GB2115890A - A plain bearing - Google Patents

Abstract

A plain bearing comprises segments (16) arranged end to end to form a ring. Each segment comprises a support member (27) and a bearing layer (31) anchored to the radial inside or outside of the support member in a shape engaging manner and providing the bearing surface (34). Each end of each segment engages an end of an adjacent segment. <IMAGE>

Description

SPECIFICATION A plain bearing This invention is concerned with a plain bearing comprising segments arranged end to end to form a ring. Such a bearing can be used for a column mounting requiring no or little maintenance in which the segments are disposed between a housing bore and a shaft.

A plain bearing is known comprising segments made of plastics, the segments being disposed in a bush or liner, butt-jointed and held by clamping segments of trapeziumshaped cross-section. This known plain bearing has the disadvantage that, in the case of large diameter bearings, the plastics segments are not held securely in the bore of the housing before installation of the shaft.

The subject of the present invention is a plain bearing such as for a column mounting, in which the segments can be installed and removed without difficulty.

The invention provides a plain bearing comprising segments arranged end to end to form a ring, wherein each segment comprises a support member and a bearing layer anchored to the radial inside or outside of the support member in a shape engaging manner and providing the bearing surface, one end of each segment engaging one end of an adjacent segment. Such a bearing can be produced economically with a minimum of machinery.

Preferably, each support member in crosssection comprises an axially extending web with radially extending flanges at its axial ends and one end of each support member has a projection and the other end has a recess corresponding to the projection. This feature ensures that the segments are held together.

For each segment the bearing layer may have portions extending into openings in the support member and heads at the free ends of the radially extending portions anchoring the bearing layer to the support member.

For each segment the openings may be in the web of the support member.

The bearing includes a tightening device preferably disposed circumferentially between two adjacent segments and having a projection engaging in a recess in the end of one segment and a recess receiving a projection at the end of the other segment. The tightening device may comprise two circumferentially spaced components, one providing the recess and the other the projection, and having opposed surfaces converging in the radially outward direction; and a radially displaceable wedge disposed between the said surfaces.

The tightening device acts to compress the segments so that they are braced without play in the circumferential direction and, when disposed in the bore of a housing, will not drop out.

The support member may be made of metal and the bearing layer may be made of plastics.

The invention also provides apparatus comprising a shaft extending through the bore of a housing, the bore having an annular recess, and a plain bearing according to the invention disposed as a push fit in the recess between the walls of the recess with the bearing layer in sliding contact with the shaft.

The bearing may be fixed against rotation relative to the housing by a screw extending through the bearing and engaging the housing.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is a view partly in longitudinal section of a column mounting with two plain cylindrical bearings; Figure 2 is an axial view showing a part of one of the plain bearings together with a tightening device; Figure 3 is a radial view from the inside of the plain bearing shown in Fig. 2; and Figure 4 is a perspective view of a segment of the plain bearing.

Fig. 1 shows a column mounting with a column or shaft 10 mounted on a base and with a bracket 11 arranged to slide up and down the shaft.- The bracket 11 includes a housing portion with a bore 1 2 through which the shaft 10 extends. Two annular recesses 1 3 having side walls 14 are machined in the bore 12 and a cylindrical plain bearing 1 5 is inserted in each recess.

Referring now to Figs. 2, 3 and 4, the plain bearing 1 5 comprises a plurality of segment 1 6 arranged end to end to form a ring. Each segment 1 6 has at one end a projection 1 7 and at the other end a corresponding recess 1 8 so that the projection 1 7 of one segment engages in the recess 1 8 of an adjacent segment. Each projection 1 7 is of a generally triangular shape somewhat like a nose.

A tightening device 1 9 is disposed circumferentially between two adjacent segments 1 6 and comprises two circumferentially spaced components 20 and 21. Component 20 has a recess 22 in which engages the projection 1 7 of one segment 16 and component 21 has a projection 23 engaging in the recess 1 8 of the other segment. The two components 20 and 21 have two flat axially extending opposed surfaces 24 converging in the radially outward direction. A wedge 25 is disposed between the opposed surfaces 24 which wedge is radially displaceable by means of a screw 26.The screw has a head engageable from radially inside of the bearing and seated on a shoulder of the wedge 25, and a shank extending with clearance through the wedge and engaging in a screw-threaded bore in the housing portion of the bracket 11.

By screwing in the screw 26, the wedge 25 is moved radially outward and displaces the components 20 and 21 circumferentially away from each other. This compresses the segments 1 6 urging each projection 1 7 into its respective recess 1 8. The segments 1 6 are then braced without play in the circumferential direction and prevented from rotating relative to the bracket housing portion.

The segment 1 6 shown in Fig. 4 comprises support member 27 which in cross-section comprises an axially extending web 28 with radially extending flange 29 at its axial ends.

The support member 27 may be made of metal and produced by casting and is provided with openings 30 in the web 28. The openings 30 may be circular bores or circumferentially extending slots. A bearing layer 31, of for example plastics and produced by injection moulding, is anchored to the radial inside of the support member 27 between the flanges 29, in a shape engaging manner. The bearing layer 31 has portions 32 extending radially through the openings 30 in the web 28 and heads 33, somewhat like rivet heads at the free ends of the radially extending portions 32 anchoring the bearing layer to the support member 27. The bearing layer 31 provides a cylindrical bearing surface 34 in sliding contact with the shaft 10.

Only the axially facing surfaces 35 of the flanges 29 and the radially outwardly facing surfaces 36 of the flanges 29 are machined so that the segment 1 6 is a secure push fit between the shoulders 14 of the annular recess 1 3 and protrudes radially the required distance from the recess.

Instead of the bearing 1 5 being secured in a recess in a bore it may be secured in a recess in a shaft, for example, with the bearing layer 31 on the radial outside.

The support member 27 may, instead of the through bores or slots 30, have recesses with enlarged inner portions so that the plastics of the bearing layer, when being moulded, flows into the recesses and forms portions with enlarged heads anchored in the support member.

Claims (11)

1. A plain bearing comprising segments arranged end to end to form a ring, wherein each segment comprises a support member and a bearing layer anchored to the radial inside or outside of the support member in a shape engaging manner and providing the bearing surface, one end of each segment engaging one end of an adjacent segment.

2. A plain bearing as claimed in claim 1, wherein each support member in cross-section comprises an axially extending web with radially extending flanges at its axial ends and one end of each support member has a projection and the other end has a recess corresponding to the projection.

3. A plain bearing as claimed in claim 1 or 2, wherein for each segment the bearing layer has portions extending into openings in the support member and heads at the free ends of the radially extending portions anchoring the bearing layer to the support member.

4. A plain bearing as claimed in claims 2 and 3, wherein for each segment the openings are in the web of of the support member.

5. A plain bearing as claimed in any preceding claim, and including a tightening device disposed circumferentially between two adjacent segments and having a projection engaging in a recess in the end of one segment and a recess receiving a projection at the end of the other segment.

6. A plain bearing as claimed in claim 5, wherein the tightening device comprises two circumferentially spaced components, one providing the recess and the other the projection, and having opposed surfaces converging in the radially outward direction, and a radially displaceable wedge disposed between the said surfaces.

7. A plain bearing as claimed in any preceding claim, wherein the support member is made of metal and the bearing layer is made of plastics.

8. A plain bearing substantially as herein described with reference to and as shown in the accompanying drawings.

9. Apparatus comprising a shaft extending through the bore of a housing, the bore having an annular recess, and a plain bearing as claimed in any preceding claim disposed as a push fit in the recess between the walls of the recess with the bearing layer in sliding contact with the shaft.

10. Apparatus as claimed in claim 9 wherein the bearing is fixed against rotation relative to the housing by a screw extending through the bearing and engaging the housing.

11. Apparatus substantially as herein described with reference to and as shown in the accompanying drawings.