Improvements in or relating to Brake Mechanism suitable for Railway Vehicles.

摘要

10,794. Bowles, G. B. May 7. Compensating for wear. - Slack-adjusting mechanism for railway brakes is provided with means for rendering the mechanism ineffective when the operating-lever requires to be moved to a greater extent than that normally necessary to take up slack, owing to the existence of abnormal clearance between the brake blocks and wheels caused by heavy loading of the vehicle. The invention may be applied in connexion with the adjusting mechanism described in Specification 25,113/09. Fig. 1 shows adjusting-mechanism comprising an operating-member c carrying a pawl b engaging a rack-bar a, which is connected to the brakes and engaged also by an anchoring pawl d carried by a fixed member e. A sliding member f is connected by pin-and. slot arrangements i, k and j, mwith the parts c, e respectively, and is formed with a shoulder g engaging a projection h on the pawl d. The slot i is made of such length that the member f is not moved, and the pawl d operates in the usual manner for taking up slack, unless abnormal clearance exists between the blocks and wheels, in which case the part c must be moved farther to apply the brakes, and the member f is thereby operated to raise the pawl d out of action, the pawl being held raised by a friction washer n on the pin m until the rack a has been returned sufficiently for the pawl d to engage in the same tooth as before. The member e serves as a stop for the pawl d, and the part c keeps the pawl from being accidentally disengaged from the rack. In a modification, the projection h engages a slot in the member f which is pivoted directly to the part c, and the pawl d is retained, when raised out of action, by a gravity catch from which it is dislodged as the parts are returned, by a nose on the part c. In the form shown in Fig. 4, in which the rack a is of sector form and the operating-pawl b is carried by a lever r, the anchoring-pawl d is lifted, when abnormal movement of the lever is made, by a member s pivoted to the lever r and resting on a fixed pin t. The pawl is retained out of action by a gravity catch u, which is released on the return of the parts by a boss w on the member s.