JP4109661B2 - Multiple HST - Google Patents

Description

  The present invention is used in agricultural machinery and construction machines that use both a hydraulic steering device and a traveling transmission, and is configured for the purpose of facilitating attachment / detachment work and simplifying the hydraulic system. It relates to continuous HST.

Conventionally, for example, in a traveling vehicle that uses HST for traveling (for forward / reverse switching and traveling shifting) and for steering (for turning corners), as shown in FIG. Separate single HSTs were prepared, and pumps were input in parallel to each HST from the engine (engine). 42, P1 is a driving HST pump, M1 is a motor, P2 is a steering HST pump, M2 is a motor, g1 and g2 are reduction gears, G is a forward / reverse switching gear mechanism, MA Is the center axle, LA is the left axle, and RA is the right axle. The description of each member will be made in detail in the explanation of FIG. Further, the oil return structure in the unitary HST is disclosed in Japanese Utility Model Laid-Open Nos. 60-89454, 60-162767, and 60-182557.
Japanese Utility Model Publication No. 60-89454 Japanese Utility Model Publication No. 60-162767 Japanese Utility Model Publication No. 60-182557

  However, when a plurality of HSTs are used for a plurality of applications, in the conventional method of using a plurality of single HSTs, an input mechanism from an engine, a charge pump, or a piping is separately used for each HST. A port block or the like must be provided, and the oil return structure is conventionally disclosed only for a single HST, which must be provided separately for each HST, and the structure is complicated. In addition, the number of parts is increased, the cost is increased, the installation space needs to be widened, and the attaching / detaching work becomes complicated.

The present invention uses the following means in order to solve the above problems. In claim 1, a multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing a single port block, the pump of the first HST being provided on one surface of the port block The second HST pump is arranged in parallel, the first HST motor and the second HST motor are arranged in parallel on the other surface of the port block, and the first HST motor and the second HST pump Are arranged in series with a port block therebetween, and the motor shaft of the first HST and the pump shaft of the second HST are directly connected.

In claim 2, a multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing one port block, wherein the port block is configured in an inverted T-shape when viewed from the front. the both pumps of the first and second HST, as both the pump shaft is horizontal direction, as well as arranged in series or in parallel to the vertical portion of the port block, of the front view inverted T-shaped port block A housing that supports the motor shafts of both the first and second HST motors in a vertical direction on the bottom surface of the horizontal portion and that has both motors arranged in a parallel manner on the left and right sides is fixed. .

  In a multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing a single port block, the first and second HST pumps are connected to each other on one side of the port block. The second HST motors and both motors and pumps are arranged in parallel, and both pump shafts are gear-engaged.

  In all the multiple HSTs described above, the first HST and the second HST share one port block, so there is no need to provide a separate port block for each HST, and the piping is also in one place. Concentrated.

  The first and second HST pumps are arranged in series across the port block, both pump shafts are directly connected, and the first and second HST motors are arranged in parallel on one side of the port block. In the multiple HST in which both motors are arranged in parallel to both pumps, the second HST pump shaft is linked to the driving of the first HST pump shaft, and the input mechanism in the second HST Is no longer necessary.

  In the multiple HST having this configuration, the coupling of the pump shaft is usually performed by using a coupling member. However, the driving reliability of the pump shaft of the second HST on the lower side through such a member is as follows. It is inferior to the pump shaft of the first HST on the input upper side. Therefore, when this multiple HST is used for traveling (forward / reverse switching and traveling speed change) and steering, it is effective to set the first HST as a frequent traveling HST in consideration of the frequency of use. It is. In addition, one pump and two motors (for example, the first HST motor and the second HST pump and motor) to be disposed on the same surface of the port block are integrated in one housing, Easy to attach and detach, and compact.

  Also, on one side of the port block, the first and second HST pumps, the first and second HST motors, and both the motor and both pumps are arranged in parallel. In the multiple HST with the gear meshing configuration, the direct connection space between the two pump shafts by the coupling member or the like in the port block is not required as compared with the multiple HST having the above configuration. Can be made thin, leading to weight reduction.

  Also, the first HST pump and motor are arranged in parallel on one side of the port block, the second HST pump and motor are arranged in parallel on the other side of the port block, and the first HST motor and second HST are arranged in parallel. In a multiple HST system in which the pumps are arranged in series and the first HST motor shaft and the second HST pump shaft are directly connected, the second HST pump shaft drives the first HST motor shaft. Therefore, if the first HST is used for traveling and the second HST is used for steering, the turning reaction speed is proportional to the traveling speed, and the same turning radius can be obtained regardless of the displacement of the vehicle speed. It is done.

  Further, both the first and second HST pumps are arranged in series or in parallel with the port block so that both pump shafts are in the horizontal direction, and both the first and second HST motors are provided on the bottom of the port block. In a multiple HST with a configuration in which both motor shafts are arranged in a vertical direction, both parallel pumps are attached to the upper surface of the transmission case with the upper end of the transmission case as a horizontal plane. The shaft can be inserted into the transmission case in the vertical direction, and the multiple HST with the above configuration is attached to the side of the transmission case because the motor shaft is in the horizontal direction. Compared to the configuration in which the shaft is horizontally inserted, the strength is superior.

  Also, in a multiple HST having a structure in which a housing divided into several parts is attached to a port block, an oil return port is provided in one housing, and an oil passage communicating from this housing to another housing is formed in the port block. By installing, the return oil from all the pumps and all the motors of both HSTs can be extracted collectively from one oil return port.

  In addition, the charge pump is mounted so as to be driven by a pump shaft that is always driven as long as the engine power is driven. The hydraulic oil is mounted on the end of one pump shaft and discharged from the charge pump. Is supplied to each of the first and second HSTs via the port block, so that the hydraulic oil can be supplied to all the HST pumps and motors in a single operation with a single charge pump.

Since the present invention is configured as described above, the following effects can be obtained.
As described in claim 1, a multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing one port block, wherein the first HST The pump and the second HST pump are arranged in parallel, the first HST motor and the second HST motor are arranged in parallel on the other surface of the port block, and the first HST motor and the second HST motor are arranged in parallel. Since the pump is arranged in series with the port block in between, the motor shaft of the first HST and the pump shaft of the second HST are directly connected. Since the driving force for both the first and second HSTs is input in a lump, the input mechanism is simplified, resulting in ease of attachment and detachment and a reduction in installation space.
In addition, since the first HST and the second HST share one port block, the number of members can be reduced compared to preparing a port block separately, and the oil passages can be provided in a concentrated manner. Is reduced, and the hydraulic piping is concentrated in one place and can be reduced.
Then, when the multiple HST having such a configuration is used as, for example, a hydraulic transmission type steering device, the forward / reverse switching and traveling speed change and the steering (interlining turning) of agricultural machinery, construction machinery, etc. are hydraulically performed. In addition to having the effect of greatly improving the utility value of the traveling vehicle having the configuration to be performed, the port block can be made thin, and light weight and space saving can be realized.

  Further, since the pump shaft of the second HST is driven by the drive of the motor shaft of the first HST, if a hydraulic transmission type steering device is applied in which the first HST is used for traveling and the second HST is used for steering. The rotation speed of the motor shaft of the second HST, that is, the turning speed is proportional to the traveling speed proportional to the driving speed of the first HST motor shaft, so that the vehicle turns slowly at a low traveling speed and rapidly at a high traveling speed. As a result, the turning radius becomes constant regardless of the traveling speed, and normally a hydraulic transmission type steering device for turning the interlining can be used as a steering device based on the steering feeling of an ordinary passenger car. Further, since the pump shaft of the second HST is not driven when traveling is stopped, there is no risk of turning in an unexpected situation.

A multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing one port block, wherein the port block has a reverse T-shape when viewed from the front. configured, both the pump of the first and second HST, as both the pump shaft is horizontal direction, as well as arranged in series or in parallel to the vertical portion of the port block, the front view inverted T-shaped port By fixing the motor shafts of both the first and second HST motors in the vertical direction on the bottom surface of the horizontal part of the block, and by fixing the housing in which both motors are installed in parallel in the left-right direction The upper end of the transmission case has a horizontal surface, the bottom surface of the motor arranged in parallel is attached to the upper surface, and the motor shaft is inserted into the transmission case in the vertical direction, so that the transmission case is Compared to a configuration in which a motor is mounted on the side of the chassis and the motor shaft is inserted horizontally, the mounting strength of both the multiple HST and the transmission case is increased, and the lateral width of the transmission case can be reduced. Space saving and cost reduction can be realized.

The invention is illustrated by means of examples based on the attached drawings. FIG. 1 is a skeleton diagram when the multiple HST is applied to a hydraulic transmission type steering apparatus, FIG. 2 is an enlarged view of FIG. 1 showing an internal configuration of a forward / reverse switching gear mechanism G, and FIG. 3 is pumps P1 and P2. FIG. 4 is a right side view, FIG. 5 is a left side view of the port block PB1, and FIG. 5 is a right side view of the multiple block HST, which is a structural example of a direct connection type multiple HST. 6 is a right side view, and FIG. 7 is a cross-sectional view taken along the line XX.

8 is also a YY sectional view, FIG. 9 is also a plan view, FIG. 10 is also a bottom view, FIG. 11 is also a ZZ sectional view, FIG. 12 is a front view, and FIG. 14 is a front cross-sectional view showing a mounting configuration of a multiple HST comprising housings H1, H4, and H5, which is an example of the configuration of the pumps P1 and P2 directly connected multiple HST, and FIG. Front sectional view of the continuous HST, FIG. 16 is also a right side view.

17 is a plan sectional view, FIG. 18 is a left side view of the port block PB2, FIG. 19 is a right side view, FIG. 20 is a sectional view taken along line X′-X ′, and FIG. FIG. 22 is a front view, FIG. 23 is a plan view, and FIG. 24 is a front sectional view of a multiple HST composed of housings H1 and H6, which is an example of the configuration of the multiple HSTs connected directly to the pumps P1 and P2. is there.

FIG. 25 is a right side view, FIG. 26 is a front sectional view showing the arrangement of pumps P1 and motors M1 of a parallel type HST of pumps P1 and P2, and FIG. 27 is the arrangement of pumps P2 and motors M2. 28 is also a left side view, FIG. 29 is also a partial plan view of the plane, and FIG. 30 is a front sectional view of a multiple HST of the motor M1 / pump P2 interlocking type which is an embodiment . Is a left side view, and FIG. 32 is a right side view.

  FIG. 33 is a front sectional view of a pump P1 and P2 series-type multiple HST which is an embodiment of the pump-motor / orthogonal-type multiple-type HST, FIG. 34 is a left side view, and FIG. 35 is a pump shaft. FIG. 2 is a front sectional view showing a mounting structure of a pump P1 and P2 parallel type multiple HST, which is an embodiment of a motor axis orthogonal type multiple HST, to a transmission case TM.

  36 is a front sectional view of a multiple HST, FIG. 37 is also a partial plan view of the plane, FIG. 38 is a left side view of the same, and FIG. 39 is an embodiment of a multiple HST of the pump shaft / motor axis orthogonal type. FIG. 40 is a plan sectional view of the same, and FIG. 41 is a left side view thereof.

First, a schematic configuration of a drive system based on the multiple HST will be described with reference to FIG. The multiple HST is configured by combining the first HST composed of the pump P1 and the motor M1 and the second HST composed of the pump P2 and the motor M2. In this configuration example, the first HST is used for traveling. A configuration example is disclosed in which the second HST is applied to the steering HST and the multiple HST is incorporated in the hydraulic transmission steering device. The hydraulic transmission type steering device having this multiple HST is employed in a construction machine (for example, a backhoe) or an agricultural machine (for example, a combine) having a crawler traveling device that requires turning of an interlining.

  The output shaft of the engine (engine) is inserted into the driving HST pump P1 on the input side, drives the pump shaft of the pump P1, and the driving HST motor M1 is driven based on the driving of the pump shaft. The output shaft of the motor M1 is transmitted to the central axle MA through the meshing of the reduction gears g1 and g2, and the rotational drive of the central axle MA projects to the left and right via the forward / reverse switching gear mechanism G. It is transmitted to the left and right axles LA and RA. 2, ring gears 39 are fixed to both ends of the central axle MA, and two planetary gears 40 and 40 are meshed with the gear portions inside the ring gears 39 so that one ring gear 39 is engaged. A sun gear 41 is interposed between the two planetary gears 40 and 40. Further, the inner ends of the left and right axles LA and RA are fixed to a connecting member 42 formed by connecting the shafts loosely fitted to the centers of the two planetary gears 40 and 40 in each ring gear 39. The left and right axles LA and RA are loosely fitted in the center of each sun gear 41 and protrude left and right. By such a gear mechanism, the left and right ring gears 39 and 39 rotate together with the central axle MA that is driven by the output shaft of the motor M1 to rotate, whereby two planetary gears 40 in each ring gear 39 are rotated.・ 40 revolves around the sun gear 41 without moving the sun gear 41, the revolving drive rotates the connecting member 42, and the left and right axles LA and RA are rotated together with the connecting members 42 and 42 to travel. To do.

  On the other hand, based on the driving of the driving HST (the driving of the pump P1 or the driving of the motor M1), the steering HST on the lower input side is driven (that is, the pump P2 is driven, and the motor M2 is driven based on it). When the output shaft of the motor M2 is inserted into the forward / reverse switching gear mechanism G and the output shaft is rotationally driven, the forward / reverse switching gear mechanism G is used depending on the rotation direction. Then, the central axle MA is tilted to the left or right, and the central axle MA, the forward / reverse switching gear mechanism G, and the left and right axles LA and RA are integrally turned left and right. 2, the bevel gear 43 is fixed to the output shaft end of the motor M2, the differential side gears 44 and 44 are meshed on both sides, and the gear shaft of each differential side gear 44 is a differential yoke shaft 45. A small gear 46 fixed to the outer end portion extends outside the sun gear 41 and meshes with a large gear 47 that loosely fits the left and right axles LA and RA. When the output shaft of the motor M2 and the bevel gear 43 are rotated, the left and right differential side gears 44 and 44 are driven to rotate in opposite directions. Accordingly, the left and right sun gears 41 and 41 rotate in opposite directions to each other via the small gear 46 and the large gear 47. When the direction of rotation (spinning) of the sun gear 41 is the same as the direction of rotation of the planetary gears 40, 40, the revolution speed of the planetary gears 40, 40 is increased, so the rotational speed of the axle LA or RA on that side is Increased speed. On the opposite side, the rotation direction of the sun gear 41 is opposite to the revolution direction of the planetary gears 40, 40, the revolution speed of the planetary gears 40, 40 is reduced, and the rotation speed of the axle LA or RA on this side is Decelerated. That is, the forward / reverse switching gear mechanism G is a differential device. Further, when the rotation speed of the sun gear 41 that rotates in the direction opposite to the rotation direction of the planetary gears 40 and 40 becomes higher than the rotation speed of the planetary gears 40 and 40 (or the planetary gears 40 and 40 are moved by stopping traveling). When the sun gear 41 rotates in the reverse direction when the revolution is stopped), the planetary gears 40 and 40 rotate in the rotation direction of the sun gear 41, and the axle LA or RA on that side is driven in reverse.

  Thus, during traveling drive, the turning-side axle is decelerated and the opposite-side axle is accelerated to turn, and when the traveling is stopped or the traveling speed is below a certain level, the turning-side axle is Driven in the reverse direction, the opposite axle is driven in the forward direction to turn the interlining. When the output shaft of the motor M2 is not driven, both the left and right axles LA and RA are driven forward at equal speed and go straight. (During reverse travel, both are driven in reverse at the same speed.)

  Compared to the case where the conventional single HST shown in FIG. 42 is used for driving and steering respectively, the engine (engine) has only one output shaft. Thus, the input mechanism need only be provided for the traveling HST pump P1, and conventionally, an input mechanism for branching the output system of the engine and inputting it to the steering HST pump P2 becomes unnecessary. In other words, the multiple HST requires only one input mechanism for the engine.

  Each of the following multiple HST configuration examples employs the drive system shown in FIG. 1, and the first HST, which is the upper input side of the multiple HST, is the driving HST, and the second input is the lower input side. It is assumed that HST is adopted for steering HST. Each of the multiple HSTs is equipped with a forward / reverse switching gear mechanism G and attached to a transmission TM that supports the left and right axles LA and RA and the central axle MA.

In addition, since the internal configurations of the pumps P1 and P2 and the motors M1 and M2 are the same in the multiple HST of each configuration example, first, this will be described based on the multiple HST shown in FIG. Keep it. Each pump P1 and P2 and each motor M1 and M2 are configured in a housing filled with hydraulic oil. Each of the pump shafts PS1 and PS2 and the motor shafts MS1 and MS2 is pivotally supported, and a plunger is provided therein. The cylinder block CB is fixed in an annular manner and is opposed to the side surface of the port block PB (the generic name of the port blocks PB1 to PB8 below is referred to as a port block PB) through a valve plate. In each pump P1 and P2, each pump shaft PS1 and PS2 is provided with a movable swash plate 1 and 2 operated by pump operation levers L1 and L2 on the upper side of each cylinder block CB. In each of the motors M1 and M2, a fixed swash plate 3 and 4 is provided in a loosely fitted manner on the lower side portion of each cylinder block CB of each motor shaft MS1 and MS2. The pump operating levers L1 and L2 are respectively connected to a speed change lever and a turning handle operated by an operator by a link mechanism (not shown).

  Since the pump H1 of the first HST is a pump at an input upper position in the multiple HST, power is input from the engine (engine). Therefore, the pump shaft PS1 is protruded to the outside from the housing, and the input pulley 5 is fixedly installed at this portion. Further, the motor shafts MS1 and MS2 of the motors M1 and M2 are projected from the housing as output shafts of the first and second HSTs and are inserted into the transmission case TM.

Based on the above, each configuration example of the multiple HST will be described below. First, the pumps P1 and P2 series type multiple HST shown in FIGS. 3 to 25 will be described. 3 to 25, three multiple HST configuration examples are disclosed, but each of the multiple HSTs in these configuration examples includes one pump P1 of the first HST. The housing H1 is attached to one side of the port block PB, while the second HST pump P2 and the first and second HST motors M1 and M2 are attached to the opposite side of the port block PB. is there.

3 to 13, the pump P2 and the motors M1 and M2 are arranged on the side where the pumps P2 and the motors M1 and M2 are disposed (the right side surface in this configuration example). As shown in FIG. 4, the two housings H2 and H3 are fixed to the side surface of the port block PB1 so that the pump P2 and the motor M2 are vertically aligned as shown in FIG. 14 to 23, the pump P2 and the motor M2 are vertically installed in the housing H4, and only the motor M1 is installed in the housing H5, as shown in FIG. Two housings H4 and H5 are fixed to the side surface of the port block PB2 so that the motor M1 and the motor M2 are arranged in parallel in the front-rear direction. That is, the multiple HST in these two configuration examples is composed of three housings.

  In the multiple HST shown in FIGS. 3 to 13, the front and rear widths (distance between the motor shafts MS1 and MS2) are equivalent to the motors M1 and M2 arranged in parallel in the front and rear in one housing H3. On the other hand, in the multiple HST shown in FIGS. 14 to 23, the pump P2 and the motor M2, which are arranged vertically in parallel, are installed in one housing H4. (Distance between pump shaft PS2 and motor MS2) is reduced. In consideration of the installation space and the shape of the transmission case TM, the former multiple HST is used when the front and rear arrangement spaces are to be reduced, and the latter is used when the upper and lower arrangement spaces are limited. A multiple HST may be selected and arranged.

  24 and 25, the pump P2 and the motors M1 and M2 are all installed in one housing H6, and one housing H6 is fixed on the side surface of the port block PB3. That is, a multiple HST is constituted by the two housings H1 and H6. Compared to the two multiple HSTs, the pump P2 and the motors M1 and M2 are installed in one housing, so the number of parts for one housing is reduced, and the pump P2 and the motor M1 Since the distance between the motors M2 (pump shaft PS2, motor shaft MS1, and motor shaft MS2) can be reduced, in addition to the housing H6 itself, the port block PB3 has also been made compact, and the entire multiple HST is compact. Leads to In addition, although an effect is brought about also in the oil path structure for return oil in the port block PB, this will be described in detail later.

  As shown in FIG. 14, the mounting structure for the transmission case TM is cut out at the upper part of one side surface of the transmission case TM, and the port block is formed at the side surface of the notched portion. The PB is fixed, and the motor shafts MS1 and MS2 of both motors M1 and M2 arranged in parallel in the horizontal direction are inserted in the horizontal direction.

In any of the configuration examples, as shown in FIGS. 3, 15, and 24, the pumps P1 and P2 are arranged in series on the left and right sides of the port block PB across the port block PB. A coupling 6 is provided inside, and both pump shafts PS1 and PS2 are fitted therein, both pump shafts PS1 and PS2 are directly connected, and the pump shaft PS2 is driven to drive the pump shaft PS1. ing. Even if the pump shaft PS1 that includes the input pulley 5 and is directly driven by the engine is disconnected from the coupling 6, the pump shaft PS1 is not cut off, but for the pump shaft PS2, the coupling is not performed. Deviating from 6 results in disconnecting the input means. Accordingly, the driving reliability of the pump P1 having the pump shaft PS1 is higher than that of the pump P2. Therefore, when the driving reliability is applied to the hydraulic transmission apparatus as shown in FIG. 1, the first HST having the pump P1 is used frequently. It is applied as a high traveling HST.

As shown in FIG. 3, the lower end of the input side of the pump shaft PS1 protrudes from the housing H1 and is inserted into the charge pump CP, and discharged from the charge pump CP thus driven. The hydraulic oil is supplied into the port block PB from the charge port C or the like at the upper end of the port block PB1, and the hydraulic oil is filled into the oil passages 21, 21, 25, 25 described later through the check valves 7, 7, It is supplemented as hydraulic oil for pumps P1 and P2 and motors M1 and M2 in each housing. The same applies to the other two configuration examples. Thus, hydraulic oil can be supplemented to all the pumps and motors of the first and second HSTs with a single charge pump.

Further, as shown in FIG. 15, outside the charge pump CP, the pump shaft P2 is extended by a spline 8 to be a PTO shaft, and a PTO pulley 9 is provided in an annular manner. The reason why the pump shaft PS2 is extended and the PTO pulley 9 is not directly connected to the pump shaft PS2 is to prevent the bending load from the belt mechanism applied to the PTO pulley from being transmitted to the pump shaft 2 and to prevent bending. The bending load from the PTO pulley 9 is absorbed only by the spline 8 and is not transmitted to the pump shaft PS2. Further, the bearing portion of the spline 8 at the outer end of the charge pump CP is configured to be loosely fitted inside the PTO pulley 9, and the bending of the PTO pulley 9 is regulated by this bearing portion. The mounting configuration of the PTO pulley 9 to the charge pump CP shown here is possible not only for the other two configuration examples but also for all the multiple HSTs described later.

  Further, in the multiple HST shown in FIGS. 3 to 13, an oil return port 10 that is normally closed is opened on the side surface of the housing H <b> 2 containing the pump P <b> 2. The port block PB1 is provided with an oil return oil passage 11 communicating with the inside of the housings H1 and H2, as shown in FIGS. 3, 6 and 13, and is further perpendicular to the oil return oil passage 11. The oil return oil passage 12 and the horizontal oil return oil passage 13 are branched and communicated with the inside of the housing H3. As a result, when oil is drained from the multiple HST, if the oil is drained from the sole oil return port 10 formed in the housing H2, the hydraulic oil in the housings H1 and H3 is also returned to the oil return oil passage 11. It can flow into the housing H <b> 2 through 12 and 13 and be removed from the oil return port 10 at once. Thus, the oil removal of the whole multiple HST can be performed only by providing one oil return port 10.

  In the multiple HST shown in FIGS. 14 to 23, the oil return port 10 is provided in the housing H4, and an oil return plug is attached. In the port block PB2, as shown in FIGS. , An oil return oil passage 11 ′ communicating with the inside of the housings H 1, H 4 is formed, and further, 14, 15, 16 communicating between the housings H 4, H 5 are formed, and the oil in the housings H 1, H 5 is formed. Can be extracted from one oil return port 10 provided in the housing H4 in the same manner as described above.

  In the multiple HST shown in FIGS. 24 and 25, the oil return port 10 is provided in the housing H6, and the oil return plug is attached. The housing H6 includes the pump P2 and both motors M1 and M2. Are formed integrally in the port block PB3, and only the oil return oil passage 11 "communicating with the housings H1 and H2 is formed in the port block PB3. Can be removed.

  Next, the configuration of the port block PB1 in the three multiple HSTs will be described. A port block PB1 of the multiple HST in which the pump P2 shown in FIGS. 3 and 4 and both motors M1 and M2 are installed in separate housings H2 and H3 is shown in FIGS. 5 to 13, and FIGS. A port block PB2 of the multiple HST in which the illustrated pump P2 and motor M1 are installed in the housing H4 and only the motor M1 is installed in the housing H5 is shown in FIGS. Both are L-shaped in a side view, and a pump shaft hole 17 for inserting the coupling 6 into which both pump shafts PS1 and PS2 are inserted is formed in the upper part, and a kidney port 20. 20, kidney ports 21 and 21 are formed around the pump shaft hole 17 on the side of the pump P2 mounting side. Also, motor shaft holes 18 and 19 for inserting the motor shafts MS1 and MS2 are formed in the lower portion, and the motor M1 and M2 mounting side surfaces are provided around the motor shaft holes 18 and 19, respectively. Kidney ports 22, 22 and 23, 23 are drilled.

  An oil passage drilling structure in each of the port blocks PB1 and PB2 in the double multiple HST will be described. First, in the port block PB1, a vertical oil passage 24 is fed so that pressure oil is sent vertically downward from the kidney ports 20 and 20 of the pump P1 on the XX cross section near the housing H1 (pump P1) mounting side.・ 24 is drilled horizontally. Further, oil passages 25 and 25 are drilled in the horizontal direction in the horizontal direction from the oil passages 24 and 24, and the oil passages 25 and 25 pass through the oil passages 26 and 26 orthogonal to each oil passage 25 and 25. The oil passages 27 and 27 that are parallel to each other are branched and drilled, and the oil passages 27 and 27 communicate with the kidney ports 22 and 22 of the motor M1. That is, the oil passages 24, 25, 26, and 27 constitute an oil passage (P1-M1 oil passage) from the pump P1 to the motor M1. On the other hand, as an oil passage (P2-M2 oil passage) from the pump P2 to the motor M2, vertical oil passages 28 and 28 are provided on the YY cross section near the housing H2 and H3 in the port block PB1. Drilled in parallel in the left-right direction, the kidney ports 21 and 21 of the pump P2 and the kidney ports 23 and 23 of the motor M2 are communicated.

  Next, the port block PB2 will be described. First, on the shape surface of the port block PB2, the mounting surface A of the housing H5 (motor M1) is closer to the inner side than the mounting surface B of the housing H4 (pump P2 and motor M2) as shown in FIGS. It has a stepped shape on the housing H1 mounting surface side. (In FIG. 17, the horizontal width of the port block PB2 is L1 <L2.) And, on the X′-X ′ cross section of the port block PB2 closer to the housing H1 mounting surface including the housing H5 mounting surface A. P1-M1 oil passages, vertical oil passages 29 and 29, horizontal oil passages 30 and 30, and vertical oil passages 31 and 31 are drilled in parallel in the left-right direction to provide a kidney for pump P1. The ports 20 and 20 are in communication with the kidney ports 22 and 22 of the motor M1. Also, vertical oil passages 32 and 32, which are P2-M2 oil passages, are drilled on the Y'-Y 'cross section only in the pump P2 and the motor M2 attachment surface B that do not include the motor M1 attachment surface A. Thus, the kidney ports 21 and 21 of the pump P2 are communicated with the kidney ports 23 and 23 of the motor M2.

  In constructing the port block, it is a kidney port that requires strict processing, and it is necessary to devise the shape of the oil passage or the port block itself so that it does not become too deep. In the PB1 and PB2, since the pump P2 and the motor M2 are mounted on the same side with respect to the port block PB, the P2-M2 oil passages (oil passages 28, 28, 32, and 32) are connected to the pump P2. The kidney port of the pump P2 and the motor M2 can be shallowed by drilling close to the mounting side of the motor M2, but the mounting side of the pump P1 and the mounting side of the motor M1 are opposite to each other across the port block PB. When the P1-M1 oil passage is drilled close to either side, the kidney port on the near side can be shallow, but the kidney port on the opposite side becomes deeper. Will occur. For example, if it is drilled closer to the pump P1, the kidney port of the motor M1 becomes deeper.

  Therefore, first, in the port block PB1, as described above, the oil passages 26 and 26 and the oil passage 27 are formed in an L shape in plan view from the horizontal oil passages 25 and 25 which are drilled closer to the housing H1. Branching 27 is provided so that the oil passages 27 and 27 are brought close to the motor M1 so that the kidney ports 22 and 22 of the motor M1 need not be deepened. On the other hand, in the port block PB2, as described above, a step is provided in the shape of the port block PB itself so that the housing H5 mounting surface A is closer to the housing H1 mounting surface side than the housing H4 mounting surface B. Therefore, the P1-M1 system oil passages 29, 29, 30, 30 and 31, 31 are not far from the motor M1, and the kidney ports 22 and 22 of the motor M1 can be shallow.

  The port block PB3 is not particularly shown in the oil passage configuration or the like, but may be configured by reducing the interval between the pump shaft hole 17 and the motor shaft holes 18 and 19 in the port block PB1. (The interval between the pump shaft hole 17 and the motor shaft hole 19 is equal to that of the port block PB2.) In addition, the interval between the motor shaft holes 18 and 19 in the port block PB2 may be reduced. In this case, it is necessary to process the inner end of the housing H6 in which the pump P2 and the motors M1 and M2 are integrally provided in accordance with the shape of the side surface of the port block PB2.

Next, a configuration example of the pumps P1 and P2 parallel multiple HST shown in FIGS. 26 to 29 will be described. In this multiple HST, the first HST pump P1 and motor M2, and the second HST pump P2 and motor M2 are all attached to one side of the port block PB. That is, a housing H7 in which both pumps P1, P2 are installed in parallel in the left-right direction, and a housing H3 in which the motors M1, M2 are installed in parallel in the front-rear direction disclosed in the multiple HST shown in FIGS. Are mounted vertically on one side surface (left side surface in the present configuration example) of the port block PB4 having a substantially rectangular shape in side view. Note that the first HST pump P1 and the motor M1 and the second HST pump P2 and the motor M2 are arranged vertically and vertically.

  In this mounting method, since the pump and the motor are mounted on the same side in both the first and second HSTs, the oil passage drilled in the port block PB4 is P1 as shown in FIGS. -Both the M1 oil passages 35 and 35 and the P2-M2 oil passages 36 and 36 can be configured by simply drilling the oil passages where each kidney port is shallow in the vertical direction, simplifying the oil passage configuration. The thickness of the port block PB4 does not require a space for installing the coupling 6 directly connecting the two pump shafts PS1 and PS2 as in the above-described multiple HST. Since the P1-M1 oil passages 35 and 35 and the P2-M2 oil passages 36 and 36 do not need to be drilled in the front-rear direction, the P1-M1 oil passages 35 and 35 do not have to be drilled.

  In the port block PB4, pump shafts PS1 and PS2 and motor shafts MS1 and MS2 are supported. Both motor shafts MS1 and MS2 protrude from the opposite side of the housing H3 mounting surface of the port block PB4, and when mounted to the transmission case TM, as shown in FIGS. 26 and 27, the housing H3 of the port block PB4 The side opposite to the mounting side is fixed to the side surface of the cutout portion on the upper side of the transmission case TM, and the projecting portions of both motor shafts MS1 and MS2 are horizontally inserted into the transmission case TM.

  On the other hand, the pump shafts PS1 and PS2 have an input housing H8 attached to the side opposite to the housing H7 mounting surface of the port block PB4, and the extension portions of both pump shafts PS1 and PS2 enter the input housing H8. In this, as shown in FIG. 29, both pump shafts PS1 and PS2 are engaged with each other by gears 33 and 34. The pump shaft PS1 protrudes from the input housing H8 as an input shaft for inputting power from the engine by attaching the input pulley 5 shown in FIG.

  The housing H7 has an oil return port 10 for draining the hydraulic oil in the pumps P1 and P2, and an oil return oil passage communicating with the lower housing H3 is formed in the port block PB4. From the oil return port 10, the oil of the entire first HST (pump P1 and motor M1) and the entire second HST (pump P2 and motor M2) can be drained.

  Further, a charge pump CP is attached to the left side surface of the housing H7, and an outer protruding portion of the pump shaft PS1 is inserted. Thus, the hydraulic oil discharged from one charge pump CP driven by one pump shaft PS1 is supplied to each oil passage 35/35, 36/36 of the port block PB4 via the check valve. Then, the first and second HST pumps P1 and P2 and the motors M1 and M2 are all supplemented.

  Next, an embodiment of the multiple HST shown in FIGS. 30 to 32 will be described. A housing H3 ′ in which the motors M1 and M2 are installed in parallel in the front-rear direction is attached to the lower part of one surface of the substantially L-shaped port block PB5 when viewed from the side. The housing H3 ′ is fitted into the transmission case TM (therefore, the housing H3 ′ is processed into a shape suitable for fitting into the transmission case TM), and the motor shafts MS1 and MS2 from the housing H3 ′. Protrudes and is inserted into the transmission case TM.

  A housing H1 'containing a pump P1 and a housing H2' containing a pump P2 are attached to the opposite side surface of the port block PB5 to the housing H3 'mounting surface in a vertically parallel manner. The housings H1 'and H2' have oil return ports 10 and 10 through which oil from the entire first HST or the entire second HST can be drained. In the pump P1, the input side end of the pump shaft PS1 is projected from the housing H3 ′ as an input shaft, and the port block PB5 is penetrated to the opposite side across the port block PB5, and the pump shaft PS1 is projected. A charge pump CP is installed. The discharge hydraulic oil from the charge pump CP is supplied to the port block PB5, passes through the oil passage through the check valve, and is supplemented to all the pumps P1 and P2 of the first and second HSTs and all the motors M1 and M2. The

  The motor M1 and the pump P2 are arranged in series in the left-right direction as viewed from the front across the port block PB5, and the motor shaft MS1 and the pump shaft PS2 are disposed in a coupling 6 provided in the port block PB5. The motor shaft MS1 and the pump shaft PS2 are directly connected with each other. That is, the pump shaft PS2 is driven to drive the motor shaft MS1, and the pump shaft PS2 is driven to rotate at the rotational direction and rotational speed of the motor shaft MS1 only when the motor shaft MS1 is driven. Become.

  Since the rotational direction and rotational speed of the pump shaft PS1 are driven by inputting engine power, they are always constant, and the driving direction and speed of the motor shaft MS1 in the motor M1 are movable slant in the pump P1 by a shift lever or the like. It is displaced by the operation of the inclination angle of the plate 1. On the other hand, the movable swash plate 2 of the pump P2 has three switching positions of left turn, neutral and right turn, and the rotation speed of the motor shaft MS2 is movable even if the rotation speed of the pump shaft PS2 is constant. It changes depending on the switching position of the swash plate 2. If the rotational speed of the motor shaft MS2 is constant regardless of the rotational speed of the motor shaft MS1, the traveling speed is proportional to the rotational speed of the motor shaft MS1, so that when the traveling speed is slow, the turning speed is relatively high. If it is too fast, the turning radius becomes small (in the case of turning on the interlining or close to the turning on the interlining), and when the running speed is high, the turning speed becomes relatively slow and the turning radius becomes large. This will cause a malfunction.

  Therefore, if the pump shaft PS2 is driven by the motor shaft MS1 as described above, the rotational speed of the motor shaft MS2 is proportional to the rotational speed of the motor shaft MS1. In other words, the turning reaction speed is proportional to the traveling speed, and if the traveling speed is slow, the vehicle turns slowly, and if the traveling speed is fast, the vehicle turns faster, so that the same turning radius can be obtained at any speed. It becomes like this. Therefore, the steering device for turning the interlining can be operated in the same manner as a passenger car. Further, if the traveling is stopped, the pump shaft PS2 is always stopped by the stop of the motor shaft MS1. That is, the second HST motor shaft M2 may be caused by an unexpected situation during the stoppage of travel, which may occur when the second HST pump shaft PS2 is always driven regardless of the driving of the first HST motor M1. There is no danger of driving and turning the interlining. In other words, when this multiple HST is used, it is impossible to turn the interlining while the traveling is stopped. Therefore, this multiple HST is used for a traveling vehicle that operates like a passenger car, not a traveling vehicle (for example, having a crawler traveling device) that turns when the traveling stops.

  The motor shaft MS1 is driven to rotate forward when moving forward, and reversely driven when moving backward, but the pump shaft PS2 is also driven. Therefore, when moving backward, the motor shaft MS2 is driven to rotate in the direction opposite to that when moving forward. For example, if the movable swash plate 2 is switched to the right turning position, the motor shaft MS2 rotates in the direction opposite to the direction rotated when moving forward, and the right axle on the turning side via the forward / reverse switching gear mechanism G. A forward drive side force is applied to RA, and a reverse drive side force is applied to the opposite left axle LA. However, since the rotational drive direction of both axles is the reverse direction, that is, the reverse direction, the right axle RA is decelerated and the left axle LA is accelerated, so that the vehicle can turn right while moving backward. Therefore, if the steering operation is performed in the direction in which the user wants to turn by operating the steering wheel or the like while moving backward, the vehicle can turn in that direction. That is, the steering wheel can be operated with the same feeling as that of a passenger car even when turning backward. The operating mechanism of the movable swash plate 3 in the motor M2 is set when three switches that are turned on when the handle is rotated to the left, when it is rotated to the right, and when it is stopped are set near the handle, and when one of the switches is turned on, Based on this, the movable swash plate 2 may be configured to be in a left turn position, a right turn position, and a neutral position.

  On the other hand, the pumps P1 and P2 series type multiple HST shown in FIGS. 3 to 25 and the pumps P1 and P2 parallel type HST shown in FIGS. The pump shaft PS2 of the HST is driven by the pump shaft PS1 of the first HST that is directly transmitted from the engine (by direct coupling by the coupling 6 or meshing of the gears 33 and 34), so that the pump shaft PS1 is constant. As long as the motor swash plate 2 is switched to a certain position in the motor M2, the motor shaft MS2 is always in the same direction regardless of the rotation direction of the motor shaft MS1, that is, whether the traveling direction is forward or reverse. Rotate. Therefore, when moving backward, for example, when the movable swash plate 2 is set at the right turn position, the right axle RA is increased, the left axle LA is decelerated, and the left turn is performed, which is opposite to the side operated when moving forward. If it is not operated to the side, it does not turn to the side to turn. Accordingly, the turning operation at the time of reverse travel becomes a sense opposite to the normal feeling. Therefore, when the pump operation lever L1 for the pump shaft PS1 is switched from forward to reverse in order to make the turn operation similar to that of an automobile. Furthermore, a link mechanism between the handle and the pump operating lever L2 for the pump shaft PS2 is crafted so that the movement of the turning handle (not shown) operated by the operator and the pump shaft PS2 are reversed ( Not shown).

  Further, even if the rotation speed is set, the rotation speed of the pump shaft PS2 is always constant as long as the rotation speed of the pump shaft PS1 is constant. The angle of the swash plate 2 must be displaced. For example, if the tilt angle of the movable swash plate 2 is made proportional to the rotational speed of the steering wheel, the steering feel is similar to that of a passenger car that turns faster if the steering wheel is turned sharply and turns slower if the steering wheel is turned slower.

Next, three examples of the pump shaft / motor shaft orthogonal multiple HST shown in FIGS. 33 to 41 will be described. In common with the three embodiments, as shown in FIG. 35, the multiple HST mounting portion of the transmission case TM has a horizontal surface formed at the upper end, and the port block PB (PB6, 7, 8) A housing H9 that has an inverted T-shape when viewed from the front and that supports the motor shafts MS1 and MS2 in the vertical direction and internally mounts the motors M1 and M2 in a laterally parallel manner is fixed to the bottom surface of the port block PB. The bottom surface of the housing H9 is in a horizontal plane, while the upper end of the transmission case TM is formed in a horizontal plane, and the bottom surface of the housing H9 is fixed to the top surface of the transmission case TM. The lower ends of MS1 and MS2 are vertically inserted from the upper surface of the transmission case TM.

As described above, since the housing H9 of the motors M1 and M2 attached to the lower part of the multiple HST is made vertical and attached to the upper surface of the transmission case TM, the transmission is as shown in the configuration examples shown in FIGS. Compared to the configuration of mounting on the side surface of the case TM, both the multiple HST and the transmission case TM have mounting strength, and the motors M1 and M2 are arranged in parallel on the left and right sides with the motor shafts MS1 and MS2 in the vertical direction. Since it is disposed, the width of the transmission case TM in the front-rear direction can be reduced.

  As described above, among the multiple HSTs of FIGS. 33 to 41 that share the mounting method of the housing H9 of the motors M1 and M2 and the mounting method to the transmission case TM, first, as shown in FIGS. I will explain things. The housings H1 and H2 in which the pumps P1 and P2 are respectively installed are arranged in series on the left and right sides of the port block PB6 at a position above the bottom surface of the port block PB6. Also, the pump shafts PS1 and PS2 are coupled to the housings H1 and H2 in the horizontal direction in the same manner as the multiple HST shown in FIGS. The projecting portion from the housing H1 of the pump shaft PS1 is an input shaft transmitted from the engine, and the projecting portion from the housing H2 of the pump shaft PS2 is inserted into the charge pump CP. The hydraulic oil discharged from the charge pump is supplied into the port block PB, and is supplemented into the housings H1, H2, and H9 via check valves. Also, the housing H2 is provided with an oil return port 10, and an oil return oil passage communicating with the inside of the housings H1 and H2 in the port block PB and a branch from the oil return oil passage are provided inside the housing H9. An oil passage communicating with the first HST and the second HST can be drained from one oil return port 10 in the housing H2. That is, the pump shaft / motor shaft orthogonal type that combines the effects of mounting the housing H9 and the transmission case TM with the effects of the multiple pump H1 of the pump P1 and P2 series type shown in FIGS. It is a multiple HST.

  35 to 38, the multiple HST shown in FIG. 35 to FIG. 38 has a housing H7 in which both pumps P1 and P2 are housed in parallel in the front and rear sides at the upper portion of the port block PB7, and both pump shafts PS1. The structure in which the input housing H8 that is fixedly supported by the PS2 and meshed by the gears 33 and 34 is fixed is the same as the pump P1 and P2 parallel type multiple HST shown in FIGS. 26 to 29. The pump shaft / motor axis orthogonal type multiple HST has the same effect as the multiple HST having this configuration.

  39 to 41, the multiple HST shown in the upper portion of the port block PB8 is pumped on one side surface like the motor M1 / pump P2 linked multiple HST shown in FIGS. 30 to 32. A housing H7 in which P1 and P2 are housed in parallel is fixed. RV is a charge relief valve. On the other side of the port block PB8, a transmission housing H10 that supports the pump shafts PS1 and PS2 is fixed. The input side end of the pump shaft PS1 protrudes from the transmission housing H10 to serve as an input shaft for transmitting engine power. A bevel gear 38 is fixed to the end of the pump shaft PS2 in the transmission housing H10. Further, the coupling 6 is provided through the port block PB8, and the upper end portion of the motor shaft MS1 is fitted into the coupling 6 from below in the transmission housing H10, and the extension motor shaft MS1 ′ is projected above it into the housing H10. The bevel gear 37 fixed to the upper end of the shaft is engaged with the bevel gear 38 provided with the pump shaft PS2, so that the motor shaft MS1 of the first HST is similar to the embodiment shown in FIGS. The second HST pump shaft PS2 is driven in response to this drive, and the same effects as in this embodiment are achieved.

  In the multiple HST of this configuration, even if the first HST and the second HST pump shafts that are directly connected by coupling or the like are disengaged from the coupling, they are directly input from the engine and the driving stops. The pump shaft of the first HST with no use is highly reliable, and when both HSTs are used for traveling and steering, the first HST is applied for traveling frequently used. Reliability in the drive system of a traveling vehicle equipped with the continuous HST is increased.

  Further, in the multiple HST of this configuration, since three members of one pump and two motors attached to one surface of the port block are mounted in an integrated housing, the number of parts is reduced and the cost is reduced. In addition, the space between the pump shafts of the pump and the motor and the motor shaft can be narrowed compared to the case where they are housed in separate housings, and the mounting space for these three members can be reduced. In addition, if one oil return port is provided in this housing, and the oil passage communicating with the pump on the opposite side is drilled in the port block, all the oil pumps of the first and second HSTs and the motor can be drained. This is possible with a single oil return port, and the number of oil return ports and the space required for installation are reduced.

  Further, in the multiple HST of this configuration, the oil in all the plurality of housings isolated from each other can be collectively discharged from one oil return port provided in one housing. In addition to facilitating work, only one space is required to provide an oil return port, reducing the number of parts, saving space and reducing costs.

  Further, in the multiple HST of this configuration, the hydraulic oil can be charged to all the pumps and all the motors of the first and second HSTs with only one charge pump attached to the end of one pump shaft. Since only one charge pump is required, the number of components can be reduced, space saving and cost reduction can be realized, and only one pipe is required from the charge pump to the port block. Can be reduced.

It is a skeleton figure at the time of applying multiple type HST to a hydraulic transmission type steering device. It is an enlarged view of FIG. 1 which shows the internal structure of the gear mechanism G for forward / reverse switching. It is front sectional drawing which shows multiple type HST which consists of housing H1, H2, and H3 which is one structural example of pump P1 * P2 direct connection type multiple type HST. Similarly, it is a right side view. It is a left view of port block PB1. Similarly, it is a right side view. Similarly it is XX sectional drawing. Similarly, it is a YY sectional view. It is also a plan view. It is a bottom view similarly. Similarly, it is a ZZ sectional view. It is also a front view. It is a front sectional view similarly. It is front sectional drawing which shows the attachment structure to the transmission case TM of multiple type HST which consists of housing H1, H4, and H5 which is one structural example of pump P1 * P2 direct connection type multiple type HST. It is a front sectional view of multiple HST similarly. Similarly, it is a right side view. It is a plane sectional view similarly. It is a left view of port block PB2. Similarly, it is a right side view. It is the same X'-X 'sectional drawing. Similarly, it is a Y'-Y 'sectional view. It is also a front view. It is also a plan view. It is front sectional drawing of multiple type HST which consists of housings H1 and H6 which are one example of composition of pumps P1 and P2 direct connection type multiple type HST. Similarly, it is a right side view. It is front sectional drawing which shows the arrangement structure of the pump P1 and the motor M1 of pump P1 * P2 parallel type | mold multiple HST. It is a front sectional view showing the arrangement composition of pump P2 and motor M2 similarly. Similarly, it is a left side view. It is a plane partial sectional view similarly. It is front sectional drawing of one Example of the motor M1 and pump P2 interlocking type multiple HST. Similarly, it is a left side view. Similarly, it is a right side view. It is front sectional drawing of pump P1 * P2 series-type multiple HST which is one structural example of the multiple axis | shaft HST of a pump shaft and a motor axis orthogonal type. Similarly, it is a left side view. It is front sectional drawing which shows the attachment structure to the transmission case TM of the pump P1 * P2 parallel-type multiple HST which is one Example of the pump-motor / motor-axis orthogonal type multiple HST. It is a front sectional view of multiple HST similarly. It is a plane partial sectional view similarly. Similarly, it is a left side view. 1 is a front sectional view of a motor H1 / pump P2 interlocking multiple HST which is an embodiment of a pump shaft / motor axis orthogonal multiple HST. FIG. It is a plane sectional view similarly. Similarly, it is a left side view. It is a skeleton figure at the time of applying a plurality of conventional single unit HST to a hydraulic transmission type steering device.

Explanation of symbols

P1 and P2 Pump M1 and M2 Motor PS1 and PS2 Pump shaft MS1 and MS2 Motor shaft L1 and L2 Pump operation lever PB (PB1 to 8) Port block TM Transmission case H1 to H7 Housing H8 Input housing H9 Housing H10 Transmission housing CP Charge pump 1 and 2 Movable swash plate 3 and 4 Fixed swash plate 5 Input pulley 6 Coupling 7 Check valve 8 Spline 9 PTO pulley 10 Oil return port 11 ・ 11 ′ ・ 11 ”Oil return oil passage 12-16 Oil return oil passage 17 Pump shaft hole 18/19 Motor shaft hole 20-23 Kidney pump 24-32 Oil passage 33/34 Gear 35/36 Oil passage 37/38 Bevel gear

Claims (2)

A multiple HST composed of a first HST on the input upper side and a second HST on the lower input side sharing a single port block, wherein the first HST pump and the second HST pump are provided on one side of the port block. The first HST motor and the second HST motor are arranged in parallel on the other side of the port block, and the first HST motor and the second HST pump are separated from each other by the port block. A multiple HST characterized in that the first HST motor shaft and the second HST pump shaft are directly connected in series. A multiple HST comprising a first HST on the input upper side and a second HST on the lower input side sharing one port block, wherein the port block is configured in a reverse T-shape when viewed from the front. Both HST pumps are arranged in series or in parallel in the vertical portion of the port block so that both pump shafts are horizontal, and on the bottom of the horizontal portion of the inverted T-shaped port block in front view, A multiple HST characterized in that the motor shafts of both the first and second HST motors are axially supported so as to be in the vertical direction, and a housing is provided in which both motors are installed in parallel in the left-right direction .

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