GB2169360A

GB2169360A - A plummer block housing

Info

Publication number: GB2169360A
Application number: GB08500301A
Authority: GB
Inventors: Ronald Francis Hamblin
Original assignee: Svenska Kullagerfabriken AB
Current assignee: SKF AB
Priority date: 1985-01-07
Filing date: 1985-01-07
Publication date: 1986-07-09
Also published as: GB2169360B; GB8500301D0

Abstract

A plummer block housing 10 has a flat base surface 15 and a bore 16 for reception of a bearing 12. The housing 10 comprises two substantially identical halves 17 having mating surfaces 18 meeting on a plane extending perpendicular to the flat base surface 15 and longitudinally bisecting the bore 16. <IMAGE>

Description

SPECIFICATION A plummer block housing This invention concerns a plummer block housing.

The majority of plummer block housings are cast from iron. Each one comprises a base to be secured by holding down bolts to a flat surface and a bore for reception of a bearing for rotatably supporting a shaft.

One type of plummer block housing, in which the base is to be secured on to a flat horizontal surface, comprises two halves meeting on a plane extending parallel to the base and longitudinally dividing the bore into two. The housing may be fitted with dowel pins or the mating surfaces may be stepped to ensure correct location of the two halves.

The two halves are secured together by vertically extending cap or attachment bolts.

In a variation of this type of plummer block housing, the two halves meet on a plane extending at 450 to the base and longitudinally dividing the bore into two.

A further type of plummer block housing, also known as a side pedestai, has a base intended to be secured to a flat vertical surface. This housing is split on a plane extending perpendicular to the base and longitudinally bisecting the bore. However, the two halves are not identical-the lower half having a large reinforcing web for accommodating the expected bending moment.

There are also other types of plummer block housings, an example of which is shown in Patent Specification GB 1204046 and comprises a horizontal base and two upper housing halves divided on a vertical plane.

The invention provides a plummer block housing having a base and a bore for reception of a bearing, wherein the housing comprises two substantially identical halves having mating surfaces meeting on a plane extending perpendicular to the base and longitudinally bisecting the bore.

Such a construction provides the advantage that when casting the housing only one mould or pattern is required. The flat mating surfaces are finish machined and then the two halves are brought together and clamped in place.

Then the base surface and the seating surface in the bore for receiving a bearing are finish machined. Preferably, the base surface is finish machined first and then the housing is clamped to a flat reference surface for finish machining of the seating surface. Such ease of manufacture facilitates automatic production, particuarly as there is no machining of stepped surfaces or bores for receiving dowel pins to accurately locate the two halves.

With the first mentioned type of plummer block housing, shear forces in the housing have to be accommodated by the attachment bolts and the dowel pins or stepped surfaces. The stepped surfaces are often provided only by relatively small lugs. With a plummer block housing according to the invention, shear forces in the housing can accommodated by whatever the housing is bolted to.

Large and pulsating shear forces occur for example when the bearing is subject to rotating outer ring loads due to an out of balance load condition. Preferably, therefore, the housing has additional blind bolt holes adjacent to the mating surfaces.

Preferably at least one bolt holds the two halves together and extends through bolt holes at the top of the housing and crosswise of the bore. Such a bolt keys the two halves longitudionally of the bore.

The two halves of the housing may be held together by bolts which extend parallel with one another and the base and extend crosswise of the bore. Two of the said bolts may be positioned at the base at opposite ends of the housing and a third said bolt may be positioned at the top of the housing furthest from the base.

An embodiment of the invention will now be described by way of example, reference being made to the accompanying drawings, of which: Figure 1 is an end view of a plummer block housing according to the invention; and Figure 2 is an exploded view, in perspective of the same plummer block housing.

The drawings show a cast-iron plummer block housing 10 mounted on a plinth 11.

The housing 10 incorporates a self-aligning ball bearing 12 supporting a shaft 13 for rotation.

Such an arrangement can be part of a fan assembly with the shaft 13 supported by a further plummer block housing and having an impeller mounted at one end and a drive at the other end. The drive can be by a V-belt pulley or a direct drive coupling. The impeller (not shown) is surrounded by a sheet-metal casing 14 through which the shaft 13 extends. The casing 14 is supported by the plinth 11.

The plummer block housing 10 comprises a base having a flat surface 15 and a bore 16 receiving the bearing 12. The axis of the bore 16 is parallel to the base surface 15. The housing 10 comprises two substantially identical halves 1 7 having mating surfaces 1 8 meeting on a plane extending perpendicular to the base surface 15. This plane includes the bore axis and so longitudinally bisects the bore 16. Each half 17 provides a foot 19 having a bolt hole 20 used to secure the housing to the plinth.

The two halves 1 7 are secured together by three bolts 21, 22 and 23 each with a screwthreaded free end receiving a nut. Bolt 21 extends through a bolt hole 24 in the upper part of each half 17 of the housing 10 furthest from the base. Bolts 22 and 23 are located in respective slots 25 and 26 in each half 17 and positioned at the base at opposite ends of the housing 10. The bolt hole 24 and slots 25 and 26, and therefore also the bolts 21, 22 and 23, extend parallel with one another and the flat base surface 15 and extend cross-wise of the axis of the bore 16.

The bearing 12 is mounted with an adapter sleeve 27 which includes a tab washer and a lock nut. The normal practice when checking the clearance of the bearing is a swivel the bearing to assess the remaining internal clearance during mounting.

In known types of such assemblies, plummer block housings have been used which are split on a plane parallel to the flat base. When the time came to service such an assembly, access had to be gained to the bearings in order to inspect the bearing and if necessary adjust the adaptor sleeve This requires removal of the housing. In order to do this without too much down time, either the housing has to be mounted on a packing block on the plinth or A-frame so that the lower half of the housing can be dropped out after removing the block, or there has to be a facility for lifting the shaft. Designers all too frequently do not allow for a packing block. Also, lifting and shaft is sometimes not practical particularly if the impellor is large. and space is limited.This has meant that to be able to inspect the bearing, which requires at least swivelling the outer ring, the upper half of the housing had to be removed, the adaptor sleeve released and the lower half of the housing together with the bearing had to be moved along the shaft until completely removed from the shaft, the drive means having been first removed from the shaft.

However, by using a plummer block housing according to the invention, it is a simple matter of undoing the holding down bolts securing the housing 10 to the plinth 11, then undoing the attachment bolts 21, 22 and 23 and sliding the two halves 17 of the housing apart to expose the bearing. This allows inspection and adjustment of the bearing to be carried out with the minimum of downtime and disturbance of the bearing and adaptor sleeve seating.

When manufacturing the housing 10, only one pattern or mould is required to cast each half 17 in iron since the two halves are the same. The mating faces 18 are finish machined first the bolt hole 24 is core drilled and then the two halves are clamped together.

Either the bearing seating surface in the bore 16 or the flat base surface 15 can be finish machined next and used as a reference for finish machining the other. Preferably, however, the fiat base surface 15 is finish machined first so that the housing can be simply clamped to a flat reference surface and then the seating surface is finish machined at the correct distance from the flat base surface.

For accommodating relatively large and pulsating shear forces, threaded blind bolt holes 28 additional to holes 20 can be provided near the mating faces 18 for receiving holding down bolts for mounting the housing 10.

Claims

1. A plummer block housing having a base and a bore for reception of a bearing, wherein the housing comprises two substantially identical halves having mating surfaces meeting on a plane extending perpendicular to the base and longitudinally bisecting the bore.

2. A housing as claimed in Claim 1, wherein additional blind bolt holes for mounting the housing are provided adjacent to the mating surfaces.

3. A housing as claimed in Claim 1 or 2, wherein at least one bolt holds the two halves together and extends through bolt holes at the top of the housing and cross-wise of the bore.

4. A housing as claimed in Claim 1 or 2, wherein the two halves are held together by bolts which extend parallel with one another and the base and extend cross-wise of the bore.

5. A housing as claimed in Claim 4, wherein two of the said bolts are positioned at the base at opposite ends of the housing and a third said bolt is positioned at the top of the housing furthest from the base.

6. A plummer block housing substantially as herein described with reference to and as shown in the accompanying drawings.