Claw brake (tram)
Claw brakes were used on trams at the turn of the 19th and 20th centuries . Jhs. used to achieve additional safety when driving on steep stretches. They served as an emergency brake if the other braking systems should fail. The functional principle of the claw brake is that a metal plate with hooks was pressed against the ground or against wooden beams laid along the tracks. The claw brake was replaced by the magnetic rail brake and is no longer used today.
history
At the turn of the century, many tram companies were established, some of which also ran routes with inclines of around 100 ‰. The search was on for a braking system that would function independently of the friction between wheel and rail; in particular, the braking system should also be effective when the wheels of the tram locked, be it by overbraking with the block brake or by the electric brake with the traction motors .
technology
There were different types of claw brakes:
System real
The system consists of a solid beam suspended from the floor of the car, which can rotate about a transverse axis to the vehicle that runs through one end of the beam. At the other end of the beam is the plate with the claws. In the event of danger, the driver can let the beam fall to the ground using a release mechanism. The beam assumes an oblique forward position and is pressed by the weight of the tram into the ground or the road surface between the rails.
The Rodez tram was the first tram to use the claw brake according to the Réal system. It drove gradients of up to 100 ‰ with heavy maximum cars .
Lausanne tram
In the old tram from Lausanne lightweight railcars sailed a 113 ‰ -Steilstrecke from the Place de la Riponne to pontaise . The claw brake on these vehicles consisted of two hook plates attached to the left and right of the vehicle, which run in vertical guides. Before driving, the panels are pulled up with a spindle, whereby strong springs are compressed. In the event of danger, the panels can be released by a release mechanism and are pressed against the floor by the springs. The hooks of the plates engaged in oak sleepers set into the street along the rails. During tests, the 8 km / h fast car came to a stop after about eight meters, with very long delays.
Individual evidence
- ↑ a b Henri Somach: Les tramways électriques de Rodez . In: Le Génie civil . December 27, 1902, Frein de sûreté, p. 131 (French, BnF Gallica ).
- ↑ August Wohnlich: Les tramways lausannois . In: Bulletin technique de la Suisse romande . tape 33 , No. 4, 1907, pp. 43 , doi : 10.5169 / SEALS-26221 .
- ^ AB: Electric tramway in Lausanne . In: Schweizerische Bauzeitung . tape 28 , issue 14, 1896, p. 106 , doi : 10.5169 / SEALS-82401 .