GB2155867A - Axle casing - Google Patents

Abstract

A casing for a vehicle axle with a pair of half-shafts driven by a drive shaft comprises a ring-shaped centre bowl (C), rolled from a pierced billet, having a front face shaped to receive the drive shaft and to mate with a drive shaft casing, and further having two apertures cut in opposite sides thereof for receiving the half-shafts; and a pair of tubes (B), for covering a portion of each half-shaft, each welded (2, 3) at a curved end (5) onto the outer surface of the bowl (C) around a respective aperture to join flush with the bowl. The bowl may have parallel, flat front and rear surfaces, with each tube end 5 being swaged to rectangular form in the plane perpendicular to the tube axis. An extended stub A may be friction welded onto the outer end of each tube B. The casing may be made of carbon-manganese steel. <IMAGE>

Description

SPECIFICATION Axle casing The present invention concerns casings for axles, of the type where a sealed casing covers a differential joint between a vehicle drive shaft and a pair of driven half-shafts.

According to one known design, the main bowlshaped centre part of the axle casing fabrication consists of two identical pressings welded together along a horizontal joint. Further welding then takes place to attach a steel ring which results in a boss, the boss then being machined into a circular facing for the attachment of the driving head of the drive shaft. The hollow forged or extruded ends of the welded pressings are then friction-welded onto the other casing parts.

A large press is required for pressing flat rolled plate into the shape required for the casing, using large male and female tools. The press and the tools are expensive, and any design changes are costly to implement. Moreover, the shapes into which the plate is cut prior to pressing are irregular, and result in much wasteage of plate. Both these problems become more severe with larger centre bowl diameters.

Other known axle casings are produced by casting or forging, but these methods are inevitably expensive.

It is an object of the invention to provide an axle casing, and a method of making the same, which does not suffer from these drawbacks and can therefore be made more cheaply.

An axle casing in accordance with the invention, for an axle with a pair of half-shafts driven by a drive shaft, comprises: a ring-shaped centre bowl having a front facing shaped to receive the drive shaft and to mate with a drive shaft casing, the bowl further having two apertures in opposite sides for receiving the half-shafts; and a pair of hollow arms for covering a portion of each halfshaft, arranged co-linearly and substantially parallel to the bowl front facing, each welded at its end onto the outer surface of the bow around a respective aperture, the said arm ends having a shape such as to join flush with the bowl outer surface.

The bowl preferably has parallel, flat front and rear facings and an annular cross-section in the plane of the facings. In one form of the invention, the arms are tubes, the perimeter of each of the said tube ends describing a rectangle in a plane pendicular to its length, and an arc of a circle in a plane parallel to the said front facing.

A method in accordance with the invention, of making a casing for an axle with a pair of halfshafts driven by a drive shaft, comprises the steps of: rolling in a rolling mill or the like an annular pierced billet into a ring shape, the resultant bowl having a front facing shaped to receive the drive shaft and to mate with a drive shaft casing; cutting two apertures in opposite sides of the bowl for receiving the half-shafts; and welding the ends of a pair of hollow arms onto opposite outer surfaces of the bowl over respective apertures, the arms being arranged co-linearly and substantially parallel to the bowl front facing, the said arm ends being shaped such as to join flush with the bowl outer surface.

In a preferred method, the billet is rolled such that the resulting bowl has parallel, flat front and rear facings and an annular cross-section in the plane of the facings.

In one example, where the arms are tubular, the method further includes the step of swaging the said ends of the arms such that the perimeter of each end describes a rectangle in a plane perpendicular to the arm length, and an arc of a circle in a plane parallel to the said front facing.

In order that the invention may be better understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which: Figure 1A is a full front view of an axle casing according to the preferred embodiment; Figure 1B is a vertical section of the axle casing of Figure 1A; Figure 2A is a side section, from the right-hand side, of the centre bowl portion of the axle casing of Figures 1A and 1B; Figure 2B is a front elevation of the centre bowl of Figure 2A; Figure 3A is an end section of a tubular part of the axle casing of Figures 1A and 1B; Figure 3B is a front section of the tubular part shown in Figure 3A; and Figure 3C is a different end section of the tubular part shown in Figures 3A and 3B, representing the opposite end from that shown in Figure 3A.

Referring to Figures 1A and 1B, a casing for the differential gear and two half-shafts of a motor vehicle, includes a centre bowl part C, two arms in the form of tubes B for covering respective halfshafts, and two stubs A on the ends of the tubes B.

Bowl C is illustrated in Figure 2A, a section viewed from the right-hand side of Figure 1A, and in Figure 28, a front elevation. It is ring-shaped, with a flat front facing 4 designed for attachment to a further casing (not shown) around the drive shaft. Apertures 6 (Figure 1B), for allowing the half shafts to pass through to the differential, are cut in the curved side walls of the bowl C.

A pair of identical tubes B are welded onto the curved side wall of the bowl C over respective apertures 6. Each tube B (Figure 3B) has one end of circular section (Figure 3C), the opposite end 5 having a rectangular section (Figure 3A). The rectangular end 5 is welded (2, 3, Figure 1A) all the way round the perimeter onto the outer bowl surface which has the same curvature (in the plane of the front facing 4).

A pair of steel stubs A are welded (at 1, Figure 1A) on to the circular ends of the tubes B,.

In this example, the arms are identical tubes B.

However, hollow arms of other cross-sections are envisaged, and for some applications the arms on each side will differ in size or shape.

The casing components are preferably of Carbon-Manganese steel.

The manufacturing steps are as follows. The bowl C is rolled from an annular, pierced billet in a rolling mill or the like. The front facing 4 is rolled into shape in the same rolling operation. Apertures 6 are cut from the bowl, after rolling. Tubes B are cut from a length of steel tubing, swaged at one end into the rectangular shape and at the same time curved to the curvature of the bowl C. The rectangular end is chamfered for the weld. Tubes B are then welded onto the bowl C. Steel stubs are formed by backward extrusion or a similar process, and friction welded onto the main body. A thin pressed steel plate is welded onto the rear facing of the bowl C, where necessary, to cover the circular aperture (to the right in Figure 2A). Further components such as brake flanges are also welded on to the casing.

The axle casing can be made more cheaply than existing casings, because: no heavy press or expensive press tools are required; the casing can be made lighter; the number of manufacturing steps is reduced, for example because no extra ring is required to form the front facing 4; and there is very little scrap metal from cutting the preforms.

Moreover, with the new design, larger bowls are easier, not more difficult, to manufacture, since they are rolled, not pressed.

Previous casings have had the same shape and weight, whether used for axles with through drive or without through drive; this involved a penalty in weight and material cost. With the present invention, which allows more flexibility, the extra weight can be eliminated on casings for non-through-drive axles.

Claims (12)

1. An axle casing for an axle with a pair of halfshafts driven by a drive shaft, comprising: a ringshaped centre bowl having a front facing shaped to receive the drive shaft and to mate with a drive shaft casing, the bowl further having two apertures in opposite sides for receiving the half-shafts; and a pair of hollow arms for covering a portion of each half-shaft, arranged co-linearly and substantially parallel to the bowl front facing, each welded at its end onto the outer surface of the bowl around a respective aperture, the said arm ends having a shape such as to join flush with the bowl outer surface.

2. An axle casing according to Claim 1, wherein the bowl has parallel, flat front and rear facings and an annular cross-section in the plane of the facings.

3. An axle casing in accordance with Claim 1 or 2, wherein the arms are tubes, the perimeter of each of the said tube ends describing a rectangle in a plane perpendicular to its length, and an arc of a circle in a plane parallel to the said front facing.

4. An axle casing in accordance with Claim 1, 2 or 3, wherein a stub is welded onto the free, outer end of each tube.

5. A method of making a casing for an axle with a pair of half-shafts driven by a drive shaft, comprising the steps of: rolling in a rolling mill or the like an annular pierced billet into a ring shape, the resultant bowl having a front facing shaped to receive the drive shaft and to mate with a drive shaft casing; cutting two apertures in opposite sides of the bowl for receiving the half-shafts; and welding the ends of a pair of arms onto opposite outer surfaces of the bowl over respective apertures, the arms being arranged co-linearly and substantially parallel to the bowl front facing, the said arm ends shaped to join flush with the bowl outer surface.

6. A method in accordance with Claim 5, wherein the billet is rolled such that the resulting bowl has parallel, flat front and rear facings and an annular cross-section in the plane of the facings.

7. A method in accordance with Claim 5 or 6, wherein the arms are tubes, and further including the step of swaging the said ends of the tubes such that the perimeter of each end describes a rectangle in a plane perpendicular to the tube length, and an arc of a circle in a plane parallel to the said front facing.

8. A method in accordance with Claim 5, 6, or 7, further including the step of friction-welding a stub onto the free, outer end of each arm.

9. An axle casing substantially as described herein with reference to the accompanying drawings.

10. A motor land vehicle fitted with an axle casing substantially as described herein with reference to the accompanying drawings.

11. A motor land vehicle fitted with an axle casing in accordance with any of claims 1 to 4.

12. A method of making an axle casing substantially as described herein with reference to the accompanying drawings.