JP6350390B2 - Drive unit for industrial vehicles - Google Patents

Description

  The present invention relates to a drive unit for an industrial vehicle.

  Patent Document 1 discloses a conventional drive unit for an industrial vehicle. The drive unit includes a housing, an axle shaft, a first conical roller bearing, and a second conical roller bearing. The first conical roller bearing and the second conical roller bearing are provided between the housing and the axle shaft, and the axle shaft can be rotated around the rotation axis with respect to the housing.

  The axle shaft has an axle as a first member that extends in the axial direction in the direction of the rotation axis, and a hub wheel as a second member that is fixed to the axle and extends in a cylindrical shape in the direction of the rotation axis.

  The first conical roller bearing has a first outer ring held by the housing and a first inner ring inserted through the axle and the hub wheel. The second conical roller bearing has a second outer ring held by the housing, and a second inner ring inserted through the axle and the hub wheel.

  The axle has a first body part, a first flange part, and a spline fitting part. The first body portion is inserted through the first inner ring. The first flange portion is formed integrally with the first main body portion, and is in contact with the first inner ring from the side opposite to the second inner ring in the rotation axis direction. The spline fitting portion is integrally formed with the first main body portion on the side opposite to the first flange portion in the rotation axis direction.

  The hub wheel has a second main body portion and a second flange portion. The second main body portion is inserted into the first inner ring and the second inner ring while the spline fitting portion is inserted therein. The second flange portion is formed integrally with the second main body portion, and is in contact with the second inner ring from the side opposite to the first inner ring in the rotation axis direction.

  In this drive unit, the axle spline fitting portion is fitted into the second main body portion of the hub wheel, and the nut is screwed into the male screw formed on the tip end side of the axle, thereby fixing the axle and the hub wheel. The At this time, when the nuts are tightened, the first and second flange portions approach each other in the direction of the rotational axis, whereby a preload is applied to the first and second conical roller bearings. A driving force is transmitted from the driving source to the first flange portion side of the axle. A wheel is connected to the second flange portion of the hub wheel. For this reason, the axle shaft is driven by the drive source to rotate the wheel.

JP 2006-240469 A

  By the way, in the conventional drive unit, if the nut is tightened excessively, the first and second flange portions are too close to each other in the rotational axis direction, and an excessive preload is applied to the first and second conical roller bearings. As a result, it is difficult to manage the preload of the first and second conical roller bearings within an appropriate range.

  For this reason, if an annular shim or the like that adjusts the distance between the first inner ring and the second inner ring in the direction of the rotational axis is provided, the industrial vehicle repeatedly moves forward and backward, or an impact acts on the wheels from the road surface or the like. As a result, there is a possibility that a minute slip is generated in the first and second members by a minute amount of spline fitting, and a relative slip may occur between the first and second members and the shim or the like. Even when the first conical roller bearing and the second conical roller bearing are separated from each other in the rotational axis direction to increase the support rigidity of the axle shaft, the relative positional deviation between the first and second conical roller bearings is likely to occur. That is the same. As a result, in this drive unit, there is a concern that durability may be reduced due to uneven wear or the like.

  The present invention has been made in view of the above-described conventional situation, and provides a drive unit for an industrial vehicle capable of suppressing a decrease in durability while managing the preload of the first and second conical roller bearings within an appropriate range. This is a problem to be solved.

A drive unit for an industrial vehicle according to the present invention is provided between a housing, an axle shaft, and the housing and the axle shaft, and allows the axle shaft to rotate about a rotation axis with respect to the housing. A conical roller bearing and a second conical roller bearing,
The axle shaft includes a first member extending in an axial shape in the rotational axis direction, and a second member fixed to the first member and extending in a cylindrical shape in the rotational axis direction,
The first conical roller bearing has a first outer ring held by the housing, and a first inner ring inserted through the first member,
The second conical roller bearing is a drive unit for industrial vehicles having a second outer ring held by the housing and a second inner ring inserted through the second member,
The first member is formed integrally with the first main body portion inserted into the first inner ring and the first main body portion, and the first inner ring from the opposite side to the second inner ring in the rotation axis direction. A first flange portion that contacts the first flange portion, and a spline fitting portion that is integrally formed with the first main body portion on the opposite side of the first flange portion in the rotational axis direction,
The second member is formed integrally with the second main body portion, the second main body portion being inserted into the second inner ring, and the spline fitting portion being inserted therein, and the second member in the rotation axis direction. A second flange abutting on the second inner ring from the side opposite to the first inner ring;
From the second inner ring side in the rotation axis direction to the first main body part or the first inner ring, and from the first inner ring side in the rotation axis direction to the second main body part or the second inner ring. A distance adjusting means that abuts and adjusts the distance between the first inner ring and the second inner ring in the rotational axis direction;
Provided between at least one of the first main body and the second main body and the distance adjusting means, and fixing the position of the distance adjusting means around the rotation axis with respect to the first member and the second member. And a fixing means.

  In the industrial vehicle drive unit of the present invention, the interval adjusting means adjusts the interval between the first inner ring and the second inner ring in the rotational axis direction, so that the preload of the first and second conical roller bearings can be managed within an appropriate range.

  Further, in this industrial vehicle drive unit, the fixing means fixes the position around the rotation axis with respect to the first member and the second member of the distance adjusting means. As a result, even if the first and second members have a small backlash of spline fitting and the industrial vehicle repeats forward / backward movement or an impact is applied to the wheels from the road surface or the like, Relative slip is unlikely to occur between the first and second members and the distance adjusting means.

  Therefore, in the drive unit for industrial vehicles of this invention, the fall of durability can be suppressed, managing the preload of a 1st, 2nd conical roller bearing in the appropriate range.

  The fixing means may have a keyway and a fixing key that fits into the keyway. The keyway and the fixed key can be provided between at least one of the first main body portion and the second main body portion and the interval adjusting means. In this case, an increase in manufacturing cost can be suppressed by a simple keyway and a fixed key.

  The interval adjusting means has a cylindrical shape extending in the direction of the rotation axis, is in contact with the first inner ring, and has one spacer formed with a fixed key protruding toward the second main body, and around the rotation axis. It is desirable to have an annular, at least one shim that is disposed between the spacer and the second main body and has a keyway. It is desirable that another key groove is formed in the second main body portion.

  The interval adjusting means is formed in the first main body portion, has a fixed key protruding toward the second main body portion, and has an annular shape around the rotation axis, and is sandwiched between the first main body portion and the second main body portion. And at least one shim in which a keyway is formed. It is desirable that another key groove is formed in the second main body portion.

  According to these specific configurations, even if the dimensions of the first member and the second member have variations within the allowable error range at the time of manufacture, the number and thickness of shims are appropriately selected according to the variations. Thereby, the space | interval of the rotating shaft center direction of a 1st inner ring | wheel and a 2nd inner ring | wheel can be adjusted easily. As a result, in this drive unit, it is possible to reliably suppress a decrease in durability while managing the preload of the first and second conical roller bearings within an appropriate range.

  The key groove formed in the shim is preferably a bottomed groove that is recessed radially outward from the inner peripheral edge. In this case, since the shim has a substantially annular shape in which the outer peripheral edge side is continuous, deformation of the shim can be suppressed as compared with a case where a substantially C-shaped shim is employed.

  In addition, the key groove formed in the shim is preferably a bottomed groove that is recessed radially inward from the outer peripheral edge. Also in this case, since the shim has a substantially annular shape in which the inner peripheral edge side is continuous, deformation of the shim can be suppressed as compared with the case where a substantially C-shaped shim is employed. In particular, in this case, since the inner peripheral edge of the shim is circular and hardly changes in dimensions, variations in shim accuracy can be reduced. As a result, the shim is not easily displaced from the rotational axis.

  The drive unit for industrial vehicles of this invention can suppress the fall of durability, managing the preload of a 1st, 2nd conical roller bearing in the appropriate range.

FIG. 1 is a schematic side view of an industrial vehicle to which the drive unit of the first embodiment is applied. FIG. 2 is a schematic cross-sectional view showing the AA cross section of FIG. 1 in the drive unit of the first embodiment. FIG. 3 is a partial schematic cross-sectional view showing an enlarged main part of FIG. 2 according to the drive unit of the first embodiment. FIG. 4 is an exploded perspective view illustrating the first and second members and the interval adjusting member according to the drive unit of the first embodiment. FIG. 5 is a partial schematic cross-sectional view showing a cross section similar to FIG. 3 according to the drive unit of the second embodiment. FIG. 6 is an exploded perspective view illustrating the first and second members and the interval adjusting member according to the drive unit of the second embodiment. FIG. 7 is a partial schematic cross-sectional view showing a cross section similar to FIG. 3 according to the drive unit of the third embodiment. FIG. 8 is a partial schematic cross-sectional view showing an enlarged main part of FIG. 7 according to the drive unit of the third embodiment. 9A is an exploded perspective view showing a modified example of the fixed key and the key groove, and FIG. 9B is an exploded perspective view showing another modified example of the fixed key and the key groove.

  Embodiments 1 to 3 embodying the present invention will be described below with reference to the drawings.

Example 1
As shown in FIG. 1, the drive unit 1 of Example 1 is an example of the specific aspect of the drive unit for industrial vehicles of this invention. This drive unit 1 is used in a battery-driven reach forklift 9. The reach forklift 9 is an example of the “industrial vehicle” in the present invention.

  As shown in FIG. 1, in the reach forklift 9, the left side in FIG. 1 that is the pair of left and right forks 20 is the front side, and the right side in FIG. 1 that is the vehicle body 8 side is the rear side. Further, the lower side in FIG. 1 which is the ground side is the lower side, and the upper side in FIG. 1 is the upper side. Further, the front side of the sheet of FIG. 1 which is the left hand side of the driver who rides forward on the reach-type forklift 9 is the left side, and the back side of the sheet of FIG. 1 which is the driver's right hand side is the right side. The directions shown for the drive unit 1 in the drawings after FIG. 2 are all displayed in correspondence with the directions shown in FIG. 1, with the steerable rear wheel 6 facing the forward direction as a reference.

  As shown in FIG. 1, a pair of left and right reach legs 7 extend forward on the vehicle body 8 of the reach type forklift 9. A front wheel 5 is provided at each front end of each reach leg 7. On the other hand, a rear wheel 6 as a drive wheel and a caster wheel (not shown) are provided at the rear end of the bottom of the vehicle body 8. A caster wheel (not shown) is disposed on the rear side in FIG.

  A mast 27 is erected in front of the front surface of the vehicle body 8. The mast 27 is movable in the front-rear direction along each reach leg 7 by being driven by a hydraulic cylinder (not shown). A pair of left and right forks 20 are disposed on the front side of the mast 27 via a lift bracket 21. Each fork 20 can be moved up and down along the mast 27 by being driven by a hydraulic cylinder (not shown).

  A standing-type cab 24 is provided at the rear of the vehicle body 8. A steering table 25 in the cab 24 is provided with a steering handle 26 that performs a steering operation of the rear wheel 6. On the bottom side of the vehicle body 8, a drive unit 1 that drives the rear wheels 6 by a motor M1 and a battery B1 that is a power source of the motor M1 are disposed.

  As shown in FIG. 2, the drive unit 1 includes a housing 10, a transmission mechanism 40, an axle shaft 100, a first conical roller bearing 160, and a second conical roller bearing 170.

  The housing 10 includes a housing body 11 in which a cavity is formed, an upper cover 18 attached to the upper part of the housing body 11, and a lower cover 19 attached to the lower part of the housing body 11. Inside the housing 10, housing spaces S1, S2, and S3 that are in communication with each other are formed.

  In the housing space S <b> 1, a downwardly recessed recess formed in the upper portion of the housing body 11 is closed from above by the upper cover 18. In the accommodation space S <b> 2, a left and right cavity formed in the lower portion of the housing body 11 is closed from the right side by the lower cover 19. The accommodation space S3 is a cavity formed in the middle portion of the housing body 11 and extending in the vertical direction, and communicates with a right region of the accommodation space S1 and a right region of the accommodation space S2.

  On the upper surface of the upper cover 18, a substantially cylindrical supported portion 18A having a steering axis X2 as a central axis is projected upward. The internal space of the supported portion 18A communicates with the accommodation space S1. The supported portion 18A is inserted into a support portion 8A provided in the vehicle body 8, and is supported by the support portion 8A so as to be rotatable around the steering axis X2.

  A gear wheel 16 having a steering axis X2 as a central axis is fixed to the upper surface of the upper cover 18. The gear wheel 16 is connected to the steering handle 26 by a transmission gear group (not shown). The operation of the steering handle 26 is transmitted to the drive unit 1 via the gear wheel 16, and the drive unit 1 rotates around the steering axis X2. As a result, the rear wheel 6 is steered in conjunction with the operation of the steering handle 26.

  The transmission mechanism 40 includes a drive shaft 49, a first transmission shaft 48, a second transmission shaft 47, bearings 61, 62, 63, 64, 65, bevel gears 41, 42, 43, 44 and a drive bevel gear 45. ing.

  The drive shaft 49 is inserted into the supported portion 18A and extends in the vertical direction. Although not shown, a motor M1 shown in FIG. 1 is supported on the upper portion of the support portion 8A. The upper end portion of the drive shaft 49 is connected to the rotation shaft of the motor M1 so as to be integrally rotatable. As shown in FIG. 2, the lower end portion of the drive shaft 49 is rotatably supported by a bearing 61 in the accommodation space S1. The first transmission shaft 48 extends in the vertical direction on the right side of the drive shaft 49 in the accommodation space S <b> 1 and is rotatably supported by bearings 62 and 63. The second transmission shaft 47 extends in the vertical direction in the accommodation space S3 and is rotatably supported by the bearings 64 and 65. The upper end portion of the second transmission shaft 47 is located in the accommodation space S1. The lower end portion of the drive shaft 47 is located in the accommodation space S2.

  The bevel gear 41 is fixed to the lower end portion of the drive shaft 49 so as to be integrally rotatable. The bevel gear 42 is fixed to the first transmission shaft 48 so as to be integrally rotatable, and meshes with the bevel gear 41. The bevel gear 43 is fixed to a portion of the first transmission shaft 48 located below the bevel gear 42 so as to be integrally rotatable. The bevel gear 44 is fixed to the upper end of the second transmission shaft 47 so as to be integrally rotatable, and meshes with the bevel gear 43. The drive bevel gear 45 is fixed to the lower end portion of the second transmission shaft 47 so as to be integrally rotatable.

  As shown in FIG. 3 in an enlarged manner, the axle shaft 100, the first conical roller bearing 160, and the second conical roller bearing 170 are disposed in the accommodation space S2.

  A first outer ring holding portion 16, a first outer ring regulating surface 16D, and a seal holding portion 15 are formed on the left end 12L side of the inner peripheral surface 12 of the housing body 11 that defines the housing space S2. The first outer ring holding portion 16 is a cylindrical surface having a rotation axis X1 extending in the left-right direction as a central axis, and extends rightward from the left end portion 12L side of the inner peripheral surface 12. The inner peripheral surface 12 has a diameter that is stepwise reduced at a portion located on the right side of the first outer ring holding portion 16, and an annular left side surface at the step portion is a first outer ring regulating surface 16 </ b> D. . The seal holding portion 15 has a left end portion 12 </ b> L of the inner peripheral surface 12 that is expanded in a step shape as compared with the first outer ring holding portion 16. The seal holding portion 15 holds a seal member 15S.

  On the other hand, a second outer ring holding portion 17 and a second outer ring regulating surface 17D are formed on the right end portion 12R of the inner peripheral surface 12. The second outer ring holding portion 17 is a cylindrical surface having the rotation axis X1 as a central axis, and extends leftward from the right end portion 12R of the inner peripheral surface 12. The inner circumferential surface 12 has a diameter that is stepwise reduced at a portion located on the left side of the second outer ring holding portion 17, and an annular right side surface at the step portion is a second outer ring regulating surface 17 </ b> D. .

  The first conical roller bearing 160 and the second conical roller bearing 170 are provided between the inner peripheral surface 12 of the housing 10 and the axle shaft 100, and the axle shaft 100 can rotate about the rotation axis X <b> 1 with respect to the housing 10. It is said.

  More specifically, the first conical roller bearing 160 has a first outer ring 163 and a first inner ring 161. The first outer ring 163 is held in the housing 10 by being fitted into the first outer ring holding portion 16 and coming into contact with the first outer ring regulating surface 16D from the left side.

  The second conical roller bearing 170 has a second outer ring 173 and a second inner ring 171. The second outer ring 173 is fitted in the second outer ring holding portion 17 and is held by the housing 10 by coming into contact with the second outer ring regulating surface 17D from the right side.

  A distance W2 between the first outer ring 163 and the second outer ring 173 in the direction of the rotation axis X1 is regulated to have a predetermined size by the first outer ring regulating surface 16D and the second outer ring regulating surface 17D.

  As shown in FIGS. 3 and 4, the axle shaft 100 includes a first member 110, a second member 120, and a nut 140.

  The first member 110 is a multistage cylindrical shaft body having the rotation axis X1 as a central axis, and extends in the left-right direction. The first member 110 has a first body portion 111, a first flange portion 115, a spline fitting portion 113 and a male screw portion 114.

  A first inner ring holding portion 116 is formed at the left end of the columnar first main body 111. The first inner ring holding portion 116 is a cylindrical surface having the rotation axis X1 as a central axis. The portion of the first main body 111 located to the right of the first inner ring holding portion 116 is reduced in diameter in two stages.

  The first flange portion 115 is integrally formed with the first main body portion 111 at a position adjacent to the first inner ring holding portion 116 from the left side. The first flange portion 115 has a larger flange shape than the first inner ring holding portion 116. Of the right side surface of the first flange portion 115, an annular portion adjacent to the first inner ring holding portion 116 is a first inner ring regulating surface 115D.

  The first inner ring holding portion 116 is fitted into the first inner ring 161. The first inner ring regulating surface 115D is in contact with the first inner ring 161 from the left side. Thereby, the first conical roller bearing 160 enables the first member 110 to rotate around the rotation axis X <b> 1 with respect to the housing 10.

  On the outer peripheral edge side of the first flange portion 115, a seal sliding contact portion 115 </ b> T is formed that is recessed stepwise from the right side surface to the left. The seal member 15S held by the seal holding part 15 is in sliding contact with the seal sliding contact part 115T. Accordingly, the seal member 15S seals between the seal holding portion 15 and the seal sliding contact portion 115T so that the lubricating oil sealed in the accommodation spaces S1, S2, and S3 does not leak.

  A plurality of hub bolt holes 115 </ b> H are formed on the outer peripheral edge side of the first flange portion 115. The wheel of the rear wheel 6 is attached to the first flange portion 115 from the left side, and the plurality of hub bolts 6H are screwed into the hub bolt holes 115H, so that the rear wheel 6 is fixed to the axle shaft 100 so as to be integrally rotatable. Is done.

  The spline fitting portion 113 is integrally formed on the right side of the first main body portion 111 and extends to the right side in a substantially cylindrical shaft shape. A male spline groove is formed on the outer peripheral surface of the spline fitting portion 113.

  The male screw portion 114 is integrally formed on the right side of the spline fitting portion 113 and extends in a substantially cylindrical shaft shape on the right side. A male screw is formed on the outer peripheral surface of the male screw portion 114. Further, a loosening prevention groove 114J is recessed in the outer peripheral surface of the male screw portion 114.

  The second member 120 is a cylindrical body having the rotation axis X1 as a central axis, and extends in the left-right direction. The second member 120 has a second main body part 121 and a second flange part 125.

  A spline fitting hole 123 is formed at the center of the cylindrical second main body 121. The spline fitting hole 123 penetrates to the second flange portion 125. A female spline groove is formed on the inner peripheral surface of the spline fitting hole 123. The spline fitting portion 113 of the first member 110 is fitted into the spline fitting hole 123.

  The outer peripheral surface of the second main body 121 is a second inner ring holding portion 127. The second inner ring holding portion 127 is a cylindrical surface with the rotation axis X1 as the central axis.

  The second flange portion 125 is integrally formed with the second main body portion 121 at a position adjacent to the second inner ring holding portion 127 from the right side. The second flange portion 125 has a larger flange shape than the second inner ring holding portion 127. Of the left side surface of the second flange portion 125, an annular portion adjacent to the second inner ring holding portion 127 is a second inner ring regulating surface 125D.

  A driven bevel gear 125 </ b> G is formed on the outer peripheral edge side of the right side surface of the second flange portion 125. The driven bevel gear 125G meshes with the drive bevel gear 45 of the transmission mechanism 40.

  The drive unit 1 further includes an interval adjusting unit 180 and a fixing unit 190.

  The interval adjusting unit 180 includes one spacer 181 and at least one shim 182. In the present embodiment, two shims 182 are illustrated for convenience in each figure, but the number and thickness of the shims 182 are appropriately changed as described below.

  The fixing means 190 includes a fixing key 181K formed on the spacer 181, a key groove 182 </ b> S formed on at least one shim 182, and a key groove 121 </ b> S formed on the second main body 121.

  More specifically, the spacer 181 is a cylindrical body having the rotation axis X1 as a central axis, and extends in the left-right direction. The inner peripheral surface of the spacer 181 has a shape that allows the first main body 111 of the first member 110 to be inserted without rattling. The left side surface 181L and the right side surface 181R of the spacer 181 are flat surfaces orthogonal to the rotation axis X1.

  The fixed key 181K protrudes from the right side surface 181R of the spacer 181 to the right in a substantially prismatic shape. The outer surface of the fixed key 181K is substantially flush with the outer peripheral surface of the spacer 181. The inner surface of the fixed key 181K is substantially flush with the inner peripheral surface of the spacer 181.

  A plurality of shims 182 having the same shape and different thicknesses are prepared. The shim 182 is formed by cutting out a part of an annular flat plate member having the rotation axis X1 as a central axis.

  The keyway 182 </ b> S is a notched portion of the shim 182. As shown in FIG. 4, the inner periphery 182M and the outer periphery 182N of the shim 182 are divided by the keyway 182S.

  As shown in FIGS. 3 and 4, the key groove 121 </ b> S is a groove that is recessed rightward from the left side surface 121 </ b> L of the second main body 121. A part of the left end edge of the second inner ring holding portion 127 and a part of the left end edge of the spline fitting hole 123 are cut out by the keyway 121S.

  The nut 140 is a hex nut formed with a female screw. The nut 140 is formed with a locking portion 140J. The locking portion 140J protrudes in a cylindrical shape from the right surface of the nut 140 to the right.

  In the second member 120, the first inner ring holding portion 116 of the first member 110 is fitted into the first inner ring 161, and the first inner ring regulating surface 115D of the first member 110 is in contact with the first inner ring 161. It is fixed to the first member 110 as follows.

  First, the spacer 181 is inserted through the first main body 111 of the first member 110 from the right side, and the left side surface 181L is brought into contact with the first inner ring 161 from the right side.

  Next, at least one shim 182 is inserted through the first main body 111 from the right side and brought into contact with the right side surface 181R of the spacer 181. At this time, the keyway 182S of the shim 182 is fitted with the fixed key 181K of the spacer 181. Here, the dimensions of the first member 110, the second member 120, and the spacer 181 vary within a range of allowable errors during manufacturing. For this reason, the number and thickness of the shims 182 are selected so that the interval W1 between the first inner ring 161 and the second inner ring 171 in the direction of the rotation axis X1 is within an allowable range even if there is a variation.

  Next, the spline fitting hole 123 formed in the second main body portion 121 of the second member 120 is fitted into the spline fitting portion 113 of the first member 110. At this time, the keyway 121S of the second main body 121 is fitted with the fixed key 181K of the spacer 181. Then, the second inner ring holding portion 127 of the second main body 121 is fitted into the second inner ring 171. Further, the second inner ring regulating surface 125D is brought into contact with the second inner ring 171 from the right side. Accordingly, the second conical roller bearing 170 enables the second member 120 to rotate about the rotation axis X <b> 1 with respect to the housing 10.

  Next, the nut 140 is screwed into the male threaded portion 114 of the first member 110 by a torque wrench so that the left side surface 121L of the second main body portion 121 is brought into contact with at least one shim 182 from the right side. At this time, the first inner ring 161 and the second inner ring 171 are rotationally rotated by the first inner ring restricting surface 115D of the first member 110 and the second inner ring restricting surface 125D of the second member 120 that are close to each other in the direction of the rotational axis X1. It is pressed so as to approach each other in the X1 direction. The spacer 181 and at least one shim 182 are sandwiched between the first inner ring 161 and the left side surface 121L of the second main body 121, so that the first inner ring 161 and the second inner ring 171 are in the direction of the rotational axis X1. The interval W1 is adjusted so as to be within an allowable range.

  Thus, in the drive unit 1, an appropriate preload is applied to the first and second conical roller bearings 160 and 170. Further, the fixed key 181K of the spacer 181 is fitted into the key groove 182S of the shim 182 and the key groove 121S of the second main body 121, whereby the first and second members 110 of the spacer 181 and at least one shim 182 are provided. The position around the rotation axis X1 with respect to 120 is fixed.

  Finally, the nut 140 is plastically deformed so as to push the locking portion 140J of the nut 140 into the locking groove 114J of the male screw portion 114, whereby the nut 140 is prevented from loosening with respect to the male screw portion 114.

  In the drive unit 1 having such a configuration, when the motor M1 rotates forward or backward, the rotational driving force is transmitted to the axle shaft 100 via the transmission mechanism 40 and the driven bevel gear 125G, and the rear wheel 6 is driven. Thus, the reach forklift 9 can move forward and backward.

  Here, in the drive unit 1 of the first embodiment, the spacer 181 as the distance adjusting means 180 and at least one shim 182 adjust the distance W1 between the first inner ring 161 and the second inner ring 171 in the direction of the rotation axis X1. The preload of the first and second conical roller bearings 160 and 170 can be managed within an appropriate range.

  In the drive unit 1, the reach forklift 9 repeats forward and backward movement, whereby the axle shaft 100 is torsionally deformed, and the spline fitting portion 113 of the first member 110 and the spline fitting hole 123 of the second member 120. There is a risk that the spline fitting will be slightly rattling. Further, due to the engagement of the driving bevel gear 45 and the driven bevel gear 125G, a force acts to incline the second flange portion 125 of the second member 120 with respect to the rotation axis X1, and the first member 110 and There is a possibility that the spline fitting with the second member 120 is slightly rattled. Further, when an impact is applied to the rear wheel 6 from the road surface or the like, the axle shaft 100 is bent and deformed, and the spline fitting between the first member 110 and the second member 120 may be slightly rattled.

  Here, in the drive unit 1, the fixed key 181 </ b> K of the spacer 181 is fitted into the key groove 182 </ b> S of the shim 182 and the key groove 121 </ b> S of the second main body 121, so that the spacer 181 and the at least one shim 182 The positions around the rotation axis X1 with respect to the first and second members 110 and 120 are fixed. As a result, even if there is a slight backlash of the spline fitting between the first member 110 and the second member 120, the first member 110 and the second member 110, relative to each other between the spacer 181 and at least one shim 182. Slip is unlikely to occur.

  Therefore, in the drive unit 1 of the first embodiment, it is possible to suppress a decrease in durability while managing the preloads of the first and second conical roller bearings 160 and 170 within an appropriate range.

  Further, in this drive unit 1, since the simple fixed key 181K and the key grooves 182S and 121S can be easily formed in the spacer 181, the shim 182 and the second main body 121, it is possible to suppress an increase in manufacturing cost.

(Example 2)
As shown in FIGS. 5 and 6, in the drive unit of the second embodiment, the spacer 181 related to the drive unit 1 of the first embodiment is eliminated. Instead, in the drive unit of the second embodiment, a second main body portion 211 in which the shape of the first main body portion 111 according to the first embodiment is changed is formed on the first member 110. In the drive unit of the second embodiment, the interval adjusting member is at least one shim 182, and the fixing means is a fixing key 211 </ b> K formed in the second main body portion 211, a key groove 182 </ b> S of the shim 182, 2 with the keyway 121S of the main body 121. Other configurations of the second embodiment are the same as those of the first embodiment. For this reason, about the same structure as Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

  In the drive unit of the second embodiment, a first inner ring holding portion 116 is formed at the left end portion of the cylindrical second main body portion 211. A portion of the first main body 211 that is located to the right of the first inner ring holding portion 116 is slightly reduced in diameter in a step shape. The right side surface 211R of the second main body 211 is a flat surface orthogonal to the rotation axis X1.

  A fixed key 211K is formed on the first main body 211. The fixed key 211K protrudes from the right side surface 211R of the second main body 211 to the right in a substantially prismatic shape.

  In the second member 120, the first inner ring holding portion 116 of the first member 110 is fitted into the first inner ring 161, and the first inner ring regulating surface 115D of the first member 110 is in contact with the first inner ring 161. It is fixed to the first member 110 as follows.

  First, at least one shim 182 is inserted through the spline fitting portion 113 from the right side and brought into contact with the right side surface 211 </ b> R of the first main body portion 211. At this time, the keyway 182S of the shim 182 is fitted with the fixed key 211K of the first main body 211.

  Next, the spline fitting hole 123 formed in the second main body portion 121 of the second member 120 is fitted into the spline fitting portion 113 of the first member 110. At this time, the keyway 121 </ b> S of the second main body 121 is fitted with the spacer 211 </ b> K of the first main body 211.

  Next, the nut 140 is screwed into the male threaded portion 114 of the first member 110 by a torque wrench so that the left side surface 121L of the second main body portion 121 is brought into contact with at least one shim 182 from the right side. At this time, at least one shim 182 is sandwiched between the right side surface 211R of the first main body portion 211 and the left side surface 121L of the second main body portion 121, so that the rotation shafts of the first inner ring 161 and the second inner ring 171 are rotated. The interval W1 in the direction of the center X1 is adjusted so as to be within an allowable range.

  Thus, in this drive unit, an appropriate preload is applied to the first and second conical roller bearings 160 and 170. In addition, the fixed key 211K of the first main body 211 is fitted into the key groove 182S of the shim 182 and the key groove 121S of the second main body 121, whereby the first and second members 110 of the at least one shim 182, The position around the rotation axis X1 with respect to 120 is fixed.

  Therefore, in the drive unit of the second embodiment, similarly to the drive unit 1 of the first embodiment, it is possible to suppress a decrease in durability while managing the preloads of the first and second conical roller bearings 160 and 170 within an appropriate range.

(Example 3)
As shown in FIGS. 7 and 8, the drive unit according to the third embodiment includes a housing 30, a transmission mechanism 70, an axle shaft 300, a first conical roller bearing 360, and a second conical roller bearing 370.

  A housing space S31 is formed in the housing 30. A motor M3 is disposed in the area on the right side of the accommodation space S31. The motor M3 rotationally drives a rotation axis M3S having a rotation axis X1 extending in the left-right direction as a central axis.

  The transmission mechanism 70 is disposed on the left side of the motor M3 in the accommodation space S31. The transmission mechanism 70 includes a sun gear 71, a plurality of planetary gears 72, and a ring gear 73. The sun gear 71 is fixed to the rotary shaft M3S so as to be integrally rotatable. The ring gear 73 is fixed to the housing 30. Each planetary gear 72 meshes with the sun gear 71 and the ring gear 73.

  The axle shaft 300, the first conical roller bearing 360, and the second conical roller bearing 370 are disposed in the left region in the accommodation space S31. In the first embodiment, the second conical roller bearing 170 is located on the right side of the first conical roller bearing 360, whereas in the third embodiment, the second conical roller bearing 370 is the first conical roller bearing 360. It is located on the left side.

  A second outer ring holding portion 37, a second outer ring regulating surface 37D, and a seal holding portion 35 are formed on the left end portion 32L side of the inner peripheral surface 32 that divides the left region of the accommodation space S31. The second outer ring holding portion 37 is a cylindrical surface having a rotation axis X1 extending in the left-right direction as a central axis, and extends rightward from the left end portion 32L side of the inner peripheral surface 32. The inner circumferential surface 32 has a stepped diameter-reduced portion located on the right side of the second outer ring holding portion 37, and an annular left side surface of the step portion serves as a second outer ring regulating surface 37D. . The seal holding portion 35 has a left end portion 32 </ b> L of the inner peripheral surface 32 that is expanded in a step shape as compared with the second outer ring holding portion 37. A seal member 35 </ b> S is held by the seal holder 35.

  On the other hand, a first outer ring holding portion 36 and a first outer ring regulating surface 36D are formed on the right end portion 32R of the inner peripheral surface 32. The first outer ring holding portion 36 is a cylindrical surface having the rotation axis X1 as a central axis, and extends leftward from the right end portion 32R of the inner peripheral surface 32. The inner peripheral surface 32 has a stepped diameter-reduced portion located on the left side of the first outer ring holding portion 36, and an annular right side surface of the step portion serves as a first outer ring regulating surface 36D. .

  The first conical roller bearing 360 and the second conical roller bearing 370 are provided between the inner peripheral surface 32 of the housing 30 and the axle shaft 300, and the axle shaft 300 can be rotated around the rotation axis X1 with respect to the housing 30. It is said.

  More specifically, the first conical roller bearing 360 has a first outer ring 363 and a first inner ring 361. The first outer ring 363 is fitted in the first outer ring holding portion 36 and is held by the housing 30 by coming into contact with the first outer ring regulating surface 36D from the right side.

  The second conical roller bearing 370 has a second outer ring 373 and a second inner ring 371. The second outer ring 373 is fitted in the second outer ring holding portion 37 and is held in the housing 30 by coming into contact with the second outer ring regulating surface 37D from the left side.

  As shown in FIG. 8, the interval W32 between the first outer ring 363 and the second outer ring 373 in the direction of the rotation axis X1 is set to a predetermined size by the first outer ring restricting surface 36D and the second outer ring restricting surface 37D. Regulated by

  As shown in FIGS. 7 and 8, the axle shaft 300 includes a first member 310, a second member 320, and a nut 340. In the first embodiment, the second member 120 and the nut 140 are positioned on the right side with respect to the first member 110, whereas in the third embodiment, the second member 320 and the nut 340 are relative to the first member 310. Located on the left side.

  The first member 310 is a multistage cylindrical shaft having the rotation axis X1 as a central axis, and extends in the left-right direction. The first member 310 includes a first main body portion 311, a first flange portion 315, a spline fitting portion 313, and a male screw portion 314.

  A first inner ring holding portion 316 is formed at the right end portion of the columnar first main body portion 311. The first inner ring holding portion 316 is a cylindrical surface having the rotation axis X1 as a central axis. A portion of the first main body portion 311 located on the left side of the first inner ring holding portion 316 is reduced in diameter in a step shape. The left side surface 316L of the first inner ring holding portion 316 is a flat surface orthogonal to the rotation axis X1.

  The first flange portion 315 is integrally formed with the first main body portion 311 at a position adjacent to the first inner ring holding portion 316 from the right side. The first flange portion 315 has a larger flange shape than the first inner ring holding portion 316. Of the left side surface of the first flange portion 315, an annular portion adjacent to the first inner ring holding portion 316 is a first inner ring regulating surface 315D. On the outer peripheral edge side of the right side surface of the first flange portion 315, each planetary gear 72 of the transmission mechanism 70 is supported so as to be capable of rotating and revolving around the rotation axis X1.

  The first inner ring holding portion 316 is fitted into the first inner ring 361. The first inner ring regulating surface 315D is in contact with the first inner ring 361 from the right side. Accordingly, the first conical roller bearing 360 enables the first member 310 to rotate about the rotation axis X <b> 1 with respect to the housing 30.

  The spline fitting portion 313 is integrally formed on the left side of the first main body portion 311 and extends in a substantially cylindrical shaft shape on the left side. A male spline groove is formed on the outer peripheral surface of the spline fitting portion 313.

  As shown in FIG. 7, the male screw portion 314 is integrally formed on the left side of the spline fitting portion 313 and extends to the left in a substantially cylindrical shaft shape. A male screw is formed on the outer peripheral surface of the male screw portion 314. Further, a loosening prevention groove 314 </ b> J is recessed in the outer peripheral surface of the male screw portion 314.

  As shown in FIG.7 and FIG.8, the 2nd member 320 is a cylindrical body centering on the rotating shaft center X1, and is extended in the left-right direction. The second member 320 has a second main body portion 321 and a second flange portion 325.

  A spline fitting hole 323 is formed at the center of the cylindrical second main body 321. The spline fitting hole 323 penetrates to the second flange portion 325. A female spline groove is formed on the inner peripheral surface of the spline fitting hole 323. The spline fitting portion 313 of the first member 310 is fitted into the spline fitting hole 323.

  An outer peripheral surface of the second main body portion 321 is a second inner ring holding portion 327. The second inner ring holding portion 327 is a cylindrical surface having the rotation axis X1 as a central axis.

  The second flange portion 325 is integrally formed with the second main body portion 321 at a position adjacent to the second inner ring holding portion 327 from the left side. The second flange portion 325 has a larger flange shape than the second inner ring holding portion 327. Of the right side surface of the second flange portion 325, an annular portion adjacent to the second inner ring holding portion 327 is a second inner ring regulating surface 325D.

  A seal sliding contact portion 325T is formed on the outer peripheral edge side of the second flange portion 325. The seal sliding contact portion 325T is recessed leftward from the right side surface. The seal member 35S held by the seal holding portion 35 is in sliding contact with the seal sliding contact portion 325T and seals between the seal holding portion 35 and the seal sliding contact portion 325T.

  A plurality of hub bolt holes 325H are formed on the outer peripheral edge side of the second flange portion 325. The wheel of the rear wheel 6 is attached to the second flange portion 325 from the left side, and the plurality of hub bolts 6H are screwed into the hub bolt holes 325H, so that the rear wheel 6 is fixed to the axle shaft 300 so as to be integrally rotatable. Is done.

  The drive unit further includes an interval adjusting unit 380 and a fixing unit 390.

  The interval adjusting means 380 has one spacer 381 and at least one shim 182. The shim 182 is as described in the first embodiment. In this embodiment, in FIG. 7 and FIG. 8, two shims 182 are illustrated for convenience, but the number and thickness of the shims 182 are appropriately changed.

  The fixing means 390 includes a fixed key 311K formed in the first main body 311, a key groove 182S formed in at least one shim 182, and a key groove 381S formed in the spacer 381.

  More specifically, the fixed key 311K protrudes from the left side surface 316L of the first inner ring holding portion 316 in the first main body portion 311 to the left in a substantially prismatic shape.

  The spacer 381 is a cylindrical body having the rotation axis X1 as a central axis, and extends in the left-right direction. The inner peripheral surface of the spacer 381 has a shape that allows a reduced diameter portion on the right side of the first inner ring holding portion 316 in the first main body portion 311 to be inserted without rattling. The left side surface 381L and the right side surface 381R of the spacer 381 are flat surfaces orthogonal to the rotation axis X1.

  The key groove 381S is a groove that is recessed leftward from the right side surface 381R of the spacer 381.

  As shown in FIG. 7, the nut 340 is a hexagonal nut in which an internal thread is formed. The nut 340 is formed with a locking portion 340J. The locking portion 340J protrudes in a cylindrical shape from the left surface of the nut 340 to the left.

  As shown in FIGS. 7 and 8, the second member 320 has the first inner ring holding portion 316 of the first member 310 fitted into the first inner ring 361 and the first inner ring regulating surface 315 </ b> D of the first member 310 is the first. In a state of being in contact with the first inner ring 361, the first member 310 is fixed as follows.

  First, at least one shim 182 is inserted from the left through the reduced diameter portion on the right side of the first inner ring holding portion 316 in the first main body portion 311 and is brought into contact with the left side surface 316L of the first inner ring holding portion 316. At this time, the keyway 182S of the shim 182 is fitted with the fixed key 311K of the first main body 311. Here, the dimensions of the first member 310, the second member 320, and the spacer 381 vary within a range of allowable errors during manufacturing. For this reason, the number and the thickness of the shims 182 are selected so that the interval W31 between the first inner ring 361 and the second inner ring 371 in the direction of the rotation axis X1 is within the allowable range even if there is a variation.

  Next, the spacer 381 is inserted into the reduced diameter portion on the right side of the first inner ring holding portion 316 in the first main body portion 311 from the left side, and the right side surface 381R is brought into contact with at least one shim 182 from the right side. At this time, the keyway 381 </ b> S of the spacer 381 is fitted with the fixed key 311 </ b> K of the first main body 311.

  Next, the spline fitting hole 323 formed in the second main body portion 321 of the second member 320 is fitted into the spline fitting portion 313 of the first member 310. Then, the second inner ring holding part 327 of the second main body part 321 is fitted into the second inner ring 371. Further, the second inner ring regulating surface 325D is brought into contact with the second inner ring 371 from the left side. Accordingly, the second conical roller bearing 370 enables the second member 320 to rotate about the rotation axis X <b> 1 with respect to the housing 30.

  Next, the nut 340 is screwed into the male screw portion 314 of the first member 310 by a torque wrench, and the right side surface 321R of the second main body portion 321 is brought into contact with the left side surface 381L of the spacer 381 from the right side. At this time, the first inner ring 361 and the second inner ring 371 are rotated by the first inner ring restricting surface 315D of the first member 310 and the second inner ring restricting surface 325D of the second member 320 which are close to each other in the direction of the rotation axis X1. It is pressed so as to approach each other in the X1 direction. The spacer 381 and at least one shim 182 are sandwiched between the left side surface 316L of the first inner ring holding portion 316 and the right side surface 321R of the second main body portion 321, whereby the first inner ring 361, the second inner ring 371, The interval W31 in the direction of the rotation axis X1 is adjusted so as to be within an allowable range.

  Thus, in this drive unit, an appropriate preload is applied to the first and second conical roller bearings 360 and 370. Further, the fixed key 311K of the first main body 311 is fitted into the key groove 182S of the shim 182 and the key groove 381S of the spacer 381, so that the first and second members 310 of the spacer 381 and at least one shim 182 are included. , 320, the position around the rotation axis X1 is fixed.

  Finally, the nut 340 is plastically deformed so as to push the loosening prevention portion 340J of the nut 340 into the loosening prevention groove 314J of the male screw portion 314, whereby the nut 340 is prevented from loosening with respect to the male screw portion 314.

  In the drive unit of the third embodiment having such a configuration, when the motor M31 rotates forward or backward, the rotational driving force is transmitted to the axle shaft 300 via the transmission mechanism 70 and the first flange portion 315, and the rear wheel. 6 is driven, and the reach forklift 9 can move forward and backward.

  Here, in the drive unit 1, the position around the rotation axis X1 with respect to the first and second members 310 and 320 of the spacer 381 and at least one shim 182 is fixed by the fixed key 311K and the key grooves 182S and 381S. . As a result, in this drive unit 1, the first member 310 and the second member 320 have minute backlash of spline fitting, and the reach forklift 9 repeats forward and backward movement, or the wheel 6 receives an impact from the road surface or the like. Even if it acts, relative backlash is unlikely to occur between the first and second members 310 and 320, the spacer 381, and at least one shim 182 due to the play.

  Therefore, in the drive unit of the third embodiment, similarly to the drive unit 1 of the first and second embodiments, it is possible to suppress a decrease in durability while managing the preloads of the first and second conical roller bearings 360 and 370 within an appropriate range.

  In the above, the present invention has been described with reference to the first to third embodiments. However, the present invention is not limited to the first to third embodiments, and can be appropriately modified and applied without departing from the spirit of the present invention. Needless to say.

  For example, as shown in a modification of the keyway and the fixed key in FIG. 9, the shape and position of the keyway and the fixed key are not limited to the configurations of the first to third embodiments.

  In the modification shown in FIG. 9A, the keyway 182S according to the first embodiment is changed to the keyway 482S, and the fixed key 181K according to the first embodiment is changed to the fixed key 481K. Other configurations are the same as those of the first embodiment. The key groove 482S formed in the shim 182 is a bottomed groove that is recessed radially outward from the inner peripheral edge 182M of the shim 182. Corresponding to such a key groove 482S, the fixed key 481K formed in the spacer 181 has a smaller radial thickness than the fixed key 181K according to the first embodiment, and the inner periphery of the spacer 181. It is arranged to be biased to the surface side. According to this configuration, the shim 182 has a substantially annular shape in which the outer peripheral edge 182N side is continuous. Therefore, deformation of the shim 182 can be suppressed as compared with the case where the substantially C-shaped shim 182 is employed.

  In another modification shown in FIG. 9B, the keyway 182S according to the first embodiment is changed to the keyway 582S, and the fixed key 181K according to the first embodiment is changed to the fixed key 581K. Other configurations are the same as those of the first embodiment. The key groove 582S formed in the shim 182 is a bottomed groove that is recessed radially inward from the outer peripheral edge 182N of the shim 182. Corresponding to such a key groove 582S, the fixed key 581K formed on the spacer 181 has a smaller radial thickness than the fixed key 181K according to the first embodiment, and the outer peripheral surface of the spacer 181. It is biased to the side. According to this configuration, since the shim 182 has a substantially annular shape in which the inner peripheral edge 182M side is continuous, deformation of the shim 182 can be suppressed as compared with the case where the substantially C-shaped shim 182 is employed. In particular, in this case, since the inner peripheral edge 182M of the shim 182 has a circular shape and is difficult to change in dimensions, variation in accuracy of the shim 182 can be reduced. As a result, the shim 182 is not easily displaced from the rotation axis X1.

  The fixing means may have, for example, a hole that is recessed in the direction of the rotation axis and a convex portion that protrudes in the direction of the rotation axis and is fitted into the hole.

  The interval adjusting member may adjust the interval between the first inner ring and the second inner ring in the rotational axis direction by contacting the first main body portion and the second inner ring. Further, the interval adjusting member may adjust the interval between the first inner ring and the second inner ring in the rotational axis direction by contacting the first inner ring and the second inner ring.

  The present invention is applicable to industrial vehicles.

1 ... drive unit 9 ... industrial vehicle (reach forklift)
DESCRIPTION OF SYMBOLS 10, 30 ... Housing 100, 300 ... Axle shaft X1 ... Rotation axis 160, 360 ... 1st cone roller bearing 170, 370 ... 2nd cone roller bearing 110, 310 ... 1st member 120, 320 ... 2nd member 163, 363 ... First outer ring 161, 361 ... First inner ring 173, 373 ... Second outer ring 171, 371 ... Second inner ring 111, 211, 311 ... First main body 115, 315 ... First flange 113, 313 ... Spline fitting Joint portion 121, 321 ... second main body portion 125, 325 ... second flange portion W1, W31 ... distance between first inner ring and second inner ring in the rotational axis direction 180, 380 ... interval adjusting means 181, 381 ... spacer 182 ... Shim 190, 390 ... Fixing means 121S, 182S, 381S, 482S, 582S ... Key groove (121S ... Key of second body portion Groove, 182S, 482S, 582S ... shim of key groove, 381S ... spacer of the key groove)
181K, 211K, 311K, 481K, 581K ... fixed key (181K, 481K, 581K ... spacer fixed key, 211K, 311K ... first main unit fixed key)
182M ... inner periphery of shim 182N ... outer periphery of shim

Claims (6)

A first conical roller bearing and a second conical roller bearing provided between the housing, the axle shaft, and the housing and the axle shaft, the axle shaft being rotatable about a rotation axis with respect to the housing; With
The axle shaft includes a first member extending in an axial shape in the rotational axis direction, and a second member fixed to the first member and extending in a cylindrical shape in the rotational axis direction,
The first conical roller bearing has a first outer ring held by the housing, and a first inner ring inserted through the first member,
The second conical roller bearing is a drive unit for industrial vehicles having a second outer ring held by the housing and a second inner ring inserted through the second member,
The first member is formed integrally with the first main body portion inserted into the first inner ring and the first main body portion, and the first inner ring from the opposite side to the second inner ring in the rotation axis direction. A first flange portion that contacts the first flange portion, and a spline fitting portion that is integrally formed with the first main body portion on the opposite side of the first flange portion in the rotational axis direction,
The second member is formed integrally with the second main body portion, the second main body portion being inserted into the second inner ring, and the spline fitting portion being inserted therein, and the second member in the rotation axis direction. A second flange abutting on the second inner ring from the side opposite to the first inner ring;
From the second inner ring side in the rotation axis direction to the first main body part or the first inner ring, and from the first inner ring side in the rotation axis direction to the second main body part or the second inner ring. A distance adjusting means that abuts and adjusts the distance between the first inner ring and the second inner ring in the rotational axis direction;
Provided between at least one of the first main body and the second main body and the distance adjusting means, and fixing the position of the distance adjusting means around the rotation axis with respect to the first member and the second member. A drive unit for an industrial vehicle, further comprising a fixing means. The fixing means has a key groove and a fixing key that fits into the key groove,
2. The industrial vehicle drive unit according to claim 1, wherein the keyway and the fixed key are provided between at least one of the first main body portion and the second main body portion and the interval adjusting means. The interval adjusting means has a cylindrical shape extending in the direction of the rotation axis, and is in contact with the first inner ring and has one spacer formed with the fixed key protruding toward the second main body portion;
An annular shape around the rotation axis, and disposed in a state sandwiched between the spacer and the second main body, and having at least one shim in which the keyway is formed;
The drive unit for an industrial vehicle according to claim 2, wherein the second main body portion is formed with another key groove. The interval adjusting means is formed on the first main body portion and protrudes toward the second main body portion;
An annular shape around the rotation axis, and disposed between the first main body portion and the second main body portion, and having at least one shim in which the key groove is formed;
The drive unit for an industrial vehicle according to claim 2, wherein the second main body portion is formed with another key groove.   The industrial vehicle drive unit according to claim 3 or 4, wherein the key groove formed in the shim is a bottomed groove that is recessed radially outward from an inner peripheral edge.   The industrial vehicle drive unit according to claim 3 or 4, wherein the key groove formed in the shim is a bottomed groove that is recessed radially inward from an outer peripheral edge.

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