GB2474301A

GB2474301A - Calliper having a lubricated bearing

Info

Publication number: GB2474301A
Application number: GB0917805A
Authority: GB
Inventors: Gary Bulley
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-12
Filing date: 2009-10-12
Publication date: 2011-04-13
Also published as: GB0917805D0

Abstract

A floating calliper 2 for a disc brake 9 includes a sealed housing 7 containing a shaft 22 having a cam 20 for actuating the brake and an adjustment mechanism 18 for automatically adjusting the clearance between brake pads 5,6 and a brake disc 9. The shaft 22 extends through a wall of the housing for connection to an actuator. The shaft is supported at the wall by a ball or roller bearing 26 held between the wall and a bearing plate (50, fig 5). A lubricant grease passage 54 extends through the bearing plate 50 to the bearing 26. The bearing 26 is arranged to allow lubricant grease to pass there-through to the adjustment mechanism 18 to lubricate the bearing 26 and the adjustment mechanism 18 within the sealed housing. The modification of an existing caliper to have a lubricated bearing is also disclosed.

Description

Callipers for disc brakes

Field of the Invention

The present invention relates to callipers of disc brakes and to disc brakes including such callipers. Embodiments of the invention relate to callipers and disc brakes for commercial vehicles and trailers.

Background of the Invention

Disc brakes are well known. Disc brakes are used on many vehicles including bicycles, motor bikes, cars, and commercial vehicles including trucks, lorries and trailers.

One type of calliper in use has a cam for actuating the brake and the cam is on a shaft extending through a wall of the calliper, via a needle roller bearing in a bearing housing, to an actuator. Operators of commercial vehicles have long experienced problems caused by seizure of the bearing. Seizure of the bearing results in the brake locking on, locking up the wheel controlled by the brake. As a result the tyre may be destroyed. In addition, the excessive heat from the seized calliper then renders the disc, calliper and pads unserviceable. Putting aside the obvious safety implications, the subsequent repair costs run into hundreds of pounds.

Summary of the Invention

In accordance with one aspect of the present invention, there is provided a floating calliper for a disc brake, the calliper including: a sealed housing containing a shaft having a cam for actuating the brake and an adjustment mechanism for automatically adjusting the clearance between brake pads and a brake disc, the shaft extending through a wall of the housing for connection to an actuator, the shaft being supported by a ball or roller bearing held between the wall and a bearing plate fixed to the exterior of the wall; and a lubricant grease passage extending through the bearing plate to the bearing; the bearing being arranged to allow lubricant grease to pass therethrough to the adjustment mechanism to lubricate the bearing and the adjustment mechanism within the sealed housing.

In an embodiment of the calliper, the lubricant passage comprises a grease nipple fixed to the bearing plate to provide the entrance to the lubricant passage.

In accordance with another aspect of the invention there is provided a method of modifiying a calliper for a disc brake, the calliper to be modified comprising a sealed housing containing a shaft having a cam for actuating the brake and an adjustment mechanism for automatically adjusting the clearance between brake pads and a brake disc, the shaft extending through a wall of the housing for connection to an actuator, the shaft being supported by a bearing in a bearing housing held between the wall and a bearing plate fixed to the exterior of the wall; the method comprising removing the said bearing plate and bearing and bearing housing, replacing the said bearing and its housing with a roller bearing or ball bearing which is constructed to allow grease to pass through the bearing and replacing the said bearing plate with a bearing plate having a lubricant grease passage therethrough for providing grease to the bearing and, via the bearing, to the adjustment mechanism.

It has been found that, in prior callipers which use a needle bearing which is unlubricated, dirt ingress can cause the needle bearing to seize. . The present inventor has many years experience in this field. The problem of bearing seizure in the actuating mechanism of the prior callipers has been known for a long time but hitherto no solution to it has been found to the best of the knowledge of the present inventor.

By replacing a needle bearing and its housing with a ball bearing or roller bearing which has provision to be lubricated there is saving in repair costs and an improvement in safety as the ball or roller bearing cannot seize in this type of application.

The ball or roller bearing may be a standard bearing: this type of bearing has not been used in this type of application to a calliper.

The ball bearing or roller bearing not only replaces the needle bearing, it also replaces the housing of the needle bearing, thereby enabling a bigger and far more robust bearing to be fitted. The ball bearing or roller bearing can deal with higher loads and is more efficient as well as not being susceptible to damage from the said dirt ingress. Additionally a means of lubricating the bearing is provided to ensure it is always encased in grease and does not let water or dirt into the bearing and into the adjustment mechanism within the sealed housing. The bearing allows grease to pass through it into the housing and thus lubricate the clearance adjustment mechanism in the housing.

A better understanding of the invention will become apparent from the following description of illustrative embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a schematic diagram illustrating the principle of operation of a disc brake having a floating calliper; Figure 2 is a schematic sectional diagram of a disc brake having a floating calliper in accordance with an embodiment of the invention; Figure 3 is a schematic cross sectional view of a sealed housing of the calliper of Figure 2; Figure 4 is a schematic view of a ball bearing of the calliper of Figure2; Figures 5A and B are plan and side views of a bearing plate of the calliper of Figure 2; and Figure 6 is a plan view of the plate of Figure 6 with a grease nipple attached.

Detailed Description of the Invention

Figure 1 illustrates, schematically, the principle of operation of a disc brake having a floating calliper 2 and a brake disc 9. A support structure 1 of the brake is fixed to the vehicle. A calliper 2 comprises a support 3 which is moveable relative to the fixed support structure 1. For example it is supported by sliders 4 (only one shown)-hence the term floating calliper. The calliper further comprises brake pads 5, 6, one (5) of which is fixed relative to the calliper support 3 and the other (6) of which is moveable relative to the calliper support 3 by a mechanism 7. The mechanism 7 may comprise a piston or a cam and is actuated by an actuator 8. The actuator 8 may be hydraulic or pneumatic

for example.

In an embodiment of the invention, the mechanism 7 is cam and the actuator 8 acts on a lever 30 (shown in Figure 3) connected to the cam 20 via a rotary shaft 22.

As the moveable pad 6 contacts the disc 9 of the brake, the moveable support 3 of the calliper moves, bringing the fixed pad 5 into contact with the disc. The result is a balanced braking force on each side of the disc 9.

Figure 2 is a schematic top plan view in partial section of a floating calliper 2 having a moveable support 3 supported by one or more sliders 4 which are fixed to a fixed support structure 1. A pad 5 is fixed to the support 3 for engaging one side of the disc 9 and a pad 6 for engaging the other side of the disc is fixed to a load plate 12. The load plate is supported by columns 14 extending through seals 19 in the wall of a sealed housing 16 containing a brake actuating mechanism 7 and a clearance adjusting mechanism 18 of which the columns 14 form part.

In this embodiment, the actuating mechanism is a cam 20 on the shaft 22. The cam 20 is an eccentric circular cylinder on the shaft in this embodiment.

As shown in the side view of Figure 3, the shaft is supported at the bottom by a bearing 24 supported at, for example within, the bottom wall of the housing 16 and at the top by a bearing 26 in the top wall: top bearing 26 will be described in more detail herein below. The bearings 24 and 26 fix the axis of the shaft 22 relative to the housing 16.

Rotation of the shaft 22 rotates the cam 20. The cam is inside a block 28 and causes the block to move relative to the fixed axis of the shaft and thus relative to the housing as the shaft rotates. The block is fixed to the columns 14 and so causes the load plate 12 and pad 6 to move.

Rotation of the shaft acts on the adjusting mechanism 18 which adjusts the clearance of the pads 5 and 6 relative to the disc in known manner. The adjustment mechanism will not be further described because the manner of adjustment is known and is not itself the subject of the present invention.

Referring to Figures 4, 5 and 6, the top wall of the housing 16 has a bore through which the shaft 22 extends. The shaft is supported by the bearing 26 which in this embodiment is a ball bearing. The ball bearing 26 is held between a seating at the periphery of the bore in the top wall of the housing and a bearing plate 50 shown in Figure 5. The bearing plate is fixed to the top wall by fixers, for example screws or bolts which extend through holes 51 and 52. The plate 50 has a bore 53 for accommodating top end of the shaft 22. The plate also has one or two tapped bores 54 for receiving grease nipples. There may be two tapped bores so the same plate can be used for left and right hand callipers which have differently positioned grease nipples: the unused bore is plugged. The example shown in Figure 6 has only one tapped bore and grease nipple. The bore(s) 54 are positioned coincident with the ball race 40 of the bearing to supply grease to the race. Thus, the nipple(s) and bore(s) provide a passage for supplying lubricant to the bearing.

The plate shown in Figure SB has a projection around the bore for locating the bearing. The projection may be omitted. A shim may be placed between the bearing and the calliper housing to space the bearing from the calliper housing and cause the bearing to engage the bearing plate.

The bearing allows grease to pass through the race to the interior of the housing where the grease lubricates the adjustment mechanism.

An existing, seized, calliper having a needle bearing and bearing housing may be modified by removing the needle bearing in its housing and placing a ball bearing 40 around the shaft 22 and fixing a bearing plate 50 with a grease nipple 60 to the top wall of the housing.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, a roller bearing which allows grease to pass through it may be used instead of the ball bearing but a ball bearing is currently preferred because it permits easier lubrication. The invention is not limited to modifying an existing calliper (whether seized or not): a new calliper may be constructed in accordance with the present invention.

It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments.

Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

Claims 1. A floating calliper for a disc brake, the calliper including: a sealed housing containing a shaft having a cam for actuating the brake and an adjustment mechanism for automatically adjusting the clearance between brake pads and a brake disc, the shaft extending through a wall of the housing for connection to an actuator, the shaft being supported by a ball or roller bearing held between the wall and a bearing plate fixed to the exterior of the wall; and a lubricant grease passage extending through the bearing plate to the bearing; the bearing being arranged to allow lubricant grease to pass therethrough to the adjustment mechanism to lubricate the bearing and the adjustment mechanism within the sealed housing.
2. A calliper according to claim 1, wherein the lubricant passage comprises a grease nipple fixed to the bearing plate to provide the entrance to the lubricant passage.
3. A disc brake comprising the calliper of claim 1 or 2.
4. A method of modifying a calliper for a disc brake, the calliper to be modified comprising a sealed housing containing a shaft having a cam for actuating the brake and an adjustment mechanism for automatically adjusting the clearance between brake pads and a brake disc, the shaft extending through a wall of the housing for connection to an actuator, the shaft being supported by a bearing held between the wall and a bearing plate fixed to the exterior of the wall; the method comprising removing the said bearing plate and bearing, replacing the said bearing with a roller bearing or ball bearing which is constructed to allow grease to pass through the bearing and replacing the said bearing plate with a bearing plate having a lubricant grease passage therethrough for providing grease to the bearing and, via the bearing, to the adjustment mechanism.
5. A calliper substantially as herein before described with reference to Figures 2 to 6 of the accompanying drawings.
6. A method of modifying a calliper substantially as herein before described with reference to Figures 2 to 6 of the accompanying drawings.