GB1113696A - Improvements in or relating to brake operating mechanisms - Google Patents

Abstract

1,113,696. Brake transmitting mechanism. SECRETARY OF STATE FOR DEFENCE, LONDON. 11 Nov., 1965 [11 Nov., 1964], No. 45990/64. Heading F2E. A quick take-up mechanism for the handbrake of a heavy vehicle comprises a planetary gear through which chain wheels 14 for operating the brake may be driven via a shaft 4, having an integral ratchet wheel 7, by repeated to- and-fro movement of a handbrake lever 16 which is pivoted on the shaft 4 and carries a spring-loaded driving pawl 23 co-operating with the wheel 7, there being a second, slidable pawl or detent 18 carried by the handbrake lever which on manual depression of a plunger 20 is engaged with a toothed wheel 15 formed integrally with the chain wheels, so that the latter are initially driven directly to take up slack quickly, after which the detent 18 is forced out of engagement with the teeth of wheel 15 so that during the setting of the brake the chain wheels 14 are driven via the planetary gear. The latter comprises a sun wheel 8 on shaft 4, planet gears 9 on a carrier 12 integral with the chain wheels 14, and a ring gear 10 which may be fixed or, as shown, be rotatable only in the direction of rotation of wheels 14 during brake application, by virtue of a one-way clutch 11, which results in rotation of the ring 10 instead of the shaft 4 during initial take-up of slack, so reducing effort and also noise (since the ratchet wheel 7 is not rotated rapidly in the brake-applying direction). To release the brake, which is held set by a holding pawl 28, the plunger is again depressed slightly and the handbrake lever can then be moved back beyond its normal rearward limit since lug 32 on detent 18 can now clear an abutment (33, Fig. 2, not shown). This simultaneously causes a peg 25 carried by pawl 23 to engage a ramp portion (27, Fig. 3, not shown) of a cam track formed in end plate 3 and also causes a cam formation on the handbrake lever to engage a peg 30 on the pawl 28, whereby both pawls 23 and 28 are disengaged from the ratchet wheel 7.