Patent GB-582437-A (GB)
Title: Improvements in brakes for vehicles, especially railway vehicles
IPC: B61H13/32
Filed: 1945-05-22
Abstract: 582,437. Vehicle brake transmitting-mechanism. SVENSKA AKTIEBOLAGET BROMSREGULATOR. May 22, 1945, No. 12786. Convention date, April 24, 1944. [Class 103 (i)] Relates to vehicle brake mechanism such as described in Specification 565,814 in which a lever pivots in succession during the application stroke about two fulcra and in which the position of the second fulcrum which gives a higher final leverage is adjustable to vary the leverage according to the vehicle load and in which further the second fulcrum is moved to its effective position during the application stroke from an out of the way low leverage position which it occupies during brake release. According to the invention, the operating connections for the second fulcrum are such that the movement thereof to the out of the way position does not, as in the prior device, impose a stress on the setting means by which the effective position is determined. The lever 1, carried by the link 7 is connected to a fluid pressure operated piston 5 and by a pull rod 8 to the brake shoes. It carries a roller 9 normally engaging a track 11 on a member 10 which provides the initial fulcrum and which is carried by a rod slidable against the action of a spring 12. The second fulcrum 2 is slidable against a fixed part 3 and is connected to a lever 14, 15 mounted in a fixed pivot 13 and bearing on roller 9. The lever 1, during its initial application movement turns about the roller 9 which travels along the track 11 as described in Specification 565,814 until having left this track it abuts the fulcrum 2 which has been moved upwardly by the action of the spring 17 on the lever 14, 15 from the lowest leverage position as shown to its effective position as determined by the engagement of a pin 19 on the lever 14, 15 with a stop 18. The support 10 yields against the spring 12 if it should be subjected to abnormal pressure. The stop 18 is slidable on a post 20 and its position and thus that of the upper position of the fulcrum 2 is determined automatically in accordance with the vehicle load by means such as described in Specification 565,517 and comprising a leaf spring 21 arranged to be deformed by forces proportional to the suspension spring pressures of the vehicle acting through pull rods 22, 23. The spring 21 is connected to the stop 18 by a lever 26, 27 pivoted at 24. Tendency of the spring 17 to move the stop is prevented by the binding action of the boss 18' of the stop on the post 20 due to the spring force acting through the pin 19 on the arm of the stop. To prevent the transmission of rapid movements of the vehicle on its springs to the stop, the end of the arm 18 thereof is weighted at 18a and the arm 26 of the lever 26, 27 is formed as a pair of leaf springs which take up those movements. In a modification Fig. 6, the stop 18 is formed as a nut 28 with quick-pitch thread engaging a spindle 20a rotatable in bearings 29. The nut is trunnioned at 30 in the forked end of the lever arm 27. Adjustment of the nut on the spindle may thus be effected by the lever 26, 27 but since the pin 19 of the lever 14, 15 acts as shown on an arm of the nut which thus jams in relation to the spindle 20a under the action of the spring 17 the nut cannot be moved by the spring. Damping action against rapid movement of the nut on the spindle is effected by the provision of a fly-wheel 31 thereon.