EP0011453B1

EP0011453B1 - Railway wagon suspension units

Info

Publication number: EP0011453B1
Application number: EP79302517A
Authority: EP
Inventors: Alan Henry Briggs
Original assignee: British Steel Corp
Current assignee: Cessione british Steel PLC
Priority date: 1978-11-14
Filing date: 1979-11-09
Publication date: 1983-01-19
Also published as: EP0011453A1; NO793625L; NZ192036A; DK482579A; DE2964558D1; NO147296C; NO147296B; ZA795881B

Description

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.
It is known to provide 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 adaptor including a curvilinear surface engaging a further surface whereby to permit pivotal lateral motion of the saddle and the housing relative to one another. Such a unit is the subject of GB-A-1 433948. With such an arrangement longitudinal motion between the axle-journal housing and the saddle, principally manifested when negotiating curves, has tended to be accommodated in a comparatively disjointed, somewhat stepwise fashion by movement of the customary wedges in the suspension system, adversely affecting the ride, particularly at slow speeds, and promoting wear.
The present invention mitigates this drawback by providing in the mounting firstly a body of elastomeric material. With this arrangement there is permitted a controlled degree of movement particularly in respect of the longitudinal motion of the kind referred to where the elastomer now yields to shear stress. Whereas this principle has been adopted in certain cases hitherto, namely, as disclosed in GB-A-1025808 and GB-A-1 532441 and US-A-3638582, in this invention lateral pivotal movement of the kind by which the saddle pivots or swings about the housing mounting adaptor is accommodated whilst direct lateral translational movement of the saddle relative to the adaptor is restrained.
More particularly, 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, as mentioned, 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.
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 under-surface 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 three 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 an elastomeric body, more particularly 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 (20) and rib (19) together with its resilient yaw mounting together form a composite rocker assembly.
Two studs 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 greater than 17860 Kg/cm, longitudinal 3570-7140 Kg/cm, 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 bounded 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 any way.
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 Fig. 3/Fig. 4 embodiments to increase lateral stiffness. Variable rate springs could be introduced instead of the multi-stage springing shown in the suspension system.

Claims

1. A railway wagon suspension unit comprising a frame (1) 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 bearing on the housing through a mounting adaptor (15) including a curvilinear surface (19) engaging a further surface (20) whereby to permit pivotal lateral motion of the saddle (2) and the housing (3) relative to one another, the mounting adaptor (15) including a body (17) of elastomeric material, characterised in that an upper plate (18) is bonded to the body (17) and is of U-shaped configuration depending over the sides of the axle-journal housing (3) the elastomeric body and the upper plate permitting a controlled degree of movement between the saddle (2) and the housing (3) particularly with respect to longitudinal motion in the direction of travel of the wagon in which the elastomer yields to shear stress and additionally accommodating the said laterial pivotal motion whilst restraining direct lateral shift.

2. A suspension unit according to claim 1, characterised in that both of the mutually engaging surfaces of the mounting adaptor (15) are curvilinear, one being in the form of a channel (20) and the other in the form of a rib (19) of smaller curvature which nestles in the channel (20), the elastomeric body (17) being bonded to the channel (20) or rib about which the said pivotal motion is effected.

3. A suspension unit according to claim 2, characterised in that the channel (20) is formed in, or housed in, the saddle (2).

4. A suspension unit according to claim 3, characterised in that the elastomeric body (17) is bonded to the rib via a plate (27) intermediate the rib and body.

5. A suspension unit according to claim 4, characterised in that the elastomeric body (17) is additionally bonded to an intermediate plate (28) mounted on the axle journal housing (3).

6. A suspension unit according to claim 5, characterised in that the elastomeric body (17) and one or both of the intermediate plates (27, 28) bonded thereto are U-shaped depending over the sides of the axle journal housing (3).

7. A suspension unit according to claim 5, or claim 6, characterised in that the constituent parts of the mounting adaptor (15) together form a separate detachable rocker assembly.

8. A suspension unit according to any one of the preceding claims, characterised in that the suspension system comprises two spring nests (6, 7) one mounted on the fore platform of the saddle (2) and the other mounted on the aft and engaging two friction wedges (8) each of which bears on the side (10) of the saddle (2) and the underside of the pedestal frame (1).

9. A suspension unit according to claim 8, characterised in that each wedge (8) bears on the underside of the pedestal frame (1) via an intermediate wedge (9), whereby the cooperating wedge angles can be selected to suite the required degree of friction control.