BACKGROUNDART Flexible rubber gaiters are used in motor cars to protect lubricated joints of, for example, steering gear defined between steering racks and steering tie rods and the steering column (the pinion) so as to prevent the ingress of dirt and moisture and the egress of lubricants.

These gaiters customarily comprise moulded tubes having cylindrical end portions suitably diametered to fit the pertaining joint members of the steering gaiter and a convoluted central portion to allow bending and change of length as the steering rack and tie rods move.

The end portions are clamped to joint members (or in the case of a housed steering rack, to the housing) by straps located in seating channels in the end portions of the gaiter.

However joint members of different motor car models have different dimensions (different diameters and/or axial spacings of joint members) and hitherto to allow for this it has been necessary to provide a corresponding range of differently dimensioned gaiters. This is not, however, wholly satisfactory having regard to the manufacturing costs and also due to the inconvenience of maintaining stocks of the different gaiters.

It is known for gaiters to have end portions adapted by the provision

of multiple fitting sections of different diameters, the gaiter being cut prior to installation to leave end fixing channels of desired diameters.

However the range of axial spacing of joint members and especially of steering gear joint members and the associated housings (to which gaiters are fixed) varies between such extremes that hitherto it has been thought necessary to provide separate short and long gaiters for the two extremes. A single stepped gaiter would require a major part of the length to be taken up by seating channels which are relative rigid and would compromise the flexibility of the gaiter.

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a gaiter which can readily be adapted to fit joints with different axially spacing of the gaiter fixing positions and which retains the requisite flexibility and axial extensibility.

According to the invention, therefore, there is provided a protective gaiter to fit around a lubricated joint between joint members said gaiter comprising a generally cylindrical flexible tubular body having first and second end portions each having a respective annular fitting section incorporating an annular seating area to receive a fixing device for clamping inner surfaces of said end portions into sealing engagement with the joint members, said central portion having folds therein so as to permit axial extension of the body characterised by the provision of a further annular fitting section incorporating an annular seating area within the said central

portion.

With this arrangement, the gaiter can be readily adapted to fit different joints in which the gaiter fitting positions have both long and short axial spacing without comprising the flexibility of the longer gaiter. When a shorter gaiter is required, the gaiter may be cut at or adjacent the further seating channel leaving a gaiter with a seating channel at either end and a convoluted central portion.

Whereas some gaiters may be fitted directly to joint members, joints maybe arranged so that the gaiter is fixed to a structure which houses the joint, for example, a steering rack housing. Therefore references herein to the attachment of gaiters to joint members should be construed as including attachment of gaiters to such housings.

Each seating area may take any suitable form and may comprise a distinct channel or simply a surface area. In one embodiment of the invention it is generally cylindrical and is axially parallel with the axis of the gaiter.

The further annular fitting section may be located at any position along the length of the central portion but preferably it is located at a position whereby both sections of the divided central portion on either side of the further annular seating channel have multiple folds.

Preferably the further annular fitting section is located approximately 4/5along the length of the gaiter.

The further annular fitting section may occupy a minor part of the

length of the gaiter.

In this way the further fitting section does not significantly reduce the flexibility of the gaiter. Indeed the presence of the section reduces the weight of the central portion, reducing material costs of production.

One or more of the fitting sections may be appropriately configured on its outer surface to allow tearing of the gaiter along predetermined line or lines.

Thus one or more of the seating areas may incorporate a groove or series of grooves extending around the circumference of the area.

The groove provides a tear-line which allows the section of the gaiter not required to be conveniently and neatly torn away without the need for cutting of the gaiter. Preferably, the depth of the groove relative to the material is such that the groove does not compromise the durability of the gaiter. In a preferred embodiment the groove is 0.8 mm deep within a wall 2 mm thick.

Each seating area may be appropriately configured on its inner surface for co-operation with a sealing configuration on the pertaining joint member.

Thus, each seating area may have one or more circumferential ribs for co-operation with a sealing groove or grooves on the joint member or joint housing.

Each seating area may be appropriately configured to receive a fixing device. Thus each seating area may be adjoined or bounded by projecting

structures for locating purposes, and these structures may be of greater width than the fixing device whereby such projecting structures act to facilitate location without making a close fit with the device necessary.

In one embodiment each fitting section has in the outer surface one or more circumferential ribs. Preferably the ribs are located on one side of the seating area toward the pertaining free end.

The above described ribs may be positioned such that an inner rib is located directly underneath ie. radially aligned with an outer rib. With this arrangement, especially where there are no sealing grooves on the joint member in use, the inner rib forces the outer rib radially outwards thereby enhancing the ability of the external rib to prevent slipping of the fixing device.

The annular seating areas of the end portions may be generally cylindrical and may be axially parallel with the axis of the gaiter.

As part of the manufacturing process, air is blown through the gaiter while it is held at one end portion, which can lead to ripping of the gaiter at that end.

Accordingly, with the aim of increasing the strength of the or each end portion, the or each end portion of the gaiter may incorporate one or more circumferential ribs. Preferably, there are two such ribs: an internal rib radially aligned with an external rib.

The ribs may have curved outer surfaces, and preferably they are generally semicircular in cross section. With this arrangement the strength

of the end portions is increased to withstand the blowing stage thereby reducing wastage.

The gaiter wall thickness may be increased at the end portions relative to the wall thickness of the central portion.

With this arrangement the robustness of the seating channels is enhanced to receive retaining clips or fixing ties while at the same time allowing for a reduction in the wall thickness of the convoluted central portion thereby enhancing flexibility of the gaiter while reducing material costs in the case where the central portion extends over a major part of length of the gaiter.

The wall thickness of further seating channel may also be increased relative to the thickness of the folds of the central portion.

The gaiter may be formed from material of sufficient flexibility so that the single fitting section at each end is stretchable over different shaft sizes.

However, one or both of the end portions may have a plurality of axially spaced annular fitting sections which may be of progressively decreasing internal diameter whereby the inner surface of each end portion can be clamped into seating engagement with said joint members of different diameters corresponding to the different said internal diameters.

Alternatively, it is desired that the axially spaced fitting sections may be of progressively increasing internal diameter.

The transition between adjacent axially spaced fitting sections may take any suitable configuration but preferably is effected via generally radially extending walls which may be generally perpendicular to the seating

channels. This arrangement allows enhanced flexibility while at the same time restricting the length of the gaiter occupied by stepped regions so that a major part of the gaiter length is occupied by the central folded portion thereby ensuring the gaiter has the requisite flexibility.

These joining walls may taper in the direction of the pertaining end portion. This taper, which is preferably only a slight taper, allows for easier manipulation of the gaiter during its manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further by way of example only and with reference to the accompanying drawings in which:- Fig. 1 is a sectional side view of one form of gaiter according to the invention; Fig. 2 is a schematic representation of the gaiter of Fig. 1 in position around a conventional steering gear.

Fig. 3 is a schematic representation of a form of conventional steering gear requiring a shorter gaiter.

Fig. 4 is a schematic representation of the gaiter of Fig. 1 shortened and mounted around the steering gaiter of Fig 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gaiter shown in Fig 1 comprises a one piece moulded rubber tube 10 generally of cylindrical form having a convoluted central portion 12, a first end portion 14 and a second end portion 16.

The first end portion 14 of the tube is stepped to define a number generally cylindrical annular fitting sections 14a and 14b of progressively decreasing diameter each of which extends parallel to the tube axis 18. The second end portion is constructed in a similar manner to define generally cylindrical annular fitting sections 16a and 16b.

The annular fitting sections provide for attachment to different sizes of shafts and housings of joints (by cutting away sections 16a and/or 14a if necessary).

Each fitting section 14a, 14b, 16a, 16b has a seating channel defined by a flat portion 13,15,17,19 (as viewed in cross section) which extends almost parallel to the gaiter axis.

Adjacent flat portions 13,15,17,19 are joined by a respective radially extending walls 14c, 16c.

Each radially extending wall 14c, 16c, is generally perpendicular to the gaiter axis except for a slight taper of walls in the direction of the pertaining free end such that the angle between the flat portion and the radially extending wall is 85°.

With this arrangement the end portions permit axial extensibility while keeping axial dimensions of the end portions to a minimum. In this way the central portion may extend over a major part of the body allowing greater flexibility.

Each outer flat portion 13 and 17 is bounded on the side toward the pertaining free end by a respective upstanding external rib 21, and on the

other side by the radial wall 14c, 16c, and seating channels 13,15,17,19 are defined to receive a fixing strap or tie.

Each inner flat portion 15 and 19 is bounded on the side toward the pertaining free end by two circumferential ribs, an internal rib 3 and an external, radially offset rib 2. Adjacent the rib 2 is a v-shaped groove, the rib and groove being juxta positioned to share a common surface 4a.

At the second end 16 of the gaiter, the flat portion 17 is bounded on the side toward the pertaining free end by two circumferential ribs, an internal rib 6 radially aligned with an external rib 8. Each rib has a curved outer surface, and is generally semicircular (as viewed is cross section).

This increases the strength of the end 16 of the gaiter which is subjected to high stress during manufacture when the end portion is held in place while the gaiter is inflated during manufacture.

The central portion is provided with a further annular fitting section 20 located approximately 4/5 along the length of the gaiter thereby dividing the central portion into two sections 22 and 24.

The further annular fitting section 20 comprises a flat portion which extends parallel to the gaiter axis to provide a further seating channel 20a.

This further seating channel is bounded on one side by an external rib 28 projecting radially outward from the channel wall and an internal rib 26 projecting radially inward from the channel wall, the two ribs 26,28 radially aligned. On the other side the further seating channel is bounded by an adjacent fold section 22.

Adjacent the rib 28 is a v-shaped circumferential groove 30 in the wall the groove and rib juxta positioned to share a common surface 29.

The groove 30 is 0.8mm deep and is 0.5mm wide at the external surface of the gaiter. This groove provides a tear line 31 which, while not compromising the strength of the gaiter in normal use about a joint will however, upon application of sufficient axial force, allow the gaiter to tear along the tear line 31.

The wall thickness of the end portions 14 and 16 and the further annular fitting section is 2mm while the wall thickness of the convoluted central portion 20 is 1.5mm.

This strengthens the end portions to provide robust seating channels able to withstand the stress imposed by the fixing tie or retaining clip whilst also allowing a reduction in the wall thickness of the central portion which increases flexibility thereof.

In use, as shown in Fig. 2, the gaiter is fitted around a conventional joint 40 defined by a steering rack 41 and a steering tie rod 42.

The configuration of the steering gear 40 is such that the gaiter must be fixed at positions relatively far apart. The entire length gaiter of Fig. 1 is therefore fitted in position (after filling with a suitable lubricant) by clamping the second end portion 16 around a large diameter steering rack housing 43 (which houses the steering rack 41) and the first end portion 14 around the smaller diameter steering tie rod 42 by means of two fixing straps: one in a selected one of the first end portion channels and other in

a selected one of the second end portion channels.

Fig. 3 shows a second conventional joint defined by a steering rack 50 and steering tie rods 52. However in this arrangement the tie rods 52 are attached at a point on the length of the rack 50 via a slot 58 in the steering rack housing 56.

A cylindrical sleeve 60 is slidably located around the housing 56 and fixed to the tie rods to prevent leakage of lubricant from within the rack housing via the slot 58.

A gaiter is fitted between axially close positions A and B and another between axially close positions C and D.

Whereas it would normally be necessary to use a separate shorter model of gaiter from that used for the steering gear of Fig. 2, the gaiter shown in Fig 1 and 2 is also readily adapted for use with steering gear of Fig. 3.

The gaiter 10 is first torn along the tear line 31 to provide a shorter gaiter having a central convoluted portion 22, the second end portion 16 as described above and a new end portion which has a seating channel 20 bounded on the side nearest the pertaining free end by ribs 26 and 28.

The gaiter is secured in position by clamping the end portion 16b around the sleeve 60 and the further seating channel 20 around the steering housing 56.

The gaiter is clamped in position by fixing straps (not shown) one in a selected one of the second end portion channels 16a or 16b and the other

in the further seating channel 20.

The rib 28 prevents slipping of the fixing strap relative to the gaiter.

The internal rib 28 forces the external rib 26 outwards and in the direction towards the fixing strap to securely retain the strap in place on the seating channel 20.

The rib 21 on the seating channel 16b serves to retain the strap in place on the seating channel 16b.

Thus, with this arrangement, the gaiter 10 may be used for different steering gears in which the axial spacing of appropriate gaiter fitting positions varies widely.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiments which are described by way of example only.