Railway wheels and axles – Wheels – Tire cushions
Reexamination Certificate
1999-10-20
2001-11-06
Morano, S. Joseph (Department: 3617)
Railway wheels and axles
Wheels
Tire cushions
C295S007000
Reexamination Certificate
active
06312033
ABSTRACT:
The invention relates to a rubber-sprung, multi-part wheel for rail vehicles with a wheel rim and a wheel hub as well as an interposed, releasable spring element.
Such wheels are often used in trolleys in order to minimize sound emissions or reduce non-sprung masses for other reasons.
In known rubber-sprung wheels for rail vehicles of the initially mentioned type, rubber plates are arranged parallel to each other (DE-PS 19 57 382, DE-PS 21 42 774). The rubber plates hereby stand under a pressure load because of the pre load exerted by screws, but are otherwise loaded almost exclusively axially. This combined load results in very long spring excursions and intense flexing work. The assembly is complicated.
In a similar manner, DE 43 00 552 A1 attempts to control the pressure and thrust tensions in a rubber-sprung wheel for rail vehicles. The fact that this is not always successful is shown by an elastic stop provided on the wheel hub which elastically catches the wheel rim in its movement relative to the wheel hub if the predefined spring excursions of the rubber disks that are arranged in a V-shape are exceeded. The assembly of the individual rubber disks and the manufacturing of precise angled surfaces on the parts of the wheel for rail vehicles is complex.
CH 156 916, DE 24 06 206 C3 and DE 33 28 321 C2 describe spring elements which are built between wheel hub and wheel rim in such a way that they are in essence only loaded by pressure. The assembly of the rubber parts is complex, since a tilting and pinching of the rubber rings must be prevented. The elasticity of the wheels is naturally very low, whereby however the ratio of axle load to spring excursion and/or hardness of the rubber also plays a role.
DE 44 30 342 A1 suggested a rubber-sprung wheel in which an axle load causes the load on the preloaded rubber elements, i.e., paired rubber disks designed in the shape of a V-shape or summarily as a truncated cone, to be relieved between wheel hub and wheel rim while they are loaded more in the zenith area, i.e., the rubber elements are put under pressure in the zenith area.
In all cases of the state of the art, it is hard to assemble the wheel for rail vehicles consisting of wheel rim and wheel hub with the elastic parts to be installed since the arrangement of the rubber disks or otherwise designed rubber parts must be exactly symmetrical. Rubber parts, especially parts on which pressure is exerted, are subject to such intense flexing work that they develop significant heat after a short time and are damaged or destroyed after a certain load (axle load measured in tons times kilometers).
In the case of the invention at hand this results in the problem of a quick and simple assembly and disassembly of replaceable spring elements, whereby the spring elements should be stressed as little as possible with the help of a corresponding design.
According to the invention this problem is solved with the characteristics of claim
1
. Further developments of the invention are found in the secondary claim.
The rubber-sprung wheel for rail vehicles according to the invention consists essentially of the wheel rim and the wheel hub with an interposed spring element comprising a center disk or an inner ring and two outer disks or annular plates between which an elastomer ring or rubber ring is fixed. The disks are preferably in a concentric or plan-parallel arrangement to each other, but may also form an angle relative to each other with their surfaces, as is the case in the state of the art. It is preferred that a complete spring element forms a system that is mirror symmetrical to a center plane of the center disk, orthogonally to the wheel axle or the axis of the wheel hub. This includes an identical shape of the two outer disks and the elastomer rings between the center disk and the outer disks.
In connection with the invention it is important that the spring element as such can be installed complete or in one piece between the wheel hub and the wheel rim and, to the extent this is reasonable or necessary for the design of the rail vehicle, for example a trolley, can be mounted with a preload. In a preferred embodiment the elastomer rings are adhesive, i.e., have been fixed to disks, usually steel disks, by vulcanizing or gluing with suitable glue. For this purpose both rubber mixtures as well as special—actually known—plastics mixtures are suitable. The section of the rings show that the spring element is oriented in a V-shape. This orientation makes it possible to put the elastomer rings under a preload relative to the inner ring or the center disk by screwing the outer rings at a predefined site into the wheel rim. On the other hand, the final assembly could also consist of first mounting the outer rings to the wheel rim, and then mounting the inner ring or the center disk with the help of suitable devices to the wheel hub. Both the outer disks on the wheel rim and the center disk on the wheel hub are able to hereby put the spring element under a preload with the help of actually known screw connections. The spring element that is constructed and mounted in this way can be easily premanufactured and, following disassembly of the wheel rim, can be easily pulled off the hub and replaced with another element.
Depending on the type of materials and their shape and load, the creeping behavior of the elastomer rings must be observed. In the case of a load mostly due to thrust forces, rubber mixtures or equivalent plastics that are primarily very low-curing should be used.
The spring elements according to the invention exert almost exclusively an axial load on the elastomer rings, so that the spring element absorbs a high radial spring deflection without entering the critical load range of the elastomer. This is the case in particular when the diameter of the elastomer rings increases towards the outer disks so that the center ring or the center disk dips into the wheel rim when the wheel axle is loaded radially against the reaction force of the elastomer rings.
If the rubber elements or elastomer rings are constructed mirror-symmetrical to the center plane of the center disk, this creates a corresponding, symmetric, high axial stiffness of the wheel, in particular if the center plane splits the width of the wheel rim in half.
Such a spring element can be adapted to any wheel rim diameters and hub diameters by varying the disk diameter; in the same way, it is possible to forsake plan-parallel disks by modifying the vulcanized elastomer rings with their V-shaped cross-section and to change over to slightly V-shaped disks if corresponding axial loads are expected or a pressure load on the elastomer rings is desired.
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Berkowitz Marvin C.
GMT Gummi-Metall-Technik GmbH
Morano S. Joseph
Nath Gary M.
Nath & Associates PLLC
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