Note: Caterpillar recommends using a Class I DIvision II Certified Hazardous Area Shifter in potentially explosive enviroments. A Caterpillar Hazardous Area Shifter will be available in approximately third quarter 2009.
The transmission for the TH35 has eight forward gears, neutral, and one reverse gear. The transmission for the TH31 has six forward gears, neutral, and one reverse gear.
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| Illustration 1 | g01194167 |
Graphic of the shift pad | |
The shift pad has six buttons for control.
| Upshift - The upshift button is used in order to increase the selected gear by one. |
| Downshift - The downshift button is used in order to decrease the selected gear by one. |
| Mode - The "Mode" button does not function with TH31 and TH35 transmissions. |
| D - The "D" button engages the clutches for forward motion. |
| N - The "N" button engages the clutch for neutral. |
| R - The "R" button engages clutches for reverse motion. |
The transmission control incorporates the following switches.
- Shift selector switch
- Alternate max gear switch (primary shifter)
- Alternate max gear switch (secondary shifter)
- Lockup clutch disable switch
- Power Take-Off (PTO) no. 1 enable switch
- PTO no. 1 increment/decrement switch
- PTO no. 2 enable switch
- PTO no. 2 increment/decrement switch
- Two-wheel drive/four-wheel drive switch
- Quick to neutral switch
Note: The quick to neutral switch is used only in applications for pumps.
Refer to Operation and Maintenance Manual, SEBU8197, "Transmission Control" for more information on the operation of the shift pad.
| NOTICE |
|---|
The machine must be stopped and the engine at low idle before changing direction. After moving the transmission control, do not accelerate until after hearing or feeling the transmission clutches engage. |
Range Selection
Roading Automatic Shift Mode
To shift the transmission into a desired range or gear, the operator selects the "D" for forward or the "R" for reverse.
Note: The transmission will not shift into a range from neutral or between "D" and "R" if the engine RPM is over 1000 RPM.
Forward Range
When "D" is selected, the maximum gear that is available for the transmission is displayed on the left side of the display for the shift pad. This value is referred to as the desired gear. The TH31 transmission has six forward gears. The TH35 transmission has eight forward gears. Both transmissions can be configured so that the maximum selectable desired gear is lower than the highest available gear for the transmission.
The digit on the right side of the display for the shift pad will display the gear that is currently active. This value is referred to as the actual gear. When "D" is selected, the actual gear displays the lowest available gear for the transmission and the transmission engages the clutches for that gear.
The transmission can also be configured so that the minimum selectable desired gear is higher than the lowest available gear for the transmission. The gear that has been configured to be the lowest available gear is the gear that is engaged when the "D" is selected.
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| Illustration 2 | g01327390 |
When the transmission shifts gears, the actual gear that is displayed on the shift pad will change in order to display the active gear in the transmission.
Once in a forward range, the operator has the ability to force a downshift by pressing the down arrow on the shift pad. This will change the desired gear. The desired gear acts as the maximum forward gear. The transmission will automatically shift below this gear and up to this gear.
Reverse Range
To select the reverse range, the operator selects the "R" button. The shift pad displays the desired gear or "R" on the left side of the display and the actual gear or "N" on the right.
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| Illustration 3 | g01625220 |
When the transmission shifts into the reverse range, the display will have an "R" in both locations. There is only one gear for the reverse range.
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into the desired range. When this happens, the value for the desired gear will flash and the transmission will not shift into the selected range.
Conditions that will prevent the transmission from shifting into the desired range include the following:
- The engine speed is too high.
- The vehicle speed is too high.
- The transmission is neutralized by the parking brake.
- The transmission does not have proper communication with the engine on the data link.
Note: If the character on the left flashes "N", then the transmission is locked in neutral by the ECU. This is normally caused when the parking brake is applied. In order to resume normal operation, release the parking brake and press the "N" button. After the "N" button is pressed, the "D" or the "R" button will respond.
Pumping Automatic Shift Mode
In order to shift the transmission into a desired range or gear, the operator must push the "D" for forward or the "R" for the transmission output shaft lock.
Note: The transmission will not shift into a gear range from neutral if the RPM of the engine is over 1000 RPM. Also, the transmission will not shift between "D" and "R" if the RPM of the engine is over 1000 RPM.
Forward Range
When "D" is selected, the maximum gear that is available for the transmission is displayed on the left side of the display for the shift pad. This value is referred to as the desired gear. The TH31 transmission has six forward gears. The TH35 transmission has eight forward gears. Both transmissions can be configured so that the maximum selectable desired gear is lower than the highest available gear for the transmission.
The digit on the right side of the display of the shift pad will display the gear that is currently active. This value is referred to as the actual gear. When "D" is selected, the actual gear displays the lowest available gear for the transmission and the transmission engages the clutches for that gear.
The transmission can also be configured so that the minimum selectable desired gear is higher than the lowest available gear for the transmission. The gear that has been configured to be the lowest available gear is the gear that is engaged when the "D" is selected.
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| Illustration 4 | g01327390 |
When the transmission shifts gears, the actual gear that is displayed on the shift pad will change in order to display the active gear in the transmission.
Once in a forward range, the operator has the ability to force a downshift by pressing the down arrow on the shift pad. This will change the desired gear. The desired gear acts as the maximum forward gear. The transmission will automatically shift below this gear and up to this gear.
Transmission Output Shaft Lock
The transmission output shaft lock feature uses transmission clutches in order to prevent the output shaft from rotating. The transmission output shaft lock is not meant to be a brake.
When "R" is selected, the desired gear (the value on the left of the display for the shift pad) will display "R". The actual gear (the value on the right of the display for the shift pad) will display an "N" until the transmission shifts into the transmission output shaft lock. The shift pad will then display an "R" for the actual gear.
The transmission will not shift into transmission output shaft lock if the transmission output speed is high. The transmission will shift into neutral if the transmission output shaft lock is selected and the output speed of the transmission is above 500 RPM. The transmission will remain in neutral until the output speed of the transmission is below 500 RPM.
Note: The reverse range is not available in pumping mode.
| NOTICE |
|---|
The transmission output shaft lock will only function if the engine is running. The transmission output shaft lock is not meant to be a dynamic machine brake. |
When the transmission output shaft lock is active, the shift pad will display "RR".
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| Illustration 5 | g01625220 |
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into a desired range. When this happens, the desired value for the gear will flash and the transmission will not shift into the selected range.
Circumstances that will prevent the transmission from shifting into the desired range include the following:
- The engine speed is too high.
- The vehicle speed is too high.
- The load based shift inhibit function is active.
- The quick to neutral function is active.
Pumping Manual Shift Mode
To shift the transmission into a desired range or gear, the operator must push the "D" for forward or the "R" for the transmission output shaft lock.
Note: The transmission will not shift into a gear range from neutral if the RPM of the engine is over 1000 RPM.
Forward Range
When "D" is selected, the left character on the shift pad will display the lowest available gear from the transmission. The right character will display the gear that is currently active. This character is referred to as the actual gear. When "D" is selected, the actual gear displays the lowest available gear for the transmission and the transmission engages the clutches for that gear.
The transmission can be configured so that the minimum selectable desired gear is higher than the lowest available gear for the transmission. The gear that has been configured to be the lowest available gear is the gear that is engaged when the "D" is selected.
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| Illustration 6 | g01625359 |
The operator must use the up arrow and the down arrow on the shift pad to manually shift the transmission. Press the up arrow once in order to shift the transmission up a single gear. Continue to press the arrow until the desired gear or the maximum forward gear is obtained. When the maximum forward gear has been obtained, pressing the up arrow will no longer have any effect.
Press of the down arrow once in order to shift the transmission down a single gear. Continue to press the down arrow until the desired gear or the minimum forward gear is obtained. When the minimum forward gear has been obtained, pressing the down arrow will no longer have any effect.
As the transmission is shifted, the actual gear that is displayed on the shift pad will change in order to represent the active gear in the transmission.
Transmission Output Shaft Lock
The transmission output shaft lock feature uses transmission clutches in order to prevent the output shaft from rotating. The transmission output shaft lock is not meant to be a brake.
When "R" is selected, the desired gear (the value on the left of the display for the shift pad) will display "R". The actual gear (the value on the right of the display for the shift pad) will display an "N" until the transmission shifts into the transmission output shaft lock. The shift pad will then display an "R" for the actual gear.
The transmission will not shift into transmission output shaft lock if the transmission output speed is high. If transmission output shaft lock is selected and the transmission output speed is above 500 RPM the transmission will shift to neutral. The transmission will remain in neutral until the transmission output speed is below 500 RPM. The transmission output shaft lock is not meant to be a brake.
Note: The reverse range is not available in pumping mode.
| NOTICE |
|---|
The transmission output shaft lock will only function if the engine is running. The transmission output shaft lock is not meant to be a dynamic machine brake. |
When the transmission output shaft lock is active, the shift pad will display "RR".
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| Illustration 7 | g01625220 |
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into a desired range. When this happens, the value for the desired gear will flash and the transmission will not shift into the selected range.
Conditions that will prevent the transmission from shifting into the desired range include the following:
- The engine speed is too high.
- The vehicle speed is too high.
- The load based shift inhibit is active.
- The quick to neutral function is active.
Low Idle Manual Shift Mode (Work Over and Trencher)
To shift the transmission into a desired range or gear, the operator must push the "D" for forward or the "R" for reverse.
Note: The transmission will not shift into a gear range from neutral if the RPM of the engine is over 1000 RPM. Also, the transmission will not shift between "D" and "R" if the RPM of the engine is over 1000 RPM.
Forward Range
When "D" is selected, the left character on the shift pad will display the lowest available gear from the transmission. The right character will display the gear that is currently active. This character is referred to as the actual gear. When "D" is selected, the actual gear displays the lowest available gear for the transmission and the transmission engages the clutches for that gear. The transmission can be configured so that the minimum selectable desired gear is higher than the lowest available gear for the transmission. The gear that has been configured to be the lowest available gear is the gear that is engaged when the "D" is selected.
| | |
| Illustration 8 | g01625359 |
The operator must use the up arrow and the down arrow on the shift pad to manually shift the transmission. Press the up arrow once in order to shift the transmission up a single gear. Continue to press the arrow until the desired gear or the maximum forward gear is obtained. When the maximum forward gear has been obtained, pressing the up arrow will no longer have any effect.
Press of the down arrow once in order to shift the transmission down a single gear. Continue to press the arrow until the desired gear or the minimum forward gear is obtained. When the minimum forward gear has been obtained, pressing the down arrow will no longer have any effect.
As the transmission is shifted, the actual gear that is displayed on the shift pad will change in order to represent the active gear in the transmission.
Reverse Range
To select the Reverse Range, the operator selects the "R" button. The shift pad displays the desired gear or "R" on the left side of the display and the actual gear or "N" on the right.
When the transmission shifts into the reverse range, the display will have an "R" in both locations. There is only one gear for the reverse range.
| | |
| Illustration 9 | g01625220 |
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into a desired range. When this happens, the value for the desired gear will flash and the transmission will not shift into the selected range.
Conditions that will prevent the transmission from shifting into the desired range include the following:
- The engine speed is too high.
- The vehicle speed is too high.