GB986382A - Improvements in or relating to hand brake mechanisms - Google Patents

Abstract

986,382. Hand brake lever mechanisms. COUNTY COMMERICAL CARS Ltd. Jan. 30, 1962 [Jan. 30, 1961], No. 3540/61. Heading F2E. A hand-actuated mechanism for applying vehicle brakes comprises spring means 21 for storing energy exerted by the operator through a hand brake lever 10 connected to a rod 18 for applying the brakes such that movement of the hand-actuating lever in the direction to release the brakes stores up energy in the spring means by compressing the latter until the points of action of the ends of the spring and the lever pivot axis become aligned whereupon continued actuation of the lever in the same sense allows decompression of the spring to a slight extent until the lever engages a stop and movement of the brake lever 10 in the opposite direction to apply the brakes releases the stored up energy which assists in the application of the brakes. In the embodiment shown in Fig. 1 a hand brake lever is pivoted on a pin 11 fixed to a stationary plate 12 and a spring means 21 is attached at one end to a lever extension 16 and to the plate 12 at 23. When the hand brake lever is moved clockwise to apply the brake the line between the pivot points of action 19 and 23 swings to the left of the line between the pivot near the centre of the pin 11 and the pivot 23 and the compression in the spring assists the operator to apply the brakes. Fig. 2 shows a modification in which the hand brake lever 10 is provided with a boss or hub 26 which is split at 27 and located on a journal 35 to form a friction clutch, the journal 35 being rotatable on a bearing pin 43 in the fixed plate 12. In the full line position shown in Fig. 2 the hand brake lever is shown in its "off" position and a pawl 36 is swung out of engagement with ratchet teeth 34 and a spring 21 is compressed. When the lever 10 is moved clockwise the split boss 26 rotates around the journal 35 until the tension in the brake operating rod 18 has increased sufficiently to cause the lug and boss 28, 26 to grip the journal portion 35 when further movement of the lever 10 will cause the arm 45 to move downwardly over the dead centre position when the spring 21 will start expanding and the pawl 36 will engage the ratchet teeth 34 transmitting the thrust of the spring 21 to the arm 33 and thereby assist the hand brake lever to apply the brakes through the rod 18. When the lever arm 10 is moved in an anticlockwise direction from the chain-line position the pawl 36 is kept in engagement with the teeth 34 so that anticlockwise movement of the lever arm and journal will compress the spring until such time that the pivot axis 37 passes over the line between the centre of the parts 23 and 35 when the pawl 36 will ratchet over the teeth 34 and be finally moved out of engagement when its arm 38 comes into engagement with the stop 39. The points at which the spring 21 becomes operative to assist the operator in applying the brakes can be adjusted by a spring-loaded set-screw 32. Fig. 4 shows a further embodiment such that the lever arm 10 at one limit of its movement is arranged to engage a stop 40 and when moved to its brake operating position the pivotal connection 19 between the spring 21 and a crossmember 46 integral with brake lever 10 moved from one side to the other of a line joining the centres of pivot pins 11, 23 and the energy stored up in the spring 21 is moved downwardly to assist the application of the brake. A further embodiment (Fig. 5, not shown) is disclosed in the Specification wherein the spring assistance may be brought into and out of operation at will.