Abstract: A monitor system for construction vehicles comprises a plurality of sensors provided on each of the vehicles and each being for a different one of check points of the vehicle. A sensor provided on each of the vehicles transmits a one-channel signal indicating an abnormal condition occurred at at least one of the sensors and a monitor station responsive to the signal transmitted from at least one of the vehicles identifies the abnormal condition and the vehicles on which the latter occurs.

Abstract: Abnormal conditions of the engine and auxiliary machines mounted on a construction equipment are detected by sensors and individually displayed by a plurality of abnormal condition display circuits connected to respective sensors, for the purpose of alarming and displaying any one of the abnormal conditions there are provided a logical sum circuit connected to receive abnormal signals from all abnormal condition display circuits and an alarming circuit energized by the output from the logical sum circuit for giving audible and visible alarms. Further, there are provided a delay circuit connected to receive the output of a sensor provided for the engine system and a deceleration mechanism operated by the output from the delay circuit for decreasing the speed of the engine or stopping it when an abnormal condition occurs in the engine system.