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| Illustration 1 | g06266320 |
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Propel Control System (1) Engine ECM (2) Machine ECM (3) Back-up alarm relay (4) Front back-up alarm (5) 360-Reverse relay (6) Rear back-up alarm (7) Keypad (8) Parking brake switch (9) Propel lever (10) Seat position switch "1" (11) Seat position switch "2" (12) Front speed sensor 2 (13) Rear speed sensor 2 (14) Diagnostic connector (15) Interlock solenoid (16) Shift solenoid (17) Propel pump solenoids (reverse) (18) Propel pump solenoids (forward) (19) Display (20) Front speed sensor 1 (21) Rear speed sensor 1 | |
Note: The blue lines in the above illustration indicate an input signal. The red lines indicate an output signal. The red and blue lines indicate two-way communication.
Note: The above illustration shows the general layout of the propel control system. Refer to the machine electrical schematic for detailed wiring information.
Machine ECM (2) analyzes information from input devices to determine how to control machine propel. The above illustration shows the connections of the direct input signals in blue. The following components provide direct input signals to the machine ECM:
- Parking brake switch (8)
- Seat position switch"1" (10)
- Seat position switch"2" (11)
- Front speed sensor 2 (12)
- Rear speed sensor 2 (13)
- Front speed sensor 1 (20)
- Rear speed sensor 1 (21)
Input signals are also sent through CAN communication lines. The CAN communication devices are shown with a blue-and-red-stripe connection in the above illustration. The following input signals are sent to machine ECM (1) through the CAN:
- Engine speed from engine ECM (1)
- Speed scale factor and propel mode from keypad (7)
- Propel lever (9) input
- Desired engine speed from display (19)
Machine ECM (2) generates output signals to control machine propel. The above illustration shows the connections of the direct output devices in red. The following components receive direct output signals from the machine ECM:
- 360-Reverse relay (5)
- Pump interlock solenoid (15)
- Shift solenoid (16)
- Propel pump solenoids (reverse) (17)
- Propel pump solenoids (forward) (18)
Machine ECM (2) evaluates input signals from the components in the propel system and transmits an output signal to pump interlock solenoid (15). When this solenoid is energized, the park brake is released and the propel pump receives control pressure.
Machine ECM (2) evaluates input signals from components in the propel system. Based on these signals, an output signal is sent to either the propel pump solenoids (forward) (18) or the propel pump solenoids (reverse) (17).
If the speed range is set to high, the machine ECM energizes shift solenoid (16).
Each of the following conditions must be met before machine ECM (2) will allow machine movement:
- The E-stop switch must be in the run position.
- The engine must be running.
- The parking brake switch must be in the OFF position.
- Propel lever (9) must be in the NEUTRAL position for 1 second before machine movement is enabled.
The engine is considered"on" when the engine speed is greater than or equal to 600 rpm for more than 1 second. If the engine speed parameter is unavailable or faulted, engine ECM (1) holds the last known value for engine speed.
Machine ECM (2) monitors the condition of parking brake switch (8) to determine the desired state of the parking brake.
Interlock solenoid (15) controls hydraulic oil flow to release park brakes and provide supply pressure to the propel pump control valves. When parking brake switch (8) is considered ON, the interlock solenoid is not energized. In this case, the park brake is set and no pressure is supplied to the propel pump control solenoids.
When park brake switch (8) is in the ON position, propel functions are disabled. If the park brakes are disengaged when propel lever (9) is out of the NEUTRAL position, machine propel is disabled. In this case, the propel status remains disabled until the propel lever is returned to the NEUTRAL position.
Note: The default position of park brake switch (8) at machine start-up is ON.
Machine ECM (2) monitors two seat position switches (10) and (11) to determine which direction the operator station is facing. At the same time, the machine ECM monitors the position of propel lever (9). The machine ECM transmits a control signal to 360-reverse relay (5) based on the direction of the operator station. Engine ECM (1) transmits power to the 360-reverse relay based on the position of the propel lever. If the propel lever is operating in the reverse range, the engine ECM energizes appropriate back-up alarm (4) or (6) via the 360-reverse relay.
Machine ECM (2) monitors input from the increase speed switch and from the decrease speed switch. The ECM assigns a scale factor from six percent to 100 percent depending upon the number of times the switches have been actuated. The value increases or decreases by a value of two percent each time one of the switches is pressed for more than one second. Each time the speed is adjusted, a pop-up message appears on display (19) showing the current setting. After five seconds the current speed is saved to memory and preserved through the key cycle. The default setting is 50 percent.
The propel mode switch allows the operator to toggle between LOW and HIGH mode. Each time the switch is pressed, a pop-up message appears on display (19) showing the current setting. After five seconds the current setting is saved to memory and preserved through the key cycle. The default setting is LOW.
Machine ECM (2) controls machine propel using open-loop logic. The ECM monitors input from the following components to determine the desired speed and direction:
- Park brake switch (8)
- Propel lever (9)
- Seat position switch"1" (10) and seat position switch"2" (11)
- Increase speed switch and decrease speed switch on keypad (7)
- Propel mode switch on the keypad
- Engine mode switch on the keypad
Machine ECM (2) uses display (19) to provide information to the operator about the propel system during operation.
Propel Joystick Signal Processing
Machine ECM (2) monitors the position of propel lever (9) through the CAN. The machine ECM assigns a value to each position of the propel lever. The values range from - 100 percent to 100 percent.
Propel lever (9) controls the direction of travel and the rate of acceleration and deceleration. When the propel lever is moved toward the front of the machine, machine ECM (2) determines that the desired travel direction is forward. When the propel lever is moved toward the rear of the machine, the machine ECM determines that the desired travel direction is reverse.
Note: Travel direction is determined with respect to the direction the operator station is facing. When the operator station is facing the rear of the machine, the value assigned to the position of the propel lever is the opposite of what is assigned when the operator station is facing the front of the machine.
To determine desired machine speed, machine ECM (2) scales the input from propel lever (9) by the value of the scale factor. The ECM then applies the appropriate speed map to the scaled speed in order calculate the desired speed.
Once the desired speed and direction have been determined, machine ECM (2) generates an output signal to the appropriate pump control solenoids.
Machine ECM (2) uses the input from the propel mode switch to control shift solenoid (16). When the propel mode is set to low, the ECM does nothing. When the propel mode is set to high, the machine ECM energizes the shift solenoid.
Machine ECM (2) controls interlock solenoid (15). When the machine ECM determines that the parking brake should be engaged, no signal is generated. When the machine ECM determines that the parking brake should be released, a signal energizes the interlock solenoid.
When the interlock solenoid is energized, the parking brakes are released and the propel pump controls are enabled. The interlock solenoid remains energized while the machine is moving. The interlock solenoid will turn off when the propel lever is in the NEUTRAL position for greater than 1 second.
If parking brake switch (8) is in the ON position, the parking brake is engaged, regardless of the position of propel lever (9).
Machine ECM (2) uses inputs from seat position switches (10) and (11) to determine the direction the operator station is facing. The machine ECM generates a signal to control 360-reverse relay (5). The 360-reverse relay determines if front back-up alarm (4) or rear back-up alarm (6) is energized when the machine is operating in the reverse direction. When the propel lever is in the reverse range, the machine ECM sends a back-up alarm request to engine ECM (1) through the CAN. The engine ECM energizes the appropriate back-up alarm via the 360-reverse relay.
Ground Speed and Distance Determination
Machine ECM (2) monitors input from front speed sensors (12) and (20) rear speed sensors (13) and (21). The machine ECM uses the inputs from these speed sensors to determine the actual machine speed and direction.
Each speed sensor provides two pulsed input signals. Machine ECM (2) compares the frequency of the signals from each speed sensor. If internal signals from the sensors are out of sync, the machine ECM generates a level-two fault. In this case, the ECM sets the propel mode to low, and the undetected movement detection logic is disabled.
The ECM averages the input from the speed sensors to calculate the machine speed. The machine ECM compares the observed machine speed to the desired machine speed.
Machine ECM (2) is programmed to detect uncommanded machine movement. When the actual ground speed is greater than
- The actual ground speed is a specified amount higher than the commanded speed for a duration of time. The default speed differential is set at 20 percent. The default time is set at 350 ms.
- The actual machine direction is opposite the commanded direction for a specified amount of time.
If machine ECM (2) detects uncommanded movement, the system generates a level-three fault. During an active uncommanded movement fault, the machine ECM disables the propel system.