Abstract: A monitoring apparatus for a construction machine having an engine includes sensors for detecting abnormality conditions at various predetermined inspection positions. A warning system, cooperating with the sensors, provides an engine idling signal and a visual display in accordance with the detected abnormality condition. A delay circuit causes the warning system to activate the visual display only if the abnormality condition continues for a predetermined time after issuance of the engine idling signal. The engine idling signal itself is provided without delay upon detection of the abnormality condition, and causes the engine to idle.

Abstract: An electric hydraulic control device for controlling hydraulic cylinders of work tools in a construction vehicle, in which control valves of the hydraulic cylinders are controlled in two ways. For some work tools which need not be controlled smoothly and finely, the corresponding control valves are controlled directly by an electric signal outputted according to the position of the operation levers, and for other work tools which must be controlled smoothly and finely, the corresponding control valves are controlled through an electric servo mechanism which is operated by an electric signal representative of the amount by which the operation lever is manipulated. In addition, there is provided a detector for detecting as to whether the transmission lever is in the locked condition, and electric systems of all of the control valves are rendered inoperative when the transmission lever is in the locked condition.

Abstract: An automatic decelerator device for use in crawler-type vehicles such as a bulldozer or the like comprising a vehicle speed change lever means having a plurality of speed stages for forward and backward drives, a plurality of solenoid operated valves provided in a transmission for controlling the same to change over the vehicle speed and/or the drive direction, controller means adapted to actuate brake means and a decelerator, a comparator for comparing an actual vehicle speed with a preset vehicle speed so as to detect whether the actual vehicle speed is higher or lower than the preset one thereby generating a signal corresponding to the detection result, and a solenoid operated valve control circuit for controlling the controller means and the solenoid operated valves in response to the signal.