Railway switches and signals – Switches – Lock
Reexamination Certificate
1999-11-17
2001-08-07
Morano, S. Joseph (Department: 3617)
Railway switches and signals
Switches
Lock
C246S449000, C246S450000, C246S451000, C246S452000
Reexamination Certificate
active
06270041
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for mechanically locking the end positions of movable point sections, with two adjusting rods, each of which is connected with one of the point sections and which are coupled mechanically with one another, with at least one locking tappet for locking the adjusting rods in each case in one of their end positions and a force limiting device, which cancels the locking, when the force, exerted by the point sections on the adjusting rods, exceeds a certain value. In particular, the invention relates to an apparatus for locking the points of streetcar rails.
In the case of point section devices, it is important that the movable point sections are held securely in their respective end position. When a vehicle runs over a facing point, that is, when the wheels of the rail-bounded vehicle first run on the free ends of the points, the one switch rail, the so-called closed switch rail, must lie tightly against the continuous rail, while the other switch rail, the so-called open switch rail, must be at a sufficient distance from the associated continuous rail, so that the wheels can safely pass through the shunt and the rail-bound vehicle is not damaged or derailed. On the other hand, when a certain force is exceeded, the points must be able to yield, so that the rails of the rail-bound vehicle can yield laterally, when the point is passed trailing and the rail is not in the correct position. In the case of points that can be forced, the points in such a case remain in the new position, in which they have been set, that is, the shunt is shifted by the wheels of the rail-bound vehicle.
Shunt-adjusting devices are known, for which the adjusting rods for adjusting the two points are uncoupled mechanically and actuated in each case directly by the driving mechanism of the adjusting device and locked by respective locking clamps (such as clamp point locks). The contacting switch rail is locked rigidly, for example, against a rigid rail, while the remote switch rail is held by the self-locking or fixable driving mechanism. This arrangement has the advantage that the contacting switch rail can be held in its end position with a force, which is significantly larger than that holding the remote switch rail. The relatively high cost of the construction is, however, a disadvantage. In addition, the driving mechanism cannot be changed over manually with an adjustment plate and, when the point is forced, the adjustment rods are separated from the driving mechanism, so that the driving mechanism must be actively tracked into the new shunt position, so that the points are ready to function once again.
From practical experience, an adjusting device of the type named above is known (Hanning & Kahl HW 60 AW adjusting device), for which the two adjusting rods are coupled mechanically. The housing of the adjusting device preferably is disposed centrally between the two points, and the mutually coaxial adjusting rods enter the housing from opposite sides. Within the housing, the adjusting rods are rigidly connected with one another by a connecting piece. The locking tappet is disposed pivotably at the connecting piece and acts, on the one hand, with a locking plate, coupled with the driving mechanism of the adjusting device, and, on the other, with the force limiting device, disposed in the housing. Due to the force limiting device, both switch rails are held in the respective end position with the same force. If this force is exceeded when the points are forced, the force limiting device yields, the lock is unlocked and the shunt is shifted into the new position, in which the locking is brought about once again with the help of the locking tappet.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a device of the type named above, for which, in every end position, one of the two movable point sections (the closed switch rail) can be held with a larger force.
Pursuant to the invention, this objective is accomplished owing to the fact that the force limiting device is formed by a coupling device, which yields when stressed and is located between the adjusting rods, and by a transfer mechanism, which converts the movement of one of the adjusting rods into a movement for unlocking the locking tappet.
The force holding one of the movable point sections is limited by the force limiting device. In practice, this shunt part usually is the open switch rail. The adjusting rod for the closed switch rail, on the other hand, is locked at the housing with the help of the locking tappet with a theoretically unlimited force. When the point is forced, this locking is canceled only when the open switch rail was deflected somewhat and, as a result, the associated adjusting rod is moved. The holding force can also be larger than the force required to adjust the shunt. Without decreasing the holding force, the adjusting device can therefore be designed so it can easily be changed over manually or with the help of a driving mechanism, which need not be self-locking.
In a special embodiment, the locking tappet is held movably at a connecting piece, and the coupling device acts between the connecting piece and each of the adjusting rods and yields in each case only when the adjusting rod is stressed in one direction.
In the case of an adjusting device disposed between the points, the two adjusting rods preferably are disposed coaxially to one another and the connecting piece lies within the housing of the adjusting device between the free ends of the adjusting rods, so that it supports the adjusting rods rigidly. Coupling elements are then disposed so that they yield, when the associated adjusting rod is pulled out of the housing with a sufficiently large force.
The coupling elements may be formed, for example, by springs, force-limiting couplings, clamping elements and the like.
The transfer mechanism preferably is formed by a locking plate, which embraces catches fastened to the free ends of the adjusting rods and has a locking contour for the locking tappet held at the connecting piece.
For a different embodiment, preferably two locking tappets are held immovably in the direction of motion of the adjusting rods at a part of the apparatus, fastened to the housing, and movable in a direction perpendicularly thereto between a locking position, in which they lock the adjusting rods positively, and an unlocking position, which releases the adjusting rods.
This solution has the advantage that the locking of the adjusting rods, instead of taking place indirectly over a connecting piece, takes place directly at the housing of the apparatus and is based not on self-inhibiting effects, but on positive locking. By these means, a high functional reliability is achieved and the position, in which the adjusting rods are locked, can be defined precisely and, if necessary, adjusted. When two locking tappets are used, the two adjusting rods can also be adjusted independently.
Preferably, the locking tappets are constructed as ledges, which extend transversely to the adjusting rods and are supported sliding over inclined surfaces or by means of roll bodies on unlocking ledges, which extend parallel to the adjusting rods and can be moved in the longitudinal direction of the latter. The locking tappets then carry out strictly a translational movement during the locking and unlocking processes. This arrangement is particularly advantageous if the locking device is used in combination with a testing device, which scans the position of the switch rail with the help of test rods disposed parallel to the adjusting rods. The locking tappets of the locking device can then extend into the testing device and function there also for locking the test rods, so that additional safety is attained. The locking tappets then fall into the locking position only if the adjusting rods, as well as the test rods, are in the correct position. By scanning the position of the locking tappets, a signal can thus be obtained, which connects the locked status of the adjusting device by a logic
Helas Wolfgang
Meinecke Jens
Worm Günter
Goldberg Richard M.
Hanning & Kahl GmbH & Co.
Jules Frantz F.
Morano S. Joseph
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