screw on the cartridge relief valve allows the set pressure
to be adjusted.
The aluminum manifold provides the passages through
which hydraulic oil is diverted to provide the desired
movement of the steer cylinder. No moving parts of the
valves slide against the manifold and so it is not subject to
any wear.
2.6 MOTOR CONTROLLER.
Modes of Operation.
1. Traction Motor Drive.
a. Drive in either forward or reverse will start only if
the following conditions are satisfied:
1. Function switches off.
2. No procedure or diagnostic faults present.
3. FWD or REV selected as appropriate.
b. Once in “drive” mode, activating a function
switch shall not cause drive mode to be exited,
the pump/traction contactor drive shall not be
energized (shall be left at the traction position). If
a function switch is selected during traction, a
procedure fault will occur when neutral is
selected, remaining until a function switch and
both directions are no longer selected.
c. When neutral is selected, the controller will con-
trol smooth stopping of the machine, using plug
braking, before the electric brake is allowed to
operate.
d. If a function switch is activated in neutral, when
the vehicl e has stopped and the brak e is
applied, then pump mode will become opera-
tional.
1. Pump Motor Drive.
a. Pump motor drive will start only if the following
conditions are satisfied:
1. FWD and REV switch off.
2. Traction mode off (brake applied).
a. Pump drive shall only be enabled when the
direction selector inputs are in neutral and the
machine is stationary. Once pump drive mode
has been entered, then the status of the direc-
tion selector inputs shall no longer interlock
pump operation. If a direction switch is selected
during pump drive, a procedure fault will occur
when the function switch is no longer selected,
remaining until both directions and the function
switch are no longer selected.
Features.
1. Features in Traction Mode.
a. Maximum Speed Control.
The controller incorporates a function to limit the maxi-
mum speed of the machine to a percentage of maximum
possible speed. The function operates in such a manner
as to control vehicle speed by limiting the percentage on
of the switching device to keep the machine speed below
the maximum permitted value or, if required, to apply vari-
able plug braking to restrict machine speed when travel-
ing down a grade. The speed is controlled based on the
percentage of accelerator input.
1. Features in Pump Mode.
a. Proportional Control of Pump Motor Speed.
The pump motor speed shall be controlled by
varying the percentage on of the switching ele-
ment in relation to a separate pump accelerator
input.
b. Soft Start.
The pump motor speed control incorporates a
“soft start” facility by applying acceleration delay
to changes in the applied percentage on of the
switching element.