Abstract: A fuel consumption saving control device for a work vehicle includes: a vehicle speed detector 11 for detecting whether the vehicle is traveling; an accelerator operation detector 16 for detecting whether an accelerator operating member is not operated; a boom operating lever 23 for detecting whether a command to carry out operation to lift a boom which performs cargo carrying work has been issued; and a controller 8 for carrying out control for increasing a speed reducing ratio of a travel transmission 4 when the vehicle speed detector 11 detects that the vehicle is traveling, the accelerator operation detector 16 detects that the accelerator operating member is not operated, and also the boom operating lever 23 detects that the command to lift the boom has been issued.

Abstract: A pressure-receiving face plate 29 is mounted on one end face of a piston 12, and a support member 26 is raised on the end face of the piston 12. Disposed on the support member 26 with an allowance are, from the pressure-receiving faceplate 29 respectively, a disk spring 27, a plate 25, and a plunger 28. A flange 26a prevents these members from slipping off the support member 26. When the piston 12 approaches a stroke end, the plunger 28 is inserted in an oil passage 20b and applies a cushioning effect to the piston 12. In addition, a gap between the pressure-receiving faceplate 29 and the plate 25 brought into contact with a cylinder bottom 17 becomes narrow, and produces a squeeze effect such that oil escapes from the narrow gap. This makes it possible to provide a hydraulic cylinder that produces a sufficient impact force at the stroke end of the piston and also reduces noise emitted by the impact force, without increasing a length of the hydraulic cylinder.

Abstract: A fuel consumption saving control device for a work vehicle includes: a vehicle speed detector 11 for detecting whether the vehicle is traveling; an accelerator operation detector 16 for detecting whether an accelerator operating member is not operated; a boom operating lever 23 for detecting whether a command to carry out operation to lift a boom which performs cargo carrying work has been issued; and a controller 8 for carrying out control for increasing a speed reducing ratio of a travel transmission 4 when the vehicle speed detector 11 detects that the vehicle is traveling, the accelerator operation detector 16 detects that the accelerator operating member is not operated, and also the boom operating lever 23 detects that the command to lift the boom has been issued.

Abstract: A fluid tank includes a tank main body that contains a fluid and a bubble removing device that is provided inside the main body and removes bubbles in the fluid. The main body includes a partition and a delivery port through which the fluid is fed to outside. The bubble removing device has an outflow port through which the fluid from which the bubbles have been removed flows to the inside of the main body and a bubble exhaust port through which the bubbles which have been removed are discharged to the inside of the main body. The delivery port is provided adjacent to the outflow port relative to the partition. The partition partitions the inside of the main body into a side in which the outflow port and the delivery port are provided and a side of the bubble exhaust port.

Abstract: A control-mode switching device includes: a plurality of actuators (2, 6, 7) that conduct different movement; driving means (10, 11, 12, 13, 14, 15) that drive the actuators; a plurality of control levers (22a-22c) that command operation of the driving means; a plurality of limit switches (72a-72e) that detect arrival of the control levers to the proximity of an end of a control range; a mode judging means (controller 23) that judges whether a priority operation mode is taken or not in accordance with a combination of on/off conditions of the limit switches; and a drive controlling means (controller 23) that, when it is judged by the mode judging means that the priority operation mode is taken, controls the driving means so that an output of selected one or more of the driving means becomes larger than that in a normal mode or the power ratio as compared with the other driving means becomes larger.

Abstract: A pressure-receiving face plate 29 is mounted on one end face of a piston 12, and a support member 26 is raised on the end face of the piston 12. Disposed on the support member 26 with an allowance are, from the pressure-receiving faceplate 29 respectively, a disk spring 27, a plate 25, and a plunger 28. A flange 26a prevents these members from slipping off the support member 26. When the piston 12 approaches a stroke end, the plunger 28 is inserted in an oil passage 20b and applies a cushioning effect to the piston 12. In addition, a gap between the pressure-receiving faceplate 29 and the plate 25 brought into contact with a cylinder bottom 17 becomes narrow, and produces a squeeze effect such that oil escapes from the narrow gap. This makes it possible to provide a hydraulic cylinder that produces a sufficient impact force at the stroke end of the piston and also reduces noise emitted by the impact force, without increasing a length of the hydraulic cylinder.

Abstract: A fluid tank includes a tank main body that contains a fluid and a bubble removing device that is provided to an inside of the tank main body and removes bubbles contained in the fluid. The tank main body includes a partition that partitions the inside of the tank main body to at least two sides and a delivery port through which the fluid is fed to an outside. The bubble removing device has an outflow port through which the fluid from which the bubbles have been removed flows to the inside of the tank main body and a bubble exhaust port through which the bubbles which have been removed are discharged to the inside of the tank main body. The delivery port is provided adjacent to the outflow port relative to the partition. The partition partitions the inside of the tank main body to a side in which the outflow port and the delivery port are provided and a side of the bubble exhaust port.

Abstract: A control-mode switching device includes: a plurality of actuators (2, 6, 7) that conduct different movement; driving means (10, 11, 12, 13, 14, 15) that drive the actuators; a plurality of control levers (22a-22c) that command operation of the driving means; a plurality of limit switches (72a-72e) that detect arrival of the control levers to the proximity of an end of a control range; a mode judging means (controller 23) that judges whether a priority operation mode is taken or not in accordance with a combination of on/off conditions of the limit switches; and a drive controlling means (controller 23) that, when it is judged by the mode judging means that the priority operation mode is taken, controls the driving means so that an output of selected one or more of the driving means becomes larger than that in a normal mode or the power ratio as compared with the other driving means becomes larger.

Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A fluid tank fluid is provided which includes a bubble removing device provided therein to remove bubbles from the fluid. The bubble removing device includes a cyclone chamber for generating a swirling current in the fluid flowing therethrough to separate bubbles from the fluid. At least one outflow port is provided through which the fluid from which the bubbles have been separated flows from the cyclone chamber. And an exhaust port is provided through which the bubbles separated from the fluid are driven from the cyclone chamber.

Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A cylinder driving system capable of reducing the number of hydraulic devices and the amount of energy loss and an energy regenerating method thereof are provided. To this end, the system includes i) a hydraulic cylinder, ii) a hydraulic pump having three suction/discharge ports of a first port for supplying oil to a bottom chamber of the hydraulic cylinder or draining oil from the bottom chamber, a second port for draining oil from a head chamber of the hydraulic cylinder or supplying oil to the head chamber, and a third port for draining oil from a tank or supplying oil to the tank, the suction rate or the discharge rate in the first port being the sum of the respective discharge rates or suction rates in the second port and the third port, and iii) a driving source for driving the hydraulic pump.

Abstract: A hydraulic excavator is equipped with one or more than one downsizing scheme of arranging a bubble removing device for removing bubbles in hydraulic fluid, using a hydraulic tank including a main tank (51) and a variable capacity tank (52) arranged separately from each other and/or fitting the variable capacity tank (52) to the rear surface of the upper cover. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a large hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large service vehicles, it is possible to significantly reduce the cost of the service vehicle.

Abstract: A supporting structure for an operator cab on a body frame of a work machine having a floor frame with a low floor portion and a high floor portion. A vibro-isolating support provided between the low and high floor portions so as to support the operator cab resiliently. At least one of said vibro-isolating supports located at either of the low floor portion having a support axis (M—M) or the high floor portion a having support axis (N—N) inclines longitudinally at a predetermined angle (&thgr;) from a vertical axis toward the center of gravity (G) of the operator cab. Either one of the vibro-isolating supports is located at the low floor portion and the high floor portion having a vertical support axis.

Abstract: A cyclone type bubble removing device 30 is arranged in a hydraulic tank 1. Therefore, it is no longer necessary to secure a space for installing a bubble removing device 30 outside the tank 1 and hence the space dedicated to the hydraulic system can be reduced. Since the bubble removing device 30 is fitted to the inside of the hydraulic tank 1 in advance, it does not need to be installed separately somewhere in the hydraulic circuit so that the installing operation can be performed quickly. Additionally, the outflow ports 322 for causing hydraulic fluid from which bubbles have been removed to flow out and the exhaust port 333 for expelling bubbles are arranged separately so that it is possible to expose the exhaust port 333 to the drain space 127. Thus, if the hydraulic tank 1 is rocked to a large extent, the hydraulic fluid coming out of the outflow ports is not mixed with bubbles and hence bubbles can be eliminated reliably.

Abstract: A cylinder driving system capable of reducing the number of hydraulic devices and the amount of energy loss and an energy regenerating method thereof are provided. To this end, the system includes i) a hydraulic cylinder, ii) a hydraulic pump having three suction/discharge ports of a first port for supplying oil to a bottom chamber of the hydraulic cylinder or draining oil from the bottom chamber, a second port for draining oil from a head chamber of the hydraulic cylinder or supplying oil to the head chamber, and a third port for draining oil from a tank or supplying oil to the tank, the suction rate or the discharge rate in the first port being the sum of the respective discharge rates or suction rates in the second port and the third port, and iii) a driving source for driving the hydraulic pump.

Abstract: Provided is a supporting structure for an operator cab on a body frame of a work machine, having a floor frame, an operator cab being mounted on said floor frame, said floor frame having a low floor portion and a high floor portion spaced longitudinally from each other at a forward location and a rearward location in a side view, and a vibro-isolating support means being provided between said low and high floor portions and said body frame so as to support the operator cab resiliently. At least one of said vibro-isolating support means located at either of the low floor portion having a support axis (M-M) or the high floor portion a having support axis (N-N) inclines longitudinally at a predetermined angle (&thgr;) from a vertical axis toward the center of gravity (G) of the operator cab.

Abstract: The present invention relates to a speed changing device for a hydraulic driving apparatus and a speed change control method thereof, which provide excellent controllability, traveling efficiency, and reliability without occurrence of cavitation. To this end, the device comprises a shifter selected position sensor (63a) for detecting a shift lever change, a motor rotational speed sensor (52) for detecting a rotational speed of a hydraulic motor (50), and a control device (60); and the control device (60) judges and controls either a powering control or a brake control, based on the change of the shift lever selection and on the comparison of the detected motor rotational speed with a memorized motor rotational speed. In addition, a two-stage back pressure valve (23) can be provided between a directional control valve (21) and an oil tank.

Abstract: A method of power transmission in a mechanical/hydraulic type transmission system, by which changeover is smoothly effected between hydraulic power transmission and mechanical power transmission is provided. To this end, there are provided a hydraulic power transmitting means, for transmitting a mechanical power (Pm), which has been converted by a hydraulic motor (42), to the outside (300) by the engagement of a clutch (A), and a mechanical power transmitting means for transmitting a mechanical power (Po) to the outside (300) by the engagement of a clutch (B). Upon changeover from hydraulic power transmission to mechanical power transmission, the releasing of the clutch (A) is performed after the engagement of the clutch (B) is started and before the engagement of the clutch (B) is completed.