Railways – Car stops – Sliding
Patent
1998-02-24
1998-11-17
Le, Mark Tuan
Railways
Car stops
Sliding
104258, B61K 700
Patent
active
058362525
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a rail brake element, in particular in connection with rail brake buffer blocks.
A rail brake element of the above-identified type has become known from German 24 53 223. The clamping plates which are of an approximately C-shaped cross-section are pressed together above the rail head by means of clamping bolts. In the lower area the clamping plates include angular friction elements which are made of a suitable friction material such as bronze. The friction elements engage the bottom side and the lateral surfaces of the rail head. A so-called lining piece is supported against the rail head, which lining piece is also made of friction material and has at its upper side tapered surfaces which are engaged by the upper legs of the clamping plates. When the clamping bolts are subjected to tension forces, compression and tension forces are exerted upon the friction elements by a wedge action such that a corresponding friction force will be generated at the rail head.
Modifications of such a brake element have become known from German 834 572 or German 34 22 230.
Apart from the friction coefficient the brake action of such a rail brake element depends on the force which urges the friction elements against the rail head. This force is applied via the clamping bolt, with a double spring ring being disposed between the clamping bolt and a clamping plate. The only possibility to preset the urging force is to measure the torque for tightening the clamping bolt. However, there are no defined relationships between the measured torque and the actual urging force because the measured torque depends also on other parameters such as the friction at the clamping bolt threads or the friction between the bolt head and the spring, etc. When there will be wear of the friction element, the reduced stroke will be compensated by the helical spring. If the helical spring exhibits an unfavorable force-displacement-relationship, which is the case normally with the used helical springs, wear will result in a significantly reduced urging force.
The actual braking effect by the rail brake element is obtained by displacing the rail brake element along the rail head, for example by a buffer block which either stands upon the rails relatively loosely or is integrated in the rail brake element. However, before this will occur, stationary friction will have to be overcome, with stationary friction theoretically being at least twice as large as sliding friction, however, in practice may be much higher due to corrosion of the rail and braking parts of the rail brake element. During the initial impact phase the rail brake element acts like a rigid barrier which begins to move only after the stationary friction has been overcome. This will cause a substantial shock for the oncoming vehicle. If a plurality of rail brake elements are disposed one after the other in abutting relationship, this will result in an excessive, unacceptable value of the described stationary friction. This is why it is common in practice to arrange the rail brake elements in spaced relationship so that the stationary friction of the individual rail brake elements will be overcome one after the other during a braking operation.
GB-A 2 060 095 discloses a rail brake element wherein clamping plates provided with friction material at its lower faces extend below a rail head and have their upper portion engage an elongated retaining element. Bolts extending therethrough connect the opposed clamping plates to the retaining element therebetween. Spaced recesses of the retaining element receive Belleville spring assemblies biased via compression disks by bolts threaded into the retaining element. The Belleville spring assemblies act upon an elongated element below the retaining element which is urged in this manner against the associated rail head. The elongated element or, respectively, a corresponding insert in the elongated element is made of suitable friction material.
The problem to be solved by the invention is to provide, in particular in connection
REFERENCES:
patent: 2762314 (1956-09-01), Hayes
patent: 2835207 (1958-05-01), Hayes
patent: 2900923 (1959-08-01), Hayes
patent: 3230898 (1966-01-01), Skelton
A. Rawie GmbH & Co.
Le Mark Tuan
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