Hitachi Construction Machinery Co., Ltd.

Seiji Tamura

Akira Tatsumi

Mitsuo Kihara

Kazuhiro Ichimura

Junichi Hosono

Kazuo Asano

Morio Oshina

Tsuyoshi Takayama

Kiyoshi Hirasawa

Hideaki Sayama

Toichi Hirata

Hiroshi Onoue

Shigetaka Nakamura

Nobuya Okabe

Toshimichi Ikeda

Yoshinori Sendai

Saburo Yoshio

Saburou Yoshio

Kouji Tahara

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.

Crawler carrier having an engine, a hydraulic pump and a heat exchanger positioned in a lateral direction

A tired roller, which permits widening the field of view on both the left and right sides of an operator's section and is convenient for steering. In a tired roller with an operator's section arranged close to a right-hand side wall of a tired roller main body and with an ingress-egress step arranged on the tired roller main body , a space for the arrangement of the ingress-egress step is formed on the tired roller main body at a position between a left-hand side wall and the operator's section. In the arrangement space , the ingress-egress step which is provided with plural treads is arranged extending aslant from the operator's section toward a lower part of the left-hand side wall, so that an operator can look down at a road surface on the left side from the operator's section through a space above the treads . When the operator looks down at the road surface on the left side, conventional tired rollers allow him to see only a point Y significantly remote from the tired roller main body . This invention however makes it possible to see a point Z which is a point adjacent to the tired roller main body 11, whereby the field of view has been substantially enlarged on the left side.

Tired roller

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. Further, the rotation of the hydraulic motor is reduced in speed at an output side of the propeller shaft, thereby making it possible to transmit the rotation in a state increased in rotating torque to the drive-axle tire train.

Tired Roller

The current operational condition is discriminated as being the vehicle propulsion condition or the performing work condition. When the vehicle propulsion operational condition is discriminated, the maximum engine revolution speed is limited to a first revolution speed and the maximum displacement is limited to a first displacement value. When the performing work condition is discriminated, the maximum engine revolution speed is limited to a second revolution speed equal to or lower than the first revolution speed and the maximum displacement is limited to a second displacement value higher than the first displacement value. The first and second revolution speeds and the first and second displacement values are so determined that the first revolution speed multiplied by the first displacement value at least as relating to pressure for vehicle propulsion on level ground is less than the second revolution speed multiplied by the second displacement value as relating to the pressure for below the range of torque limitation control. By this, the pump output flow during vehicle propulsion on level ground is made lower than while performing work and, during vehicle propulsion, reduction of the pressure loss is made possible. Even with the identical pump pressure, the effective motor pressure is increased, so that its output torque can be increased. Because also the maximum displacement of the motor can be reduced according to the reduction of the maximum pump output flow amount, the construction of the hydraulic circuit can be made more compact.

Control device for hydraulically propelled work vehicle

Lockable suspension system for a work vehicle having a stabilizing link

Apparatus for controlling revolution speed of prime mover for

Hydraulic control apparatus for hydraulic construction machine

Engine revolution speed control device for a hydraulically driven vehicle

A control system of hydraulic construction machinery includes a prime mover, at least one variable displacement pump driven by the prime mover, at least one actuator hydraulically driven by the pump, maximum revolution number altering device for the prime mover, maximum displacment volume altering device for the pump and an information provider device for providing information on the operation mode of the actuator, whereby the maximum revolution number altering means and maximum displacement volume altering means are controlled by the information provider device to provide a maximum number of revolutions and a maximum displacement volume which suit the operation mode indicated by the output signal. A product of the maximum displacement volume and the number of revolutions becomes at a constant always at the same time when the maximum displacement volume of the pump is varied in response to an output signal of the information provider device, whereby a change in the quantity of pumped fluid can be avoided when the maximum displacement volume of the pump is altered.

Control system of hydraulic construction machinery

A hydraulic circuit system for civil engineering and architectural machinery having at least first and second hydraulic pumps, a plurality of actuators driven by hydraulic fluid from said pumps, and a plurality of directional control valves for controlling the direction and flow rate of the hydraulic fluid supplied from the pumps to the actuators. In the directional control valves, a first boom directional control valve and one of right and left travelling directional control valves are connected to the first pump in parallel with each other, a swing directional control valve, an arm directional control valve and a second boom directional control valve are connected to the second pump in parallel with one another, and the other of the right and left travelling directional control valve is connected in tandem to the swing, arm and second boom directional control valves at a location downstream thereof. A connecting line is provided for communication between an inlet port of the one travelling directional control valve and an inlet port of the other travelling directional control valve.

Hydraulic circuit system for civil engineering and architectural

Growing community of inventors

Ibaraki, Japan

Seiji Tamura