950G Series II Wheel Loader, 962G Series II Wheel Loader and IT62G Series II Integrated Toolcarrier Power Train Integrated Braking System Caterpillar

Illustration 1	g00888873
Block Diagram of the Integrated Braking System (1) Power train electronic control module (ECM) (2) AVS Data Link (3) Transmission direction and speed control lever (conventional steering) (4) Transmission direction and speed control (command control steering) (5) Transmission downshift switch (conventional steering) (6) Autoshift switch (command control steering) (7) Indicator for the transmission neutralizer (8) Engine speed sensor (9) Transmission neutralizer enable/disable switch (10) Torque converter output speed sensor (11) Transmission output speed sensor (12) Left pedal position sensor (13) Transmission output speed sensor

The Integrated Braking System enables the operator to downshift the transmission by depressing the left brake pedal. Downshifting the transmission reduces the ground speed of the machine before the brakes are actually applied. The Integrated Braking System only changes the transmission speed. The Integrated Braking System does not change the transmission direction. The Integrated Braking System neutralizes the transmission if the following conditions are met:

• First speed is engaged or second speed is engaged.

• The transmission neutralizer is enabled.

• The left brake pedal is depressed past the transmission neutralization point.

Illustration 2	g00888908
(14) Calibrated initial brake pressure point (15) Transmission neutralization point (16) Maximum pedal travel (17) Stop light limit switch (18) Left brake pedal position sensor (A) Left brake pedal deadband (B) Downshifting - No service brakes applied (C) Downshifting - Service brakes applied

Illustration 3	g00888915
(19) Autoshift switch (conventional steering) (20) Autoshift switch (command control steering)

The Integrated Braking System uses the following inputs in order to downshift the transmission:

• IBS Manual Enable configuration in the power train ECM

• Left Brake Pedal Position

• Position of the Autoshift Switch

• Actual Transmission Speed

• Calibrated Initial Brake Pressure Point

• Torque Converter Output Speed

• Transmission Output Speed

• Engine Speed

The Integrated Braking System is enabled if the following conditions are met:

• IBS Manual configuration must be set to enable.

• The position sensor for the left brake pedal has been calibrated.

• Engine speed is below 2425 RPM.

• The left brake pedal is depressed beyond left brake pedal deadband (A) .

• The torque converter output speed sensor, transmission output speed sensors, and the position sensor for the left brake pedal do not show any diagnostic codes.

Initial Mode and Normal Mode

The Integrated Braking System is in initial mode (B) when the operator depresses the left brake pedal between left brake pedal deadband (A) and calibrated initial brake pressure point (14). The Integrated Braking System is in normal mode (C) when the operator depresses the left brake pedal between calibrated initial brake pressure point (14) and the point of maximum pedal travel (16) .

The Integrated Braking System performs the following functions when the operator depresses the left brake pedal in initial mode or normal mode:

If the transmission is in third speed or fourth speed, the transmission will downshift one speed at a time until second speed is reached. The transmission will downshift regardless of the position of the autoshift switch. Each downshift will occur when the transmission output speed decreases to the shift point for the current transmission speed.

The transmission will downshift from second speed to first speed if the autoshift switch is in the AUTO 1-4 position. The transmission will downshift when the transmission output speed decreases to the 2-1 shift point for initial mode or for normal mode.

Illustration 4	g00888952
Transmission Downshift Switch (Conventional Steering)

Illustration 5	g00888953
Speed Selector Switch (Command Control Steering)

If the autoshift switch is not in the AUTO 1-4 position, the transmission will not downshift from second speed to first speed unless the operator depresses the transmission downshift switch. The operator may need to depress the transmission downshift switch twice. The ground speed of the machine determines if the transmission downshift switch is depressed one time or two times.

Depress the switch one time if the ground speed is below the AUTO 2-1 ground speed.

Depress the switch two times if the ground speed is above the AUTO 2-1 ground speed.

Illustration 6	g00888862
Transmission Direction and Speed Control Lever (Conventional Steering)

After the operator releases the left brake pedal and the left brake pedal returns beyond left brake pedal deadband (A), the events that follow occur:

• If the autoshift switch is in the MANUAL position, the Integrated Braking System shuts off. The power train ECM upshifts the transmission sequentially to the speed that is selected by the transmission direction and speed control. This occurs only in machines that are equipped with conventional steering.

• If the autoshift switch is in the MANUAL position, the Integrated Braking System shuts off. The transmission remains in the speed that was engaged. This occurs only in machines that are equipped with command control steering.

• If the autoshift switch is in any of the AUTO positions, the Integrated Braking System shuts off. The transmission resumes automatic control of speed shifts. This occurs in machines that are equipped with conventional steering or command control steering.

Safe Mode

The Integrated Braking System will enter safe mode if the engine speed exceeds 2550 RPM or torque converter output speed exceeds 3500 RPM.

If the Integrated Braking System enters safe mode, the Integrated Braking System will signal the power train ECM to upshift the transmission speed.

When the transmission output speed is less than the corresponding safe mode shift point, the Integrated Braking System signals the power train ECM to downshift the transmission speed. The Integrated Braking System will return to the initial mode or to the normal mode. The mode is dependent upon the position of the left brake pedal.

Note: The Integrated Braking System is disabled if the left brake pedal is released beyond left brake pedal deadband (A). After the Integrated Braking System is disabled, the power train ECM controls the transmission shifts according to the normal power train ECM shift logic.

Transmission Neutralizer

The transmission neutralizer override switch is the only input to the transmission neutralizer enable control. The transmission neutralizer enable control will be enabled when the machine is started. The indicator for the transmission neutralizer is not illuminated when the transmission neutralizer enable control is enabled.

The transmission neutralizer enable control is alternately enabled or disabled when the momentary transmission neutralizer override switch is depressed. The transmission neutralizer enable control is disabled if there are any diagnostic codes in the left brake pedal position sensor.

The transmission neutralizer control uses the inputs that follow: left brake pedal position, engaged transmission speed, transmission neutralization point, status of the transmission neutralizer enable control and ground speed of the machine.

The following conditions must be met in order for the transmission to be neutralized:

• First speed must be engaged for transmission mode AUTO 1-4.

• Second speed must be engaged for all transmission mode switch positions except AUTO 1-4.

• The left brake pedal must be depressed beyond the neutralization setpoint (15)

• The transmission neutralizer enable control must be enabled.

The transmission engages after neutralization if the left brake pedal is released and the left brake pedal travels at least four degrees upward from the maximum depressed position. The transmission will be neutralized again if the left brake pedal is depressed two degrees from the current left pedal position.

The transmission engages after neutralization if the transmission neutralizer enable control is disabled.

Reference: For more information on calibrating the neutralization point, refer to Testing and Adjusting, "Position Sensor (Left Brake Pedal) - Calibrate" for the machine that is being serviced.

Disable / Enable IBS in ET

Illustration 7	g00975034
(21) Diagnostic Connector (ET)

1. Connect ET to diagnostic connector (21) .

2. Turn the engine start switch key to the ON position, but do not start the engine.

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Illustration 8	g00987763

3. Start the ET software and select "Transmission" under the heading "Available ECM's".

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Illustration 9	g00975046

4. Select the "Service" menu and then select "Configuration".

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Illustration 10	g00975048

5. Select "Integrated Braking System Manual Mode Enable Status", as shown.

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Illustration 11	g00975050

6. Select "Enable" or "Disable" from the pop up menu.

When "IBS Manual Disable" is configured and the transmission control is in the "Manual" position, the transmission will not downshift when the left brake pedal is depressed. The transmission will be neutralized when the left brake pedal is depressed to the neutralization set point (15) or beyond. The transmission will re-engage when the left brake pedal is released 4 degrees. The transmission will be neutralized if the left pedal is depressed 2 degrees. The transmission is re-engaged and remains in current speed gear when the pedal is fully released.

Reference: For more information on changing the neutralization point, refer to Testing and Adjusting, RENR4310, " IT62G Series Series II Integrated Toolcarrier and 950G Series Series II and 962G Series Series II Wheel Loaders Power Train", "Position Sensor (Left Brake Pedal) (AVSpare Monitoring System) - Calibrate".