Railways – Track layers – Track raising car
Reexamination Certificate
2003-05-30
2004-12-21
Jules, Frantz F. (Department: 3617)
Railways
Track layers
Track raising car
C104S007200
Reexamination Certificate
active
06832559
ABSTRACT:
TECHNICAL FIELD
This invention relates to equipment used in railway maintenance. More particularly, the invention relates to equipment used for lifting a section of track. Specifically, the invention is concerned with equipment referred to in the art as a “rail clamp”.
BACKGROUND ART
Railways generally consist of a track supported by a bed of crushed rock or gravel, this bed being referred to as “ballast” in the art. Most tracks comprise a pair of rails fixed to lateral members known as “sleepers” (or in some countries, “cross-ties”). Sleepers are formed from steel, timber or concrete.
There is often a need during railway construction or maintenance for lifting of the track. For example, replacement of ballast is simplified by lifting the track as a whole to allow access to the ballast. When new ballast has been placed on top of a section of track, the track has to be lifted up through the ballast so that it can be on top of the added ballast. Other instances where track lifting is required include tamping and lining operations for resurfacing of a railway. Track realignment often requires lifting of the track while replacement of sleepers may also require some degree of track lifting.
For the efficient execution of the procedures referred to in the preceding paragraph, the machinery is propelled or drawn along the railway at the highest possible speed consistent with quality, machine wear and tear, and safety requirements. The track lift point thus moves with the machinery. Special equipment is required for lifting under such circumstances, the most usual equipment employed being a “rail clamp”.
There are two general categories of rail clamps—roller and non-roller. Roller clamps are able to move along the rail with out being disengaged, whereas the non-roller clamp must be opened (disengaged) before being moved. It will be appreciated that only roller rail clamps are suitable for use in conjunction with machinery designed to move along the railway during operation of the machine. Consequently, the clamps must be capable of holding the lifted section of track—which can have a down force of the order of 35 tonne—and in addition must be capable of moving along the track. This is achieved solely through the gripping of the heads of the rails by the clamps.
In moving along a section of track, roller rail clamps can be obstructed. This most frequently occurs through the clamp meeting a fishplate or excessive weld flashing at a junction between rail sections. If a roller rail clamp is not designed to traverse an obstruction, the rail gripped by a particular clamp can be released with the potential for release of the entire lifted section. Such a “derailing” of the lifted section can have serious consequences including damage to the track. In addition, the clamps per se can be damaged.
A limitation of known roller rail clamps is that they are either incapable of traversing obstructions on the rails or have a limited capacity to traverse obstructions whilst lifting. There is thus a need for a roller rail clamp that overcomes the foregoing limitations of existing roller rail clamps.
SUMMARY OF THE INVENTION
The object of the invention is to provide a roller rail clamp that overcomes the limitations referred to in the previous paragraph.
In a broad format, the invention provides roller rail clamp apparatus for use with track comprising a pair of parallel rails, said apparatus comprising:
parallel pairs of spaced-apart lift roller assemblies mounted to a support for positioning a pair for clamping to a rail of said track, each said lift roller assembly comprising at least one pair of rollers, wherein each said roller of a roller pair rotates on an axis in an essentially vertical plane adjacent a rail and said rollers are on opposite sides of a rail when a lift roller assembly is clamped thereto with the head of said rail releasably retained between said rollers;
means for adjustably connecting said apparatus to a carrier thereof;
a lift mechanism for adjusting the vertical position of said support relative to said carrier of said apparatus; and
a tilt mechanism for applying torque about a horizontal axis to linkage between members of a pair of lift roller assemblies.
The principle embodied by the roller rail clamp apparatus defined in the preceding paragraph is that load bearing is transferred between lift roller assemblies when traversing an obstacle in the rails of the track to which the apparatus is clamped for lifting. This is achieved through applying torque to a member that links the lift roller assemblies of a pair, the torque being applied about a horizontal axis. Alteration of the slope of the assembly of parallel pairs of spaced-apart lift roller assemblies can result from this application of torque and hence the positions of the roller assemblies relative to the horizontal. This will be explained in more detail below but briefly, in a normal working position on open track, torque on the member linking the lift roller assemblies of a pair is such that the rear roller assemblies are bearing the track. Opening of the front rollers (momentarily) as they traverse an obstacle is sensed and after clearing the obstacle, the torque is reversed through the action of the tilt mechanism so as to confer load bearing on the front lift roller assemblies. This allows the rear assemblies to traverse the obstacle with momentary opening of the rollers. Closure of the rollers on passing the obstacle is sensed and by way of the tilt mechanism, load bearing reverts to the rear roller assemblies.
The roller rail clamp apparatus of the invention can be adapted for use with any machine where lifting of track for the operation of the machine is required. For example, the apparatus can be part of a machine for removal of ballast. In such an application, the apparatus is used to suspend the track above an under-wagon plough that excavates the ballast as the machine moves along the railway. Other applications of the apparatus of the invention include lifting of track through ballast newly applied over the top thereof, re-alignment of track, and undercutting of track. The apparatus can also be used to stabilise on track lifting equipment and mobile work platforms.
Particular features of the roller rail clamp apparatus will be detailed below as will optional features and preferments. Broadly, however, the apparatus can be connected to any suitable wagon or machine-frame. Usually, apparatus is mounted midway between the wheels of a wagon. However, the apparatus can also be mounted ahead of, behind, or anywhere between the wheels of a wagon. Furthermore, the apparatus can also be supported by an off track machine such as an excavator, crane or gantry.
The support for the pairs of lift roller assemblies advantageously comprises a longitudinal beam for each pair of assemblies, there thus being two beams in the apparatus that are about the same distance apart as the rails of the track. A crosspiece to which they are pivotally mounted to allow tilting of the beams typically links the beams. It will be appreciated however that the support can be any assembly of members that appropriately positions the lift roller assemblies for clamping to rails yet permits tilting of the pairs of assemblies.
The means for adjustably connecting the apparatus to the wagon or equipment carrying it can be any suitable means. For example, the connection means can be a series of vertical and horizontal slides, a drawbar or a push bar. In place of a drawbar, a parallelogram linkage can be used. In a preferred form of the apparatus in which the support for the lift roller assemblies comprises linked longitudinal beams, the connecting means is conveniently a drawbar pivotally linked to a wagon carrying the apparatus. This drawbar is advantageously pivotally connected to the crosspiece between the lifting beams so that lateral and some angular movement of the beams is permitted.
The distance between the lift roller assemblies of each pair is determined by the maximum length of the obstacle to be traversed and the intended maximum speed of
Hoffman Wasson & Gitler PC
Jules Frantz F.
Queensland Rail
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