Patent GB-718553-A (GB)
Title: Improvements relating to variable load braking apparatus for railway and like vehicles
Inventor: BRACKENBURY ALOYSIUS GRAHAM
IPC: B61H13/32
Filed: 1952-06-04
Abstract: 718,553. Variable load braking devices. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. May 18. 1953 [June 4, 1952], No. 14091/52. Class 103(1) In variable load braking apparatus for the control of the braking of a railway or like vehicle in accordance with the load carried by the less loaded axle, according to Figs. 1 and 2, a proportioning lever 4 is provided with a pair of fulcrum pivots 2 and 7 situated one at each end of the lever 4. To fulcrum pivot 2 is pivoted a first link 3 to which a force P1, proportional to the load carried by the more heavily loaded axle of the vehicle, is applied in the direction of the arrow against a fulcrum abutment 1. To fulcrum pivot 7 is pivoted a second link 8 to which a force P2 proportional to the load caused by the less loaded axle of the vehicle, is applied in the direction of the arrow against a fulcrum abutment la. Midway between the fulcrum pivots 2 and 7 a third link 6 is pivoted to the proportioning lever at 5 and to the link 6, in the direction of the arrow, is applied a third force P3, opposite to forces P1 and P2. The third force may be derived from a spring or like means tending to position a movable fulcrum by means of which the leverage at which the brake force is applied to the wheel. Alternatively, the link 6 may be coupled to the movable pivot of the mechanism described in Specification 705,978, Fig. 1 illustrates the position of the apparatus when the brakes are released and P3 is zero. Owing to link 3 being associated with the more heavily loaded axle and link 8 with the less loaded axle, P2 will be less than P1 and upon a brake application being made, force P3 will be increased until it becomes twice P2 when the proportioning lever will assume the position illustrated in exaggerated form in Fig. 2. When the braking force is determined in accordance with the less loaded axle only, the size of the load on the other axle having no effect, there is liable to be too great a difference between the braking of evenly and unevenly loaded wagons. on the same train. Figs. 3 and 4 illustrate the case where this may be overcome by taking into account a given proportion of the load on the more heavily loaded axle in addition to that carried by the less loaded axle. Fig. 3 illustrates the proportioning arm 4 in the brakes release position where links 3 and 8 are pivoted at 9 and 10 situated between fulcrum pivots 2 and 7. In the brakes applied position, illustrated in exaggerated form in Fig. 4, although force P1 maintains fulcrum pivot 2 against the abutment 1 the force P3 is made up of that due to P2, as before, plus a proportion of P1 in the ratio of the distance between fulcrum pivot 2 and pivots 9 and 5. Thus, to the force due to the load on the less loaded axle is added a force due to a proportion of the load on the more heavily loaded axle. Provision may be made for adjusting the position of pivots 9 and 10 along the proportioning arm 4 so as to render adjustable the proportion of the load on the more heavily loaded axle which is added to that on the less loaded axle, or provision of means may be made for guiding the movement of the fulcrum pivots 2 and 7 along predetermined paths.