950G Wheel Loader, 962G Wheel Loader and IT62G Integrated Toolcarrier Power Train Caterpillar

Conventional Steering

Illustration 1	g00315967
Overhead of a Cab that is Equipped with Conventional Steering (1) Transmission Auto/Manual switch

Illustration 2	g00316043
Right Side of a Cab that is Equipped with Conventional Steering (3) Transmission downshift switch.

Illustration 3	g00771705
Transmission Direction and Speed Control of a Machine that is Equipped with Conventional Steering (4) Transmission direction and speed control lever.

In order for the transmission to shift automatically, the two-position auto/manual switch (1) must be in the AUTO position. The power train electronic control module (ECM) shifts the transmission automatically. The power train ECM evaluates the input that is sent from the engine speed sensor, transmission speed sensors and the torque converter output speed sensor in order to regulate transmission shifts. The power train ECM does not allow upshifts to a speed that is higher than the speed that is selected with transmission direction and speed control lever (4). There is no automatic downshift from second speed to first speed. The downshift from second speed to first speed occurs only when transmission downshift switch (3) is depressed or transmission speed control (4) is rotated to first speed.

When transmission downshift switch (3) is depressed, transmission downshift switch (3) signals the power train ECM to downshift the transmission by one speed. Pressing and holding transmission downshift switch (3) signals the power train ECM to continue to downshift the transmission. Each downshift must be fully complete before the power train ECM will allow another downshift. The torque converter output speed must be less than 2500 rpm before a downshift is permitted. The power train ECM delays resuming automatic upshifts for five seconds after transmission downshift switch (3) is released. Automatic upshifts are enabled if transmission direction and speed control lever (4) is moved from the current direction. Moving the transmission direction and speed control lever or the five second delay will enable automatic upshifts.

When the key start switch is turned from the OFF position to the ON position, the power train ECM is activated. When the power train ECM is first activated all the clutch solenoid modulating valves are de-energized regardless of the position of transmission direction and speed control lever (4). The power train ECM then determines if transmission direction and speed control lever (4) is in the NEUTRAL position. The power train ECM disables the transmission if the NEUTRAL position is NOT selected. If the NEUTRAL position is NOT selected, transmission direction and speed control lever (4) must be returned to the NEUTRAL position before a direction can be selected. The power train ECM activates the start relay and the power train ECM allows the engine to start if transmission direction and speed control lever (4) is in the NEUTRAL position.

The power train ECM energizes the clutch solenoid modulating valve of the maximum allowable speed when the engine starts. The maximum allowable speed is determined by the position of the speed selector of transmission direction and speed control lever (4). If the speed selector of transmission direction and speed control lever (4) is in the THIRD SPEED position, the maximum allowable speed is third speed. When the two-position auto/manual switch is in the AUTO position the power train ECM shifts the transmission from third speed to second speed because the machine ground speed is zero. The power train ECM allows the initial selected speed to be changed if transmission direction and speed control lever (4) is in the NEUTRAL position.

Note: Transmission direction and speed control lever (4) must be in the NEUTRAL position when the key start switch is turned to the START position. If transmission direction and speed control lever (4) is not in the NEUTRAL position, the start relay will not be activated when the key start switch is turned. For additional information on the neutral start function, refer to the Service Manual moduleSystem Operations, "Power Train Electronic Control System(Neutral Start Function)".

Reference: For more information on the Caterpillar Monitoring System, refer to the Service Manual module Systems Operation, "Caterpillar Monitoring System" for the machine that is being serviced.

Reference: For more information on the key start switch, refer to the Service Manual module Systems Operation, "Switches" for the machine that is being serviced.

Reference: For more information on the switches for the transmission direction and speed control lever, refer to the Service Manual module Systems Operation, "Switches" for the machine that is being serviced.

Reference: For more information on the power train electronic control module (ECM), refer to the Service Manual module Systems Operation, "Electronic Control Module (Power Train)" for the machine that is being serviced.

Command Control Steering

Illustration 4	g00496505
Transmission Direction and Speed Control of a Machine that is Equipped with Command Control Steering (5) Transmission direction control switch. (6) Transmission upshift switch. (7) Transmission downshift switch.

Illustration 5	g00474409
Right Side of the Cab of a Machine that is Equipped with Command Control Steering, Overhead (8) Transmission auto/manual switch. (9) Manual mode position. (10) Fourth speed position. (11) Third speed position. (12) Second Speed position.

The optional shift control logic input can be selected with the configuration screen of the Caterpillar Electronic Technician (ET). The optional shift control logic input can be selected with the calibration modes of the Caterpillar Monitoring System. The optional shift control logic input must be selected if the machine is equipped with Command Control Steering.

Reference: For more information on the Caterpillar Monitoring System, refer to the Service Manual module for Systems Operation, "Caterpillar Monitoring System" for the machine that is being serviced.

In order for the transmission to shift automatically, the four-position auto/manual switch (8) must be in one of the three AUTO positions. The power train ECM automatically shifts the transmission if transmission auto/manual switch (8) is in one of the three AUTO positions. The power train ECM evaluates the input that is sent from the engine speed sensor, transmission speed sensors and the torque converter output speed sensor in order to regulate transmission shifts. The power train ECM does not allow automatic upshifts to a speed that is higher than the speed that is selected with the auto/manual switch. The power train ECM will not automatically downshift from second speed to first speed. Downshifts from second speed to first speed occur only when transmission downshift switch (7) is depressed.

The operator can override the autoshift function by depressing transmission downshift switch (7). The operator must perform one of the procedures that follow in order to resume automatic upshifts. Either depress transmission upshift switch (6), or shift to a different direction of travel. Momentarily depressing transmission downshift switch (7) signals the power train ECM to downshift the transmission by one speed. Pressing and holding transmission downshift switch (7) signals the power train ECM to continue to downshift the transmission as the machine speed decreases.

When the key start switch is turned from the OFF position to the ON position, the power train ECM is activated. When the power train ECM is first activated all the clutch solenoid modulating valves are de-energized regardless of the position of transmission direction control switch (5). The power train ECM then determines if transmission direction control switch (5) is in the NEUTRAL position. The power train ECM disables the transmission if the NEUTRAL position is NOT selected. If the NEUTRAL position is NOT selected, transmission direction control switch (5) must be returned to the NEUTRAL position before a direction can be selected. The power train ECM activates the start relay and the power train ECM allows the engine to start if transmission direction control switch (5) is in the NEUTRAL position.

The power train ECM energizes the clutch solenoid modulating valve of the maximum allowable speed when the engine starts. The maximum allowable speed is determined by the position of four-position auto/manual switch (8). If four-position auto/manual switch (8) is in FOURTH SPEED position (10), the maximum allowable speed is fourth speed. When four-position auto/manual switch (8) is in FOURTH SPEED position (10) the power train ECM shifts the transmission from fourth speed to third speed. The power train ECM shifts the transmission if the machine ground speed is zero. The power train ECM shifts the transmission from third speed to second speed when four-position auto/manual switch (8) is in THIRD SPEED position (11). The power train ECM shifts the transmission when the machine ground speed is zero. The power train ECM allows the initial selected speed to be changed if transmission direction control switch (5) is in the NEUTRAL position.

Note: Transmission direction control switch (5) must be in the NEUTRAL position when the key start switch is turned to the START position. If transmission direction control switch (5) is not in the NEUTRAL position, the start relay will not be activated when the key start switch is turned. For information on the neutral start function, refer to the Service Manual moduleSystems Operation, "Power Train Electronic Control System" for the machine that is being serviced.

Reference: For more information on the Caterpillar Monitoring System, refer to the Service Manual module Systems Operation, "Caterpillar Monitoring System" for the machine that is being serviced.

Reference: Refer to the Service Manual module Systems Operation, "Switches" for information on the following switches: transmission upshift switch, transmission direction control switch and transmission downshift switch .

Reference: For more information on the key start switch, refer to the Service Manual module Systems Operation, "Switches" for the machine that is being serviced.

Reference: For more information on the power train electronic control module (ECM), refer to the Service Manual module Systems Operation, "Electronic Control Module (Power Train)" for the machine that is being serviced.