Abstract: A method of controlling an engine mounted on a construction vehicle comprising the steps of reducing the rotation of the engine to a primary number of revolutions per minute, which is in the vicinity of the rated number of revolutions per minute of the engine under earth moving operation conditions, immediately after all operating levers associated with all of the control valves for turning the vehicle body, for actuating work implements and for running of the vehicle are shifted to their neutral positions, maintaining the engine under such a low speed running condition for a predetermined period of time, and then reducing further the rotation of the engine to a lower, secondary number of revolutions per minute which corresponds to the number of revolutions per minute under idle running conditions thereby achieving reduction in fuel consumption and level of noise generated by the engine.

Abstract: A civil machine having a flow-rate controller which applies a preset signal instead of a normal flow-rate signal to a variable type hydraulic pump when delivery pressure of the hydraulic pump exceeds a preset pressure value. The normal flow-rate signal corresponds to the position of an operating lever. The preset signal has a value of minimum flow rate to hold a working tool in a certain posture. With this control system, pressure loss and temperature rise in hydraulic operating oil as well as fuel consumption of the machine can be reduced and cycle time of the work can be improved.

Abstract: A semi-automatic hydraulic excavator capable of automatically controlling arm and bucket angles when bringing the bucket back to the original excavation posture after completion of dumping excavated soil. For this purpose, arm and bucket angle detectors are provided therein and the automatic control is performed by negatively feeding back values detected by these detectors to minimize deviations between these values and preset values produced from arm and bucket angle setters corresponding to the arm and bucket angles in the original excavation posture. The automatic control mode is selected by a signal from an automatic control command signal producing circuit. With this system, the bucket is swiftly brought back to the original excavation posture from the dumping posture without requiring much operator's skill and efforts.

Abstract: A hydraulic excavator comprising a vehicle, a boom pivotally connected at one end to the vehicle, a stick pivotally connected at one end to the other end of the boom, a bucket pivotally connected to the other end of the stick. A bucket attitude maintaining arrangement is provided to maintain a substantially fixed preselected attitude of the bucket with respect to the ground upon movement of the stick about its pivotal connection to the boom. The bucket attitude maintaining arrangement includes a lever pivotally mounted at one end to the stick and a compensating cylinder pivotally connected at one end to the stick and at the other end to the lever.

Abstract: A transmission gear for a vehicle of the type having a swivelling upper structure with respect to an undercarriage which comprises an input gear rotatably mounted on the upper structure, the input gear being connected to a prime mover, an output gear rotatably mounted on the undercarriage and, an idler gear mounted coaxially with a center swivel joint of the swivelling upper structure and the undercarriage.

Abstract: An apparatus for controlling bucket in tractor mounted loader, characterized in that a reach lever is pivoted to the body of tractor so as to be swingable in the forward and backward directions; a lift arm is pivoted to the free end of said reach lever so as to be raised and lowered; a bucket is rotatably pivoted to the forward end of said lift arm by use of a tilt cylinder; a reach cylinder is pivoted to said reach lever at the pivoting portion thereof, the contractibly extending end of said reach cylinder being pivoted to the lift arm; and a lift cylinder is pivotably connected between the lift arm and body of the tractor.

Abstract: A steering apparatus for a vehicle of the type having a revolving upper body with respect to a lower body thereof in which a directional control valve is provided in a hydraulic circuit to maintain the same steering control when upper body of the vehicle is rotated to 180.degree.. The apparatus comprising a pair of valves for steering, a pair of steering pedal connected to said pair of valves, a directional control valve connected to said pair of valves through hydraulic conduits for right and left steering, a cam provided at around revolving center of the lower body of the vehicle, a switch connected to the directional control valve and, a rocking lever provided on the upper body of the vehicle.