Abstract: Disclosed is a lower track for mounting rubber pads on a track shoe to be attachable and detachable after assembling a steel plate which is adhered with divisionally formed rubber pads as a single unit without additionally perforating coupling through-holes in the track shoe when the rubber pad which forms the lower track and the track shoe which is formed of a metal material are coupled. The lower track of a crawler excavator according to the present invention comprises: first and second rubber pads which are divisionally formed; a first steel plate which supports the bottom surface of the first rubber pad by surrounding the same, and has first hooks formed on the bottom surface thereof and coupling holes formed in a connection stepped-portion.

Abstract: The operability when performing a combined arm-crowd and bucket operation can be improved. A hydraulic drive device for a hydraulic excavator includes: a bucket directional control valve and a second arm directional control valve, which are connected in parallel tandem with a first hydraulic pump; a first arm directional control valve that is connected to a second hydraulic pump; and a flow rate restriction device that restricts the flow rate of pressure oil supplied to the second arm directional control valve, during crowd operation of a bucket. This flow rate restriction device includes a variable throttle whose opening is controlled so as to become smaller as a bucket operating device is operated to the crowd side, the variable throttle being provided in a bypass path connecting to the supply port of the second arm directional control valve.

Abstract: In a hydraulic excavator, a hydraulic cylinder drives a boom via a hydraulic fluid discharged from a first hydraulic pump. A first hydraulic circuit connects the first hydraulic pump and the hydraulic cylinder and forms a closed circuit therebetween. A hydraulic motor rotates a revolving upper unit with hydraulic fluid discharged from a second hydraulic pump. A second hydraulic circuit independent from the first hydraulic circuit connects the second hydraulic pump and the hydraulic motor. A motor hydraulic pressure reduction unit reduces the driving hydraulic pressure of the hydraulic motor when a predetermined condition is satisfied. The predetermined condition is a condition in which an operation of the boom operating member to raise the boom and an operation of the rotation operating member to rotate the revolving upper unit are conducted together and an operation amount of the boom operating member is equal to or greater than a predetermined threshold.

Abstract: A rotation prioritizing valve serving as a flow rate control valve of a hydraulic pilot type is provided on the meter-in side of an arm cylinder. At the time of a combined operation of arm pulling and rotation, the rotation prioritizing valve is activated by rotation pilot pressure so that a meter-in flow rate of the arm cylinder is throttled to prioritize rotation movement. On the premise of the above, a switching valve is provided in a pilot line of the rotation prioritizing valve and switched so as to release a throttling effect of the rotation prioritizing valve when boom lowering movement is added to the combined operation of arm pulling and rotation so that a rotation prioritizing function is cancelled.

Abstract: A method of operating a work machine includes moving a work implement via a first actuator having a range of motion, and ameliorating an end of stroke effect on a second actuator if an end of stroke condition of the first actuator is sensed. A work machine includes an electronic controller having software control logic for sensing a stroke condition of an actuator in a work implement system, and for ameliorating an end of stroke effect on a hydraulic actuator of the work implement system if an end of stroke condition of a first actuator is sensed.

Abstract: A preventative stop valve system for a wheeled trailer carrying hydraulic equipment is disclosed comprising a stop valve fitted for insertion in-line into the hydraulic line servicing the trailer equipment; the stop valve comprising a reciprocating piston moveable between open and closed positions. The stop valve is connected to the pressurized air line extending to the air brakes of the trailer. Actuation of the stop valve is controlled pneumatically by the setting and release of the air brakes of the trailer by the operator, utilizing conventional controls for the air brakes. A manual override mechanism is further provided for opening the stop valve manually in the event that the hydraulic equipment carried by the trailer must be utilized when pressurized air line to the trailers is disconnected.

Abstract: A center bypass line (13) and a parallel line (14) are connected to a hydraulic pump (10). The center bypass line (13) is adapted to sequentially feed working fluid to a plurality of throttling selector valves (28),(15),(16),(29). The parallel line (14) is adapted to independently feed working fluid to the throttling selector valves (28),(15),(16),(29). Between the swing selector valve (15) and the arm-dedicated selector valve (16), a supply port of the arm-dedicated selector valve (16) is connected to a supply line (18) and another supply line (19), which branch off respectively from the center bypass line (13) and the parallel line (14), and a swing priority valve (21) is disposed in the supply line (19). Degree of opening-area of the swing priority valve (21) is pilot-controlled by a pressure reducing valve (31), which is designed such that its delivery pressure (P1) is reduced according to increase in remote control pressure that is used to operate the swing selector valve (15).

Abstract: A fluid power interlock system and method for providing same including a circuit having a first valve shiftable between a first and second state having an input and a pair of selectively operable first outputs. One of the first outputs is operatively connectable to a first actuator and the other of the first outputs is operatively connected to a second valve shiftable between a first and second state. The second valve has a pair of selectively operable outputs, one of the second valve outputs is operatively connectable to a second actuator, and the other of the second valve outputs is operatively connected to the first valve and provides a pilot signal thereto for permitting the first valve to shift from a first state to a second state. Shifting state of either of the first and second valves interrupts the pilot signal thereby preventing the non actuated valve from being actuated and shifting state. The system may also include a manifold, wherein the first and second valves are secured to the manifold.

Abstract: A method and apparatus for lifting a work implement attached to a work machine. The method and apparatus includes delivering a lift command to a hydraulic lift circuit, diverting a portion of the lift command to a hydraulic tilt circuit, and responsively tilting the work implement to a rack-back position in cooperation with lifting the work implement.

Abstract: A cut-off valve is mounted so that it can open and close an oil passage which leads a pressure oil discharged from a first pump into a hydraulic oil tank in a neutral state of a spool valve for boom. When an operating lever for boom and an operating lever for arm have simultaneously been operated to a boom raising side and an arm pulling side, respectively, the cut-off valve is closed in proportion to a boom raising or arm pulling pilot pressure. The cut-off valve is controlled using as a parameter a differential pressure between the arm pulling pilot pressure and the boom raising pilot pressure. By doing so, there is obtained a low gain operability in the crane work, while in the parallel pulling work there is obtained an operability of a relatively high gain which matches a quick motion of the arm.

Abstract: A controller 520 has a data portion 520c in which the relationship between a pump delivery pressure and a target opening area of a variable throttle 300a of a control valve 300 is set such that the target opening area is large when the pump delivery pressure is low, and small when the pump delivery pressure is high. An input portion 520a takes in a detection signal from a pump pressure sensor 700, a processing portion 520b reads the data from the data portion 520c and calculates a signal output to a solenoid proportional valve 590, and an output portion 520d converts the calculated signal into a command signal for the solenoid proportional valve 590 and outputs the command signal. Upon receiving the command signal from the controller 520, the solenoid proportional valve 590 produces a command pilot pressure for the control valve 300 corresponding to the input signal and controls the opening area of the variable throttle 300a.

Abstract: A straight travelling apparatus for heavy construction equipment, equipped with a travel supplement circuit, including a variable orifice disposed in a fluid line connected to the supply-side of the control valve of a bucket and controlled to vary an opening degree thereof by a predetermined pilot signal that is applied to the variable orifice in response to an operation of at least one of right and left travel motors in order to keep the variable orifice at a relatively closed state while being released in response to the travel motors not operating in order to keep the variable orifice in a relatively opened state, thereby capable of supplementing a sufficient amount of fluid to a travelling system when the bucket is operated during, thereby preventing an abrupt reduction in travelling speed caused by operatings the straight travelling apparatus.

Abstract: A control system is provided for a hydraulic circuit having first and second hydraulic valves, a valve spool position sensor, and first and second input devices for producing first and second operation signals. A controller receives a signal from the valve spool position sensor and the second operation signal and responsively modifies the value of the second operation signal in response to the valve spool position signal.

Abstract: The present invention provides an apparatus for controllably actuating a work implement. The work implement includes at least a first linkage and a second linkage. The apparatus produces a control signal, senses the position and velocity of the first and second linkages and responsively produces position and velocity signals. The apparatus responsively produces a command signal as a function of the control signal and the position and velocity signals. The command signal controls actuation of the first linkage such that dynamic coupling between the first and second linkages is minimized.

Abstract: A hydraulic system includes a hydraulic pump which provides pressurized fluid at an output port as a function of pressure in a load sensing port, a hydraulic reservoir, and a load pressure sensing line connected to the load sensing port. A solenoid operated implement control valve controls fluid communication to and from a hydraulic function such as a cylinder. A supply control valve has a first position wherein the reservoir is communicated with the load sensing port and a second position wherein the pump output port is communicated with the load sensing port. A spring urges the valve member to its first position, and a solenoid is energizable to move the valve member to its second position. The solenoid is energized when the implement control valve is activated so that the supply control valve communicates pump pressure to the load sensing port and the pump will operate at full capacity whenever the second hydraulic function is operated.

Abstract: A loading vehicle has a boom pivotally mounted thereon for movement in a vertical plane, the boom supporting a loading unit at its distal end. A fluid control system includes a boom cylinder for raising and lowering the boom, a loading unit cylinder for tilting the loading unit relative to the boom, a tank for holding fluid and a pump for selectively pumping fluid to the cylinders through manually controlled selector valves. The loading unit attitude is controlled by a system including a bypass valve, a flow splitting valve and a boom position detector for actuating the bypass valve. Fluid forced from a lowering chamber of the boom cylinder as the boom is raised is applied to the bypass valve. As long as the boom is in a position falling within a lower range of positions the boom position detector does not actuate the bypass valve and all fluid from the lowering chamber is diverted to the tank.

Abstract: A reliable pilot valve assembly having a control lever is produced at low cost while installed without requiring any additional switch and wiring and piping work. The assembly has a main valve body (1). A spool (27) is slidably mounted in the body (1) so as to be movable between a first and a second position. The spool (27) permits the pressure oil to circulate in a forward direction through a pair of the outlet ports and a pair of main outlet ports of the assembly when the spool (1) stays in the first position, and permits the pressure oil to circulate in a reverse direction (opposite to the forward one) through the pair of the outlet ports and the pair of the main outlet ports when the spool (1) stays in the second position, the main outlet ports being connected with a hydraulic circuit.

Abstract: A system for automatically controlling the actuators of a construction vehicle. The system comprises electronic controller, an automatic selecting switch for selecting automatic control for actuators, as requested, control levers for being manipulated by an operator in order to instruct the controller of desired operations of the actuators, and positional sensors for sensing respective positions of the actuators and outputtng signals corresponding to the positions of the actuators to the controller. In the system, the actuators during performing repeated operations are such automatically controlled that they are controlled during a first operation by the operator's manipulations for the control levers, thereafter, during each sequential operation, they are automatically controlled by the controller on the basis of electric control currents having been automatically calculated by virtue of a displacement ratio between the actuators during a just previous operation.

Abstract: A hydraulic control valve which is equipped with two direction change-over valve groups individually having traveling change-over valves, and first and second hydraulic pumps corresponding to those direction change-over valve groups. The traveling section valve of one of the change-over groups is equipped with a communication valve. Each section valve has its valve body formed therethrough with signal conduits individually extending perpendicular to spool bores. The two traveling section valves are formed with annular grooves in spool bores positioned to correspond to said signal conduits. The individual working machine section valves other than the traveling section valves are formed with annular grooves in the spool portions corresponding to the signal conduits to provide the communications between the upstreams and downstreams of the signal conduits only when the spools are in their neutral states.

Abstract: A control system having a flow-dividing selector valve mechanism (52) for changing the channels for causing a pressure fluid to flow from two main pumps (40), (50) into two control valve groups (60), (70) therethrough, and confluent selector valve mechanisms (80), (90) for causing the pressure fluid flowing into each group to flow into a working device control valve of the other group. The confluent selector valve mechanism (80) of the group wherein the working device control valve (62) has a need to compensate for the flow of fluid thereinto cancels the confluence function. The system has a mechanism for restricting the stroke of the spool of a working device control valve (160) to be subjected to varying loads to cause the fluid discharged from the actuator connected thereto to flow into the actuator again when the load is small. A sequence valve (170) operates the spool stroke restricting mechanism (190) by a pilot primary pressure.

Abstract: Load sensing hydraulic systems conserve energy by generating only the fluid flow demanded by the system and at a pressure only slightly greater than the highest load pressure of the system. Optimizing the operating characteristics of the system for certain applications also caused the variable displacement pump to go to its maximum displacement setting with the excess fluid generated thereby not doing any useful work. The load sensing hydraulic system includes a flow control valve connected to a directional control valve and has an operating position in which fluid exhausted from a hydraulic jack is transmitted therethrough to a tank. A signal valve is disposed in a control pressure signal line for controlling fluid flow therethrough from a supply conduit to one end of the flow control valve. When the signal valve is blocking fluid flow through the signal line, the flow control valve is in the above-noted operating position.

Abstract: An electronic bucket positioning and control system for a vehicle of the type including a hydraulically controlled boom assembly and bucket. The bucket positioning and control system can operate in a bucket positioning mode, bucket return to position mode, bucket anti-rollback mode, and tilt cushion mode.

Abstract: The present invention relates to, in combination, a vehicle utilizing a first hydraulic cylinder to operate lifting means and a second hydraulic cylinder to operate end effector means, each of the cylinders including a piston, the pistons when moved toward their "up" sides causing the lifting means and end defector means to move in a first direction and when moved toward their "down" sides causing the lifting means and means to move in a second direction, and a load self-leveling system for the vehicle, the system comprising a pair of fluid flow dividers interposed in flow lines between a source of hydraulic fluid under pressure and the first and second hydraulic cylinders, the flow dividers being structured to direct a greater flow of hydraulic fluid to the first cylinder and a lesser flow to the second cylinder, each of the flow dividers comprising adjustable spool valve means located in flow passages between the source of hydraulic fluid and the first and second hydraulic cylinders.

Abstract: A hydraulic drive system for a construction machine in which a hydraulic circuit has at least one hydraulic pump, at least first and second hydraulic actuators driven by a hydraulic fluid discharged from the pump, and at least first and second directional control valves connected to the pump in parallel with each other for controlling flows of hydraulic fluid supplied from the pump to the first and second actuators, respectively, and a control unit is responsive to first and second operation signals for driving the first and second actuators, respectively, to produce first and second control signals for actuating the first and second valves and deliver such control signals thereto, respectively, each of the first and second valves having a degree of opening changed in accordance with a level of the corresponding one of the first and second control signals for controlling a flow rate of hydraulic fluid supplied to the corresponding one of the first and second actuators.

Abstract: A fluid powered actuator system includes two identical fluid powered actuators operable by respective supply pressures which are controlled by respective identical valve arrangements. Operating positions of flow control elements of the valve arrangements are applied through respective couplings to a differential arrangement which operates, if these positions differ by an unacceptable amount, to apply an error indication through respective coupling to prevent the supply pressures from being applied to the respective actuators.

Abstract: An automatic, hydraulically actuated, sequencing valve for use with a pair of hydraulic acutators (e.g. double acting hydraulic cylinders) includes a valve body having a cylindrical bore therein. Cam members at either end of the bore are engaged by pins on the ends of a cylindrical spool, thereby rotating the spool 30.degree. each time it engages one of the cam members. A third cam member incorporated into the spool alternately locks open one of a pair of check valves as said spool is pressure shifted between the two bore cam members. The third cam member operates a locking system which permits only one of the two hydraulic cylinders to operate at a time and in sequence.

Abstract: A pneumatically actuated tool for setting blind rivets of the type having a body, a head and breakaway pull mandrel. The tool comprises a body having a double-acting cylinder therein, a handle attached to the body, a guide body affixed to the body beneath the cylinder, a pull track in the guide body for the rivets and a bore in the body connecting the cylinder and the pull track, the cylinder, the bore, and the pull track being coaxial. The tool is provided with a rivet pickup and pull mechanism comprising a lower load piston having a downwardly depending tubular assembly slidable within the body bore and pull track and terminating in a nose piece, and an upper pull piston having a downwardly depending tubular assembly telescopicly and shiftably located within the lower load piston tubular assembly and terminating in a chuck provided with mandrel-engaging jaws. The tool has a magazine connected to the guide body and containing a strip of rivets.

Abstract: Control systems are required to selectively control fluid actuated devices, such as clutches, in a transmission. In order to reduce shock loads on the internal elements of the transmission, it is necessary to ensure that only one clutch can be engaged at one time and that no major speed changes or change in direction is allowed. The present invention provides an interlocking arrangement that operates to control a source of pressurized fluid to a plurality of valve mechanism and a plurality of signal control devices. The operation of one of the plurality of valve mechanisms interrupts the flow of fluid to other ones of the plurality of valve mechanisms and to ones of the signal control devices. With this subject arrangement, the shock loads to the transmission are substantially reduced.

Abstract: A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path from the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow returning to the control valve downstream of the boom valve along with the return flow from the rod end of the bucket cylinder which is also returned to the control valve downstream of the boom valve whereby the bucket valve can be separately actuated concurrent with the boom valve and supplied with oil so as to override the self-leveling function if desired.

Abstract: A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path of the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow connected to one of the boom valve motor ports. An improved boom lower circuit which bypasses the flow divider valve as the boom is lowered to achieve a faster boom lower rate and the inclusion of an unloading valve in the bucket circuit which includes the dual function of preventing cavitation and relieving high pressure.

Abstract: A control valve for controlling the distribution of pumped hydrodynamic fluid to the trailer brakes of a tractor and trailer combination in response to hydrostatic pressure applied from the tractor braking system has an inlet for pumped fluid, a spool valve operable in response to a control piston to control the flow of pumped fluid to a first working trailer braking circuit through an outlet and to a tank, or reservoir, through an outlet, a flow control valve which provides a passageway communicating with a first flow path for pumped fluid to the spool valve and which is operable in response to pumped fluid pressure to control the flow of pumped fluid to a second working implement circuit through an outlet, and a second flow path for pumped fluid extending between the inlet and spool valve independent from and parallel with the first flow path, so that the spool valve controls the flow of pumped fluid through the second flow path to the fluid outlet leading to the trailer braking circuit.

Abstract: An electrohydraulic control system which includes first and second electrically controlled fully variable hydraulic pumps adapted to be driven by the vehicle engine. In the specific embodiment of the invention herein disclosed, the first pump is coupled to the steering and braking control valves, and the second pump is coupled to the bucket and hoist control valves. An electrically controlled poppet valve selectively interconnects the respective pump outputs. Operator-responsive controllers, namely a bucket/hoist joy-stick controller, a vehicle propulsion controller and a steering controller, provide associated electrical signals as respective functions of operator demand. Electrically operated valves control application of hydraulic fluid to the bucket and hoist drive mechanisms, and pressure and position sensors are connected to such valves and actuating mechanisms.

Abstract: A quick changeover hydraulic circuit for use in an auger drive mode or percussion hammer mode, controllable in each mode by the same flow regulator. The circuit comprises a first branch circuit which powers a first auxiliary hydraulic powered device and a hydraulic motor for drill steel rotation. A second branch circuit powers a hydraulic percussion motor for a drill steel hammer or a rotary hydraulic motor for an auger, only one of which is in the circuit at one time. An interbranch circuit comprises a priority flow divider which distributes flow. In a first mode with the percussion motor for the drill steel hammer connected into the second branch the flow is delivered to the steel rotation motor and the first auxiliary device. In a second mode with the auger motor connected into the second branch, combined flow from both branches is delivered to the auger motor.

Abstract: An electric hydraulic control device for controlling hydraulic cylinders of work tools in a construction vehicle, in which control valves of the hydraulic cylinders are controlled in two ways. For some work tools which need not be controlled smoothly and finely, the corresponding control valves are controlled directly by an electric signal outputted according to the position of the operation levers, and for other work tools which must be controlled smoothly and finely, the corresponding control valves are controlled through an electric servo mechanism which is operated by an electric signal representative of the amount by which the operation lever is manipulated. In addition, there is provided a detector for detecting as to whether the transmission lever is in the locked condition, and electric systems of all of the control valves are rendered inoperative when the transmission lever is in the locked condition.

Abstract: A sequencing valve utilized with a tractor-propelled planter having two row arms which pivot downward to the ground in an alternating sequence as the planter changes directions in the field. The sequencing valve is connected with the conventional hydraulic system which raises and lowers the planter at the end of each row so as to automatically lower alternate marker arms. This is achieved by pressurizing opposite ends of the sequencing valve spool for longitudinal movement through a cam means, causing the spool to rotate during movement in one direction whereby alternating lowering of the planter arms is achieved each time the planter is hydraulically lowered to the ground.

Abstract: A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path from the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow connected to one of the boom valve motor ports whereby the bucket valve can be separately actuated concurrent with the boom valve and supplied with oil so as to override the self-leveling function if desired.

Abstract: There is disclosed a hydraulic brake booster comprising a valve spool providing for alternate connection of a booster chamber with a source of pressure-transmitting fluid and an unpressurized return reservoir. The source of pressure-transmitting fluid is a pump-circulated fluid adapted to be throttled by a mechanically actuatable throttle valve arranged coaxially with the valve spool. Since the throttle valve is actuated independently of the pressure in the booster chamber, the need to produce a supply pressure when the brake is not actuated is eliminated. The pump is subjected to load only during the relatively short period of brake activation.