950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Electrohydraulic Control Caterpillar


Electrohydraulic Control
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Illustration 1g03567045
Implement control pod
(1) Bucket lever (Tilt back, Hold, Dump).
(2) Lift lever (Raise, Hold, Lower, Float).
(3) Auxiliary Third function lever (optional attachment).
(4) Hydraulic lockout switch.
(5) Auxiliary Fourth function switch (optional attachment).

Bucket control lever (1), lift control lever (2), auxiliary control lever (3), and auxiliary control switch (5) are controlled manually by the operator. The control levers send electronic signals to the implement electronic control module (ECM). Then, the implement ECM sends the appropriate amount of current to the solenoid valve (pilot proportioning) on the pilot valve (oil manifold). The solenoid valve sends a low-pressure signal to the main control valve. This signal causes a stem in the main control valve to move. Then, pump supply oil is sent to the implement cylinders. The cylinder rods will extend or the cylinder rods will retract.

The optional auxiliary implement system has an auxiliary pilot valve and an auxiliary control valve. To control the auxiliary implement system, auxiliary control lever (3) is added in the operator station for third function controls while a roller switch (5) is added for fourth function controls.

The electrohydraulic control levers are equipped with soft detents. The soft detents do not hold the lever in place. The soft detents require an increased force near the end of lever travel in order to initiate the kickout. The soft detents are controlled by the software within the implement (ECM). As the control lever is moved into the detent position and released, the linkage will travel to a kickout position that is preprogrammed. The lever should be released to return the lever to the HOLD position automatically. The linkage movement will continue until the kickout is reached. Any 6° movement of the control lever from the HOLD position will disable the soft detents. The soft detents will not be activated if the control lever is held in the detent position for more that 1 second.

The lift lever has two detents. The rearward detent will initiate a lift kickout. The forward detent will initiate a lower kickout if the linkage is above the preprogrammed kickout position. If the linkage is at the kickout setpoint or below the lower kickout setpoint, the forward detent will initiate the float function. The FLOAT position will lower the attachment to the ground. Never use the FLOAT position to lower a loaded bucket.

The tilt lever has two detents. The rearward detent will initiate a tilt back kickout. The forward detent will initiate a dump kickout.



Illustration 2g03573057
Implement control pod with Joystick
(4) Hydraulic lockout switch.
(6) Joystick.
(7) F/N/R switch.
(8) Horn.
(9) Auxiliary Third function switch (optional attachment).
(10) Auxiliary Fourth function switch (optional attachment).

If the machine is equipped with a joystick control (1), the joystick control combines two-function levers or three-function levers into one control. The joystick is equipped with a pulse width modulated sensor for the lift, tilt, and the auxiliary functions. The arrows going from right to left, describe the tilt function. The arrows that are going up and down are for the lift function. The roller switches (9,10) control the auxiliary function. The joystick control has soft detents. The soft detents are controlled by the software within the implement ECM. As the joystick control is moved into the detent position, the linkage will travel to the kickout position that is preprogrammed. The joystick control should be released in order to return the joystick to the HOLD position automatically. The linkage movement will continue until the kickout is reached. Any 6° movement of the joystick control from the HOLD position will disable the detent. The soft detents will not be activated if the joystick control is held in the detent position for more than 1 second.

The hydraulic lockout switch (4) is used to disable the implement pilot system. When the switch is in the LOCKED position, the solenoid valve (hydraulic lockout) is de-energized. No pilot oil is allowed to flow through the pilot valve (oil manifold). When the switch is in the UNLOCKED position, the solenoid valve (hydraulic lockout) is energized. Pilot oil is allowed to flow through the pilot valve (oil manifold).

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