Railway switches and signals – Switches – Lock
Reexamination Certificate
1999-11-24
2002-03-12
Morano, S. Joseph (Department: 3617)
Railway switches and signals
Switches
Lock
C246S41500R
Reexamination Certificate
active
06354541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for locking the end positions of movable railway switch parts, in particular a switch lock, in which two parts capable of being axially displaced relative to each other are displaceable into a position coupled to each other in a positive and force-transmitting manner in at least one moving direction, wherein the relatively displaceable parts are formed by a tube and a rod guided within the tube and are arranged at least partially in a stationary external tube, wherein locking elements comprised of balls cooperate with the axially displaceable parts and the external tube and are displaceable in the radial direction into a lock position into a recess or internal ring groove of the external tube.
2. Prior Art
A device of the above-mentioned kind has already become known from EP-A 603 156, in which locking elements comprised of balls are pressed into their lock positions by means of stops comprised of thickened rod regions, said locking elements in the lock positions lying in a recess of the external tube and on a partial rod region formed with the full diameter. The balls pass through openings of the tubes surrounding the rod and being respectively connected with a tongue such that a relative displacement of that structural part connected with the tongue, i.e., the tube, relative to the external tube will be effectively prevented if the balls are pressed into their outer positions, thus effecting locking between the external tube and the tubular structural part. To undo such a lock, the rod must be displaced, whereby the ball can fall back onto regions having smaller diameters, thus emerging from the lock position within the groove of the external tube.
In the known device only one side, i.e., the closed tongue, was appropriately locked at the line and the correct position of the open tongue was ensured by additional devices such as, for instance, a coupling rod. Such coupling rods, as a rule, are required by the pertinent rail authorities for safety reasons. While, during the displacement movement of the tongue, the forces to be taken up by the ball are limited by the maximum displacement force admissible, the balls may be strained by a multiple in the lock position. Switching forces, as a rule, are in the range of 150 kp, whereas the forces acting on the locking components may be in the range of 10,000 kp and more. Since those locking forces can be taken up by balls only via a line point contact, the points of contact are exposed to an excessively high load, which may lead to inadmissible deformations.
SUMMARY OF THE INVENTION
The invention aims to improve the function in a device of the initially defined kind and also guarantee the absorption of extremely high locking forces without the risk of premature impairment of the function of the locking means. To solve this object, the configuration according to the invention essentially consists in that the balls are encompassed by an expandable ring or a ring comprised of segments, that the segments or the ring, respectively, are resiliently held in a position having an outer diameter smaller than, or equal to, the outer diameter of the axially displaceable tube guided within the external tube and are/is immersed in a peripheral groove of the tube, and that the balls are arranged in openings of the tube between the rod and the ring comprised of segments. Due to the fact that the balls no longer directly cooperate with the edges of the grooves of the external tube in the lock position, an extreme load on the edges is avoided and the accordingly high load is taken up by the ring segments or the expandable ring, which, in turn, may have appropriate cross sections in order to ensure surface contact on the side walls of the grooves that are effective for locking. By those segments being resiliently pulled inwards, it is safeguarded simultaneously with a displacement of the rod into a position in which the balls can recede onto a region of reduced cross section, that this radially inwardly directed movement of the balls is assisted by the force of the springs such that, in the following, a minimum displacement resistance between the structural part coupled with the tongue and the external tube will be ensured. To this end, the segments of the ring are immersed in a peripheral groove of the tube with the balls themselves being guided in radial openings of the tube, as in the known configuration.
Advantageously, the configuration is devised such that the ring segments have end faces extending normal to the axial displacement direction or inclined at an acute angle, which end faces cooperate with the stops of the external tube in the lock position so as to ensure the effective and reliable support of high locking forces in the lock position.
In a particularly simple manner, the spring of the ring segments may be constituted by springs extending in the peripheral direction or a spring band. In principle, the individual ring segments may be interconnected by separate springs, wherein a configuration comprising an externally peripheral continuous spring band is particularly simple to produce.
In order to further enhance safety, and not only lock the respectively closed tongue but, at the same time, also be able to lock the respectively open tongue in an appropriate position, the configuration advantageously is devised such that the rod in its end region comprises two axial regions reduced to smaller diameters and an intermediately located axial region having the full diameter, whose axial length is smaller than the distance of two balls neighboring in the axial direction of the tube. With such a configuration, a plurality of planes adjacent in the axial direction may, thus, be utilized as locking planes and a large displacement path with suitable locking of the end positions may be reached at compact structural dimensions. In a particularly advantageous manner, the configuration is devised such that each axially displaceable tube respectively connected with a switch tongue includes openings at an axial distance (l
1
) which are offset in the axial direction and that the external tube comprises at least two stops so as to be opposed to each other at an axial distance (l
2
)>(l
1
) and located on a radius exceeding the diameter of the internal tube, the distance (l
2
) reduced by the distance (l
1
) corresponding to the axial displacement path between the closed and open end positions of a tongue. With such a configuration, locking of the open tongue by an internally arranged plane of balls and segments, and locking of the tongue being in the abutment position by an externally arranged plane of balls and segments, may each be ensured, wherein it can be safeguarded, at the same time, that the respectively desired direction of locking will be obtained in both cases. In other words, this means that the tongue being in the closed position is secured against moving back into an open position and the tongue being in the open position is secured against moving into the closed position.
The device according to the invention for locking the end positions, at the same time, may be employed as an actuating means for displacing the tongues into the closed position or into the open position. Such a compact displacement actuator may be designed in a particularly simple manner in that the displaceable rod immersing into the tubes is continuously designed over its axial length and in a central region is connected with an actuating means, in particular a piston which is drivable in an axially displaceable manner by fluid within an external tube designed as the cylinder of a double-acting cylinder piston unit. The rod, thus, acts as a piston rod of a double-acting cylinder piston unit and, due to the two rings each arranged to be offset in the axial direction with their respective ring segments and the pertaining balls, one of the thus formed planes may each be utilized for the displacement actuator and/or the lock. In the lock position, the balls rest on a partial region o
Achleitner Herbert
Hörtler Josef
Joyce Kevin E.
McCarry, Jr. Robert J.
Morano S. Joseph
VAE Aktiengesellschaft
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