980H Wheel Loader Caterpillar

Illustration 1	g00991543
Block Diagram of the Integrated Braking System (1) Power train electronic control module (ECM) (2) CAT Data Link (3) Transmission neutralizer on/off indicator (4) Transmission direction and speed control (5) Transmission neutralizer override switch (6) Five-position transmission auto/manual switch (7) Left pedal position sensor (8) Engine speed sensor (9) Transmission output speed sensor

The Integrated Braking System enables the operator to downshift the transmission and the Integrated Braking System enables the operator to neutralize the transmission by depressing the left brake pedal. In initial mode, downshifting the transmission reduces the ground speed of the machine before the brakes are applied. In normal mode, the service brakes are applied and the ground speed of the machine is reduced. 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.

• The IBS Manual configuration is enabled in the power train ECM.

• First speed or second speed is engaged.

• The transmission neutralizer is enabled.

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

Illustration 2	g00955691
Left Brake Pedal (10) Calibrated Initial Brake Pressure Point (11) Calibrated neutralization point (12) Maximum pedal travel (13) Stop light limit switch (14) Left brake pedal position sensor (A) Left brake pedal deadband (B) Initial mode (C) Normal mode

Illustration 3	g03404586
(15) Transmission Auto/Manual Switch

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 Transmission Auto/Manual Switch

• Engaged Transmission Speed

• Calibrated Initial Brake Pressure Point

• Transmission Output Speed

• Engine Speed

The Integrated Braking System is enabled in all of the positions of the transmission auto/manual switch 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 transmission output speed sensors, or 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 (10) .

Note: The service brakes are not applied in initial mode.

The Integrated Braking System is in normal mode (C) when the operator depresses the left brake pedal between calibrated initial brake pressure point (10) and the point of maximum pedal travel (12) .

Note: The service brakes are applied in normal mode.

The Integrated Braking System performs the functions that follow 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 transmission auto/manual switch. Each downshift will occur when the transmission output speed decreases to the shift point for the current transmission speed. The transmission is automatically shifted to neutral when the machine downshifts to the lowest speed gear.

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

Illustration 4	g00774950
Transmission Downshift Switch

If the transmission auto/manual 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.

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 transmission auto/manual switch is in the MANUAL position, the Integrated Braking System shuts off. The transmission remains in the speed that was engaged.

• If the transmission auto/manual switch is in any of the AUTO positions, the Integrated Braking System shuts off. The transmission autoshift control resumes control of speed shifts.

Safe Mode

The Integrated Braking System will enter safe mode if the engine speed exceeds 2550 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 (A) left brake pedal deadband. 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. If the transmission neutralizer enable control is enabled, the transmission neutralizer on/off indicator is not illuminated.

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 position sensor for the left brake pedal.

The transmission neutralizer control uses the inputs that follow: left brake pedal position, position of the transmission auto/manual switch, engaged transmission speed, transmission neutralization setpoint, 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.

• The left brake pedal must be depressed beyond the transmission neutralization setpoint (13) .

• The transmission neutralizer enable control must be enabled.

• First speed or second speed must be engaged.

The transmission will downshift into second speed (for all transmission modes except 1-4 auto) or first speed (for 1-4 auto) when the left brake pedal is depressed. The transmission will not be neutralized when the transmission is in third speed or fourth speed.

Note: The transmission shifts directly into neutral when the transmission downshifts to second speed or first speed (for 1-4 auto) if the left brake pedal is depressed beyond the transmission neutralization setpoint (11) .

After the left brake pedal returns to the fully released position, the neutralization pedal position is reset to the transmission neutralization setpoint (11) .

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

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

ReferenceFor more information on changing the neutralization point, refer to Testing and Adjusting, RENR8666, " 980H Wheel Loader Power Train", "Position Sensor (Left Brake Pedal)(Operator Monitor) - Calibrate".

Disable / Enable IBS in ET

Illustration 5	g03404589
Service Connector for the Caterpillar Electronic Technician

1. Connect the laptop computer to the service connector in the cab. The service connector is located to the left of the key start switch.

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

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Illustration 6	g01100136

3. Start the ET software and select "Transmission 980H" from the "ECM Selector" menu.

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Illustration 7	g01111464

4. Select the "Service" menu item from the toolbar. Select the "Configuration" menu item.

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Illustration 8	g01114105

5. Select "Configuration Group 1" under the "Transmission 980" item on the "Available ECM(s)" list and click the "Change" button.

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Illustration 9	g01114107

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 transmission neutralization setpoint (11). The transmission will re-engage when the left brake pedal is released 5 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.

ReferenceFor more information on changing the neutralization point, refer to Testing and Adjusting, UENR1625, "Wheel Loader Power Train", "Position Sensor (Left Brake Pedal)(Operator Monitor) - Calibrate".