GB2126539A - Spring axle connections - Google Patents

Abstract

In a goods vehicle suspension where an axle 20 is held to leaf springs 10 that also act as trailing arms a wedge 31,32 is driven into the gap that exists between the leafspring 10 and upper clamping bracket 22, to take up play and prevent surface fretting resulting in fatigue cracking and corrosion. <IMAGE>

Description

SPECIFICATION Improvements in vehicle suspensions The present invention relates to a leaf-spring suspension for a vehicle having improved spring life.

Broadly stated the invention provides a suspension assembly for a goods vehicle comprising in combina- tion first and second hanger brackets for rigid attachmentto opposite sides of a vehicle chassis, first and second trailing arms in the form of leaf springs pivotally supported at their leading ends in the hanger brackets for movement in vertical planes, attached at an intermediate position to the axle and attached at theirtrailing ends to first and second air springs depending from the vehicle chassis, wherein each trailing arm istrapped between upperand lower axle brackets at least one ofwhich is formed with a recess in which the trailing arm locates and wherein a wedge member is inserted into said recess to take up play between the axle bracket and the trailing arm.The suspension assembly of the invention is less prone to surface fretting and premature failure ofthe trailing arms.

An embodiment of the invention will now be described byway of example only with reference to the accompanying drawings in which: Figures 1 and 2 are side and end views of a conventional air suspension for a goods vehicle; Figure 3 is a view in transverse section ofthe axle to trailing arm joint in a first embodiment of the invention; Figures 4a and 4b are respectively diagrammatic horizontal longitudinal and vertical transverse sections of an axle trailing arm joint according to a second embodiment of the invention; and Figure 5 is a diagrammatic longitudinal horizontal section of an axle to trailing arm joint according to a third embodiment of the invention.

In a typical air suspension for, for example, a platform semi-trailer, a leaf spring loins formed at its leading end with an eye 12 by means of which itis secured in a hanger bracket 14 attached to a vehicle chassis member 16. An air bag unit 18 is fitted between the trailing end ofthe leaf spring and the vehicle chassis. An axle 2 is secured to the spring 10 approximately midway along its length by means of an axle bracket 22 welded thereto, a lower clamp bracket 24 and a pair of U-shaped retaining bolts 26 that pass aroundthe axle and are held to the lower clamp bracket by studs 28. A hydraulic damper unit30 is mounted between the axle bracket 22 and the hanger bracket 14as shown.

The spring 10 acts as a trailing arm in a suspension of the above kind and has been found to be prone to failure by reason of surface fretting against the axle bracket resulting in fatigue cracking and corrosion.

This is because the spring is not a tight fit within the recess 21 in bracket 22 in which it is intended to be located owing to the tolerances necessary. The suspension is subjected in service to extremely high sidewaysforces at the joints between the axle 20 and the spring 10 that can bring about large movements resulting in spring misalignment.

In Figure 3, play between trailing arm 10 and axle bracket 22 is eliminated by means of a wedge having a vertical taper and longer than the nominal distance between the upper and lower clamping brackets. The upper portion 30 is rigid and is driven into the small gap between the spring 10 and bracket 22. The lower portion 32 is less robust and as the studs 28 are tightened, driving plate brackets 22, 24together, the portion 32 progressively collapses. It will beappreci- ated thatthere may be more than one such wedge on a singlesideofthetrailingarm lOorthere may be wedges on both sides thereof.

In Figures 4a and 4b the wedge 40 tapers in the longitudinal direction and is held in place by a weld 41.

In Figure 5the wedge 41' is held in place by a screw 42 that locates in threaded bore 43 in the bracket 22. The wedge may in fact be held in place by any suitable means, such as welding, adhesion, friction or a screw fixing. Any number of wedges may be used to achieve secure clamping - a single wedge may be sufficient but wedges may be inserted from opposed ends ofthe axle bracket and on a single side or on both sides.

1. Asuspension assemblyfora goods vehicle comprising in combination first and second hanger brackets for rigid attachment to opposite sides of a vehicle chassis, first and second trailing arms in the form of leaf springs pivotally supported at their leading ends in the hanger brackets for movement in vertical planes, attached at an intermediate position to the axle and attached attheirtrailing ends to first and second air springs depending from the vehicle chassis, wherein each trailing arm is trapped between upper and lower axle brackets at least one of which is formed with a recess in which the trailing arm locates and wherein a wedge member is inserted into said recess to take up play between the axle bracket and the trailing arm.The suspension assembly of the invention is less prone to surface fretting and premature failure of the trailing arms.

2. Asuspension assembly according to Claim 1 whereinthewedgetapers in a direction normal to the plane ofthetrailing arm and is inserted in compression between the upper and lower axle brackets.

3. Asuspension assembly according to Claim 2 wherein the wedge has a rigid tapered section that becomes inserted between the trailing arm and the recess and a deformable section that after insertion is complete, collapses progressively as the joint between the axle and the trailing arm is tightened.

4. A suspension assembly according to Claim 1 wherein the wedge tapers in a direction parallel to the trailing arm and is inserted in a direction parallel thereto.

5. A suspension assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in vehicle suspensions The present invention relates to a leaf-spring suspension for a vehicle having improved spring life. Broadly stated the invention provides a suspension assembly for a goods vehicle comprising in combina- tion first and second hanger brackets for rigid attachmentto opposite sides of a vehicle chassis, first and second trailing arms in the form of leaf springs pivotally supported at their leading ends in the hanger brackets for movement in vertical planes, attached at an intermediate position to the axle and attached at theirtrailing ends to first and second air springs depending from the vehicle chassis, wherein each trailing arm istrapped between upperand lower axle brackets at least one ofwhich is formed with a recess in which the trailing arm locates and wherein a wedge member is inserted into said recess to take up play between the axle bracket and the trailing arm.The suspension assembly of the invention is less prone to surface fretting and premature failure ofthe trailing arms. An embodiment of the invention will now be described byway of example only with reference to the accompanying drawings in which: Figures 1 and 2 are side and end views of a conventional air suspension for a goods vehicle; Figure 3 is a view in transverse section ofthe axle to trailing arm joint in a first embodiment of the invention; Figures 4a and 4b are respectively diagrammatic horizontal longitudinal and vertical transverse sections of an axle trailing arm joint according to a second embodiment of the invention; and Figure 5 is a diagrammatic longitudinal horizontal section of an axle to trailing arm joint according to a third embodiment of the invention. In a typical air suspension for, for example, a platform semi-trailer, a leaf spring loins formed at its leading end with an eye 12 by means of which itis secured in a hanger bracket 14 attached to a vehicle chassis member 16. An air bag unit 18 is fitted between the trailing end ofthe leaf spring and the vehicle chassis. An axle 2 is secured to the spring 10 approximately midway along its length by means of an axle bracket 22 welded thereto, a lower clamp bracket 24 and a pair of U-shaped retaining bolts 26 that pass aroundthe axle and are held to the lower clamp bracket by studs 28. A hydraulic damper unit30 is mounted between the axle bracket 22 and the hanger bracket 14as shown. The spring 10 acts as a trailing arm in a suspension of the above kind and has been found to be prone to failure by reason of surface fretting against the axle bracket resulting in fatigue cracking and corrosion. This is because the spring is not a tight fit within the recess 21 in bracket 22 in which it is intended to be located owing to the tolerances necessary. The suspension is subjected in service to extremely high sidewaysforces at the joints between the axle 20 and the spring 10 that can bring about large movements resulting in spring misalignment. In Figure 3, play between trailing arm 10 and axle bracket 22 is eliminated by means of a wedge having a vertical taper and longer than the nominal distance between the upper and lower clamping brackets. The upper portion 30 is rigid and is driven into the small gap between the spring 10 and bracket 22. The lower portion 32 is less robust and as the studs 28 are tightened, driving plate brackets 22, 24together, the portion 32 progressively collapses. It will beappreci- ated thatthere may be more than one such wedge on a singlesideofthetrailingarm lOorthere may be wedges on both sides thereof. In Figures 4a and 4b the wedge 40 tapers in the longitudinal direction and is held in place by a weld 41. In Figure 5the wedge 41' is held in place by a screw 42 that locates in threaded bore 43 in the bracket 22. The wedge may in fact be held in place by any suitable means, such as welding, adhesion, friction or a screw fixing. Any number of wedges may be used to achieve secure clamping - a single wedge may be sufficient but wedges may be inserted from opposed ends ofthe axle bracket and on a single side or on both sides. CLAIMS

1. Asuspension assemblyfora goods vehicle comprising in combination first and second hanger brackets for rigid attachment to opposite sides of a vehicle chassis, first and second trailing arms in the form of leaf springs pivotally supported at their leading ends in the hanger brackets for movement in vertical planes, attached at an intermediate position to the axle and attached attheirtrailing ends to first and second air springs depending from the vehicle chassis, wherein each trailing arm is trapped between upper and lower axle brackets at least one of which is formed with a recess in which the trailing arm locates and wherein a wedge member is inserted into said recess to take up play between the axle bracket and the trailing arm.The suspension assembly of the invention is less prone to surface fretting and premature failure of the trailing arms.

2. Asuspension assembly according to Claim 1 whereinthewedgetapers in a direction normal to the plane ofthetrailing arm and is inserted in compression between the upper and lower axle brackets.

3. Asuspension assembly according to Claim 2 wherein the wedge has a rigid tapered section that becomes inserted between the trailing arm and the recess and a deformable section that after insertion is complete, collapses progressively as the joint between the axle and the trailing arm is tightened.

4. A suspension assembly according to Claim 1 wherein the wedge tapers in a direction parallel to the trailing arm and is inserted in a direction parallel thereto.

5. A suspension assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.