GB2271161A

GB2271161A - Gearbox lubrication

Info

Publication number: GB2271161A
Application number: GB9319688A
Authority: GB
Inventors: Barry Firth; Stewart Williams
Original assignee: David Brown Gear Industries; BROWN GEAR IND
Current assignee: David Brown Gear Industries; BROWN GEAR IND
Priority date: 1992-10-01
Filing date: 1993-09-23
Publication date: 1994-04-06
Anticipated expiration: 2013-09-23
Also published as: GB9319688D0; ZA936005B; GB2271161B

Abstract

In a gearbox comprising a housing having a pair of opposed side walls, and a plurality of shafts supported in bearings 22 mounted in the side walls, the hearings are lubricated by a lubrication system which comprises a sump 30 located at an elevated position within the housing, and a flow passage 31 which extends down each side wall. Oil flowing from the sump down the flow passages is used to lubricate the bearings. The flow passages are preferably formed at least partially within each of the respective side walls 5. <IMAGE>

Description

"GEARBOX LUBRICATION" THIS invention relates to a multi-shaft gearbox, and more particularly, to the lubrication of such a gearbox. The invention is described with particular reference to an industrial gearbox but it is to be understood that the invention can be used in many different applications.

Conventionally, industrial gearboxes comprise a sealed housing within which a plurality of gear supporting shafts are mounted. The shafts are mounted in bearings mounted in suitable recesses formed in the side walls of the housing. The housing is filled to a pre-determined level with lubricating oil which lies in a sump at the bottom of the gearbox.

Lubrication of the individual gears and shaft bearings is achieved by splashing of oil in the sump by the rotating gears. Clearly this lubrication system is somewhat haphazard and it is found that certain components are frequently not lubricated properly.

The level to which the lubricating oil is filled into the sump is also critical in order to achieve effective lubrication. If there is too little oil in the sump there will not be sufficient splashing of lubricating oil in order to properly coat and lubricate all surfaces and components. If there is too much oil in the sump the efficiency of the gearbox will be reduced and the extent of splashing will also reduce which results in improper lubrication to some components and possible excessive heat being generated. The splashing is also temperature dependent which is undesirable since it is important that all components are lubricated irrespective of the temperature of the lubricating oil.

According to the invention there is provided a gearbox which comprises a housing having a pair of opposed side walls, a plurality of shafts supported in bearings mounted in said side walls, and a lubrication system comprising a sump located at an elevated position within the housing and a flow passage extending down each side wall, said flow passages being in flow communication with said sump and being inclined downwardly from said sump along a significant portion of the length of the side walls, said flow passages being in flow communication with said bearings.

Preferably the sump is located at one end of the housing and the flow passages extend towards the other end of the housing. The flow passages are preferably defined at least partially within the side walls of the housing.

These and further features of the invention will be made apparent from the description of a preferred embodiment thereof given below by way of example. In the description reference is made to the accompanying drawings.

Figure 1 shows a perspective view of a gearbox of the type with which the invention can be used; Figure 2 shows a cross sectional view along line II-II in Figure 1; Figure 3 shows a side view of the central portion of the gearbox which incorporates a lubrication system according to the invention; Figure 4 shows a half-section view taken along line IV-IV of Figure 3; and Figure 5 shows a half-section view taken along the line V-V of Figure 3.

As shown in the drawings, a gearbox 1 has an input shaft 2 and an output shaft 3. The gearbox has a housing 4 which is defined in part by a pair of side walls 5. The gearbox 1 includes a lubrication system which is best described with reference to Figures 2 to 5 of the drawings.

As shown in Figure 2 the input shaft 2 is connected bv means of a bevel gear 10 to a gear 11 on transverse shaft 12. Shaft 12 is connected by means of gears 13 and 14 to transverse shaft 15. Shaft 15 is connected by means of gears 16 and 17 to output shaft 3. It should be noted that the internal configuration of the gearing can differ from that described herein. Shafts 12, 15 and 3 are mounted in bearings indicated at numeral 20. These bearings in each case have an outer race 21 which is mounted into the side walls 5 of the housing 4 and an inner race 22 which, in each case, is mounted to the respective shaft on which that bearing is located. The bearings include rollers 23 located between the inner and outer races.

Lubrication of the bearings 20 is an important aspect of efficient gearbox operation. The lubrication system for lubricating the bearings 20 is shown by the heavily shaded areas in Figures 2 to 5 of the drawings.

The lubrication system includes a sump 30 towards one end 29 of the gearbox 1 and a pair of channels or flow passages 31 which extend down the two side walls 5 of the gearbox. The sump 30 is positioned at an.

elevated position at the end 29 of the gearbox 1 and the sump 30 will be filled continuously by oil splashed by bevel gear 10. The sump 30 will thus act as a reservoir for lubricating oil flowing down flow passages 31 in the side walls 5 of the gearbox.

The configuration of the flow passages 31 are best shown in Figure 3 of the drawings. The flow passages 31 commence at the sump 30 near end 29 of the gearbox and flow downwardly in step-like manner towards the other end 33 of the gearbox. It will be noted from Figure 3 that the side walls 5 include circular recesses 35 within which the outer races 21 of the bearings are mounted. These circular recesses 35 form part of the flow passages 31. All of the circular recesses 35 are at the same elevation (indicated by dotted line 36). However, since the pair of circular recesses 35 near end 33 are of larger diameter than the recesses 35 near end 29 there is a general downward stepping of the flow passages 31 as they extend along the length of the side walls 5 from end 29 to end 33. The flow passages 31 each have a pair of linking passages 37 which join together the circular recesses 35.These linking passages 37 ensure that there is a continuous flow communication extending down the length of each side wall. The linking passages 37 are preferably formed within the side walls 5. Lubricating oil will flow under the influence of gravity along the length of the flow passages 31.

It will be noted that with the flow passages 31 extending down each side wall the bearings 20 will in each case be lubricated. The direction of lubricating flow is indicated by arrows 38 in Figures 2, 4 and 5 of the drawings. Lubricating oil will thus flow from the flow passages 31 into the circular recesses 35 and thereby lubricate the bearings 20 on each end of shafts 12, 15 and 3.

It will be appreciated that the bearings 20, in each case, are positively lubricated in that lubricating oil will flow from the elevated sump 30 along flow passages 31 on a continuous basis. The splashing of oil from the bottom of the housing may, of course, also lubricate those bearings but that lubrication is not the only lubrication facility for the gearbox bearings. Since lubrication occurs from flow passage 31 in the direction of arrows 38 there is provided guaranteed lubrication for all of the bearings 20. Since lubrication of bearings 20 is guaranteed it should be possible to reduce the volume of oil in the gearbox and thereby increase the efficiency of the gearbox.

Clearly the invention is not limited to the configuration of the flow passages described herein. However, it is considered that providing a lubrication channel on the side walls of a gearbox housing could be advantageously employed in many different types of gearboxes.

Claims

1. A gearbox comprising a housing having a pair of opposed side walls, a plurality of shafts supported in bearings mounted in said side walls, and a lubrication system comprising a sump located at an elevated position within the housing and a flow passage extending down each side wall, said flow passages being in flow communication with said sump and being inclined downwardly from said sump along a significant portion of the length of the side walls, said flow passages being in flow communication with said bearings.

2. A gearbox according to claim 1 wherein the sump is located at one end of the housing and the flow passages extend towards the other end of the housing.

3. A gearbox housing according to either preceding claim wherein the flow passages are at least partially formed within the respective side walls of the housing.

4. A gearbox according to claim 3 wherein the shafts are mounted in bearings located in circular recesses in the side walls and the circular recesses form part of the respective flow passages, linking passages which pass through the respective side walls connecting adjacent circular recesses together.

5. A gearbox substantially as hereinbefore described with reference to the drawings.