GB2035238A - Railway wagon suspension units - Google Patents

Abstract

A frame (1) is mounted over a saddle (2) accommodating an axle journal housing (3) with a load spring suspension system (6) disposed between the frame and the saddle. The saddle bears on the housing through a mounting which includes a rubber block (17) together with the conventional rib (19) and channel (20) structure, the rubber yielding in shear to permit a controlled degree of movement between the saddle and the housing principally restricted to longitudinal motion in the direction of travel of the wagon, and lateral motion by which the saddle pivots on the mounting about the housing. The axle is thus permitted to self steer into tight curves at low speed whilst retaining satisfactory high speed performance, whereas hitherto, the wedges have tended to accommodate longitudinal motion on curves only in a comparatively disjointed fashion by somewhat 'stepwise' slipping and this has been particularly marked at low speeds. <IMAGE>

Description

SPECIFICATION Railway wagon suspension units This invention relates to railway wagon suspension units; such units may be used separately in conjunction with each wheel of a single axle two-wheel assembly, i.e. a pedestal, or embodied in side frames in a composite bogie structure, e.g. a four-wheel two axle or six-wheel three axle bogie.

The present invention provides a railway wagon suspension unit comprising a frame mounted over a saddle accommodating an axle-journal housing, with a load spring suspension system disposed between the frame and the saddle, the saddle bearing on the housing through a mounting including a body of elastromeric material whereby to permit a controlled degree of movement between the saddle and the housing principally restricted to longitudinal motion in the direction of travel of the wagon in which the elastomer yields to shear stress and lateral motion by which the saddle pivots on the mounting.

Preferably, the mounting comprises mutually engaging surfaces each of curved cross section, one being in the form of a channel and the other in the form of a rib of smaller curvature which nestles in the channel, the elastomeric body being bonded to the channel or rib (preferably through an intermediate plate) about which the said pivotal (or swinging) motion is effected.

The channel may be formed in, or housed in, the saddle. Similarly the rib may be formed in or mounted on the axle-journal housing or more particularly the journal housing adaptor, i.e. a separate part mounted on the journal housing proper. Advantageously the elastomer is sandwiched between and bonded to plates, the whole sub-assembly defining a U-shaped structure depending over the sides of the axle-journal housing whereby to restrain lateral stresses on the elastomer.

Preferably, both the rib and the channel are housed in their respective parts rather than being integral with them thus forming a separately identifiable rocker assembly which may be readily detachable.

The load spring suspension system may conveniently embody two spring nests, one mounted on the fore platform of the saddle and the other on the aft and engaging two friction wedges each of which bears on the side of the saddle and the underside of the pedestal unit. The latter bearing may be through a further wedge interposed between the friction wedge and the pedestal frame itself. This use of the separate (further) wedges is a useful facility since the wedge angles can be selected to suit the required friction control.

The spring nests may include dual or triple springs of different rates exhibiting multi-stage springing, or variable rate springes.

As distinct from more conventional pedestal designs hitherto, there is a larger degree of clearance for longitudinal movement between the axle-journal housing/adaptor and the saddle walls so as to accommodate such movement when the elastomeric body is subjected to shear stress. With this invention, such longitudinal movement, which is principally manifested when negotiating curves, is wholly accommodated by the elastomer up to a load rate equal to that at which the friction on the wedges in the load spring suspension system is overcome.

The principal advantage of the introduction of this elastomeric mounting is that the axle is permitted to self steer into tight curves at low speed whilst retaining satisfactory high speed performance; this enables a higher mileage to be obtained between tyre turning i.e. re-furbishing worn tyres on the wheels. Hitherto, the wedges have tended to accommodate longitudinal motion on curves only in a comparatively disjointed fashion by somewhat 'stepwise' slipping and this has been particularly marked at low speeds.

In order that the invention may be fully understood some embodiments thereof will now be described with reference to the accompanying drawings in which, Figure 1 is a part sectional side elevation of a pedestal unit in accordance with this invention.

Figure 2 is a part sectional end elevation through the wheel axle.

Figure 3 is one modified form of elastomeric mounting, and Figure 4 is another modified form of mounting.

Referring now to Figures 1 and 2 in the drawings there is shown a railway wagon pedestal unit comprising a frame 1 mounted over a saddle 2 accommodating an axle-journal housing 3. The saddle embodies a platform having a fore-section 4 and an aft section 5. Mounted on these sections are spring nests 6, 7 respectively engaging friction wedges, only one pair of which 8, 9 is visible.

The wedge 8 bears on a friction pad 10 on the side of the saddle and a pad 11 on the inclined undersurface of the wedge 9, which wedge itself nestles in a right angled recess 12 formed in the frame 1.

The spring nests comprise a combination of springs having different rates which together effect two stage springing.

The journal housing accommodates a wheel axle 13 in roller bearings 14. Surmounting the journal housing is an 'adaptor' 15 comprising a cast member 16 having a recess in its upper surface accommodating a rubber block 17 which is bonded to an upper plate 18 carrying an elongated rib 19. The rib 19 has a curved surface on which bears an inversely curved elongated channel member 20 which is mounted on the underside of the saddle aperture.

The channel and rib together with its resilient yaw mounting together form a composite rocker assembly.

Two stubs 21, 22 extend from the top of the saddle casting into slots, only one of which (23) is visible, in the pedestal frame 1. This ensures retention of the saddle within the pedestal unit should the latter be lifted.

A curved clip member 24 is located on the bottom of the saddle aperture to prevent the journal housing from becoming detached from this aperture and a pair of 'stop' blocks 25 are welded to the sides of the saddle to limit relative longitudinal motion between the journal housing adaptor and the saddle.

When the unit is in service the saddle is rocked about this composite rocker assembly imparting lateral shear stresses on the load spring nests lateral stresses on the rubber block itself are restrained by plate 18 bearing on the side of the cast member 16.

Longitudinal motion is accommodated by the rubber block up to a certain limiting value beyond which the friction on the wedges in the load spring suspension system is overcome whereby, for motion in the left hand direction in Figure 1 the wedge will move in that direction compressing the load springs 6 and the right hand wedge will likewise move in that direction under the expansive forces of springs 7.

The rubber block 17 is shearing longitudinally up to and during the stage at which the wedges start to move, limited only by the casting 16 abutting the stop block 25.

Vertical loading is accommodated directly by the load springs sets 6,7 and the rubber block in compression. It is necessary to select the vertical and longitudinal load rates of the rubber block to be compatible with the vertical suspension spring rates and the desired axle yaw performance at slow speed in tight curves and at high speed on normal track.

Typical specific rates selected may be vertical grea tes than 50 tons/inch, longitudinal 10 - 20 tons/inch, the figure in any one instance being dependent on vehicle characteristics, performance data and track to be negotiated.

Alternative forms of mounting are shown in Figures 3 and 4, both designed to eliminate lateral clearance. In the former case the rubber block (26) is bonded to upper and lower plates 27, 28, the upper plate 27 additionally being spigotted at 29 to the elongated metal rib 19, the whole defining a 'flared' U-shaped configuration. In the other case, Figure 4, the design is similar but the lower plate is actually made up of three separate elements including two side plates of which only 28A is visible. The intermediate plate within the rubber mounting is omitted.

Whilst the lateral stiffness is increased, neither restrict the longitudinal stiffness in anyway.

The pedestal unit described may be manufactured as shown complete with the rocker assembly or the latter may be separately incorporated in 'converted' units, i.e. existing units which have been machined to accommodate the rocker assembly conversion.

Although this suspension unit has been described with reference to the specific embodiments illustrated, it is to be understood that various modifications may be made without departing from the scope of this invention. For example, other forms of wedge configuration and load spring nests could readily be adopted as indeed could other forms of the elastomeric mounting, e.g. an additional plate could be inserted in the side rubbers in the Figure 3/Figure 4 embodiments to increase lateral stiffness.

Claims (11)

1. A railway wagon suspension unit comprising a frame mounted over a saddle accommodating an axle-journal housing, with a load spring suspension system disposed between the frame and the saddle, the saddle bearing on the housing through a mounting including a body of elastomeric material whereby to permit a controlled degree of movement between the saddle and the housing principally restricted to longitudinal motion in the direction of travel of the wagon in which the elastomer yields to shear stress and lateral motion by which the saddle pivots on the mounting about the housing.

2. A suspension unit according to claim 1, in which the mounting includes mutually engaging surfaces each of curved cross-section one being in the form of a channel and the other in the form of a rib of smaller curvature which nestles in the channel, the elastomeric body being bonded to the channel or rib about which the said pivotal motion is effected.

3. A suspension unit according to claim 2, in which the elastomeric body is bonded to the rib via a plate intermediate the rib and body.

4. A suspension unit according to claim 3, in which the channel is formed in, or housed in, the saddle.

5. A suspension unit according to claim 4, in which the elastomeric body is additionally bonded to an intermediate plate mounted on the axle journal housing.

6. A suspension unit according to claim 5, in which the elastomeric body and one or both of the intermediate plates bonded thereto are U-shaped depending over the sides of the axle journal housing whereby to restrain lateral stresses on the elastomer.

7. A suspension unit according to claim 5 or claim 6, in which both the channel and the rib and their said associated parts together form a separately identifiable detachable rocker assembly.

8. Asuspension unit according to any one of the preceding claims, in which the suspension system comprises two spring nests one mounted on the fore platform of the saddle and the other mounted on the aft and engaging two friction wedges each of which bears on the side of the saddle and the underside of the pedestal frame.

9. A suspension unit according to claim 8, in which each wedge bears on the underside of the pedestal frame via an intermediate wedge, whereby the co-operating wedge angles can be selected to suit the required degree of friction control.

10. A suspension unit according to claim 8 or claim 9, in which each spring nest includes a plurality of springs.

11. A railway wagon suspension unit substantially as herein described with reference to the accompanying drawings.