Power Distribution
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| Illustration 1 | g03271016 |
Propel Electrical Schematic (1) From machine ECM number two fuse (2) From display/keypad fuse (3) From propel/steer fuse (4) From engine ECM number two fuse (5) From engine ECM number one fuse (6) From machine ECM number one fuse (7) From engine actuators fuse (8) Machine ECM number one (9) Parking brake switch (10) Keypad (11) Propel lever (12) Display (13) Engine ECM (14) Split drum ECM (15) CAN resistor "2" (16) Seat position switch "1" (17) CAN resistor "1" (18) Back up alarm relay (19) Seat position switch "2" (20) Propel reverse solenoid "1" (21) Propel forward solenoid "1" (22) 360-reverse relay (23) Propel reverse solenoid "2" (24) LH front drum speed sensor (25) RH rear drum speed sensor (26) Propel forward solenoid "2" (27) Interlock valve solenoid (28) Machine ECM number two (29) Front back-up alarm (30) Rear back-up alarm (31) RH front drum speed sensor | |
When the electrical disconnect switch is in the ON position, power transfers from the engine ECM "2" fuse (4) to terminals "J1-3" and "J1-5" of engine ECM (13). At the same time, power transfers from the engine ECM "1" fuse (5) to terminal "J1-1" of the engine ECM. This voltage provides the main power source for the engine ECM. The engine ECM is grounded at the following terminals: "J1-2", "J1-4" and "J1-6".
When the engine start switch is in the ON position, power transfers from propel/steer fuse (3) to terminal "J1-54" of engine ECM (13). This voltage provides the wake-up signal to the engine ECM.
When the engine start switch is in the ON position, machine ECM number one fuse (6) is energized. Power transfers from machine ECM number one fuse to the following terminals of machine ECM number one (8) : "2", "47", "48", "49" and "50". This voltage provides the main power source for the machine ECM number one and also provides the wake-up signal. The machine ECM number one is grounded at terminal "1".
When the engine start switch is in the ON position, machine ECM number two fuse (1) is energized. Power transfers from machine ECM number two fuse to terminal "J1-2" of split drum ECM (14). This voltage provides the main power source for the split drum ECM and also provides the wake-up signal. The split drum ECM is grounded at terminal "J1-1".
When the engine start switch is in the ON position and the machine main relay is energized, power transfers to display/keypad fuse (2). Power transfers from the display/keypad fuse to the following locations:
- Contact "1" and contact "5" of keypad (10)
- Contact "2" of display (12)
- Contact "3" of seat position switch "2" (19)
When the engine start switch is in the ON position and the machine main relay is energized, power transfers to propel/steer fuse (3). Power transfers from the propel/steer fuse to the following locations:
- Contact "2" of propel lever (11)
- Contact "54" of engine ECM (13)
- Contact "5" of parking brake switch (9)
- Contact "3" of seat position switch "1" (16)
CAN Communication
Keypad (10), propel lever (11), display (12), engine ECM (13), split drum ECM (14), machine ECM number one (8) and machine ECM number two (28) communicate through a CAN.
In order to prevent data loss in the communication lines, termination resistors are required at the ends of the CAN bus. CAN resistors (15) and (17) act as termination resistors. The CAN resistors absorb unwanted noise in the communication system which can result in abnormal machine operation.
Differences in materials along the CAN bus can cause data pulses in the bus to reflect back through the bus. This reflection, also known as "jitter", creates unwanted noise in the CAN bus. Jitter in the communication lines between computers can distort the original data signals. The distortion can result in data loss.
Data in the CAN bus can also be contaminated with radio frequency interference (RFI). This interference can be caused by a number of devices which operate on or near the machine. RFI creates noise in the communication lines which can also distort the original data signals and cause data loss.
Parking Brake Control
Machine ECM number one (8) monitors the circuits at terminal "6" and terminal "7" in order to determine the condition of parking brake switch (9). When the circuit at terminal "6" is closed and the circuit at "7" is open, the machine ECM number one determines that the parking brake switch is in the OFF position. When the circuit at terminal "6" is open and the circuit at "7" is closed, the machine ECM number one determines that the parking brake switch is in the ON position. If the circuits at these two terminals are simultaneously open or closed, the machine ECM number one generates a level three fault.
Machine ECM number one (8) controls interlock valve solenoid (27) with a digital output signal from terminal "41". When the machine ECM number one determines that the parking brake should be engaged, no signal is generated. When the machine ECM number one determines that the parking brake should be released, a signal is generated.
If parking brake switch (9) is in the ON position, the parking brake is engaged, regardless of the position of propel lever (11) .
Desired Speed and Direction
Machine ECM number one (8) controls machine propel using open loop logic. The ECM monitors input from the following components in order to determine the desired speed and direction:
- Propel lever (11)
- Increase speed switch and decrease speed switch-on keypad (10)
- Propel mode switch-on keypad (10)
Machine ECM number one (8) monitors the position of propel lever (11) through the CAN. The machine ECM number one assigns a value to each position of the propel lever. The values range from 100 percent to 100 percent.
Machine ECM number one (8) monitors input from the increase speed switch and from the decrease speed switch through the CAN. The ECM assigns a scale factor from zero percent to 100 percent depending upon the number of times the switches have been actuated.
Machine ECM number one (8) monitors input from the propel mode switch through the CAN. The ECM toggles between low and high with each actuation of the switch. The software in the machine ECM number one contains a speed map for each propel mode.
In order to determine the desired direction of travel, machine ECM number one (8) evaluates the value assigned to position of the propel lever. Negative values indicate reverse travel. Positive values indicate forward travel. A value of zero percent indicates that the propel lever is in the NEUTRAL position. The 100 percent value is assigned to the FULL REVERSE position of the lever, and the 100 percent value is assigned to the FULL FORWARD position.
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.
In order to determine the desired machine speed, machine ECM number one (8) scales the input from propel lever (11) by the value of the scale factor. Then, the ECM applies the appropriate speed map to the scaled speed in order to calculate the desired speed.
Once the desired speed and direction have been determined, machine ECM number one (8) generates an output signal to the appropriate pump control solenoids.
Back-up Alarm Control
Machine ECM number one (8) uses the input from seat position switches (16) and (19) in order to determine the direction the operator station is facing. The machine ECM number one communicates this information to machine ECM number two (28) via the CAN lines. The machine ECM number two generates a signal to control 360 reverse relay (22). The 360 reverse relay determines if front back-up alarm (29) or rear back-up alarm (30) will be energized when the machine is operating in the reverse direction. When the propel lever is in the reverse range, the machine ECM number one sends a back-up alarm request to engine ECM (13) through the CAN. The engine ECM generates a signal from contact "49" and energizes the coil of back-up alarm relay (18). When this stutuation happens, power is transferred from engine actuators fuse (7) to the gate of the 360 reverse relay. The 360 reverse relay transfers this power to the appropriate back-up alarm.
Uncommanded Movement Detection
Machine ECM number one (8) is programmed to detect uncommanded machine movement. When the actual ground speed is greater than 1 km/hr (0.6 mph), this logic will stop machine movement under the following conditions:
- 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 250 ms.
- The actual machine direction is opposite the commanded direction for a specified amount of time.
If machine ECM number one (8) detects uncommanded movement, the system generates a level three fault. During an active uncommanded movement fault, the machine ECM number one disables the propel system and the vibratory system.
Machine ECM number one (8) monitors input from right front speed sensor (31). Display (12) monitors input from left rear speed sensor (32) and transmits this information to the machine ECM number one via CAN lines. Contact "1" of these speed sensors receives an 8 V power supply signal from terminal "8" of the machine ECM number one. Contact "3" of both sensors are grounded at a common 8 V sensor return at terminal "9" of the machine ECM number one.
Split drum ECM (14) monitors input from left front speed sensor (24) and right rear speed sensor (25). The split drum ECM transmits this information to the machine ECM number one via CAN lines. Contact "1" of these speed sensors receives an 8 V power supply signal from terminal "J1-8" of the split drum ECM. Contact "3" of both sensors are grounded at a common 8 V sensor return at terminal "J1-9" of the split drum ECM.
Each speed sensor provides two pulsed input signals. Left rear speed sensor (32) provides input signals to terminal "10" and terminal "11" of display (12). Right front speed sensor (31) provides input signals to terminal "18" and terminal "19" of machine ECM number one (8). Left front speed sensor (24) provides input signals to terminal "J1-10" and terminal "J1-11" of split drum ECM (14). Right rear speed sensor (25) provides input signals to terminal "J2-1" and terminal "J2-2" of the split drum ECM.
Machine ECM number one (8) compares the frequency of the two signals from each speed sensor. If one signal is zero and the other is a non-zero, the machine ECM number one generates a level two fault. In this case, the ECM sets the propel mode to low, and the undetected movement detection logic and the vibratory system are disabled.
Machine ECM number one (8) uses the inputs from the speed sensors in order to determine the actual machine speed and direction. The ECM averages the inputs from right front speed sensor (31) and left rear speed sensor (32) in order to calculate the machine speed. The machine ECM number one compares the observed machine speed to the desired machine speed.