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| Illustration 1 | g01316743 |
| (1) Transmission Electronic Control Unit (ECU) | |
Note: When a new transmission is put into service the electronic control unit (ECU) must be informed of the type of well servicing application the unit will be placed into. This must also be done when the transmission ECU is reflashed. This procedure is found in Special Instruction, REHS4541, "Software Configuration Guide".
The transmission ECU monitors the condition of the machine for proper system operation. Components sense the condition of the machine. Components then send electrical signals to the inputs of the electronic control unit (ECU).
Warning Light Indicators
Caterpillar requires that OEM transmission users install a RED and AMBER operator warning lamps. The lamps may have several locations within the operator's station depending on the OEM's design. The lamps provide an indication of transmission condition.
- AMBER Caution Lamp
The diagnostic lamp is yellow or AMBER. The diagnostic lamp will communicate the status of the transmission electronic system. If the amber lamp is activated, it alerts the operator that a diagnostic condition is active within the transmission. The amber lamp does not require immediate operator attention, but normal operation of the transmission may be affected.
- 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.
This section describes various transmission control features. Refer to Special Instruction, REHS3514, "Electrical Application and Installation Guide" for more information.
Neutralizer (Quick to Neutral)
The Neutralizer Feature, or Quick to Neutral, provides the ability for the operator to quickly shift to neutral. When this switch is activated, the transmission will immediately shift to neutral regardless of operating conditions. Once the transmission is in neutral, the operator must press the "N" button on the shift selector in order to make the desired gear NEUTRAL before the transmission will shift out of neutral. If the desired gear is not NEUTRAL, the transmission will not shift out of neutral.
The lock to neutral feature prevents the transmission from shifting out of neutral into forward or reverse. When the transmission is in neutral and the feature is active, the transmission will not shift into forward or reverse when either the "R" or "D" button is pressed. If the transmission is in a gear when the feature is activated, the transmission will inhibit upshifts and allow downshifts until the transmission is in neutral. When the transmission reachesNeutral it will not allow shifts out of Neutral until the feature is deactivated.
The Starter Interlock Output is a 2-amp battery voltage driver. When all conditions are met, the Starter Interlock Output will be enabled when battery voltage is applied to Key Start. The conditions necessary for starting are as follows:
- Requested gear from the shifters is neutral
- Actual gear is neutral
- Engine speed is zero
The Starter Interlock Output will be disabled once the transmission is no longer in neutral, the shifter is not requesting neutral, or when the engine speed approaches Low Idle Speed.
Transmission Output Shaft Speed Driver
The Transmission Output Shaft Speed Driver is a 300 mA, low side driver that generates an output signal that is proportional to the transmission output shaft speed. The frequency is based on the 16-tooth chopper wheel standard. For each revolution of the transmission output shaft, 16 pulses are produced. External controls and indicating devices can use this signal for vehicle speed calculations. By providing this output, the transmission will not need another output speed sensor for engine or external control systems.
Torque Converter Output Shaft Speed Driver
The Torque Converter Output Speed Driver generates an output signal that is proportional to the torque converter output shaft speed. The frequency is based on the 16-tooth chopper wheel standard. For each revolution of the transmission torque converter output shaft, 16 pulses are produced. External controls and indicating devices can use this signal for speed calculations.
Transmission Output Shaft Lock (Park Gear)
The Transmission Output Shaft Lock feature activates clutches that prevent the transmission output shaft from rotating. This feature is only available if the transmission has been configured as a manual shift or auto shift pump application. Pressing the "R" button on the keypad activates the Transmission Output Shaft Lock. When the Transmission Output Shaft Lock is active, the shifter will display "PP" on the shift selector. There are speed limits on the engagement of this feature to protect the transmission clutches from being damaged. The Transmission Output Shaft Lock will not engage if the transmission output shaft speed is greater than 500 rpm, or if the engine speed is above 1000 rpm. If either speed is too high when the "R" button is pressed on the shift selector, the transmission will shift to NEUTRAL and wait for the speeds to fall within the limits before engaging the Transmission Output Shaft Lock. It will also display "PN" on the shift selector and the "P" will flash indicating that the gear has been selected but not achieved.
Note: The Transmission Output Shaft Lock is not meant to function as a dynamic vehicle brake or as a vehicle parking brake. The ECU must have power and the engine must be running for the feature to function.
Note: The output lock feature has a static torque capacity of 2965 lb-ft for the CX31-P600 and 4543 lb-ft for the CX35-P800.
When the Warm-Up feature is activated, the secondary mode LED on the shift selectors will indicate the feature status. If the indicator is flashing, warm-up has been selected but has not been able to fully engage due to conditions not being fully met or conditions were exceeded which required the exit of warm-up, such as high oil temperatures. If the indicator is solid, warm-up is currently engaged.
The Transmission Warm-Up Mode is activated by turning on the Warm-Up Mode switch. When the switch is moved to the ON position, the transmission will engage the Transmission Output Shaft Lock, using the applicable speed limits. Next, it will stall the input shaft and then send the engine an elevated idle speed request of 1000 rpm. Locking both the input and output shafts of the transmission stalls the torque converter which in turn churns the transmission oil and generates heat. Elevating the engine idle and stalling the torque converter will help reduce power train warm-up times. The feature will be deactivated if the switch is turned OFF, the transmission sump temperature rises above
If a directional shift is requested during warm-up on the shift selector, the transmission will acknowledge the request, exit warm-up mode, and go to the desired gear range. If the transmission leaves warm-up mode, the warm-up switch must be toggled for it to re-enter.
The lockup clutch disable feature allows the operator to prevent the lockup clutch from engaging. The feature is activated by moving the switch to the ON position. If the lockup clutch is disengaged when the switch is moved to the ON position, the transmission will prevent the lockup clutch from engaging when the lockup clutch engagement would normally occur. If the lockup clutch is engaged when the switch is moved to the ON position, the lockup clutch will immediately disengage.
If the converter auto downshift feature is enabled and the transmission is in converter drive for more than 30 seconds and the engine speed is greater than 1500 rpm, the transmission will downshift to the next lower gear.
The direct shift gear feature allows the operator to quickly toggle between gears. This feature is only available when the transmission is configured as a draw works application. When the direct shift gear switch is pressed and released the transmission will shift directly to the configured gear. When the switch is pressed and released again, the transmission will shift directly back to the previously selected gear. The transmission will only perform the shift if the engine is below 850 rpm, and the engine percent load is below 20% to prevent damage to the clutches.
Note: This feature utilizes a special shift type to execute the shift in a minimum amount of time. Due to the aggressiveness of the shift and the large ratio changes occurring, no load should be placed on the transmission output shaft during quick gear select shifts.
The Alternate Maximum Gear feature allows the operator to set a second maximum gear limit for each shifter. The feature is activated by moving the alternate maximum gear switch to the ON position.
When the feature is activated in roading and auto shift pumping configurations, the transmission will not force downshifts to the new top gear if the current transmission gear is above the new top gear, but inhibit upshifts and allow downshifts until the new top gear has been attained.
When the feature is activated in draw works configurations, the transmission will shift directly to the new top gear if the current transmission gear is above the new top gear and engine speed is less than 850 rpm.
This feature can be programmed to use the shift selector mode button. When the mode button is pressed and the LED indicator light is on, the transmission will limit gear selection to the programmed alternate maximum gear values. When the mode button is pressed again and the LED indicator light is off, the transmission will limit to the programmed primary maximum gear limit.
The Hold Current Gear feature will hold the transmission in the current gear during automatic shifting operations. If the feature is activated, the transmission will only up-shift to prevent an engine overspeed condition and only downshift to prevent an engine stall. The feature is activated by pressing and releasing the Hold switch. The feature is deactivated by pressing and releasing the Hold switch again.
The Output Shaft Speed Limit feature allows a technician or the operator to set an output shaft speed limit for the transmission using Caterpillar Electronic Technician. When the limit is set, the transmission will limit the engine speed so that the output shaft speed will not exceed the programmed limit.
Note: Output Shaft Speed limiting is only available in non-roading application modes. While in Roading Automatic Shift mode, Vehicle Speed Limiting will be used.
The Output Shaft Torque Limit feature allows a technician or the operator to set an output shaft torque limit for the transmission using Caterpillar Electronic Technician. When the limit is set, the transmission will limit the engine torque so that the transmission output shaft torque will not exceed the programmed limit.
The Converter Drive Indicator feature will turn on a lamp (amber) when the transmission is in converter drive. The lamp will turn off when the transmission lockup clutch is engaged.
Primary Shift Selector Indicator
The Primary Shift Selector Indicator feature will turn on a lamp (green) whenever the primary shift selector is active. The lamp will be off when the primary shift selector is not the active shift selector. Caterpillar recommends that applications using two shift selectors install both shift selector indicators next to the shift selector to inform the operator of the active shift selector.
The Transmission PTO feature controls two PTO enable output drivers. The PTO enable driver is used to control an OEM supplied control system connected to the transmission auxiliary output shaft(s). This output will be turned ON when the switch is in the ON position and all the programmed conditions have been met.
Note: The PTO Enable Output will NOT be enabled if the PTO Enable Switch input is in the ON position at key switch ON. The switch input must be toggled from OFF to ON before the output will be enabled. This prevents the output from being engaged without operator interaction.
PTO #1 driver will be active when PTO #1 switch is in the ON position (closed to sensor common). PTO #2 driver will be active when PTO #2 switch is in the ON position (closed to sensor common).
The PTO will not operate below the programmed minimum gear. The PTO will not turn ON below the programmed minimum gear and will turn OFF if the actual gear goes below the programmed minimum gear when the PTO is already engaged. A separate minimum gear can be set for both PTO controls.
The PTO will not operate above the programmed maximum gear. The PTO will not turn ON above the programmed maximum gear and will turn OFF if the actual gear goes above the programmed maximum gear when the PTO is already engaged. A separate maximum gear can be set for both PTO controls.
When this parameter is set to ENABLED, the transmission will allow the PTO to operate when the transmission is in NEUTRAL. When this parameter is set to DISABLED, the PTO will not be allowed to operate in NEUTRAL.
PTO Reverse Gear Enable Status
When this parameter is set to ENABLED, the transmission will allow the PTO to operate when the transmission is in REVERSE. When this parameter is set to DISABLED, the PTO will not be allowed to operate in REVERSE.
When this parameter is set to ENABLED, the transmission will allow the PTO to operate when the TRANSMISSION OUTPUT SHAFT LOCK is engaged. When this parameter is set to DISABLED, the PTO will not be allowed to operate when the TRANSMISSION OUTPUT SHAFT LOCK is engaged.
The PTO will not operate below the programmed minimum engine speed. The PTO will turn ON when the engine speed reaches the programmed minimum engine speed + 50 rpm and will turn OFF if the engine speed goes below the programmed minimum engine speed. A separate minimum engine speed can be set for both PTO controls.
The PTO will not operate above the programmed maximum engine speed. The PTO will turn OFF when the engine speed goes above the programmed maximum engine speed and will turn ON when the engine speed falls below the programmed maximum engine speed – 50 rpm. A separate maximum engine speed can be set for both controls.
PTO Minimum Transmission Output Speed
The PTO will not operate below the programmed minimum transmission output speed. The PTO will turn ON when the transmission output speed reaches the programmed minimum transmission output speed + 50 rpm and will turn OFF if the transmission output speed goes below the programmed minimum transmission output speed. A separate minimum transmission output speed can be set for both PTO controls.
Note: If the PTO minimum transmission output speed is programmed to 0 rpm, the output will turn ON at 0 rpm and will not disable based on a minimum transmission output speed.
PTO Maximum Transmission Output Speed
The PTO will not operate above the programmed maximum transmission output speed. The PTO will turn OFF when the transmission output speed goes above the programmed maximum transmission output speed and will turn ON when the transmission output speed falls below the programmed maximum transmission output speed – 50 rpm. A separate maximum transmission output speed can be set for both controls.
PTO Pump Displacement Control (Variable Current Output Driver)
When this parameter is set to INSTALLED, the PTO driver will output a current that is variable between 0 amp and 2 amp. This feature can be used to control variable displacement PTO pumps or other variable input equipment. The feature is activated using the normal PTO enable switches. Another switch, the current control switch, is used to control the output of the PTO driver. When the PTO enable switch is turned on, the PTO driver outputs a 500 mA current. When the current control switch is moved to the INCREASE position, the current ramps up at 50 mA per 400 ms until 2 amps are reached. When the current control switch is moved to the DECREASE position, the current will ramp down at 50 mA per 400 ms until 0 amps is reached. When the current control switch is moved to the NEUTRAL position, the current will hold at the present value. When the PTO enable switch is moved to the OFF position, the feature will be deactivated and will go to 0 amp.