WO2005014235A1

WO2005014235A1 - Brake calliper piston removal tool

Info

Publication number: WO2005014235A1
Application number: PCT/GB2004/003413
Authority: WO
Inventors: Darren Leak
Original assignee: Darren Leak
Priority date: 2003-08-06
Filing date: 2004-08-06
Publication date: 2005-02-17
Also published as: EP1660279A1; GB0318395D0

Abstract

A tool (2) for releasing a piston (32) from a brake calliper, the tool (2) comprising a shank (20) having a head member (6) at a first end thereof, a second end of the shank (20) being adapted to be displaced axially in to a body member (12), and piston engagement means (28) adapted to be placed, in use, around the head member (6) and to abut against the body member (12), wherein in use, axial displacement of the second end of the shank (20) in to the body member (12) urges the piston engagement means (28) radially outwardly such that it frictionally engages with an inner surface of a piston (32) in a calliper.

Description

BRAKE CALLIPER PISTON REMOVAL TOOL

The present invention relates to a tool for removing a piston from a brake calliper, and in particular for removing a motorcycle brake calliper piston, and a method relating to the same.

Motorcycle braking systems require frequent and regular maintenance to ensure the safety of the motorcycle. Constant use of a motorcycle in all climates allows brake calliper bodies to quickly deteriorate and corrode. Problems occur from natural flexing of brake calliper piston seals, as the brakes are applied and released. This natural flexing of the piston seals allows the ingress of moisture to enter the area around where the seals are fitted. Corrosion of the aluminium calliper body begins, and, in a very short time the seals become surrounded by white fur deposits of corrosion reducing their natural flexing ability and ultimately causing the pistons to stick or freeze in the bodies. Only by complete dismantling can the problem be rectified. However, the problem will re-occur again and again.

A known method of removing a piston from a motorcycle brake calliper involves pumping brake fluid through the system until part of the piston is gradually eased out of position in the calliper, and then gripping on to the external wall of the exposed part of the piston with molegrips, and manually pulling it out of the calliper. Problems associated with this method are that it is very time consuming and laborious and, occasionally, a piston seizes so tightly in position in the calliper that it is not practically possible to extract the frozen piston completely by pumping brake fluid against it. Problems occur with calliper design and ultimately all pistons need removing at this stage. This can often result in the piston being damaged due to excessive force being applied thereto.

US 4,009,515 discloses a tool for removing a frozen piston from a brake calliper of a car. The tool is unsuitable for removing brake calliper pistons from most vehicles including motorcycles due to its size, and because the tool requires a ϋ' -shaped, rigid cross-piece which bears against the car brake calliper itself and against which force is applied for removal of the piston. This often results in the calliper itself being damaged due to excessive force being applied thereto during removal of the piston. In addition, this tool can only be used for one size of piston and hence, brake calliper, so it is not very versatile. Finally, the number of parts involved make it complicated and expensive to manufacture.

It is one aim of embodiments of the present invention to address the above problems, and to provide a tool for removing a brake calliper piston, which can be effectively and simply used to remove pistons which are frozen or seized in position in a brake calliper.

According to a first aspect of the present invention, there is provided a tool for releasing a piston from a brake calliper, the tool comprising a shank having a head member at a first end thereof, a second end of the shank being adapted to be displaced axially in to a body member, and piston engagement means adapted to be placed, in use, around the head member and to abut against the body member, wherein in use, axial displacement of the second end of the shank in to the body member urges the piston engagement means radially outwardly such that it frictionally engages with an inner surface of a piston in a calliper.

Preferably, the body member comprises a channel extending therethrough, preferably along a longitudinal axis thereof. Preferably, the channel is threaded. Preferably, the second end of the shank comprises a threaded region, which is adapted to threadedly engage with the channel in the body member.

The body member may be integral with the shank. Preferably, the piston engagement means is adapted to directly abut on to the body member. Preferably, the piston engagement means is adapted to abut an underside of the body member. Preferably, axial movement of the second end of the shank in to the body member is adapted to cause axial movement of the head member away from and, preferably out of the piston. Advantageously, and preferably, abutment of the piston engagement means against the underside of the body member and axial movement of the head member in to the body member results in radial expansion of the engagement means which thereby grips the inside of the piston.

Preferably, the tool comprises means to produce a force, which is directed substantially away from the brake calliper to thereby release the piston engagement means and piston from the brake calliper. Preferably, the means to produce the force comprises means to provide a jolt or jerk to the head member, preferably, the piston engagement means, and preferably, the piston. Preferably, the force is directed axially along the shank.

Preferably, the means to produce the force comprises a slide hammer. Preferably, the means to produce the force comprises an elongate rod, a first end of which preferably extends out of the body member, and a second end of which preferably comprises an end stop. Preferably, the end stop comprises a nut, which nut is preferably threadedly attached to the second end of the elongate rod. Preferably, the tool comprises a substantial weight, which is slideably retained on the elongate rod. Preferably, the weight is adapted to slide up and down the elongate rod. Preferably, the first end of the elongate rod comprises a threaded region, which is adapted to threadedly engage with the channel in the body member.

Disadvantageously, use of the prior art tool to remove a piston results in a leverage force being applied directly on to the calliper, which results in damage thereof. Advantageously, and preferably, in the present invention, the force produced by the slide hammer is exerted directly on to the piston itself and not on to the calliper.

Preferably, the second end of the shank is adapted to be axially displaced by hand pressure. Advantageously, use of hand pressure means that not too much pressure is used so the piston would not be overtightened. Disadvantageously, a spanner must be used to produce a force using the prior art device.

Preferably, the head member of the tool is frusto-conical in shape, preferably having an upper face and a lower face. Preferably, the upper face is substantially smaller in section and/or area than the lower face. The width of the head member tapers inwardly as it extends from the lower face to the upper face. Preferably, the head member is non-circular in section, preferably, substantially oval in section, for example, when viewed from below.

Advantageously, the non-circular cross-section of the head member of the present invention helps to prevent locking of the head member against the inner wall of the piston, by reducing the surface area of the head member in contact with the collets, which allows the head member to exert, a much greater force against the collets.

Alternatively and preferably the head member is substantially circular in cross-section.

Preferably, the piston engagement means is suitably sized to fit inside a brake calliper piston. Preferably, the tool comprises a set of differently-sized piston engagement means. Advantageously, this allows the same tool to be used to release different sized pistons, for example, on a motorbike brake calliper.

Preferably, the piston engagement means comprises a collet, which preferably comprises at least one member, and preferably two members or two halves. The piston engagement means may comprise more than two members. A plurality of members may be linked together by linking means, which may be resilient, and which may comprise a spring. Preferably, the piston engagement means is adapted to fit around the head member, preferably thereby forming a substantially circular outer cross-section. Advantageously, this provides an improved fit between the piston engagement means and the inner surface of the piston itself.

Alternatively and preferably the piston engagement means comprises at least one member having at least one cut away section extending along a portion of a longitudinal axis thereof. Preferably, the piston engagement means comprises a collet having a plurality of cut away sections extending along a portion of its longitudinal axis and preferably, a circumferential ridge toward an upper end thereof. Preferably, the piston engagement means is formed from a material having elastic properties.

Advantageously, the plurality of cut away sections extending along a portion of the longitudinal axis of the piston engagement means allows the piston engagement means to elastically splay radially outward in order to grip the internal wall of a piston. In this manner, a one piece collet, which is easier to use and manufacture, may be used.

Preferably, at least a portion of an exterior surface of the piston engagement means is knurled. Preferably, substantially all of the exterior surface of the piston engagement means is knurled. Preferably, a portion of the piston engagement means which, in use, contacts the piston has a knurled surface.

Preferably, the piston engagement means undergoes a hardening procedure during its production. Advantageously, the level of grip between the piston engagement means and the piston is increased by providing a knurled finish to the exterior wall of the piston engagement means. Furthermore, by hardening the piston engagement means, the knurled finish is less likely to wear away over repeated use.

Preferably, the piston engagement means comprises an upper face and a lower face. Preferably, the piston engagement means, or each member thereof, comprises a channel cut out from an inner surface thereof. Preferably, the channel tapers inwardly as it extends from the lower face to the upper face of the piston engagement means. Preferably, the angle of taper of the channel in the inner surface of the piston engagement means closely matches the taper of the outer surface of the head member, and vice versa. Preferably, the piston engagement means is adapted to be arranged around the head member so that the taper of the channel on the inner surface of the piston engagement means is arranged opposite to the taper of the outer surface of the head member. Advantageously, this results in the outer surface of the piston engagement means being circular in outer cross-section and being able to be inserted in to the piston.

Alternatively and preferably, the angle of taper of the channel in the inner surface of the piston engagement means is slightly less than the angle of taper of the outer surface of the head member.

Advantageously, the outer surface of the head member only contacts the inner surface of the piston engagement means over a small portion of its surface area such that a greater local pressure can be applied at the contact point between the head member and the piston engagement means. Consequently, the problems associated with a head member which is circular in cross section may be overcome.

Preferably, the head member comprises alignment means adapted to locate the piston engagement means around the head member. Preferably, the alignment means comprises a pin, which extends transversely away therefrom. Preferably, and advantageously, where the piston engagement means comprises a plurality of members, the alignment means is adapted to locate the members around the head member. This is particularly important when the head member is non-circular in cross-section as it would otherwise take time for a mechanic to align the members correctly therearound.

The tool may comprise a collar against which the piston engagement means may abut. Preferably, the collar comprises a channel, which extends therethrough, which channel is .preferably unthreaded. Preferably, the shaft extends through the channel. Preferably, the shaft is adapted to freely rotate in the channel.

Preferably, the body member comprises at least one, and preferably two handles, which extends substantially transversely away therefrom. Preferably, the collar comprises at least one handle extending substantially transversely away therefrom. Advantageously, the handles may be gripped by a user to assist the threading of the shaft in to the body member. According to a second aspect of the present invention, there is provided a kit for removing a piston from a brake calliper, the kit comprising a tool as defined by the first aspect and a plurality of differently sized piston engagement means which are adapted to engage with an inner surface of a number of differently sized pistons.

By "differently sized", we mean the piston engagement means have external diameters which are different, and the pistons have internal diameters which are different.

According to a third aspect of the present invention, there is provided a method of removing a piston from a brake calliper, the method comprising inserting the piston engagement means of a tool defined in the first aspect in to a piston such that the engagement means abuts the body member, axially displacing the shank in to the body member of the tool so that the piston engagement means frictionally engages with an inner surface of a piston in a brake calliper, and removing the piston engagement means and piston from the brake calliper.

Preferably, the piston is removed by providing a jolt to the tool, which is preferably caused by a slide hammer.

All of the features described herein may be combined with any of the above aspects, in any combination.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:- Figure 1 shows a schematic side view of a tool for removing a motorcycle brake calliper piston;

Figure 2 shows a schematic side view of a head section and shank of the tool shown in Figure 1;

Figure 3 shows a schematic cross-sectional view of a collar section of the tool;

Figure 4 shows a schematic cross-sectional side view of a body section of the tool;

Figure 5 shows a schematic side view of an upper section of the tool;

Figure 6 shows a schematic end view of the head section of the tool along axis A-A shown in Figure 2;

Figure 7 shows a schematic end view of the head section shown in Figure 6 fitted with two halves of a collet, in accordance with the invention;

Figure 8 shows a schematic perspective view of one half of the collet shown in Figure 7;

Figure 9 shows an enlarged side view of the tool in a first configuration with a motorcycle brake piston;

Figure 10 shows an enlarged side view of the tool in a second configuration with a motorcycle brake piston;

Figure 11 shows a schematic end view of an alternate embodiment of the head section of the tool; Figure 12 shows a schematic end view of the head section shown in figure 11 fitted with an alternative embodiment of a collet;

Figure 13 shows a cross sectional view through the collet shown in figure 12;

Figure 14 shows an enlarged side view of the embodiment of the tool shown in figures 11 to 13 in a first configuration with a motorcycle brake piston; and

Figure 15 shows an enlarged side view of the embodiment of the tool shown in figures 11 to 13 in a second configuration with a motorcycle brake piston.

Referring to the Figures, there is shown a tool 2 which is used to remove a piston 32 which has seized, frozen or has some how become stuck inside a motorcycle brake calliper (not shown) .

As shown in Figure 1, the tool 2 consists of an elongate rod 4, a neck section 8 at one end of the elongate rod 4, a body section 12 attached to the neck section 8, and a head section 6 attached to the body section 12.

Referring to Figure 5, there is shown the upper section of the tool 2 in greater detail. One end of the elongate rod 4 is threaded so that a top nut 16 can be screwed thereon. The opposite end of the elongate rod 4 is also threaded for engagement with the neck section 8 as will be described hereinafter. A heavy weight 26, having a channel extending therethrough, is slideably mounted on the elongate rod 4. Apart from at each end, the elongate rod 4 is not threaded which allows the weight 26 to slide therealong to act as a slide hammer.

Referring to Figure 4, there is shown the body section 8 of the tool in greater detail. The body section 8 has an inner channel 24, which extends through a central longitudinal axis thereof. The inner surface of the channel 24 is threaded for engagement with the elongate rod 4 and a threaded section 22 of a shank 2a which will be described hereinafter. The neck section 8 has two arms 10, which extend transversely away therefrom, in opposite directions. The arms 10 are provided to allow a mechanic to rotate the body section when in use.

Referring to Figures 2 and 6, there is shown greater detail of the head section 6 of the tool 2. The head section 6 is frusto-conical in shape, having a smaller end and a larger end. A shank 20 extends out of the smaller end of the frustoconical head 6, which shank 20 has a threaded section 22 at the opposite end thereof. The rest of the shank 20 is not threaded.

Referring to Figure 6, the head section 6 can be seen in cross-section as being oval in shape. The oval has two mutually opposing curved sides and two mutually opposing flatter sides. A small pin 18 extends transversely away from one of the flatter sides of the head section 6.

Referring to Figure 3, there is shown greater detail of the collar section 12. The collar section 12 has an inner channel 25, which extends through a central longitudinal axis thereof. The inner surface of the channel 25 is not threaded. The collar section 12 has an arm 14, which extends transversely away therefrom, and an underside 40 adjacent the head section 6 as indicated in Figure 1. The arm 14 is provided to allow a mechanic to steady the tool 2 when in use.

The tool 2 is assembled by inserting the shank 20 of the head section 2 in to, and through, the channel 25 of the collar section 12. The shank 20 is sufficiently long such that the threaded section 22 extends out through the other side of the channel 24 of the collar section 12 and threadedly engages with the threaded channel 24 of the body section 8. The threaded section 22 of the elongate rod 4 threadedly engages with other side of the neck section. Hence, the upper section of shank 20 of the head section 6 and the lower section of elongate rod 4 are screwed into either side of the body section 8 with the collar section 12 being free to rotate about the shank 20 due to the unthreaded channel 25.

Once assembled, the tool 2 is used as follows with reference to Figures 7, 8, 9 and 10. A mechanic wishing to remove a piston 32 from a motorcycle brake calliper (not shown) first chooses two halves 28a, 28b of a collet 28 which is suitably sized to fit inside the piston 32 to be removed.

Referring to Figure 8, there is shown one half 28a, 28b of the collet 28, in accordance with the present invention. Each half of the collet 28 forms one half of an oval by it's internal surface, and are half of a circle by it's external surface, and has an upper face 34 and a lower face 36. A channel 30 has been cut out of the inside face of each half of the collet 28a, 28b, the channel 30 tapering inwards as it extends from the lower face 36 to the upper face 34. A set of differently sized, but similarly designed, collets are provided with the tool 2, each of which may be used with the tool 2 to remove any size of brake calliper piston 32. For example, for removing a larger piston 32, a larger collet 28 is required which fits therein.

Referring to Figure 9, the mechanic unscrews a little of the threaded section 22 of shank 20 of the head section 6 so that only a small portion of the shank 20 engages the threaded channel 24 of the body section 8. The result of this is that there is a gap 46 between the underside 40 of the collar section 12 and the upper part of the frusto- conical head 6 as shown in Figure 9.

Referring to Figure 7 to 9, once a correctly-sized collet 28 has been chosen, the mechanic then places each half of the collet 28 around the outside of the head section 6 of the tool 2, with the narrow section of the tapered channel 30 of each collet half 28a, 28b being positioned against the upper part of the frusto-conical head 6. The pin 18 on the head β ensures that each collet half 28a, 28b is correctly arranged with respect to the other half, around the oval shaped head 6. The pin 18 is positioned in between the two halves 28a, 28b of the collet 28 to facilitate quick and correct configuration of the two collet halves 28a, 28b around the head section 6. Without the pin 18, the mechanic would have to spend time having to ensure by eye that they are correctly positioned around the head 6. The upper face 34 of each of the two halves of the collet 28 is placed against the underside 40 of the collar section 12.

The mechanic then inserts the frusto-conical head 6 of the tool 2 fitted with the collet 28 arranged therearound into the inside of piston 32 of a motorcycle brake calliper 32. Normally, there is a small gap 42 between the outer curved surface of the collet 28 and the inner wall of the piston 32 as shown in Figure 9. While holding the arm 14 of the collar section 12 steady, the mechanic then rotates the body section 8 of the tool 2 using arms 10, such that the head section 6 is further threaded in to neck section 8. The shank 20 of the head section 6 is drawn upwards towards the collar section 12 in a direction as indicated by arrow Z' in Figure 9. The gap 40 shown in Figure 9 gradually closes as the head section 6 nears the underside 40 of the collar section 12.

Referring to Figure 10, the frusto-conical shape of the head section 6 ensures that, as the head section 6 is screwed further up into the body section 8, both halves of the collet 28a, 28b are forced radially outwardly in a direction as indicated by arrows ^ΛY' as shown in Figure

10. It should be noted that, because both halves of the collet 28a, 28b abut the underside 40 of the collar section

12, they are not able to move axially, only radially outwardly. In so doing, any gap 42 between the collet 28 and piston 32 decreases until the collet 28 is tightly secured against the inner side of the piston 32. Accordingly, axially retracting the shank 20 of the head section 6 in to the threaded channel 24 of the body section causes a radial expansion of the two collet halves 28a, 28b which thereby grip the piston 32 as shown in Figure 10.

Once the frozen piston 32 has been gripped by the collet 28, the mechanic then causes it to be jolted out of the brake calliper, by either pulling the tool 2 away from the calliper, or by using the heavy weight 26. The mechanic urges the heavy weight 26 to slide along elongate rod 4 such that it slams against the top 16 thereby causing a jolt, which lifts the frozen piston 32 out of the calliper .

Figures 11, 12, 13, 14 and 15 show an alternate embodiment of the head section and collet. Like reference numerals have been used to those in figures 1 to 10 where the parts are the same .

Referring to figure 11, the head section 106 can be seen in cross section as being circular in shape. Unlike the previous embodiment, the head section 106 does not have a small pin extending transversely away therefrom.

Figure 12 shows a cross section of the head section 106 around which is fitted a collet 128. The collet 128 is a single piece, unlike the previous embodiment, and has four apertures 129 extending partially along its length.

A cross section through the collet 128 is shown in figure 13 having an upper face 134, a lower face 136 and one of the four apertures 129. The collet 128 has a circumferential groove 131 around its perimeter toward the upper face 134 thereof. The circumferential groove 131 in combination with the apertures 129 allow the walls of the collet 128 to flare out at the bottom when an internal radial pressure is applied by the axial displacement of the head section 106.

The internal surface of the collet 128 is tapered toward the upper face 134 thereof. The head section 106 is also tapered so as to fit inside the collet 128. However the angle of taper of the head section 106 is slightly greater than that of the internal surface of the collet 128. This means that the head section 106 only contacts the internal surface of the collet 128 at a lower end of the head section 106. This results in the advantage that the head section 106, when displaced axially with respect to the collet 128 (ie. is drawn up through the collet 128), only applies pressure toward the lower face 136 of the collet 128 thereby forcing the collet 128 to flare outward toward a lower face thereof. A further advantage is that the contact area between the head section 106 and the interior surface of the collet 128 is small. This decrease in area leads to an increase in pressure between the two faces meaning that the head section 106 is less likely to slip and rotate when engaged with the internal surface of the collet 128.

Use of the tool having the alternate embodiment of head section 106 and collet 128 is carried out in a similar manner to the previous embodiment. The shank 20 of the head section 106 is inserted through the collet 128 and through the collar section 12. The tool 2 is then assembled in the same manner as in the previous embodiment . Figures 14 and 15 show the tool 2 having head section 106 and collet 128 inside a cross section of a motorcycle brake piston 32. Figure 14 shows the tool 2 prior to engagement with the interior wall of the piston 32. In order to engage the tool 2 with the interior wall of the piston 32 the head section 106 is displaced axially with regard to the collet 128 (by screwing the neck section 8 on to the threaded section 22 of the elongate rod 4) . This draws the head section 106 up through the collet 128 thus forcing the sides of the collet to flare radially outwardly. As shown in figure 15, the aperture 129 can open elastically and the circumferential groove 131 can similarly close elastically to allow the collet 128 to flare radially outwardly.

When the collet 128 is engaged with the piston 32, the piston 32 may be removed from the brake calliper is described above in relation to the first embodiment.

Advantages of the tool 2 reside in the simple and efficient way in which a piston 32 may be removed out of a motorcycle brake calliper without incurring any damage thereto. The tool 2 is provided with a range of collets 28 of different sizes and diameters such that the tool 2 can be used to remove motorcycle brake calliper pistons having different diameters, for example, for different manufacturer's type, size of motorcycle. In addition, the cross-sectional shape of the head section 6 is oval as opposed to circular, which prevents each half of the collet 28a, 28b from sticking thereto or themselves locking up as the body section 8 is rotated to further thread the shank 20 therein. In addition, the oval head section is able to slide within the collets 28 thereby pushing the collets 28 outwardly against the inner wall of the piston 32.

In addition, the pin 18 extending out of the head section 6 facilitates and ensures that the two halves of the collet 28a, 28b are always correctly aligned on the oval head section 6, thereby forming a substantially circular profile which fits inside the piston 32. Finally, the tool 2 is very simple to use and manufacture consisting of very few parts.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A tool for releasing a piston from a brake calliper, the tool comprising a shank having a head member at a first end thereof, a second end of the shank being adapted to be displaced axially in to a body member, and piston engagement means adapted to be placed, in use, around the head member and to abut against the body member, wherein in use, axial displacement of the second end of the shank in to the body member urges the piston engagement means radially outwardly such that it frictionally engages with an inner surface of a piston in a calliper.

2. A tool according to claim 1, wherein the body member comprises a threaded channel extending therethrough.

3. A tool according to claim 2, wherein the second end of the shank comprises a threaded region, which is adapted to threadedly engage with the channel in the body member.

4. A tool according to any preceding claim, wherein the piston engagement means is adapted to directly abut on to the body member.

5. A tool according to any preceding claim, wherein the piston engagement means is adapted to abut an underside of the body member.

6. A tool according to any preceding claim, wherein axial movement of the second end of the shank into the body member is adapted to cause axial movement of the head member away from and out of the piston.

7. A tool according to any preceding claim, wherein the tool comprises means to produce a force, which is directed substantially away from the brake calliper to thereby release the piston engagement means and piston from the brake calliper.

8. A tool according to claim 8, wherein the force is directed axially along the shank.

9. A tool according to either claim 7 or claim 8, wherein the means to produce the force comprises a slide hammer.

10. A tool according to any preceding claim, wherein the second end of the shank is adapted to be axially displaced by hand pressure.

11. A tool according to any preceding claim, wherein the head member is substantially circular in cross-section.

12. A tool according to any preceding claim, wherein the piston engagement means comprises a collet.

13. A tool according to any preceding claim, wherein the piston engagement means is adapted to fit around the head member.

14. A tool according to any preceding claim, wherein the piston engagement means comprises two members or two halves .

15. A tool according to any preceding claim, wherein the piston engagement means comprises at least one member having at least one cut away section extending along a portion of a longitudinal axis thereof.

16. A tool according to any preceding claim, wherein the piston engagement means comprises a collet having a plurality of cut away sections extending along a portion of its longitudinal axis and a circumferential ridge toward an upper end thereof.

17. A tool according to any of claims 14 to 16, wherein the piston engagement means, or each member thereof, comprises a channel cut out from an inner surface thereof.

18. A tool according to claim 17, wherein the channel tapers inwardly as it extends from a lower face to an upper face of the piston engagement means.

19. A tool according to claim 18, wherein the angle of taper of the channel in the inner surface of the piston engagement means is slightly less than the angle of taper of the outer surface of the head member.

20. A tool according to any preceding claim, wherein the tool comprises a collar against which the piston engagement means may abut.

21. A kit for removing a piston from a brake calliper, the kit comprising a tool as defined by any of claims 1 to 20 and a plurality of differently sized piston engagement means which are adapted to engage with an inner surface of a number of differently sized pistons.

22. A method of removing a piston from a brake calliper, the method comprising inserting the piston engagement means of a tool defined in any of claims 1 to 20 in to a piston such that the engagement means abuts the body member, axially displacing the shank in to the body member of the tool so that the piston engagement means frictionally engages with an inner surface of a piston in a brake calliper, and removing the piston engagement means and piston from the brake calliper.

23. A method according to claim 22, wherein the piston is removed by providing a jolt to the tool.

24. A method according to claim 23, wherein the jolt is caused by a slide hammer.

25. A tool substantially as described herein and with reference to the accompanying drawings .

26. A kit substantially as described herein and with reference to the accompanying drawings.

27. A method substantially as described herein and with reference to the accompanying drawings.