| |
| Illustration 1 | g06097137 |
|
Machine General Information | |
The propulsion control system contains an electrical portion, a hydraulic portion, and a mechanical portion. The electrical portion is made up of electronic control modules (ECMs) and input and output devices.
The hydraulic portion of the propulsion control system consists of two closed-circuit hydrostatic drive loops. In each hydrostatic drive loop, the ECMs on the machine control a variable-displacement propulsion pump.
Each propulsion pump drives a two-speed propulsion motor. Each motor drives a single speed planetary final drive. The final drives transfer power from the propulsion motors to the tracks.
The planetary final drives have spring-applied, hydraulically released parking brakes. The charge system supplies oil to release the brakes. The ECMs on the machine control the engagement of the parking brake and the shifting of the machine.
The electronic control system monitors the machine and monitors engine operating conditions. The ECMs on the machine and the engine communicate through controller area network (CAN) lines.
The control system determines if an output signal should be sent to the pump solenoids. During normal operation, the propulsion system is controlled through closed-loop logic. The system prevents the machine from moving under the following conditions:
- The propulsion lever is out of the NEUTRAL position when the machine is started.
- The parking brake status is set to "engaged".
- The propulsion lever is in the NEUTRAL position.
- The propulsion speed dial status is set to "0", and the propulsion mode status is set to "pave" or "travel".
- The decelerator pedal is fully depressed.
- A fault is detected in a circuit to any of the following components: propulsion solenoid, propulsion lever, or parking brake solenoid.
- The machine is in a runaway condition, in a rollback condition, or uncommanded machine movement has been detected.
The electronic control system is also programmed with underspeed control logic. The underspeed control logic automatically adjusts the machine speed during low engine speed conditions to prevent the engine from stalling.