JPH10281265A - Reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage of a bearing due to a foreign matter, such as wear powder and to perform stable operation of a rotary shaft or a reduction mechanism for a long period. SOLUTION: By setting the outside diameter D of a nut member 46 larger than the diameter (d) of an outer ring 16B, the upper side of the upper bearing 16 is covered with a nut member 46 and a taper surface 47 is formed on the upper surface of the nut member 46. This constitution flies a foreign matter A, settled in lubrication oil to the outer peripheral side of the nut member 46 along the taper surface 47 by the centrifugal force of the nut member 46 rotated together with an output shaft 18, and captures the foreign matter in a recessed groove 45 formed in the shaft support part 44 of a lower housing 43. As a result, the upper bearing 16 is prevented from damage due to mixture of the foreign matter A, mixed in the lubrication oil, in the upper bearing 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed reducer suitable for use in a turning device such as a hydraulic excavator or a hydraulic crane.

[0002]

2. Description of the Related Art A turning device for turning an upper revolving structure such as a hydraulic excavator or a hydraulic crane on a lower traveling structure includes:
Generally, a reduction gear for increasing the output of the rotation source is mounted.

[0003] Therefore, a description will be given of an example in which this kind of conventional reduction gear is applied to a turning device of a hydraulic shovel shown in FIGS. 4 and 5.

In the drawing, reference numeral 1 denotes a turning device disposed between a lower traveling structure of an excavator and an upper turning structure (both not shown). The turning device 1 is supplied with hydraulic oil from the outside. A hydraulic motor 2 as a rotation source for rotating the output shaft 2A by being discharged, and a reduction gear 4 for reducing the rotation of the output shaft 2A of the hydraulic motor 2 and transmitting the rotation to the turning wheel 3 are roughly constituted. I have.

The revolving wheel 3 is provided between the round body 5 of the lower traveling body and the revolving frame 6 of the upper revolving body.
, An outer ring 8 fixed to the turning frame 6, and a plurality of steel balls 9 (only one is shown) disposed between the outer ring 8 and the inner ring 7. Then, the outer ring 8 rotates around the inner ring 7 via the steel balls 9, and the outer ring 8 rotates.
When the revolving frame 6 rotates, the upper revolving unit rotates with respect to the lower traveling unit.

Reference numeral 10 denotes a grease bus provided on the inner peripheral side of the revolving wheel 3. The grease bus 10 is formed on the inner peripheral surface of the round body 5 in a concave annular shape over the entire circumference. And a grease for lubricating a meshing portion between the internal teeth 7A formed on the pinion and a pinion 19 described later.

Reference numeral 11 denotes a housing which forms an outer shell of the speed reducer 4 and is disposed vertically on the revolving frame 6. The housing 11 includes an upper housing 13 having an inner peripheral side serving as a speed reduction mechanism housing 12, A lower housing 15 provided with a shaft supporting portion 14 on the inner peripheral side has a hydraulic motor 2 fixed to an upper end of the upper housing 13.
The upper housing 13 and the lower housing 15 are fixed by a plurality of bolts, and the lower housing 15 is fixed on the revolving frame 6 by a plurality of bolts. Here, internal teeth 13 </ b> A are formed on the entire inner circumference of the upper housing 13.

[0008] Reference numeral 16 denotes an upper bearing provided between the shaft support portion 14 provided on the lower housing 15 and the output shaft 18. As shown in FIG.
And a plurality of rolling elements 16C provided between the inner ring 16A and the outer ring 16B to form a tapered roller bearing. I have. A lower bearing 17 is provided below the upper bearing 16 and provided between the shaft support portion 14 and the output shaft 18. The lower bearing 17 includes an inner ring 17 </ b> A fitted to the output shaft 18, An outer ring 17B attached to the lower center of the support portion 14 and a plurality of rolling elements 17C provided between the inner ring 17A and the outer ring 17B constitute a tapered roller bearing.

Reference numeral 18 denotes a shaft supporting portion 14 of the lower housing 15.
And an output shaft rotatably supported by the upper bearing 16 and the lower bearing 17. A tooth portion which is spline-coupled to a carrier 32 of a planetary gear mechanism 28 described later is provided on an outer periphery of an upper end of the output shaft 18. 18A is formed, and the tooth portion 18A is formed.
A screw portion 18B into which a nut member 33 described later is screwed is provided below A. The lower end of the output shaft 18 projects below the turning frame 6 to form a pinion 19, which meshes with internal teeth 7 </ b> A formed on the inner ring 7 of the turning wheel 3. As a result, the output shaft 18 revolves while rotating along with the pinion 19 via the internal teeth 7A of the inner race 7, and the revolving force causes the revolving frame 6 to revolve via the housing 11.

Reference numeral 20 denotes an annular retainer which is inserted into the lower end of the output shaft 18. The retainer 20 is located between the pinion 19 of the output shaft 18 and the lower bearing 17.
7 are held. Reference numeral 21 denotes an annular partition plate provided between the lower bearing 17 and the retainer 20.
1 prevents the grease filled in the grease bath 10 from being ejected by the pumping action due to the engagement between the internal teeth 7 </ b> A of the turning wheel 3 and the pinion 19 and entering the housing 11.

Reference numeral 22 denotes an annular seal member provided between the upper bearing 16 and the lower bearing 17 and provided in the housing 11. The outer periphery of the seal member 22 is the shaft support portion 14 of the lower housing 15. And the inner peripheral side thereof is in liquid-tight sliding contact with the output shaft 18 with an appropriate elastic force. Then, the sealing member 22 seals the lubricating oil for lubricating the planetary gear mechanisms 23, 28 and the like in the speed reduction mechanism accommodating portion 12, and the grease bath 10
It separates from the grease filled inside.

Numeral 23 designates 1 which is located below the hydraulic motor 2 and disposed in the speed reduction mechanism accommodating portion 12 of the upper housing 13.
The planetary gear mechanism of the first stage is shown, and the planetary gear mechanism 23 meshes with a sun gear 24 spline-coupled to the output shaft 2A of the hydraulic motor 2, the sun gear 24 and the internal teeth 13A of the upper housing 13, The planetary gears 25 are roughly constituted by a plurality of planetary gears 25 (only one is shown) which revolves around the sun gear 24 while rotating around the sun gear 24, and a carrier 27 which rotatably supports the respective planetary gears 25 via pins 26. .

Reference numeral 28 denotes a second-stage planetary gear mechanism which is located below the planetary gear mechanism 23 and is disposed in the reduction mechanism accommodating portion 12 of the upper housing 13.
A sun gear 29 spline-coupled to an internal tooth provided on a carrier 27 of the planetary gear mechanism 23;
And a plurality of planetary gears 3 meshing with the internal teeth 13 </ b> A of the upper housing 13 and revolving while rotating around the sun gear 29.
0 (only one is shown) and a carrier 32 that rotatably supports each planetary gear 30 via a pin 31.

The internal teeth formed on the carrier 32 are spline-coupled to the teeth 18A of the output shaft 18 to transmit the revolution of each planetary gear 30 to the output shaft 18. Thereby, the rotation of the output shaft 2A of the hydraulic motor 2 is
The speed is reduced in two stages by the planetary gear mechanisms 23 and 28, and the output shaft 18 is rotated with a large torque.

Numeral 33 denotes a nut member located above the upper bearing 16 and disposed on the outer peripheral side of the output shaft 18. The nut member 33 is screwed into a screw portion 18 B of the output shaft 18. The upper bearing 16 moves in the axial direction of the output shaft 18 and is positioned in the axial direction between the output shaft 18 and the shaft support 14 of the lower housing 15.

The reduction gear 4 according to the prior art has the above-described configuration. When pressure oil is supplied and discharged from the outside to the hydraulic motor 2 and the output shaft 2A is driven to rotate, the rotation is reduced within the housing 11 of the reduction gear 4. Thus, the speed is reduced in two stages by the planetary gear mechanisms 23 and 28, and a high torque rotational force is transmitted to the output shaft 18.

The pinion 19 of the output shaft 18 meshes with the internal teeth 7A of the revolving wheel 3, and the revolving wheel 3 has the inner wheel 7 fixed to the round body 5 of the lower traveling body and the outer wheel 8 formed of the upper revolving body. Since the pinion 19 is fixed to the revolving frame 6, the pinion 19 revolves while rotating through the internal teeth 7 </ b> A of the inner race 7, and the revolving is transmitted from the output shaft 18 to the revolving frame 6 via the housing 11, and Turns on the undercarriage.

[0018]

In the speed reducer 4 according to the prior art described above, the planetary gear mechanisms 23, 28 and the like are always lubricated by the lubricating oil stored in the housing 11. The planetary gear mechanism 23,
As shown in FIG. 5, foreign matter A such as abrasion powder generated by the engagement of the gears constituting the gear 28 sinks in the lubricating oil and enters between the inner ring 16A and the outer ring 16B of the upper bearing 16. As a result, the rolling elements 16C and the like of the upper bearing 16 are damaged, and there is a problem that the smooth rotation of the output shaft 18 is hindered.

The foreign matter A passing through the upper bearing 16 is
When the seal member 22 enters the sliding contact portion between the seal member 22 and the output shaft 18, the seal member 22 is worn or damaged at an early stage, and the lubricating oil leaks from the housing 11. There is a problem that the stable operation such as is impaired.

The present invention has been made in view of the above-described problems of the prior art, and prevents a bearing or the like from being damaged by foreign matter such as abrasion powder, and operates a rotating shaft or a speed reduction mechanism stably for a long period of time. It is an object of the present invention to provide a speed reducer that can be driven.

[0021]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a housing vertically arranged with an upper portion serving as a reduction mechanism accommodating portion and a lower portion serving as a shaft support portion, and a speed reduction mechanism for the housing. A speed reduction mechanism provided in the housing portion for reducing the rotation of the rotation source, an output shaft provided through the shaft support portion of the housing and outputting the rotation reduced by the speed reduction mechanism, and a shaft support portion of the housing. A bearing provided rotatably supporting the output shaft, and a nut member provided on the outer peripheral side of the output shaft so as to be located above the bearing and positioning the bearing between the shaft support portion of the housing; Applied to a speed reducer composed of

A feature of the structure adopted by the invention of claim 1 is that the nut is provided to prevent foreign matters mixed in lubricating oil for lubricating the speed reduction mechanism in the housing from entering the bearing. The outer diameter of the member is set to be equal to or larger than the diameter of the outer ring constituting the bearing.

With this configuration, since the upper side of the bearing is covered by the nut member having an outer diameter larger than the diameter of the outer ring constituting the bearing, it is assumed that foreign matter has entered the lubricating oil for lubricating the speed reduction mechanism. Also, the foreign matter can be prevented from entering the bearing by the nut member.

Further, the invention according to claim 2 is characterized in that the upper surface of the nut member is provided with a tapered surface whose outer peripheral side is gradually inclined downward.

With this configuration, foreign matter that has fallen on the upper surface of the nut member can be guided to the outer peripheral side of the bearing along the tapered surface.

Further, according to the invention of claim 3, the shaft supporting portion of the housing is provided with an annular concave groove located on the outer peripheral side of the bearing for catching foreign matter scattered from the outer peripheral side of the nut member. It is in the configuration.

With this configuration, the foreign matter mixed in the lubricating oil scatters from the outer peripheral side of the nut member and is captured in the concave groove. In this case, the foreign matter trapped in the concave groove is accumulated in the concave groove by its own weight, so that even if the lubricating oil is agitated by the operation of the speed reduction mechanism, the foreign substance can be prevented from entering the bearing.

According to a fourth aspect of the present invention, a detent pin inserted into a pin hole provided in the nut member is provided on a lower surface of the carrier of the speed reduction mechanism which meshes with the rotation shaft. At least a part of the lower surface is configured to face the upper surface of the inner race constituting the bearing.

With this configuration, for example, even if the locking pin is loosened with respect to the carrier at the time of operation of the speed reduction mechanism, the lower surface of the locking pin contacts the upper surface of the inner ring of the bearing. In addition, the locking pin can be prevented from coming off the carrier, and the nut member can be kept in the locking state.

Further, according to a fifth aspect of the present invention, the nut member is provided with a plurality of pin holes on a circumference having a constant radius, and the detent pin is inserted into any one of the pin holes. And that

According to the above configuration, the rotation stop pin provided on the carrier of the speed reduction mechanism is inserted into one of the plurality of pin holes provided on the nut member, so that the rotation of the nut member with respect to the rotating shaft can be easily stopped. It can be carried out.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 show an example in which the speed reducer according to the present invention is used for a turning device of a hydraulic shovel. In the present embodiment, the same components as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 41 denotes a reduction gear according to the present embodiment.
2 and the lower housing 43
However, the configuration of the lower housing 43 is different from that of the prior art.

43 is a lower housing 15 according to the prior art.
Instead of the lower housing applied to the present embodiment, the lower housing 43 is a lower housing 1 according to the related art.
5, the upper end is fixed to the upper housing 13 by a plurality of bolts, and the lower end is fixed to the revolving frame 6 by a plurality of bolts. A shaft support 44 for supporting the output shaft 18 via the upper bearing 16 and the lower bearing 17 is provided on the inner peripheral side of the lower housing 43, but on the upper surface side of the shaft support 44. Is an annular concave groove 4
5 are formed.

Here, the concave groove 45 is located on the outer periphery side of the outer ring 16B of the upper bearing 16 and is formed on the upper surface side of the shaft support portion 44 over the entire periphery, and is provided on the outer periphery side of a nut member 46 described later. Foreign matter A scattered from the air.

Numeral 46 denotes a nut member applied to the present embodiment in place of the nut member 33 according to the prior art. The nut member 46 is formed in a substantially hollow disk shape as shown in FIG. On the side, a female screw screwed into the screw portion 18B of the output shaft 18 is screwed. Here, the nut member 46
Has an outer diameter dimension D set to be equal to or greater than the diameter d of the outer ring 16B of the upper bearing 16 (D ≧ d), and covers the upper bearing 16 from above over the entire circumference (see FIG. 2).

Reference numeral 47 denotes a tapered surface formed on the upper surface of the nut member 46. The tapered surface 47 is formed so as to be gradually inclined downward toward the outer peripheral side, and is provided in the lubricating oil sealed in the housing 42. When the mixed foreign matter A falls on the nut member 46 by its own weight, the foreign matter A is guided to the outer peripheral side of the nut member 46.

Are four pin holes formed in the nut member 46. Each of the pin holes 48 is
6 on a circumference 49 (shown by a dashed line in FIG. 3) having a constant radius from the center of the axis. Then, by inserting a rotation-preventing pin 50 described later into any one of the pin holes 48, the nut member 4
6 is prevented from rotating with respect to the output shaft 18.

Reference numeral 50 denotes a locking pin provided on the lower surface of the carrier 32 constituting the planetary gear mechanism 28 and extending downward. The locking pin 50 is provided in each pin hole 4 of the nut member 46.
The diameter is smaller than 8. And the detent pin 5
0 is a fitting hole 5 formed in the lower surface of the carrier 32.
When the carrier 32 is press-fitted into the inside 1 and the carrier 32 is engaged with the tooth portion 18A of the output shaft 18, the lower end side of the locking pin 50 is inserted into any one of the pin holes 48 of the nut member 46. Thereby, the nut member 46 is stopped from rotating with respect to the output shaft 18.

In this case, each pin hole 48 of the nut member 46
Are provided on a circumference 49 having a constant radius, so that when the carrier 32 is engaged with the tooth portion 18A of the output shaft 18, the detent pin 50 is inserted into the four pin holes 48. One can be reliably inserted. This eliminates the need to tighten the nut member 46 into the screw portion 18B of the output shaft 18, for example, in order to align the detent pin 50 with the pin hole 48, and the detent of the nut member 46 can be easily performed. In addition to this, it is possible to prevent the smooth rotation of the upper bearing 16 and the like from being hindered by excessive tightening of the nut member 46.

As shown in FIG. 2, a part of the lower surface 50A of the rotation-stop pin 50 is formed on the inner race 16A of the upper bearing 16.
The mounting position with respect to the carrier 32 is considered so as to face the upper surface. As a result, even when the locking pin 50 is loosened in the fitting hole 51 of the carrier 32, the lower surface 50A of the locking pin 50 is fixed to the inner ring 16A of the upper bearing 16.
By contacting the upper surface, the rotation preventing pin 50 is prevented from coming off from the carrier 32, and the nut member 46 can be kept in the rotation stopped state.

The speed reducer 41 according to the present embodiment has the above-described structure. When pressure oil is supplied and discharged from the outside to the hydraulic motor 2, the output shaft 2A rotates.
The speed is reduced in two stages by the planetary gear mechanisms 23 and 28 in the housing 42, and a high torque rotational force is transmitted to the output shaft 18. As a result, the pinion 19 is
A revolves while rotating through A, and this revolution is transmitted from the output shaft 18 to the revolving frame 6 via the housing 42,
The upper revolving unit performs a turning operation on the lower traveling unit.

At this time, the planetary gear mechanisms 23 and 28 that operate to reduce the rotation of the output shaft 2A of the hydraulic motor 2 are always lubricated by the lubricating oil sealed in the housing 42, and the planetary gear mechanisms 23 and 28 The foreign substances A such as abrasion powder generated by the meshing of the respective gears settle down in the lubricating oil by their own weight.

However, in this embodiment, since the upper side of the upper bearing 16 is covered by the nut member 46 having an outer diameter D equal to or larger than the diameter d of the outer race 16B constituting the upper bearing 16, the lubricating oil After reaching the upper surface of the nut member 46, the foreign matter A that sediments is scattered around the nut member 46 by the centrifugal force of the nut member 46 that rotates together with the output shaft 18. Thus, the foreign matter A is captured in the concave groove 45 provided in the shaft support portion 44 of the lower housing 43 without entering the upper bearing 16.

In this case, the upper surface of the nut member 46 is formed with a tapered surface 47 inclined downward toward the outer peripheral side.
It can be reliably guided into the concave groove 45 along the tapered surface 47.

Then, the foreign matter A trapped in the concave groove 45
Is accumulated in the recessed groove 45 at a position lower than the upper surface of the outer ring 16B of the upper bearing 16 due to its own weight. Therefore, even if the lubricating oil is agitated by the operation of the planetary gear mechanisms 23 and 28, the foreign matter A is recessed. Upper bearing 16 beyond groove 45
Can be prevented from entering the inside.

Therefore, the foreign matter A in the lubricating oil is
To prevent damage to the rolling elements 16C of the upper bearing 16 and the like, and to smoothly rotate the output shaft 18 for a long period of time.
Also, a seal member 22 disposed below the upper bearing 16
It is also possible to prevent foreign matter A from entering the sliding contact portion between the motor and the output shaft 18 and the like, and the sealing property of the seal member 22 can be kept good.

Further, by setting the outer diameter D of the nut member 46 to be large, the nut member 46 is connected to the output shaft 18.
The torque when tightening the screw portion 18B can be increased. This makes it easier to manage the tightening torque for the nut member 46, and stabilizes the operation of the upper bearing 16 and the like positioned between the nut member 46 and the shaft support 44 of the housing 42.

Further, in this embodiment, the foreign matter A mixed in the lubricating oil enters the upper bearing 16 or the like by using the nut member 46 for positioning the upper bearing 16 or the like with the shaft supporting portion 44 of the housing 42. Since the configuration is such that it is possible to prevent the foreign matter A from entering the upper bearing 16 or the like, for example, it is possible to prevent an increase in the number of parts and the number of assembling steps as compared with a case in which a separate component is provided only for preventing .

In the above embodiment, the reduction gear provided with the two-stage planetary gear mechanism has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this.
The present invention may be applied to a reduction gear provided with a planetary gear mechanism having more than one stage, and further may be applied to a reduction gear provided with, for example, a type of reduction mechanism using no planetary gear.

In the above embodiment, the case where the upper bearing 16 and the lower bearing 17 are used as the bearing for supporting the output shaft 18 has been described as an example. However, the present invention is not limited to this, and one bearing is used. Alternatively, the output shaft may be supported by three or more bearings.

Further, in the above-described embodiment, the case where the tapered roller bearing is used as the upper bearing 16 and the lower bearing 17 has been described as an example. However, the present invention is not limited to this, and the load in the radial direction and the thrust direction is received. Other types of bearings, such as ball bearings positioned by bearing nut members, may be used.

[0054]

As described above in detail, according to the first aspect of the present invention, the outer diameter of the nut member for positioning the bearing with respect to the shaft supporting portion of the housing is set to be equal to or larger than the diameter of the outer ring constituting the bearing. With this configuration, even if foreign matter such as abrasion powder enters the lubricating oil for lubricating the speed reduction mechanism, the nut member covering the upper side of the bearing can reliably prevent the foreign matter from entering the bearing. As a result, it is possible to prevent the bearing from being damaged by foreign matters in the lubricating oil, and to smoothly rotate the rotating shaft. In addition, it is possible to prevent the seal member disposed below the bearing from being damaged by foreign matter and to prevent the leakage of the lubricating oil from the inside of the housing, and to stably operate the speed reduction mechanism for a long period of time.

According to the second aspect of the present invention, since the taper surface whose outer peripheral side is gradually inclined downward is provided on the upper surface of the nut member, foreign matter that has fallen on the upper surface of the nut member is carried along the tapered surface. Can be guided to the outer peripheral side of the bearing, and the intrusion of foreign matter into the bearing can be more reliably prevented.

Further, according to the third aspect of the present invention, the shaft supporting portion of the housing is provided with an annular concave groove for catching foreign matter scattered from the outer peripheral side of the nut member.
Foreign matter scattered from the outer peripheral side of the nut member and captured in the concave groove is deposited in the concave groove by its own weight,
Even if the lubricating oil is agitated by the operation of the speed reduction mechanism,
Foreign matter can be prevented from entering the bearing.

According to the fourth aspect of the present invention, a locking pin inserted into a pin hole provided in the nut member is provided on the lower surface of the carrier of the speed reduction mechanism that meshes with the rotating shaft. Since at least a part of the lower surface is configured to face the upper surface of the inner ring of the bearing, for example, even if the detent pin is loosened with respect to the carrier during operation of the speed reduction mechanism, the lower surface of the detent pin is formed on the bearing. By contacting the upper surface of the inner race, the locking pin can be prevented from coming off from the carrier, and the nut member can be kept in the locking state.

Further, according to the fifth aspect of the present invention, the nut member is provided with a plurality of pin holes on a circle having a constant radius, and the detent pin is inserted into any one of the pin holes. Therefore, when the carrier is meshed with the rotating shaft, the locking pin can be reliably inserted into one of the plurality of pin holes. Thereby, for example, in order to align the locking pin with the pin hole, the work of tightening the nut member to the rotating shaft can be eliminated, and the rotation of the nut member can be easily stopped, and the excessive use of the nut member can be achieved. It is possible to prevent smooth rotation of the bearing from being hindered by proper tightening.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a speed reducer according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part showing an upper bearing, a nut member and the like in FIG. 1 in an enlarged manner.

FIG. 3 is an enlarged perspective view showing a nut member in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a conventional reduction gear transmission.

FIG. 5 is an enlarged sectional view showing an upper bearing, a nut member and the like in FIG. 5 in an enlarged manner.

[Explanation of symbols]

 2 Hydraulic motor (rotation source) 12 Reduction mechanism housing 16 Upper bearing 16A Inner ring 16B Outer ring 17 Lower bearing 18 Output shaft 23, 28 Planetary gear mechanism (reduction mechanism) 42 Housing 44 Shaft support 45 Concave groove 46 Nut member 47 Taper Surface 48 Pin hole 50 Lock pin 50A Bottom surface 51 Fitting hole

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kise 2492, Miyamachi, Shigaraki-cho, Koka-gun, Shiga Prefecture (72) Yasuyuki Okada 9-374 -4, Kibogaoka-Honcho, Konan-cho, Koga-gun, Shiga Prefecture

Claims (5)

[Claims] 1. A housing which is disposed in an up-down direction with an upper portion serving as a speed reduction mechanism housing portion and a lower portion serving as a shaft support portion,
A deceleration mechanism provided in the deceleration mechanism accommodating portion of the housing for decelerating the rotation of the rotation source; an output shaft provided through the shaft support portion of the housing for outputting the rotation decelerated by the deceleration mechanism; A bearing provided on the shaft support portion for rotatably supporting the output shaft, and a bearing provided on the outer peripheral side of the output shaft located above the bearing and provided between the shaft support portion of the housing. In a speed reducer comprising a nut member to be positioned, the outer diameter of the nut member is set to the outer diameter of the nut member in order to prevent foreign matter mixed in lubricating oil for lubricating the speed reducer in the housing from entering the bearing. A speed reducer, wherein the diameter is set to be equal to or larger than the diameter of an outer ring constituting a bearing. 2. The reduction gear transmission according to claim 1, wherein the upper surface of the nut member is provided with a tapered surface whose outer peripheral side is gradually inclined downward. 3. The shaft supporting portion of the housing is provided with an annular concave groove located on the outer peripheral side of the bearing for catching foreign matter scattered from the outer peripheral side of the nut member. 3. The reduction gear transmission according to 2. 4. A locking pin inserted into a pin hole provided in the nut member is provided on a lower surface of the carrier of the speed reduction mechanism that meshes with the rotation shaft, and at least a part of the lower surface of the locking pin is the said locking member. The reduction gear transmission according to claim 1, 2 or 3, wherein the reduction gear transmission has a configuration facing the upper surface of the inner ring constituting the bearing. 5. The nut member according to claim 1, wherein a plurality of pin holes are provided on a circumference having a constant radius, and wherein said locking pin is inserted into one of said pin holes.
5. The reduction gear transmission according to 2, 3, or 4.