Bearing system and balancer

A bearing system can reduce the relative velocity between a bearing member and a rotation shaft and a rotating member to decrease a load on the bearing member although the rotation shaft and the rotating member rotate in opposite directions with the bearing member therebetween. The bearing system includes a case and a rotation shaft supported by the case. A rotating member is disposed coaxially outside the rotation shaft and rotates in the direction opposite to that of the rotation shaft. A housing is interposed between the rotation shaft and the rotating member and is fixed to the case. A bearing member that rotatably supports the rotating member is interposed between the housing and the rotating member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a bearing system and balancer.

2. Description of Related Art

Conventional engines for vehicles, such as motorcycle engines, have a balancer for reducing the vibration of the engines housed in the crankcase.

In general, the balancer is used to cancel an inertial force generated by a reciprocating component represented by a piston and a con'rod. The balancer has a balance weight that rotates in the direction opposite to that of the crankshaft at the same speed. The balance weight is disposed coaxially on the shaft of the crankshaft or on a shaft different from the crankshaft. In either case, the balance weight is driven by the power transmitted from the crankshaft.

The balance weight disposed coaxially with the crankshaft has a boss through which the shaft of the crankshaft passes. The boss is supported rotatably around the outer circumference of the shaft via a slide bearing. The slide bearing is press-fitted in a bearing hole opened in the boss. The shaft of the crankshaft is fitted in the slide bearing with clearance therebetween. The slide bearing is supported floatingly by the crankshaft and is rotated with the balance weight.

Referring to Japanese Patent Document JP-UM-B-50-32641, the slide bearing that supports the balance weight rotates in the direction opposite to that of the crankshaft. The reverse rotation doubles the relative velocity generated between the crankshaft and the slide bearing at the maximum, which increases the load on the slide bearing. This poses disadvantages of decreasing the life of the slide bearing and generating extraordinary wear, which may cause seizing, in the slide bearing.

SUMMARY OF THE INVENTION

The present invention relates to a bearing system for coaxially supporting a rotating member on a rotating shaft that rotates in one direction. The rotating member rotates in a direction opposite to that of the rotating shaft.

The present invention relates to a balancer having a balance weight on the shaft of a crankshaft. The balance weight rotates in the direction opposite to that of the crankshaft.

The present invention relates to a structure that reduces a load to a bearing member interposed between the balance weight and the shaft.

Accordingly, it is an object of the invention to provide a bearing system that can reduce the relative velocity between a bearing member and a rotation shaft and a rotating member to decrease a load on the bearing member although the rotation shaft and the rotating member rotate in opposite directions with the bearing member therebetween.

It is another object of the invention to provide a balancer that can reduce the relative velocity between the bearing member and a crankshaft and a balance weight to decrease the load on the bearing member although the crankshaft and the balance weight rotate in opposite directions with the bearing member therebetween.

To achieve the above object, a bearing system according to an aspect of the invention includes a case and a rotation shaft supported by the case. A rotating member is disposed coaxially outside the rotation shaft and rotating in the direction opposite to that of the rotation shaft. A housing is fixed to the case and interposed between the rotation shaft and the rotating member. A bearing member is interposed between the housing and the rotating member and rotatably supports the rotating member.

To achieve the above object, a balancer according to an aspect of the invention includes a crankcase and a crankshaft supported by the crankcase and having a shaft. A balance weight includes a boss through which the shaft passes coaxially and rotating in the direction opposite to that of the crankshaft. A housing is fixed to the crankcase and interposed between the shaft of the crankshaft and the boss of the balance weight. A bearing member is interposed between the housing and the boss and supports the boss rotatably.

According to an aspect of the present invention, the velocity of a bearing member relative to a component rotating in the opposite direction can be decreased because the bearing member is separated from the component. Therefore, the load on the bearing member can be reduced so that the life of the bearing member can be increased and the occurrence of extraordinary wear that may cause seizing or the like can be prevented.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the invention will be described below with reference toFIGS. 1 to 6.

FIG. 1discloses a vehicle, such as a motorcycle1, according to one embodiment of the present invention. The motorcycle1includes a frame2shaped like a cradle. The frame2supports a front fork3, a rear swing arm4, a fuel tank5, and a seat6.

The frame2supports, for example, an air-cooled four-cycle V-2 engine7. The engine7is disposed behind the front fork3and below the fuel tank5.

The engine7includes a crankcase8, a front cylinder9, and a rear cylinder10. As shown inFIG. 3, the crankcase8is divided into a left case8aand a right case8b. The left case8ahas a support wall11. The right case8bhas a support wall12. The support walls11and12extend along the length of the crankcase8and are opposed to each other along the width of the crankcase8with a space therebetween. Between the left case8aand the right case8b, a crank chamber13and a transmission chamber14are provided. The transmission chamber14is located behind the crank chamber13.

The outer side of the left case8ais covered by a clutch cover15. The clutch cover15forms a clutch chamber16between it and the left case8a. The outer side of the right case8bis covered by a generator cover17. The generator cover17forms a generator chamber18between it and the right case8b. The generator chamber18is located at the front end of the crankcase8.

The crankcase8houses a crankshaft20. The crankshaft20is an example of a rotation shaft, which is disposed horizontally along the width of the motorcycle1. The crankshaft20includes a pair of shafts21aand21b, a pair of crank webs22aand22b, and a crank pin23. The shaft21ais located at the left end of the crankshaft20. The shaft21bis located at the right end of the crankshaft20. The shaft21a, which is located at the left end of the crankshaft20, has a first portion24aand a second portion24b. The first and second portions24aand24bare disposed coaxially along the axis of the crankshaft20.

The first portion24aof the shaft21ais rotatably supported by the support wall11of the left case8avia a slide bearing25. The second portion24bof the shaft21aand the part of the shaft21aadjacent to the end relative to the second portion24bare introduced into the clutch chamber16. A reduction pinion26is fixed to the end of the shaft21a.

The shaft21b, which is disposed at the right end of the crankshaft20, is rotatably supported by the support wall12of the right case8bvia the slide bearing27. The crank webs22aand22bof the crankshaft20and the crank pin23are housed in the crank chamber13between the support walls11and12. A driving gear28is fixed on the shaft21bof the crankshaft20. The driving gear28is interposed between the crank web22bon the left and the support wall12and in the crank chamber13.

As shown inFIG. 4, the support wall11of the crankcase8has a feed passage29and a return passage30communicating with an oil pump (not shown). Lubricating oil fed from the oil pump is supplied via the feed passage29to the slide bearing25. Part of the lubricating oil that has lubricated the slide bearing25is introduced from the slide bearing25into the crank pin23via a delivery passage31aformed in the crankshaft20. The remainder of the lubricating oil that has lubricated the slide bearing25is introduced to the other lubrication part of the engine7through the return passage30.

Similarly, the support wall12of the crankcase8has a feed passage (not shown) for supplying lubricating oil to the slide bearing27. The lubricating oil that has lubricated the slide bearing27is introduced to the crank pin23through another delivery passage31bformed in the crankshaft20.

As shown inFIG. 2, the front cylinder9of the engine7houses a piston32, and the rear cylinder10houses a piston33. The pistons32and33connect to the crank pin23of the crankshaft20via con'rods34and35, respectively. In this embodiment, the piston32of the front cylinder9and the piston33of the rear cylinder10reciprocate substantially at the same timing, and as such, the crankshaft20rotates in one direction.

As shown inFIG. 3, the shaft21bof the crankshaft20projects outward from the support wall12of the right case8b. The right case8bhas a cylindrical part37that encloses the shaft21b. The projecting end of the cylindrical part37is covered by a case cover38. The case cover38and the cylindrical part37cooperate in defining a cam chamber39.

The shaft21bprojects externally from the cam chamber39through the case cover38. A cam driving gear41and a balancer driving gear42are fixed coaxially on the projecting end of the shaft21b.

As shown inFIG. 2, two cam shafts43and44are housed in the cam chamber39of the right case8b. The cam shafts43and44are disposed in the front and rear of the crankcase8in parallel with the crankshaft20. The rear cam shaft43includes a valve driving gear that drives the intake valve and the exhaust valve of the rear cylinder10. The front cam shaft44includes a valve driving cam that drives the intake valve and the exhaust valve of the front cylinder9.

Intermediate gears45and46are fixed to the ends of the cam shafts43and44, respectively. The intermediate gears45and46are in engagement with each other to thereby rotate the two cam shafts43and44synchronously. The rear cam shaft43includes a timing gear47. The timing gear47is in engagement with the cam driving gear41that rotates integrally with the crankshaft20. The cam shafts43and44rotate by the power transmitted from the crankshaft20.

As shown inFIG. 3, a gear transmission48is housed in the transmission chamber14of the crankcase8. The gear transmission48includes first and second change gear shafts49and50and a plurality of change gear trains51mounted on the change gear shafts49and50. The first and second change gear shafts49and50extend between the left case8aand the right case8band in parallel with the crankshaft20.

A friction clutch52is fixed to one end of the first change gear shaft49. The friction clutch52transmits or interrupts the torque of the crankshaft20to the gear transmission48and is housed in the clutch chamber16. The friction clutch52includes a reduction gear wheel53. The reduction gear wheel53is in engagement with the reduction pinion26on the crankshaft20. This engagement allows transmission of torque of the crankshaft20to the gear transmission48via the friction clutch52.

A relay shaft55is disposed at the front end of the crank chamber13. The relay shaft55extends between the left case8aand the right case8band in parallel with the crankshaft20. A driven gear56is fixed on the relay shaft55. The driven gear56is in engagement with the driving gear28that rotates with the crankshaft20. Thus, the relay shaft55rotates at a rotation speed as twice as that of the crankshaft20in the opposite direction.

A generator57is fixed to one end of the relay shaft55. The generator57is housed in the generator chamber18.

As shown inFIG. 3, the engine7includes a balancer60for reducing the vibration of the engine7. In one aspect, the balancer60is used to cancel the primary component of the inertial force generated by the reciprocating components, such as the pistons32and33and the con'rods34and35and includes a first balance weight61and a second balance weight62.

The first balance weight61is disposed on a dedicated balancer shaft63. The balancer shaft63extends between the support wall12of the right case8band the case cover38. The balancer shaft63is located in parallel with the shaft21bof the crankshaft20and at the rear of the shaft21b.

The end of the balancer shaft63projects outward from the cam chamber39through the case cover38. A driven gear64is fixed to the end of the balancer shaft63. The driven gear64is in engagement with the balancer driving gear42that rotates with the crankshaft20. This engagement allows the balancer shaft63and the first balance weight61to rotate at the same speed as that of the crankshaft20in the opposite direction thereto.

The second balance weight62is an example of a rotating member, which is held coaxially around the shaft21aof the crankshaft20. The second balance weight62is located on the outer circumference of the second portion24bof the shaft21aand between the support wall11of the left case8aand the reduction pinion26. The second balance weight62is housed in the clutch chamber16.

As shown inFIG. 6, the second balance weight62includes a boss66and first and second weights67and68. The boss66and the first weight67are separate from each other. The boss66and the second weight68are separate from each other.

The boss66is in a cylindrical shape having a bearing hole69through which the shaft21apasses coaxially. A disc-shaped flange70is provided around the outer circumference of the boss66. The flange70extends coaxially from the axial center66′ of the boss66radially outward. A plurality of teeth71is formed around the outer periphery of the flange70. In other words, the flange70has a balancer driving gear72on the boss66. The balancer driving gear72is smaller in diameter than the reduction pinion26and is integrated with the second balance weight62.

As shown inFIG. 5, the first and second weights67and68are arc-shaped plates. The first weight67and the second weight68are opposed to each other with the flange70therebetween and are fixed to the flange70with multiple bolts73. The first and second weights67and68are thus disposed in symmetry with the axial center66′ of the boss66therebetween (FIG. 6). The first and second weights67and68extend radially outward with respect to the balancer driving gear72.

The second balance weight62rotates by the torque from the relay shaft55. The transfer route of the torque will be described. As shown inFIG. 3, a second end of the relay shaft55passes through the support wall11of the left case8ainto the clutch chamber16. A driving gear74is fixed to the second end of the relay shaft55.

An idle gear75is interposed between the driving gear74and the balancer driving gear72. The idle gear75is supported by the support wall11via an axis76and is in engagement with the driving gear74and the balancer driving gear72. The engagement leads to a decrease in the number of rotation of the relay shaft55to half and allows transmission of the torque of the relay shaft55to the second balance weight62integrated with the balancer driving gear72. As a result, the second balance weight62rotates at the same speed as that of the crankshaft20in the opposite direction thereto.

As shown inFIG. 6, the axis76passes through the boss77in the center of the rotation of the idle gear75. The first and second weights67and68of the second balance weight62each have an arc-shaped outer periphery. The outer peripheries of the first and second weights67and68are adjacent to the outer circumference of the boss77. The engaged portion of the idle gear75and the balancer driving gear72are between the first weight67and the second weight68.

As shown inFIG. 6, a housing80is fixed to the support wall11of the left case8a. The housing80is made of, for example, a high-rigidity metal material such as chromium molybdenum steel. The housing80includes a boss81and a flange82. The boss81is in the shape of a hollow cylinder having a through hole83through which the second portion24bof the shaft21bpasses and is interposed between the second portion24bof the shaft21band the boss66of the second balance weight62.

The flange82is shaped like a disc extending from the outer circumference of the boss81outward radially and is coaxial with the boss81. The diameter of the flange82is larger than that of the balancer driving gear72and smaller than that of the reduction pinion26.

The flange82has a projection84projecting from the outer periphery to the support wall11. The projection84continues along the circumference of the flange82and is fitted in the recess85of the support wall11. Thus the housing80is aligned with the support wall11. The presence of the projection84makes the thickness of the outer periphery of the flange82the maximum of the flange82.

The recess85of the support wall11encloses the first portion24aof the shaft21ain a radially separate position. Therefore, the part of the support wall11where the shaft21apasses through is sufficiently thick, thus increasing the rigidity of the bearing part that supports the crankshaft20.

As shown inFIGS. 4 and 6, a pair of knock pins87aand87bis fixed to the bottom of the recess85of the support wall11. The knock pins87aand87bdeviate from each other along the circumference of the shaft21aand project to the flange82. The flange82has a pair of fitting holes88(only one is shown) in which the knock pins87aand87bare tightly fitted.

With the knock pins87aand87bfitted in the fitting holes88, the axes of the shaft21aof the crankshaft20and the boss81of the housing80can be agreed with high accuracy. Accordingly, a circumferentially continuous even clearance is formed between the outer circumference of the second portion24bof the shaft21a, and the inner circumference of the through hole83of the boss81.

Accordingly, in this embodiment, the knock pins87aand87band the fitting holes88serve as positioning means.

As shown inFIGS. 5 and 6, the outer periphery of the flange82is fixed to the support wall11with multiple bolts89. The bolt89is an example of a fastening member and has a large-diameter head89a. The bolts89are screwed into the support wall11through the projection84of the flange82. Thus, the housing80is fixed to the support wall11with the boss81and the shaft21adisposed coaxially with each other.

A plurality of depressions90are formed around the outer periphery of the flange82. The depressions90are for use in housing the heads89aof the bolts89and are disposed at intervals along the circumference of the flange82. The depressions90are open only in the direction of the second balance weight62. Therefore, the outer periphery of the flange82continues circumferentially without a decrease in thickness so that the flange82may hardly be deformed even when the bolts89are tightened.

As shown inFIGS. 5 and 6, the second balance weight62is rotatably supported on the boss81of the housing80via a slide bearing91. The slide bearing91is an example of a bearing member, which is interposed between the boss66of the second balance weight62and the boss81of the housing80.

Specifically, the slide bearing91is press fitted into the bearing hole69of the boss66and is rotated with the second balance weight62. Furthermore, the slide bearing91is fitted in the boss81of the housing80with clearance into slide contact with the outer circumference of the boss81. In other words, the boss81of the housing80separates the slide bearing91from the crankshaft20that rotates in the direction opposite to that of the second balance weight62.

As shown inFIG. 6, a washer93is interposed between the boss66of the second balance weight62and the reduction pinion26. The washer93is interposed between the reduction pinion26and the boss66when the reduction pinion26is fixed to the shaft21aof the crankshaft20to hold the boss66between it and the flange82of the housing80. Thus, the second balance weight62can be aligned axially to the crankshaft20, and the clearance between the reduction pinion26and the second balance weight62can be controlled.

As shown inFIGS. 5 and 6, a pair of oil passages95are provided in the boss81of the housing80. The oil passages95extend along the axis of the boss81. One end of the oil passage95is closed by a stopper96, and the other end is open to the end face of the flange82facing the support wall11. The boss81has a filler port97. The filler port97communicates with the oil passage95and is open to the outer circumference of the boss81.

As shown inFIG. 4, the support wall11has first and second oil ports98aand98b. The first oil port98aconnects the downstream end of the feed passage29and one oil passage95. The second oil port98bconnects the upstream end of the return passage30and the other oil passage95. Accordingly, part of the lubricating oil that lubricates the bearing portion of the crankshaft20flows through the first and second oil ports98aand98binto the oil passages95, from which it is supplied through the filler port97into the clearance between the slide bearing91and the boss81. As a result, an oil film is formed between the slide bearing91and the boss81, so that the slide bearing91is supported floatingly relative to the boss81.

A sealing member99, such as an O-ring, is sandwiched between the support wall11and the flange82of the housing80. The sealing member99is combined with the support wall11and encloses the part that communicates the first and second oil ports98aand98bwith the oil passages95.

According to the first embodiment of the present invention, the boss81of the housing80is interposed between the shaft21aof the crankshaft20and the boss66of the second balance weight62, and the housing80is fixed to the support wall11of the crankcase8. The slide bearing91, that is press-fitted into the boss66of the second balance weight62, is fitted in the boss81of the housing80with clearance therebetween.

Accordingly, the slide bearing91can be separated from the crankshaft20by the housing80even though the slide bearing91rotates in the direction opposite to that of the crankshaft20, thus decreasing the relative velocity between the slide bearing91and the crankshaft20. This reduces the load on the slide bearing91to increase the life of the slide bearing91and prevents extraordinary wear that can cause seizing. Thus the reliability of the bearing portion that supports the second balance weight62is improved.

With such a structure, the second balance weight62includes the boss66into which the slide bearing91is press-fitted and the first and second weights67and68fixed to the flange70of the boss66. The first and second weights67and68are disposed in symmetry while sandwiching the axial center66′ of the boss66.

The weight of the first and second weights67and68is distributed across the entire length of the boss66, thereby preventing an offset load on the slide bearing91that supports the boss66. This prevents local wear of the slide bearing91, thereby increasing the life of the slide bearing91.

In addition, since the housing80supports the rotating second balance weight62, the flange82of the housing80fixed to the support wall11undergoes the inertial force of the second balance weight62. With the above-described structure, the outer periphery of the flange82fixed to the support wall11with the bolts89is largest in thickness of the flange82and continues circumferentially without decreasing the thickness.

As a result, the outer periphery of the flange82is provided with high rigidity and has sufficient resistance to the inertial force of the second balance weight62. This offers the advantages of easily agreeing the axes of the shaft21aof the crankshaft20and the second balance weight62to each other.

It should be understood that the present invention is not limited to the first embodiment.

FIG. 7discloses a second embodiment of the invention. The difference between the second embodiment and the first embodiment is the structure for supplying lubricating oil to the clearance between the boss81of the housing80and the slide bearing91. The other structure is the same as that of the first embodiment. Accordingly, the components of the second embodiment the same as those of the first components are given the same reference numerals and their description will be omitted.

As shown inFIG. 7, a feed passage110is provided in the shaft21aof the crankshaft20. The feed passage110branches from the delivery passage31ain the crankshaft20and extends along the axis of the shaft21a. Furthermore, an oil passage111is provided in the shaft21a. The oil passage111extends along the radius of the shaft21aso as to cross the feed passage110at right angles. One end of the oil passage111continues to the feed passage110, and the other end of the oil passage111is open to the outer circumference of the second portion24bof the shaft21a.

An oil port112is provided in the boss81of the housing80. The oil port112extends along the radius of the boss81. A first end of the oil port112is open to the through hole83of the boss81. A second end of the oil port112is open to the outer circumference of the boss81. The first end of the oil port112is located on the locus of rotation of the second end of the oil passage111when the crankshaft20rotates.

With such a structure, the lubricating oil, that has lubricated the bearing portion of the crankshaft20, flows from the delivery passage31ainto the feed passage110. The lubricating oil is then supplied to the clearance between the slide bearing91and the boss81through the oil port112every time the oil passage111and the oil port112agree with each other at the rotation of the crankshaft20. As a result, an oil film is formed between the slide bearing91and the boss81, so that the slide bearing91is supported floatingly relative to the boss81.

According to the second embodiment of the invention, lubricating oil can be supplied from the crankshaft20to the slide bearing91. Therefore, there is no need to have a complicated passage in the housing80or the support wall11for distributing the lubricating oil flowing in the feed passage29to the slide bearing91. This can simplify the structure of the housing80, thereby reducing the manufacturing cost for the housing80.

FIGS. 8 and 9disclose a third embodiment of the invention.

The difference between the third embodiment and the second embodiment is the structure for rotatably supporting the second balance weight62. The other structure is the same as that of the second embodiment. Accordingly, the components of the third embodiment the same as those of the second components are given the same reference numerals and their description will be omitted.

As shown inFIG. 8, the second portion24bof the shaft21apasses through the boss66of the second balance weight62coaxially. The slide bearing91is interposed between the outer circumference of the second portion24band the inner circumference of the bearing hole69of the boss66. The slide bearing91is fitted to the outer circumference of the second portion24band the inner circumference of the bearing hole69with clearance therebetween, respectively.

Accordingly, as shown inFIG. 9, the slide bearing91defines a clearance114between it and the outer circumference of the second portion24band defines a clearance115between it and the inner circumference of the bearing hole69. The first and second clearances114and115continue along the circumference of the slide bearing91.

The oil passage111of the crankshaft20is open to the first clearance114. The slide bearing91has a plurality of oil ports116. The oil ports116are aligned at intervals along the circumference of the slide bearing91and pass through the thickness of the slide bearing91. Accordingly, the first clearance114and the second clearance115are communicated with each other through the oil ports116. The oil ports116are located on the rotation path drawn by the opening end of the oil passage111when the crankshaft20rotates.

A first washer118is disposed between the boss66of the second balance weight62and the reduction pinion26. Similarly, a second washer119is disposed between the boss66of the second balance weight62and the support wall11of the left case8a. The reduction pinion26clamps the first washer118, the second washer119, and the boss66between it and the support wall11when fixed to the shaft21aof the crankshaft20.

The second balance weight62is positioned to the axis of the crankshaft20, and the clearance between the reduction pinion26and the second balance weight62and the clearance between the support wall11and the second balance weight62are controlled.

With such a structure, the lubricating oil that has lubricated the bearing portion of the crankshaft20flows from the delivery passage31ainto the feed passage110. The lubricating oil then flows into the first clearance114between the second portion24bof the shaft21aand the slide bearing91through the oil passage111to form an oil film between the second portion24band the slide bearing91.

The lubricating oil introduced into the first clearance114flows into the second clearance115between the slide bearing91and the second balance weight62through the oil ports116of the slide bearing91to form an oil film between the slide bearing91and the second balance weight62. As a result, the slide bearing91floats between the shaft21aand the second balance weight62, thereby allowing the relative rotation of the slide bearing91separately from the shaft21aand the second balance weight62.

According to the third embodiment of the invention, the slide bearing91located between the crankshaft20and the second balance weight62is separated from both of the crankshaft20and the second balance weight62via the oil film interposed between the first and second clearances114and115.

In other words, when the rotation speed (a first speed) of one of the crankshaft20and the second balance weight62is expressed as a positive value, and the other (a second speed) is expressed as a negative value, the slide bearing91has a rotation speed higher than the second speed and lower than the first speed.

Accordingly, the relative velocity between the slide bearing91and the crankshaft20and that between the slide bearing91and the second balance weight62can be reduced although the crankshaft20and the second balance weight62rotate in the opposite direction from each other. This reduces the load on the slide bearing91to increase the life thereof and to prevent extraordinary wear that may cause, for example, seizing. Thus, the reliability of the bearing portion that supports the second balance weight62is improved.

With such a structure, it is sufficient to dispose the slide bearing91between the crankshaft20and the second balance weight62. The structure of the bearing portion of the second balance weight62can therefore be simplified.

It should be understood that the invention is not limited to the foregoing embodiments, but various modifications may be made therein without departing from the spirit and scope of the invention.

For example, the boss of the second balance weight and the first and second weights may not necessarily be separate components but may be integrated to one piece.

The rotation shaft may not necessarily be the crankshaft. The rotating member that rotates in the direction opposite to that of the rotation shaft may not necessarily be the balance weight but may be another component such as a gear.

The bearing member is not limited to the slide bearing but may be a ball bearing.