Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Michio Fushiki

Tomohiko Yasuda

Takashi Yagyu

Yasuo Tanaka

Satoru Kaneko

Toshikazu Minoshima

Takao Kurosawa

Katsumi Tamura

Hajimu Kozawa

Takayuki Sato

Kazuhiro Imaie

Atsushi Kitaguchi

Kazunori Ishihara

Shinji Akino

Yasuki Kita

Yoshifumi Nabeshima

Takayoshi Murahashi

Takehito Ikema

Takashi Yagyuu

Naokazu Oda

Katsuhiko Shimizu

Takeo Yamamoto

Takashi Tateyama

An object of the present invention is to provide a haulage vehicle that enables precisely confirming that work for dumping a load is completed. The present invention is based upon a haulage vehicle provided with a vehicle frame (), a vessel () tiltably mounted on the vehicle frame and a hoist cylinder () which is provided between the vehicle frame and the vessel and which tilts the vessel, and has a characteristic that a load detector (A,B,) that detects force that acts in an extended or a contracted direction of the hoist cylinder and an empty load determination unit () that determines whether the vessel is empty on the basis of a detection signal from the load detector or not are provided.

Haulage vehicle

One 3-position selector valve is used as a main control valve that controls hoist cylinders. A control valve is provided for supplying hydraulic oil from a low-pressure hydraulic pressure source to rod chambers of the hoist cylinders upon lowering a vessel. Provided between the rod chambers of the hoist cylinders and an oil tank is a check valve that enables to supply hydraulic oil from the oil tank to the rod chambers upon a vessel FLOAT operation. When an operation command from a control device is a vessel-lowering command, a controller switches the main control valve to a FLOAT position, and also switches the vessel LOWER operation control valve and supplies hydraulic oil of a low pressure from the low-pressure hydraulic pressure source to the rod chambers of the hoist cylinders.

Hoist device for dump truck

A vehicle status is judged with respect to whether the following conditions are met: the shift position of a shift leveris F or R (condition 1); the brakes are inactive (condition 2); the vehicle stands still (condition 3); the accelerator pedal is depressed equal to or less than &#x3b4; (condition 4); and the rotational speed of the engine is equal to or less than a medium rotational speed (condition 5). The engine is controlled such that the rotational speed is set to a minimum if conditions 1, 2, and 4 are met and condition 3 is not met or if condition 1 is met and condition 2 is not met; and the rotational speed is set to the medium rotational speed if conditions 1, 2, 3, and 5 are met or if conditions 1, 2, and 5 are met and conditions 3 and 4 are not met.

Engine rotation control system

In case a burden is discharged from a vessel (), the vessel () is raised obliquely backward with respect to a vehicle body () by a hoist cylinder (). However, when discharging work is stopped on the way, the vessel () is temporarily lowered to a position at which this sits on the vehicle body (). When the vessel () lowers, a weight of the burden left loaded thereon acts on the hoist cylinder () as a load in addition to the weight of the vessel (). A controller () determines whether the vessel () lowers in a burden loading state based on various detection signals. When the vessel () lowers in the burden loading state, switching of directional control valves () and () is controlled so as to decrease a contracting speed of the hoist cylinder (), thereby prevent the vessel () from colliding against the vehicle body ().

Transporter vehicle

A control valve device comprises two direction control valves. The direction control valve includes an expansion side variable throttle portion and a contraction side variable throttle portion. The direction control valve includes an expansion side variable throttle portion and a contraction side variable throttle portion. When a hoist cylinder is telescopically operated to raise or lower a vessel, as the hoist cylinder approaches a stop position, a controller determines that the hoist cylinder gets close to the stop position. Based upon this determination, the controller variably adjusts a flow passage area of the direction control valve using the variable throttle portions or variably adjusts a flow passage area of the direction control valve using the variable throttle portions in such a manner as to slow down or speed up the telescopic speed of the hoist cylinder corresponding to the weight in the side of vessel.

Rear wheel tires of a vehicle body are spaced apart from each other in the vehicle width direction. A foreign object removing device is provided between an outer tire and an inner tire of the rear wheels on one side of the vehicle for removing foreign objects between the tires. The foreign object removing device includes a bar-shaped member inserted in a suspended state between the tires, and a shoe provided in a lower end side of the bar-shaped member to collide with foreign objects such as earth and sand, and stones getting in between the tires for flicking out the foreign objects from between the tires. The shoe is replaceably attached to the lower end side of the bar-shaped member by using a bolt. In a case where the shoe wears down, only the shoe is replaced.

An upper cross beamfor supporting a rear side of a cabfrom below is formed as a separate member from a base frame. This upper cross beamis separably mounted on left and right column portionsE of the base frameby using bolts. Namely, when an engineis mounted to the base frame, the upper cross beamis separated in advance from the base frame. Consequently, at the time of the operation of carrying in the engine, it merely suffices to vertically hoist or lower the engineby use of a crane. It is thereby possible to carry in the enginebetween the column portionsE of the base framewithout being hampered by the upper cross beam

An electrically-driven dump truckuses resistors to convert electric power generated during retarder braking operation into heat energy. A body framehas front and rear wheels, a support baseA, a cabmounted on an upper left surface of the support base, and a control cabinetmounted on an upper surface of the support base. A plurality of resistor boxesare mounted on an upper base plateB and are arranged in a stacked manner such that the plurality of resistor boxesare located to the right of the control cabinetin order to secure right side visibility from the cab. Each resistor box has a casing with plural resistors connected in parallel, an inlet port and an outlet port. A fan for cooling the resistors is housed in the casing.

Electrically-driven dump truck

A hydraulic drive system is provided with a generatorfor outputting electricity corresponding to a rotation speed of an engine, an electric motordrivable responsive to the electricity from the generator, hydraulic pumpsdrivable by the electric motor, truck-body elevating cylindersfor pivoting a truck bodyin an up-and-down direction, and a stroke detectorfor detecting a stroke of the control apparatus of the truck-body elevating cylinders, and is also provided with a controllerfor performing control of engine rotation speed. The controllerincludes a motor electric-power computing meansfor determining electric power for the electric motor, which corresponds to the stroke detected by the stroke detector, and a discrimination meansfor discriminating whether or not the electricity from the generatorhas become greater than the thus-determined electric power for the electric motor

Hydraulic drive device for dump truck

In a hydraulic drive device for vertical pivoting movement of a load carrying platform, a first directional control valve has only three switchover positions, including a neutral position relating to operation of stopping and holding a load carrying platform, a switching position relating to operation of lifting the load carrying platform, and a switch over position relating to operation of forced lowering of the load carrying platform. A second directional control valve has only three switchover positions, including a neutral position, a switching position, and a switchover position relating to operation of allowing the load carrying platform to fall by its own weight. The device includes a first on-off valve, a second on-off valve, and a third on-off valve that are proportional control solenoid valves for switching an appropriate one of the first and second directional control valves.

Growing community of inventors

Tsuchiura, Japan

Michio Fushiki