HOUSING 5V1185 - Caterpillar

Illustration 1 g02629419
The propel 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 consists of two closed circuit hydrostatic drive loops. The mechanical portion is comprised of a single, planetary final drive which drives each track.In each hydrostatic drive loop, the ECMs on the machine control a variable displacement propel pump. This pump drives a single speed propel motor. Each motor drives a two speed, planetary final drive. The final drives transfer power from the propel motors to the tracks. The planetary final drives have spring applied, hydraulically released parking brakes. The auxiliary hydraulic pump supplies oil pressure which releases the brakes. Oil from the auxiliary pump also shifts the two speed planetary. 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 machine contains four control modules, the screed contains one control module, and the engine contains one control module. The ECMs on the machine, the screed, and the engine communicate through controller area network (CAN) lines, and as a backup, through the Cat Data Link in some cases. The electronic control system determines if an output signal should be sent to the pump electronic displacement controls (EDCs). During normal operation, the propel system is controlled through closed loop logic. The system prevents the machine from moving under the following conditions:
The propel lever is out of the NEUTRAL position when the machine is started.
The parking brake switch on either operator station is in the ON position.
The propel lever is in the NEUTRAL position.
The propel speed dial is in the MINIMUM SPEED position, and the propel mode switch is in either the PAVE position, the MANEUVER position, or the TRAVEL position.
The decelerator pedal (optional) is fully depressed.
A fault is detected in a circuit to any of the following components: parking brake switch, propel EDC, propel lever, steering sensor, or parking brake solenoid.
The machine is in a runaway condition or in a rollback condition.The propel system section of this presentation is divided into segments. The first seven segments show the location of all hydraulic and electrical components which are involved in machine propel. A brief discussion of each component is provided in these segments. Cross sectional views of selected components are also used in order to explain further the operation of components in the propel system.The last two segments explain the operation of the electrical and hydraulic systems. Electrical and hydraulic schematics are used in these segments in order to trace current through the electrical system and in order to trace hydraulic oil through the hydraulic system. Note: Because this section is meant to stand alone, some components may have been discussed in previous sections.