Abstract: A crawler carrier capable of smoothly operating a driving force source even at a slant. The driving force source is arranged between a dump body and a cab and laid in a lateral direction and at the same time the driving force source and a heat exchanger are arranged in series in a lateral direction. With such an arrangement as above, the driving force source can be arranged at an upper structure frame under a state in which it becomes substantially horizontal without interfering with the dump body. Even when the crawler carrier performs work at a slant the engine can always be lubricated with lubricant oil and the driving force source can be operated smoothly.

Abstract: There is provided a crawler carrier capable of smoothly operating the driving force source even at a slant ground or the like. The driving force source is arranged between the dump body and the cab and laid in a lateral direction and at the same time the driving force source and the heat exchanger are arranged in series in a lateral direction. With such an arrangement as above, the driving force source can be arranged at the upper structure frame under a state in which it becomes substantially horizontal without being interfered with the dump body. With such an arrangement as above, even in the case that the crawler carrier performs a work at the slant ground such as a mountain area having a high gradient, the engine can always be lubricated with lubricant oil and the driving force source can be operated smoothly.

Abstract: A tired roller is provided with a prime mover and a speed change unit of the HST type. The speed change unit includes an HST hydraulic pump of the variable displacement type driven by the prime mover and an HST hydraulic motor driven by pressure oil from the hydraulic pump, and can change a rotational speed of the hydraulic motor by varying a delivery rate of pressure oil from the hydraulic pump. Rotation of the hydraulic motor is therefore transmitted at a lower speed to a drive-axle tire train. A propeller shaft is connected to the hydraulic motor without interposition of any speed reduction mechanism, so that the propeller shaft is rotated at a high speed with a low torque. This has made it possible to form the propeller shaft smaller in diameter and hence to arrange it in a narrow space between tires in the drive-axle tire train.

Abstract: A speed command value X1 for a first arm 3 is decided depending on a lever input amount in the direction c, d. Assuming that the side d corresponding to move-up of the first arm is positive, the side c corresponding to move-down thereof is negative, and a speed command value resulted upon full lever operation and corresponding to a rated speed of the first arm is 1, X1 is given by -1<X1<1. A speed command value X3 for a third arm 5 is decided depending on a lever input amount in the direction e, f. Assuming that the side f corresponding to dumping of the third arm is positive, the side e corresponding to crowding thereof is negative, and a speed command value resulted upon full lever operation and corresponding to a rated speed of the third arm is 1, X3 is given by -1<X3<1. A speed command value X2 for a second arm 4 is here given by X2=K1.times.X1+K3.times.X3 on condition that the side corresponding to move-up of the second arm is positive.

Abstract: Two control lever units 11, 12 for operating a first arm 3, a second arm 4 and a third arm 5 of a 3-articulation work front 2 are provided, and signals 132, 133 from the two control lever units are sent to a controller 131. On condition that a virtual 2-articulation type work front comprising a virtual first arm 13 and a virtual second arm 14 is imaginarily provided and the relationship in movement between the virtual second arm and the actual third arm is set in advance as if both the arms constitute a rigid body together, the controller 131 determines respective command values .omega..sub.1, .omega..sub.2 and .omega..sub.

Abstract: A hydraulic drive system of the invention comprises a plurality of flow rate sensors (10A, 10B) for detecting respective flow rates supplied to a plurality of hydraulic actuators (3A, 3B), valve controllers (11A, 11B) for respectively controlling a plurality of flow control valves (40A, 40B) such that the flow rates detected by the plurality of flow rate sensors are coincident with the flow rates instructed by a plurality of control levers (5A, 5B), and a pump tilting controller (12; 12A-12F) for controlling a delivery rate of a hydraulic pump (1) such that the delivery rate of the hydraulic pump is smaller by a predetermined flow rate (.DELTA.Q.sub.ref ; X.sub.ref) than the total of the flow rates instructed by the plurality of control levers. The pump tilting controller controls the delivery rate of the hydraulic pump (1) by using flow rate deviations (.DELTA.Q.sub.1, .DELTA.Q.sub.

Abstract: A first hydraulic circuit comprises a variable displacement hydraulic pump driven by a prime mover, a variable displacement hydraulic motor connected in a closed circuit to the variable displacement hydraulic pump, and a displacement control means for controlling a displacement of the variable displacement hydraulic motor. A second hydraulic circuit comprises a hydraulic pump driven by the prime mover, and drives a loader attachment. A displacement limitation means limits the maximum value of the displacement of the variable displacement hydraulic motor in accordance with a load pressure of the second hydraulic circuit. For example, the displacement limitation means reduces the maximum value of the displacement of the variable displacement hydraulic motor in proportion to the pressure in the second hydraulic circuit. The motor torque is controlled by directly adjusting the displacement of the motor, and a load of the hydraulic motor can thus be stably controlled.

Abstract: A control apparatus for an electromagnetic device having a proportional solenoid has a duty factor calculation circuit for calculating a duty factor on the basis of a control target value, a pulse signal formation circuit for forming a pulse signal based on the calculated duty factor, an exciting current formation circuit for forming an exciting current for electrically stimulating the coil of an electromagnetic apparatus in response to the formed pulse signal, and an integration circuit for integrating the exciting current of the coil in synchronization with the pulse signal. This control apparatus calculates the duty factor using the duty factor calculation circuit from a control target value and the integration value output from the integration circuit.

Abstract: A variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit. A pressure oil supply means includes the variable displacement hydraulic pump and a tilting controlling means for controlling a tilt angle of the hydraulic pump and supplies an amount of pressure oil corresponding to the tilt angle of the hydraulic pump to the hydraulic motor. When rotation of a prime mover is detected by a rotation detecting means, an opening and closing valve is changed over to a first position in which the pressure oil supply means is permitted to supply pressure oil. When stopping of the prime mover is detected by the rotation detecting means, the opening and closing valve is changed to a second position in which the pressure oil supply means is inhibited from supplying pressure oil.

Abstract: A hydraulic drive system is equipped with an engine, a plurality of hydraulic pumps adapted to be driven by the engine and including a variable displacement hydraulic pump provided with a displacement varying mechanism, a hydraulic motor connected to the variable displacement pump, a hydraulic actuator for actuating the displacement varying mechanism of the variable displacement hydraulic pump, a working fluid feeding means for feeding the hydraulic actuator with a hydraulic fluid of a pressure according to the degree of control of an accelerator lever which is adapted to instruct a target revolution number of the engine, and a low-pressure circuit for allowing the hydraulic fluid to be discharged therethrough from the hydraulic actuator.

Abstract: A hydraulic drive circuit system is equipped with an accelerator pedal and an accelerator lever for respectively instructing target revolution numbers for an engine, a link plate for selecting greater one of the instruction values, and a linkage and a switch for controlling valves respectively so as to close the flow passage of a line interposed between a charge pump and a low pressure line irrespective of the instruction value of the accelerator pedal when the accelerator lever has not been controlled but for controlling the valves so as to restrict the flow passage of the line in accordance with the instruction value of the accelerator pedal when the accelerator lever has been controlled.