JPH06305336A - Driving device of power working vehicle - Google Patents

Abstract

PURPOSE:To constitute a driving device of a power working vehicle which is a combination of a static oil pressure type continuously variable transmission and a speed reducer to be simple in construction and compact, and improve maintainability of the continuously variable transmission. CONSTITUTION:A pair of static oil pressure type continuously variable transmission 25 are fitted to both right and left sides of the upper part of a transmission case 18, meanwhile a pair of right and left drive shafts 26 are journaled on the lower part of the transmission case 18, a pair of right and left speed reducers each connecting together the motor shaft 51 of the transmission 25 and the drive shaft 26 on the same side and having speed reducing function of three steps are arranged in the transmission case 18, and the inside end of each side crawler 7 is projected in a space 87 between the transmission 25 and the drive shaft 26 on each same side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive system for a power carrier vehicle and other power work vehicles, and more particularly to a drive system combining a hydrostatic continuously variable transmission and a speed reducer.

[0002]

2. Description of the Related Art Conventionally, as such a drive unit, one end portion of a pair of auxiliary cases is joined to both left and right side surfaces of an upper portion of a mission case which supports a pair of left and right drive shafts at the bottom, and both of these auxiliary cases A pair of left and right primary reduction gears and secondary reduction gears that connect the pair of left and right hydrostatic continuously variable transmissions to the inner surface of the end and connect the motor shaft of each continuously variable transmission to the drive shaft on the same side are auxiliary cases. It is also known that they are respectively arranged in a mission case (see, for example, Japanese Utility Model Laid-Open No. 62-13726).

[0003]

In the conventional device as described above, the number of parts is large and the structure is complicated, and since a pair of continuously variable transmissions are arranged between the left and right auxiliary cases, maintenance of them is required. In this case, the auxiliary case becomes an obstacle and makes the work difficult.

The present invention has been made in view of the above circumstances, and has a simple structure and is compact, and the hydrostatic stepless transmission is easily maintained. An object is to provide a drive device for a vehicle.

[0005]

In order to achieve the above object, the present invention supports a pair of left and right drive shafts, which are relatively rotatable, on a lower end of a mission case fixed to a frame of a vehicle, and these drive shafts are supported. A pair of left and right brakes for braking the vehicle is installed on both sides of the lower part of the mission case, and both sides of the upper part of the mission case are connected to the left and right drive shafts via a pair of speed reducers installed inside. Install a pair of left and right hydrostatic continuously variable transmissions to define a space between each continuously variable transmission and the brake on the same side, and inside the traveling means mounted on the outer end of each drive shaft. The first feature is that the end is projected into the void on the same side.

In addition to the first feature of the present invention, each speed reducer is fixed to a drive shaft on the same side as the drive transmission wheel fixed to the motor shaft of the hydrostatic continuously variable transmission on the same side. It is configured that the driven transmission wheel provided is connected through at least two stepped transmission wheels to reduce the rotation of the motor shaft by at least three stages and transmit the rotation to the drive shaft. Characterize.

In addition to the first or second feature, the present invention further comprises a distributor plate having a hydraulic closed circuit of each hydrostatic continuously variable transmission, which is separably joined to the outer surface of the transmission case. A third feature is that a replenishment pump for replenishing hydraulic oil to the hydraulic closed circuit is mounted on the plate, and the suction port of this replenishment pump and an oil filter covering the suction port are immersed in an oil reservoir in the mission case.

Furthermore, the present invention provides the first, second or third
In addition to the above features, the mission case includes a pair of left and right case bodies that are joined to each other, and a pair of left and right brake covers that are joined to the lower outer surfaces of both case halves to define a pair of brake chambers between them. A fourth feature is that the drive shaft on the same side is supported by the case halves on the same side and the brake cover, and a brake capable of braking the drive shaft is housed in the brake chamber on the same side. To do.

Further, in addition to the fourth characteristic, the present invention makes each case half support a relay shaft penetrating therethrough above the traveling means, and an inner lever fixed to the inner end of the relay shaft. While interlocking the brake operating lever on the same side in the mission case, the external brake operating member is interlocked with the outer lever fixed to the outer end of the relay shaft.
It is a feature of.

Furthermore, the present invention has a mission case, a prime mover mounted on the mission case via a prime mover bed, a pump shaft and a motor shaft which are arranged in parallel with each other, and is configured symmetrically to each other. A pair of left and right hydrostatic continuously variable transmissions mounted on the left and right sides of the upper part, a pair of left and right drive shafts supported at the bottom of the mission case, and rotation of each motor shaft in the mission case on the same side A power unit is composed of a pair of left and right speed reducers that reduce and transmit at least three stages to the shaft, and connect the output shaft of the prime mover to one pump shaft via a transmission device and also connect the left and right pump shafts to each other, A sixth feature is that the inner end of the traveling means attached to the outer end of each drive shaft is projected into the space between the continuously variable transmission and the drive shaft on the same side.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, a power carrier 1 as a work vehicle has a power unit 4 attached to a rear end of a frame 3 supporting a cargo bed 2, and a pair of left and right drives driven by a drive shaft 26 of the power unit 4. Crawlers 7, 7 as a traveling means are wound between the wheels 5, 5 and a pair of left and right driven wheels 6, 6 pivotally supported in the front and rear of the frame 3. In addition, a plurality of guide wheels 8, 8 that press the inner surface of the lower belt middle portion of each crawler 7 are pivotally supported in the middle portion of the frame 3. A steering handle 9 having a base end fixed to the frame 3 is formed in a gate shape surrounding the power unit 4 and extending to the upper and rear sides thereof, and a step 10 is formed at the rear end of the steering handle 9, that is, below the grip portion 9a. It is fixed to the power unit 4.
This power carrier 1 drives the crawlers 7 and 7 via the drive wheels 5 by the output of the power unit 4 to run, and at that time, the operator who operates the travel handle 9 normally walks, but in step 10. Sometimes I get on.

As shown in FIGS. 1 and 2, the frame 3 includes a pair of left and right main frames 11, 11 and both main frames 1.
The cross member 12 connects between the main frames 11 and 11 at the front intermediate part thereof, and the support frame 13 connects between the main frames 11 and 11 at the rear intermediate part thereof. A power unit bracket 14 is welded to the.

The support frame 13 is composed of the left and right main frames 11, 1.
1 has a step portion 13a extending in a diagonally upward and rearward direction from a joint portion with 1, and has a step portion 13a in an intermediate portion higher than the crawler 7, and a rear pedestal 15r welded to the step portion 13a, both main frames 11, The loading platform 2 is mounted on a front receiving platform 15f that is fixed to the front end of the 11 and extends above the crawler 7.

A pair of handle brackets 16, 16 for supporting the left and right base ends of the steering handle 9 are fixed to the left and right side walls above the support frame 13 with bolts 17.

As shown in FIGS. 2 and 3, the power unit 4 includes a mission case 18, a prime mover bed 20 having a U-shaped cross section fixed to the upper portion of the mission case 18 with bolts 19, and a prime mover bed 20 mounted on the prime mover bed 20. The transmission case 18 is fixed to the left and right power unit brackets 14 and 14 with bolts 22 in a posture in which the transmission case 18 is tilted upward and rearward of the vehicle by a predetermined angle. Further, in the engine 21, the crankshaft 23 as its output shaft has the drive shaft 2
The cylinder block 24 is arranged substantially directly above 6 in parallel with it, and the cylinder block 24 is inclined in the same direction as the mission case 18.

Thus, the rearward tilted arrangement of the transmission case 18 and the cylinder block 24 lowers the overall height of the power unit 4 and contributes to lowering the center of gravity of the vehicle. Further, the arrangement of the crankshaft 23 directly above the drive shaft 26, together with the rearward tilted arrangement of the transmission case 18 and the cylinder block 24, contributes to downsizing of the power unit 4.

The front end portion of the prime mover bed 20 is fixed to the support frame 13 with bolts 32. Therefore, the prime mover bed 20, the transmission case 18, the support frame 13, and the main frames 11, 11 constitute a closed rigid frame, which reinforces the frame 3 and strengthens the support rigidity of the power unit 4.

As shown in FIG. 4, the mission case 18
Is a pair of left and right case halves 2 joined by bolts 29
8 and 28, and a pair of left and right cup-shaped brake covers 30 and 30 connected to the outer surfaces of the lower end portions of the case halves 28 and 28 with through bolts 31. Each of the brake covers 30 includes the power unit bracket. A pair of upper and lower bosses 30a, 30a fixed to the bolt 14 by bolts 22 are integrally formed.

The power unit 4 includes a pair of left and right hydrostatic continuously variable transmissions (hereinafter, simply referred to as transmissions) 25, 25 mounted on both outer side surfaces of the upper portion of the transmission case 18,
Motor shafts 51 and 51 of these transmissions 25 and 25, which will be described later.
And a pair of left and right drive shafts 26, 26 supported at the lower end of the mission case 18, and a pair of left and right speed reducers 27, 27 for connecting the left and right drive shafts 26, 26 in the mission case 18.

Each speed reducer 27 has a motor shaft 5 on the same side as the speed reducer 27.
A drive gear 33 (drive transmission wheel) fixed to the inner end of 1,
A first stepped gear 34 (stepped transmission wheel) for engaging a large diameter gear 34a with the drive gear 33, and a second stepped gear 34 for engaging a small diameter gear 34b of the first stepped gear 34 with a large diameter gear 35a. 35 (stepped transmission wheel) and a driven gear 36 (driven transmission wheel) fixed to the inner end of the drive shaft 26 on the same side and meshed with the small diameter gear 35b of the second stepped gear 35. . Left and right first and second stepped gears 34, 34; 35, 3
5 is rotatably supported by common first and second idle shafts 37 and 38 that are horizontally mounted between the left and right case halves 28 and 28. These idle shafts 37 and 38 are drive shafts 26 and 26.
It is placed in parallel with.

Thus, in each speed reducer 27, the rotation of the motor shaft 51 on the same side is controlled by the first and second stepped gears 34 and 35.
Since the stages are also decelerated and transmitted to the drive shaft 26 on the same side, even if there is a slight rotation difference between the left and right motor shafts 51, 51 when the vehicle goes straight, the influence on the drive shafts 26, 26 is suppressed. be able to.

As shown in FIGS. 5 and 6, the left and right transmissions 25, 25 have the same structure and are symmetrically arranged. Each transmission 25 has a distribution plate 39 that is detachably bolted to the outer surface of the case half 28 on the same side, a housing 40 that is connected to the distribution plate 39 with bolts 41, and is disposed in the housing 40. The hydraulic pump 42 and the hydraulic motor 43 are provided. The hydraulic pump 42 includes a pump shaft 44 penetrating the distribution plate 39, a pump main body 45 spline-coupled to the pump shaft 44 and in close contact with the distribution plate 39 so as to be rotatable and slidable, and an annular arrangement state surrounding the pump shaft 44. A large number of pump plungers 46, 46 ... Slidably fitted in the pump body 45, a pump swash plate 47 abutting the outer ends of these pump plungers 46, 46. And a pair of trunnion shafts 5 whose axes are orthogonal to the axis of the pump shaft 44.
The pump swash plate 47 is supported by the housing 40 via 0, 50, and passes through the upright position (neutral position) of the pump swash plate 47 orthogonal to the pump shaft 44 to one maximum tilt position (straight TOP position) and the other maximum tilt position ( It can be tilted with respect to the reverse TOP position).

On the other hand, the hydraulic motor 43 includes a motor shaft 51 penetrating the distribution plate 39, a motor main body 52 spline-coupled to the motor shaft 51 and in close contact with the distribution plate 39 in a rotatable and slidable manner, and a motor shaft 51. A large number of motor plungers 53, 53 ... Slidably fitted in the motor main body 52 in the surrounding annular arrangement state, and these motor plungers 53, 5
3 and a motor swash plate 54 contacting the outer ends of
The rear surface of the motor swash plate 54 is supported by the housing 40 via a thrust bearing 55 in a state of being inclined at a constant angle with respect to the motor shaft 51. At the outer end of the trunnion shaft 50 of each of the left and right swash plate holders 49, the boss 12 of the speed change lever 120 is provided.
0a is fitted, and the angle of each pump swash plate 47 can be adjusted by rotating the speed change lever 120. The shift lever 120 is operated by a control lever 121 (see FIGS. 1 and 8) provided on the steering handle 9 via a control cable (not shown).

As shown in FIG. 11, in each transmission 25, the hydraulic pump 42 and the hydraulic motor 43 are connected to each other by a hydraulic closed circuit 56. The hydraulic closed circuit 56 is provided with a bypass passage 57 that connects between the high pressure side and the low pressure side, and the clutch valve 5 that is manually opened and closed is provided in the bypass passage 57.
8 is interposed. The hydraulic pump 42 has its pump shaft 4
The replenishment pump 59 driven by 4 is connected. The replenishment pump 59 pumps hydraulic oil from the oil sump 60 and pressure-feeds it to the oil supply passage 61. The oil supply passage 61 has a closed hydraulic circuit 5.
The high pressure side and the low pressure side of 6 are connected via one-way valves 62, 62, respectively. Further, the oil supply passage 61 is connected to the oil sump 60 via a relief valve 63 and a suction valve 64 which are in parallel with each other.

When the clutch valve 58 is closed and the hydraulic pump 42 is driven while the pump swash plate 47 is tilted to the forward side, the hydraulic oil flows through the closed hydraulic circuit 56 in the direction of the solid line arrow. Capacity of Hydraulic Pump 42 and Hydraulic Motor 4
The motor shaft 51 of the hydraulic motor 43 rotates in the normal direction, and the pump swash plate 47 inclines to the reverse side. Flow and the motor shaft 51 reverses. During this time, the hydraulic closed circuit 5
When oil leaks in 6, the one-way valve 62 corresponding to the low pressure side at that time is opened, and the hydraulic oil is replenished from the replenishment pump 59 to the hydraulic closed circuit 56. When the oil supply passage 61 rises above a certain value, the relief valve 63 opens to prevent excessive increase in the oil supply passage 61, and the high pressure side and the low pressure side in the hydraulic closed circuit 56 are suddenly reversed by engine braking. In this case, when the supply of the hydraulic oil to the low pressure side by the supply pump 59 is insufficient, the suction valve 64 opens to suck the oil in the oil sump 60 to the low pressure side, thereby sucking the air in the hydraulic closed circuit 56. Can be prevented.

Referring again to FIG. 5, the hydraulic closed circuit 56,
The supply pump 59, the oil supply passage 61, the one-way valves 62, 62, the relief valve 63, and the suction valve 64 are provided on the distribution plate 39. The hydraulic closed circuit 57 and the one-way valve 62 are not shown in FIG.

The oil sump 60 is the mission case 18
It is defined between the two opposite cases 28, 28. Then, inside the distribution plate 39, the oil filter 6 which covers the respective suction ports of the replenishment pump 59 and the suction valve 64 and is immersed in the oil sump 60.
5 is attached to filter the hydraulic oil to be supplied to the replenishment pump 59 and the suction valve 64.

The pump shaft 44 and the motor shaft 51 are both arranged parallel to the drive shaft 26. The left and right pump shafts 44, 44 are directly connected to each other via the joint 66 in the oil sump 60, and the one pump shaft 44 is connected to the housing 4
The input shaft 67 projecting outside 0 is press-fitted and coupled. Therefore, by rotating the input shaft 67, the left and right pump shafts 44, 4
4 can be driven simultaneously.

By the way, the transmission 25 mounted on the outer surface of the upper end portion of the mission case 18 tilted outward from the frame 3 in the front-rear direction occupies a position separated from the frame 3 and the crawlers 7. Since the pump shaft 44 and the motor shaft 51 of 25 are parallel to the drive shaft 26, the transmission 25 can be easily disassembled and assembled, which is advantageous in terms of maintenance. Further, the inside of the mission case 18 is used as the oil sump 60, and the distribution plate 39 having the replenishment pump 59 immersed therein is joined to the outer side surface of the mission case 18, which simplifies the structure by eliminating the need for piping. This is effective in reducing hydraulic oil leakage.

Referring again to FIG. 3, the crankshaft 23 of the engine 21 and the input shaft 67 of the transmission 25 are connected via a transmission device 68 having a clutch function, and usually covered with a cover 78 (see FIG. 1). The transmission device 68 includes a drive pulley 69 and a driven pulley 70 fixed to the crankshaft 23 and the input shaft 67, and the pulleys 69,
A belt 71 wound between 70 and a belt tensioner 72 that controls the tightening force of the belt 71. The belt tensioner 72 is provided with a tensioner pulley 75 that is in contact with the slack side of the belt 71 at the swing end of an arm 73 pivotally supported by the mission case 18, and the arm 73
A tensioner cable 77 is connected to the coil via a coil spring 76. Then, when the tensioner cable 77 is pulled to apply a tensile force to the coil spring 76, this tensile force is transmitted to the arm 73 and the tensioner pulley 75 is moved to the belt 71.
When the belt 71 is in a tensioned state to enable the power transmission and the coil spring 76 is loosened, the belt 71 is pressed.
Becomes a relaxation state and cuts off power transmission.

Referring again to FIG. 4, the left and right drive shafts 26
Is supported by the case half 28 and the brake cover 30 on the same side via bearings 80 and 81. The left and right drive shafts 26, 26 have their inner ends abutted against each other so that they can rotate relative to each other. A hub 82 is fixed to the outer end portion of each drive shaft 26 with a key 83 and a bolt 84, and the drive wheel 5 is fixed to a mounting plate 85 welded to the hub 82 with a bolt 86. The crawler 7 that engages with the drive wheel 5 extends outward from the drive wheel 5, and the inwardly extending portion 7 a of the upper band of the crawler 7 is defined by the transmission 25 and the brake cover 30. It has been rushed into the empty space 87. This allows the crawler 7 to approach the mission case 18 without being interfered by the transmission 25 and set a desired tread.

Each of the left and right brake covers 30 defines a dry brake chamber 88 between itself and the case half 28 on the same side, and the brake chamber 88 is braked by the corresponding drive shaft 26. An inner expansion type drum brake 89 is provided. Each drum brake 89 has a corresponding drive shaft 26
The brake drum 90 is spline-coupled with the brake drum 90, and the brake shoe 91 is provided in the brake drum 90. One end of the brake shoe 91 swings to the anchor pin 92 fixed to the corresponding case half body 28. A cam portion 94a of a brake cam shaft 94 that is movably supported and has the other end penetrating the case half body 28 and rotatably supported therein.
Is engaged with. Therefore, when the brake cam shaft 94 is rotated in the operating direction, the brake shoe 91 can be expanded and brought into pressure contact with the inner peripheral surface of the brake drum 90, and the corresponding drive shaft 26 can be braked. When is rotated in the return direction, the brake shoe 91 is contracted by the force of a return spring (not shown), and the braking of the drive shaft 26 can be released.

As shown in FIG. 7, operating levers 95 are fixed to the inner ends of the left and right brake cam shafts 94 that protrude into the case half body 28. A relay shaft 96 parallel to the crawler 7 penetrates each case half 28 and is rotatably supported on the half cylinder 28. Case half 2 of this relay shaft 96
8. An outer lever 98 is fixed to the outer end protruding outward, and an inner lever 99 is fixed to the inner end protruding into the case half 28. The inner lever 99 and the brake cam shaft 94
The operating lever 95 is connected via the interlocking link 100. Brake cable 1 for each left and right outer lever 98
01 is connected, and the lever 98 is urged in the returning direction of the brake cam shaft 94 by the force of the returning spring 102.

Since the brake 89 system below the relay shaft 96 occupying the upper position of the crawler 7 is housed in the mission case 18 in this way, the brake system can be protected from the soil and sand scraped up by the crawler 7.

8 and 9, the left and right arm portions 104b of the handle lever 104 are fixed to the left and right side portions of the steering handle 9 and protrude downward, and the left and right arm portions 104b of the handle lever 104 are connected to each other via a horizontal pivot 105. As shown in FIG. 9, the handle lever 104 is supported by the gripping portion 104a of the steering handle 9 at a traveling position A in which the grip portion 104a is close to the grip portion 9a of the steering handle 9. It is possible to rotate between the stop position B and the stop position B which are spaced apart from the front lower side. The handle lever 104 is connected to the tensioner cable 77 and the left and right brake cables 10.
1, 101 are connected as follows.

That is, on the right arm portion 104b of the handle lever 104, there is a first connecting shaft 106 which is offset from the pivot 105 toward the grip portion 104a, and a first connecting shaft 1 from the pivot 105.
A second connecting shaft 107 that is offset to the side opposite to 06 is provided, a tensioner cable 77 is connected to the first connecting shaft 106, and a spring cylinder 108 is swingably connected to the second connecting shaft 107. .

As shown in FIG. 9, the spring cylinder 108 has a rod 109 penetrating the tip wall of the cylinder 108 and a compression coil spring in which a movable end is brought into contact with a retainer 110 fixed to the inner end of the rod 109. 111 and 111 are stored. Then, one end of a main brake cable 112 is connected to the outer end of the rod 109, and the left and right brake cables 101, 101 are connected to the other end via an equalizer 113.
The equalizer 113 is a known one that evenly distributes the traction force of the main brake cable 112 to the left and right brake cables 101, 101.

The right arm portion 1 of the handle lever 104
04b is provided with a locking shaft 114 deviated from the pivot 105 to the grip 104a side, and this locking shaft 114 and a locking plate 115 fixed to the cross member 9b of the steering handle 9.
A brake spring 116, which is a coil spring, is stretched between and. The pulling force of this brake spring 116 is the spring cylinder 10.
8 is set to be larger than the compression force of the compression coil spring 111. Also, the line of action 117 of the brake spring 116
Is designed to move upward or downward through a thought point C intersecting with the axis of the pivot 105 as the handle lever 104 rotates.
Is set at a position slightly rotated downward from the traveling position A. Therefore, when the handle lever 104 goes over the thought point C upward, it is urged to the traveling position A side by the pulling force of the brake spring 116, and conversely, when it goes over the thought point C downward, it is stopped by the pulling force of the brake spring 116. It is biased to the position B side.

As shown by the solid line in FIG. 9, when the handle lever 104 is rotated from the stop position B to the traveling position A, the first connecting shaft 106 moves rearward to pull the tensioner cable 77, Since the tensile force is applied to the coil spring 76, the belt 71 is in the tightened state as described above, and power transmission from the crankshaft 23 to the input shaft 67 is enabled.

On the other hand, the second connecting shaft 107 is the first connecting shaft 76.
On the contrary, since it moves forward, the repulsive force of the compression coil spring 111 in the spring cylinder 108 is weakened, and the main brake cable 112 and the left and right brake cables 101, 101 are in a relaxed state. As a result, the left and right outer levers 98 rotate the brake cam shaft 94 in the returning direction via the interlocking link 100 by the force of the return spring 102, so that the left and right brakes 89, 89 as described above.
Are both released.

Therefore, the power transmitted from the engine 21 to the input shaft 67 is distributed to the left and right transmissions 25, 25, and after being appropriately changed in speed, the left and right drive shafts 26, 26 are respectively transmitted through the reduction gears 27, 27. And the left and right crawlers 7, 7 are driven via the drive wheels 5, 5, so that the transport vehicle 1 can travel. In this case, the left and right transmissions 25, 2
5, when both pump swash plates 47, 47 are tilted to the forward side, both motor shafts 51, 51 are normally rotated to move the carrier 1 forward, and both pump swash plates 47, 47 are tilted to the reverse side. If it does so, both motor shafts 51 and 51 will reverse and the truck 1 can be moved backward. Further, if the transmission ratios of the two transmissions 25, 25 are made different by making the angles of the left and right pump swash plates 47, 47 different, a difference occurs in the rotational speeds of the left and right motor shafts 51, 51, and the transport vehicle 1 turns Can be made. Further, if the left and right pump swash plates 47, 47 are tilted in mutually opposite directions, the left and right motor shafts 51, 51 rotate in mutually opposite directions, and the carrier 1 can be pivotally turned.

Next, when the handle lever 104 is rotated below the thought point C, the handle lever 104 is rotated toward the stop position B by a large pulling force of the brake spring 116, and accordingly, the first connecting shaft is rotated. While 106 moves forward, the second connecting shaft 107 moves backward. As a result, the first connecting shaft 106 loosens the tensioner cable 77 and weakens the tension of the coil spring 76, so that the belt 71 is put into the relaxed state and the power transmission from the crankshaft 23 to the input shaft 67 is cut off as described above. . On the other hand, the second connecting shaft 10
7 pulls the spring cylinder 108, so that the spring cylinder 108 compresses the internal compression coil spring 111 and pulls the main brake cable 112 via the rod 109, and the pulling force of the main brake cable 112 is applied to the left and right brakes via the equalizer 113. Cable 1
It is distributed to 01 and 101. When the traction force exceeds a predetermined value, the left and right outer levers 98 are returned to the return springs 102.
The rotation power is transmitted to the operating lever 95 through the inner lever 99 and the interlocking link 100 to rotate each brake cam shaft 94 in the operating direction. It is possible to simultaneously actuate both drum brakes 89, 89 to brake both drive shafts 26, 26, and thus both drive wheels 5, 5.

In FIG. 8, reference numeral 123 is the engine 2
The throttle lever which controls the throttle valve of 1 is shown.

In the above embodiment, various design changes can be made without departing from the gist of the present invention. For example,
Instead of the crawler 7, tires may be attached to the drive wheels 5. It is also possible to replace the internal combustion engine 21 with an electric motor. Further, the speed reducer 27 may be configured as a chain type, in which case the stepped gears 34 and 35 are replaced with stepped sprockets. Also the drum brake 89
Can be replaced by a wet type disc brake. Furthermore, the present invention can be applied to a snowplow and a bulldozer.

[0046]

As described above, according to the first feature of the present invention, a pair of left and right drive shafts, which are rotatable relative to each other, are supported at the lower end of the mission case fixed to the frame of the vehicle, and these drive shafts are supported. A pair of left and right brakes for braking is provided on both sides of the lower part of the mission case, and both sides of the upper part of the mission case are connected to the left and right drive shafts through a pair of reduction gears provided therein. A pair of left and right hydrostatic continuously variable transmissions are attached to define a space between each continuously variable transmission and the brake on the same side, and the inner end of the traveling means mounted on the outer end of each drive shaft. Since all the reducers are housed in a single mission case, the structure is simple with a small number of parts, and a pair of stepless wheels located on the left and right outer sides of the mission case are installed. The transmission is a mission case. Assembly without interference what, etc.,
It is easy to disassemble and its maintainability is good.
Furthermore, a desired tread should be provided between the left and right traveling means with the inner end protruding into the space between the continuously variable transmission and the brake on the left and right sides, without being interfered by the continuously variable transmission and the brake. You can

According to the second aspect of the present invention, each speed reducer is fixed to the drive shaft on the same side as the drive transmission wheel fixed to the motor shaft of the hydrostatic continuously variable transmission on the same side. By connecting at least two stepped transmission wheels with the driven transmission wheel,
Since the rotation of the motor shaft is decelerated by at least three stages and transmitted to the drive shaft, a slight rotational difference between the left and right motor shafts when the vehicle goes straight is caused by the large reduction action of the left and right reducers. It is possible to reduce the influence on both drive shafts and to ensure straightness, and the presence of the speed reducer increases the distance between the continuously variable transmission and the drive shaft. The interference of can be avoided more reliably.

Further, according to the third aspect of the present invention, a distribution plate having a hydraulic closed circuit of each hydrostatic continuously variable transmission is detachably joined to an outer surface of the transmission case, and the distribution plate is provided with a hydraulic pressure. Since a replenishment pump for replenishing hydraulic oil was installed in the closed circuit, and the intake port of this replenishment pump and the oil filter covering it were immersed in the oil sump in the mission case.
In each continuously variable transmission, piping is not required to simplify the structure, leakage of hydraulic oil can be reduced, and clean hydraulic oil can be constantly supplied to the hydraulic closed circuit.

Further, according to a fourth aspect of the present invention, a pair of left and right case bodies joined to each other and a pair of brake chambers defined between the lower outer surfaces of both case halves are joined. A transmission case is composed of a pair of left and right brake covers, and a drive shaft on the same side is supported by the case halves on the same side and the brake covers, and a brake capable of braking this drive shaft is provided in the brake chamber on the same side. Since it is housed, each drive shaft can be firmly supported at at least two places, and the space between both bearings can be used to enclose the brake in the mission case. Therefore, the brake can be waterproof and dustproof. , Can contribute to the improvement of its durability.

Furthermore, according to the fifth feature of the present invention,
Above each traveling means, each case half is made to support a relay shaft passing through it, and an inner lever fixed to the inner end of this relay shaft is interlocked with an operating lever of a brake on the same side in the transmission case, Since the external brake operating member is interlocked with the outer lever fixed to the outer end of the relay shaft, the lower part of the brake operating system can be enclosed in the mission case, and therefore the lower part of the operating system can be run. The means protects against soil and sand scraped up by the means and can contribute to the improvement of durability.

Furthermore, according to the sixth feature of the present invention,
A mission case, a prime mover mounted on the mission case via a prime mover bed, and a pump shaft and a motor shaft that are arranged in parallel with each other, are configured symmetrically with each other, and are mounted on both left and right side surfaces of the upper part of the mission case. A pair of left and right hydrostatic continuously variable transmissions, a pair of left and right drive shafts supported at the bottom of the mission case, and at least 3 rotations of each motor shaft in the mission case to the same drive shaft.
A power unit is composed of a pair of left and right reducers that perform stepwise reduction and transmission, and the output shaft of the prime mover is connected to one pump shaft via a transmission device, and the left and right pump shafts are connected to each other, and Since the inner end of the traveling means attached to the outer end is thrust into the space between the continuously variable transmission and the drive shaft on the same side, the left and right continuously variable transmissions have the same structure and are symmetrically arranged. Since it is obtained, the mass productivity is high, and the desired tread can be set by approaching the left and right running means to both sides of the mission case without being interfered by these continuously variable transmissions, and the vehicle can go straight. At this time, the rotation difference that occurs between the left and right motor shafts can be alleviated by the gear reducer, and the influence on the drive shaft can be almost eliminated, and the straight line of the vehicle can be secured.

[Brief description of drawings]

FIG. 1 is a side view of a power carrier according to an embodiment of the present invention.

FIG. 2 is a plan view of a part of the frame and power unit of the power carrier.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is a sectional view taken along line 4-4 of FIG.

5 is an enlarged vertical sectional view of the hydrostatic continuously variable transmission shown in FIG.

6 is an enlarged sectional view taken along line 6-6 of FIG.

7 is a sectional view taken along line 7-7 of FIG.

FIG. 8 is a view taken in the direction of arrow 8 in FIG.

9 is an enlarged sectional view taken along line 9-9 of FIG.

10 is a sectional view taken along line 10-10 of FIG.

FIG. 11 is a hydraulic circuit diagram of the left and right hydrostatic oil break transmissions in FIG.

[Explanation of symbols]

 1 Power Transport Vehicle as a Power Work Vehicle 3 Frame 4 Power Unit 7 Crawler as a Traveling Device 18 Mission Case 20 Motor Bed 21 Internal Engine as a Motor 23 Crankshaft 25 Crankshaft 25 Hydrostatic Stepless Transmission 26 Drive Shaft 27 Reducer 28 Case Main body 30 Brake cover 33 Drive gear as a drive transmission wheel 34 First stepped gear as a stepped transmission wheel 35 Second stepped gear as a stepped transmission wheel 36 Driven gear as a driven transmission wheel 39 Distribution plate 42 Hydraulic pump 43 hydraulic motor 44 pump shaft 51 motor shaft 56 hydraulic closed circuit 59 replenishing pump 60 oil sump 65 oil filter 67 input shaft 87 void space 88 brake chamber 89 brake 95 actuating lever 96 relay shaft 98 outer lever 99 inner lever 104 as a brake operating member Handle lever

Claims (6)

[Claims] 1. A pair of left and right drive shafts (26), which are rotatable relative to each other, are supported on the lower end of a mission case (18) fixed to a frame (3) of a vehicle, and the drive shafts (26) are braked. Left and right pair of brakes (89)
On both sides of the lower part of the mission case (18), and on both side surfaces of the upper part of the mission case (18) via a pair of speed reducers (27) disposed inside thereof, the left and right drive shafts (26 A pair of left and right hydrostatic continuously variable transmissions (25) connected to each other are attached to define a space (87) between each continuously variable transmission (25) and the brake (89) on the same side. A drive unit for a power work vehicle, wherein an inner end of a traveling means (7) mounted on an outer end of each drive shaft (26) is projected into the empty space (87) on the same side. 2. The drive transmission wheel (33) according to claim 1, wherein each speed reducer (27) is fixed to a motor shaft (51) of the hydrostatic continuously variable transmission (25) on the same side. ) And a driven transmission wheel (36) fixedly mounted on the drive shaft (26) on the same side, are connected via at least two stepped transmission wheels (34, 35) to provide a motor shaft (51). The drive device for a power work vehicle, wherein the rotation of the vehicle is reduced by at least three stages and transmitted to the drive shaft (36). 3. The distribution plate (39) having a hydraulic closed circuit (56) of each hydrostatic continuously variable transmission (25) according to claim 1 or 2, on the outer surface of the mission case (18). A replenishment pump (59) that removably joins is attached to the distribution plate (39) to replenish the hydraulic closed circuit (56) with hydraulic oil, and the suction port of this replenishment pump (59) and the oil that covers it. A drive device for a power work vehicle, wherein the filter (65) is immersed in an oil sump (60) in the mission case (18). 4. The pair of left and right case bodies (28) according to claim 1, 2 or 3, which are joined to each other.
And a pair of left and right brake covers (30) that are joined to the lower outer surfaces of both case halves (28) to define a pair of brake chambers (88) between them and form a mission case (18). , The same half of the case half (28) and the brake cover (30) support the drive shaft (26) of the same side, and the brake (89) capable of braking the drive shaft (26) is provided on the same side. A drive device for a power work vehicle, which is housed in a brake chamber (88). 5. A relay shaft (96) according to claim 4, wherein each case half (28) is supported above said traveling means (7) by a relay shaft (96) passing therethrough, the inside of said relay shaft (96). Attach the inner lever (99) fixed to the end to the brake (8) on the same side.
9) The operating lever (95) is attached to the mission case (18).
While interlocking in the inside, an external lever (98) fixed to the outer end of the relay shaft (96) is connected to an external brake operating member (10).
4) A drive device for a power work vehicle, characterized in that it is interlocked. 6. A mission case (18), a prime mover (21) mounted on the mission case (18) via a prime mover bed (20), a pump shaft (44) and a motor shaft (51) arranged in parallel. ), And a pair of left and right hydrostatic continuously variable transmissions (25) mounted on the left and right side surfaces of the upper part of the mission case (18) and supported on the lower part of the mission case (18). Pair of left and right drive shafts (26) and a pair of left and right reducers for decelerating and transmitting the rotation of each motor shaft (51) in the mission case (18) to the drive shaft (26) on the same side by at least three stages. (27) constitutes a power unit (4), and the output shaft (23) of the prime mover (21) is connected to one pump shaft (44) via the transmission (18), and
The left and right pump shafts (44) are connected to each other, and each drive shaft (2
The inner end of the traveling means (7) mounted on the outer end of (6) is provided with a space (8) between the continuously variable transmission (25) and the drive shaft (26) on the same side.
7) A drive device for a power work vehicle, characterized in that