The transmission for the TH35 has eight forward gears, neutral, and one reverse gear.
Transmission Gear Selector (Operator Usage of Shift Pad)
Warning Light Indicator
Caterpillar requires that OEM transmission users install a RED operator warning lamp. The lamp may have several locations within the operator's station depending on the OEM's design. The lamp provides an indication of transmission condition.
- RED Warning Lamp
The RED warning lamp warns the operator of conditions which require immediate attention. The warning lamp indicates either a transmission oil filter by-pass or an excessive oil temperature. Immediate operator action is required to reduce transmission oil temperature or to service the oil filters.
Operation of the Caterpillar Shift Selector Pad
The Transmission Control in Illustration 1 is the operator interface for Caterpillar's TH31 and TH35 transmissions.
- The Transmission Shift Selector Pad has six operator buttons and a two-digit display. The shift pad operation buttons are described in Illustration 1 and the shift pad operation is described in table 1.
Basic Operation
With the ignition Key switch ON, the Shift Selector Pad will display a pair of "N's" on the display, indicating that the transmission is in Neutral.
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| Illustration 1 | g01616934 |
(1) Left character (maximum requested gear) (2) Right Character (actual gear) (3) Mode two decal and lamp (4) Mode one decal and LED light | |
Note: If the desired gear is flashing the shift is being inhibited.
Shift Pad Operation
| Shift Pad Operation | ||||
| Button Pressed | Action | Description | ||
| D | Selects Forward gear | The D button activates transmission forward gears. Pressing this button will cause the transmission to shift into the first forward gear. | ||
| N | Selects Neutral gear | The N button activates transmission neutral. Pressing this button will cause the transmission to shift to neutral. | ||
| R | Selects Reverse gear | The R button activates transmission reverse gear. Pressing this button will cause the transmission to shift into the reverse gear. | ||
| Up Arrow | Upshift | The up arrow button is used to upshift the transmission one gear per activation. | ||
| Down Arrow | Downshift | The down arrow button is used to downshift the transmission one gear per activation. | ||
| MODE | Various | The mode button is used to access different shift modes available in the transmission software. This button has an embedded red LED that will illuminate indicating that the mode button has been pressed. | ||
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's RPM is over 1000 RPM.
Forward Range
When "D" is selected, the shift selector pad will display the maximum gear the transmission has available. This character is known as the desired gear. The maximum gear is either the maximum forward gear available from the transmission (The TH31 transmission has six forward gears and the TH35 transmission has eight forward gears) or a lower gear that was configured as the maximum.
The right character will display the gear that is currently active. This character is known as the actual gear and will be the lowest available gear from the transmission or a higher configured minimum gear.
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| Illustration 2 | g01327390 |
The actual gear will be displayed on the right side of the shift selector pad as the transmission shifts.
Once in a forward range, the operator has the ability to force a downshift by pressing the down arrow on the shift selector pad. This will change the desired gear. The desired gear acts as the maximum forward gear and the transmission will auto-shift below and up to this gear.
Reverse Range
To select the Reverse Range, the operator selects the "R" button. The shift selector 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 reverse range, the display will have an "R" in both locations. There is only one gear in the reverse range.
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into a desired range. When this happens, the desired gear value will flash and the transmission will not shift into the selected range.
Circumstances preventing shift into the desired range include:
- Engine speed too high
- Vehicle speed too high
- Neutralized by park brake
Note: If the left character "flashes" "N", then the transmission is locked in Neutral by the ECU. The most common cause of a "flash" "N" is when the parking brake is applied. To resume operation, the "N" button needs to be pressed before the "D" or "R" button will respond.
Pumping Automatic Shift Mode
To shift the transmission into a desired range or gear, the operator must push the "D" for forward or the "R" for park gear.
Note: The transmission will not shift into a range from neutral or between "D" and "R" if the engines RPM is over 1000 RPM. The transmission will not engage park gear until output speed is below 500 RPM and engine speed is below 1000 RPM.
Forward Range
When "D" is selected, the left character on the shift selector pad will display the maximum gear the transmission has available. This character is known as the desired gear. The maximum gear is either the maximum forward gear available from the transmission (The TH31 transmissions has six forward gears and the TH35 has eight forward gears) or a lower gear that was configured as the maximum. The right character will display the gear that is currently active. This character is know as the actual gear and will be the lowest available gear from the transmission or a higher configured minimum gear.
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| Illustration 4 | g01327390 |
As the transmission shifts, the actual gear will change to reflect the gear that the transmission is currently in.
Once in forward range the operator has the ability to force a downshift by pressing the down arrow on the shift selector pad. This will change the desired gear. The desired gear acts as the maximum forward gear and the transmission will auto shift below and up to this gear.
Park Gear
When "R" is selected, the left character or desired gear on the shift selector pad will display "R". The right character or actual gear will display an "N" until the transmission shifts into the park gear where it will display an "R". If the park gear is selected when the transmission output speed is above 500 RPM the transmission will shift to neutral and remain there until the transmission output speed is below 500 RPM.The park gear is not meant to be a brake.
WARNING: The park gear will only function if the engine is running. The park gear is not meant to be a dynamic machine brake.
Note: Reverse range is not available in pumping mode
When the transmission park gear is active, the shift selector 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 gear value will flash and the transmission will not shift into the selected range.
Circumstances preventing shifts into the desired range include:
- Engine speed too high
- Vehicle speed too high
- Load based shift inhibit
- Quick to neutral 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 park gear.
Note: The transmission will not shift into a range from neutral or between "D" and "R" if the engines RPM is over 1000 RPM.
Forward Range
When "D" is selected, the left character on the shift selector pad will display the lowest available gear from the transmission or a higher configured minimum gear. This character is known as the desired gear. The right character will display the gear that is currently active. This character is known as the actual gear and will be the lowest available gear from the transmission or a higher configured minimum gear.
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| Illustration 6 | g01625359 |
The operator must use the arrows on the shift selector pad to manually shift up and down through the gears. Each press of the up arrow will result in a single gear up-shift until the maximum forward gear has been achieved. When the maximum gear has been reached, pressing the up arrow will not result in any action. Each press of the down arrow will result in a single gear down-shift until the minimum gear has been achieved. When the minimum gear has been reached, pressing the down arrow will not result in any action.
As the transmission shifts, the actual gear will change to reflect the gear that the transmission is currently in.
Park Gear
When "R" is selected, the left character or desired gear on the shift selector pad will display "R". The right character or actual gear will display an "N" until the transmission shifts into the park gear where it will display an "R". The transmission will not shift into the park gear if the transmission output speed is high. The transmission will not shift into the park gear if the transmission output speed is high. If the park gear is selected when the transmission output speed is above 500 RPM the transmission will shift to neutral and remain there until the transmission output speed is below 500 RPM. The park gear is not meant to be a brake. The transmission will not engage park gear until output speed is below 500 RPM and engine speed is below 1000 RPM.
WARNING: The park gear will only function if the engine is running. The park gear is not meant to be a dynamic machine brake.
Note: Reverse range is not available in pumping mode.
When the transmission park gear is active, the shift selector pad will display "RR".
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| Illustration 7 | g01625220 |
Flashing Desired Gear
Several circumstances may prevent the transmission for shifting into a desired range. When this happens, the desired gear value will flash and the transmission will not shift into the selected range.
Circumstances preventing shifts into the desired range include:
- Engine speed too high
- Vehicle speed too high
- Load based shift inhibit
- Quick to neutral 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 park gear.
Note: The transmission will not shift into a range from neutral or between "D" and "R" if the engines RPM is over 850 RPM.
Forward Range
When "D" is selected, the left character on the shift selector pad will display the lowest available gear from the transmission or a higher configured minimum gear. This character is known as the desired gear. The right character will display the gear that is currently active. This character is known as the actual gear and will be the lowest available gear from the transmission or a higher configured minimum gear. The transmission will not shift between gears if engine speed is above 850 RPM.
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| Illustration 8 | g01625359 |
The operator must use the arrows on the shift selector pad to manually shift up and down through the gears. Each press of the up arrow will result in a single gear up-shift until the maximum forward gear has been achieved. When the maximum gear has been reached, pressing the up arrow will not result in any action. Each press of the down arrow will result in a single gear down-shift until the minimum gear has been achieved. When the minimum gear has been reached, pressing the down arrow will not result in any action.
As the transmission shifts, the actual gear will change to reflect the gear that the transmission is currently in.
Reverse Range
When "R" is selected, the left character or desired gear on the shift selector pad will display "R". The right character or actual gear will display an "N" until the transmission shifts into the reverse range where it will display an "R". There is only one gear in the reverse range.
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| Illustration 9 | g01625220 |
Flashing Desired Gear
Several circumstances may prevent the transmission from shifting into a desired range. When this happens, the desired gear value will flash and the transmission will not shift into the selected range.
Circumstances preventing shifts into the desired range include:
- Engine speed too high
- Vehicle speed too high
Control Switches
The Transmission control incorporates the following switches.
- Shifter selector switch
- Pump applications only: quick to neutral switch
- Optional switch for disabling the lock up clutch
- Optional alternate maximum gear switches
- Optional control switches for the PTO
- Transmission with drop box "2WD/4WD" switch
- Service brake switch
- Park brake switch
The transmission can have the following optional indicator lights
- Power train warning
- Primary shifter
- Secondary shifter
- Converter drive indicator
Refer to Operation and Maintenance Manual, "Transmission Control".
| NOTICE |
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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. |
Stop the drive shaft and ensure that the engine is at low idle. When you move the transmission control from the "N" position to the "D" position, first gear and torque converter drive will be engaged.
In order to limit the highest gear that can be engaged, select the gear by using the arrows for the up/down on the keypad.