Yanmar Co., Ltd.

Yanmar Diesel Engine Co., Ltd.

Kunihiko Sakamoto

Nagahiro Ogata

Masaaki Yamashita

Makiko Tajima

Hiroaki Ayabe

Yousuke Yamashita

Seiji Sakada

Yukio Kubota

Kouichi Takata

Shuji Shiozaki

Hisanori Mori

Junichi Hitachi

Hiroshi Matsuyama

Takeshi Oouchida

Hayato Tsuji

Syoubu Aramaki

Yasuhiko Hori

Yasuo Tokieda

Riki Fujita

A hydraulic apparatus for a hydraulic work vehicle capable of supplying pressure oil to any of a bucket cylinder, an arm cylinder, a boom cylinder, a swing cylinder, a blade cylinder, a turning hydraulic motor, a left traveling hydraulic motor, a right traveling hydraulic motor, and a PTO hydraulic motor by a first hydraulic pump, a second hydraulic pump, or a third hydraulic pump. The pressure oil can be branched off from a discharge oil passage of the third hydraulic pump and supplied through an external pipe to a downstream side of a load check valve disposed on an oil passage communicating with a pump port of a PTO control valve for switching supply of pressure oil from the second hydraulic pump to an external hydraulic work machine.

Hydraulic apparatus

A working vehicle provided with a fixed-capacity hydraulic pump driven by power from an engine and a working hydraulic actuator driven by working oil pumped from the fixed-capacity hydraulic pump is a rotary working vehicle which is provided with an electromagnetic relief valve for modifying the pressure of working oil from the fixed-capacity hydraulic pump, and the rotary working vehicle is such that if the actual number of revolutions (N) of the engine is reduced by a set number of revolutions (Ns) as the load on the engine increases, then the electromagnetic relief valve operates in accordance with the deviation (e) between the actual number of revolutions (N) of the engine and the specified number of revolutions (Ns), and the pressure of the working oil from the fixed-capacity hydraulic pump is modified.

Engine overload prevention using a speed differential operated relief valve

A working vehicle, wherein flows of hydraulic oil delivered under pressure from two or more hydraulic pumps are joined together and the joined hydraulic oil can be taken out. A working vehicle is provided with two hydraulic pumps independent of each other and adapted to deliver hydraulic oil under pressure, a mode switching valve () capable of being switched to a flow joining position (K) at which flows of the hydraulic oil delivered under pressure by the two hydraulic pumps are joined together, PTO ports () out of which the hydraulic oil is taken, and a PTO switching valve () provided downstream of the mode switching valve () and switching flow of the hydraulic oil so that the oil can be delivered under pressure to the PTO ports ().

Hydraulic circuit for working machine

A selector valve operating mechanism is provided with operating pistons which are hydraulic pistons connected through an operation link to a spool of a PTO selector valve, an solenoid valve for hydraulically controlling reciprocation of the operating pistons, and a controller which is a control device for transmitting an operation signal to the solenoid valve. Control of operation of the solenoid valve moves the spool through the operating pistons and the operation link to switch the PTO selector valve.

Selector valve operating mechanism for working vehicle

In the conventional connection and fixture part between a working vehicle and an excavator, a connection pin is made to contact a guide plate to be fixed in position, thereby requiring a high rigidity of the guide plate, accuracy of recreation of positioning of the connection pin, and high cost for manufacturing the guide plate. Thus, a guide plate of a connection portion has a chevron-shaped introduction part including two sector curves. A U-shaped bent member serving as a knob is provided on a rear side surface of a connection pin in the axial direction of the connection pin, so that the proper position of the inserted connection pin is defined as the position thereof when tips of the knob come into contact with the insertion-target member.

Fixing structure of work machine

It is an object, in a hydraulic stepless transmission, to change capacity of a hydraulic pump to thereby make output characteristic different between forward and reverse travel and obtain efficient output characteristics. In the hydraulic stepless transmission formed of the hydraulic pumpand a variable displacement-type hydraulic motorand including control meansfor carrying out capacity control based on a load received by the hydraulic stepless transmission, a pressure control valveis connected to control pressure portions of the control meansfor carrying out the capacity control according to pressure in a hydraulic circuiton a discharge side of the hydraulic pumpto carry out the capacity control of the variable pump and the motor

Hydraulic stepless transmission

The purpose of the invention is to simplify the linkage mechanism of a shift operating device and to unitize the shift operating device so as to improve the reliability of assemble accuracy. A forward traveling pedal and a rearward traveling pedal are rotatably supported by a installation plate; the installation plate rotatably supports a shift operating rotary sleeve connected through one link to the basal end of the forward traveling pedal (a forward traveling pedal rotary sleeve) and connected through one link to the basal end of the rearward traveling pedal (a rearward traveling pedal rotary sleeve); the forward traveling pedal, the rearward traveling pedal, the shift operating rotary sleeve and the installation plate are constructed as an integral unit; and the shift operating rotary sleeve is rotated forward and rearward interlockingly with the operation of the forward traveling pedal and the rearward traveling pedal so as to slant swash plates of a hydraulic pump and a hydraulic motor of a HST.

Shift operating device for traveling vehicle

Rigidity of a frame of a working vehicle is improved by a simple structure and production costs are reduced by reducing the number of parts of a working vehicle. Pipesare provided on both left and right sides at the center in the front-rear direction of a side frame, and each pipehas a rectangular cross-section and penetrates an intermediate partition in the front-rear direction from a mast sectionup to a transmission section. Tie-down holes are formed in a front face plateto which the front end of a frameis connected, and a plateconnected to a side frameis provided at the bottom surface of each mast sectionprotruding outward from the side frame. Tanks installed on the working vehicle are suspended from the plate bodies, and a lift arm installation boss provided at each mast sectionis supported at both ends. A U-shaped reinforcement memberconnects the upper surface of mast partition plate of a mast sectionand left and right bosses.

Frame structure for working vehicle

It is an object to accurately control swash plate angles of movable swash plates of a hydraulic pump and/or a hydraulic motor. In a hydraulic stepless speed changing device, a hydraulic pump and/or a hydraulic motor, at least one of which is of a variable displacement type, and a hydraulic servo mechanism for controlling swash plate angles of movable swash plates of the hydraulic pump and/or the hydraulic motor are integrated and the movable swash plates are tilted thorough operation of a speed change operation lever. Load control mechanisms are formed by integrally providing actuators having a cylinder, a spool, and the like for sliding speed change drive members to the speed reduction side, the speed change drive members tilting the movable swash plates of the hydraulic servo mechanism. The load control mechanisms are actuated by pressurized oil led from a main oil path of a closed circuit formed by connecting the hydraulic pump and the hydraulic motor to the actuators.

Hydraulic stepless speed changing device

Production of a working vehicle frame consumes high costs because it requires high rigidity. A simple construction improves the rigidity of the frame and reduces costs required for the production. In a structure of a frame () for a working vehicle (), side sections of the frame () are constructed in a boat form, and, in a front view, the width of a lower section of the frame () is set smaller than that of the central section in the vertical direction of the frame (). Further, a mast plate () for supporting a front loader () and a front axle installation plate section () are integrated, and side frames () constructing the side section of the frame () and the mast plate () are jointed in a lateral T shape in a side view.

An object of the invention is to change a layout structure of a hydraulic continuously variable transmission apparatus (HST) particularly constituting a hydromechanical continuously variable transmission apparatus (HMT) as a continuously variable transmission apparatus, thereby achieving a simplification of structures of a working vehicle and a traveling drive system, and an easiness of a maintenance. In a working vehicle provided with an HMT structured such as to combine an HST and a planetary gear mechanism as the traveling drive system so as to output and rotate a power of an engine while shifting gear, the HST is provided with a hydraulic pump and a hydraulic motor integrally in a front wall of a transmission case, and is arranged in an upper side of a transmission shaft transmitting the power to the transmission case from the engine.

Working vehicle

Tractor

A hydraulic continuously variable transmission has a variable displacement type first hydraulic system having a first plunger and a plunger abutting section which actuates the first plunger, and a second hydraulic system having a second plunger and provided with an output rotary section which rotates with abutment on the second plunger. A cylinder block rotates about an axis and has a first plunger hole and a second plunger hole which respectively retain the first and second plungers. A hydraulic closing circuit connects the first and second plunger holes and circulates a working oil between the first and second plunger holes. The continuously variable transmission has a distributing valve for controlling circulation of the working oil in the hydraulic closing circuit, a valve hole, formed in the cylinder block, for retaining the distributing valve, and a shaft which penetrates the cylinder block. The shaft and the cylinder block rotate synchronously and the output rotary section is rotatably supported around the shaft. The valve hole is formed in parallel to the shaft, and restriction means is arranged inclined with respect to the shaft and rotates in synchronism with the cylinder block to reciprocate the distributing valve with the distributing valve being restricted.

Hydraulic continuously variable transmission and power transmission apparatus

In a configuration comprising a hydraulic servo mechanism ( ) having a spool ( ) as a hydraulic valve for controlling the swash plate angle disposed within a body housing ( ) of a hydraulic continuously variable transmission ( or ), and a manual operation member ( ) for operating the hydraulic servo mechanism disposed outside of the body housing, a casing ( ) is provided between the manual operation member and the body housing, a neutral position holding mechanism ( ) for holding the neutral position of a movable swash plate and a rotation control mechanism ( ) for controlling the maximum rotating angle of the movable swash plate are installed in the casing, and further an over-stroke absorbing mechanism ( ) for absorbing the over-stroke of the manual operation member is installed in an area ranging from the inside of the casing to the inside of the body housing, and moreover a spool operating member ( ) moving by operation of the manual operation member is disposed movably almost integrally with the spool.

Growing community of inventors

Chikugo, Japan

Kunihiko Sakamoto