Abstract: A system for preventing engine overheat in a vehicle such as a motor scraper or the like having a front engine and a rear engine mounted thereon. An actuator is operatively connected to the rear engine for controlling speed thereof and also is connected to a source of pressurized fluid through a solenoid-operated valve. A plurality of detectors are mounted in the rear engine each detecting a preset abnormal condition of the rear engine. Provided in the system is a relay responsive to a signal from the detectors for simultaneously turning on a warning lamp and energizing the solenoid-operated valve thereby blocking communication between the source of pressurized fluid and the actuator, thereby reducing the speed of the rear engine to its idle speed.

Abstract: A control system for a differential gear lock mechanism including a power transmission having at least two forward drives and a backward drive and a manually operated speed change lever associated with said power transmission.The control system comprises a differential gear, an air tank containing compressed air therein, a conduit for connecting said air tank with said differential gear, a valve disposed in said conduit for selectively supplying compressed air to said differential gear when actuated, and a solenoid-controlled valve disposed in said conduit for interrupting air supply to said differential gear when actuated wherein said solenoid-controlled valve is adapted to be actuated when said speed change lever is shifted to a higher drive.