GB266275A - Improved locking mechanism for levers - Google Patents

Abstract

266,275. Cunningham, J., and Dickson & Mann, Ltd. Sept. 8, 1926. Hand and foot actuation; force-transmitting mechanism.-Brake or other hand or intermediate operating levers are eccentrically pivoted in relation to a fixed toothed quadrant and are locked thereto by means of a lost motion connection to a concentrically pivoted pawl carrier. The pawl carrier E, Figs. 1 and 7, is pivoted at o concentrically with the fixed quadrant A and is formed with an arcuate slot e in which engages a roller K carried by a hand-operating lever B. As shown, the lever B is pivoted to a bell crank F rocking about the centre a and serving to operate a brake rod G, the pull of the brake rod serving to retain the roller K in either of its extreme positions at the ends of the arcuate slot. The roller K coacts with a pivoted locking pawl E so that when in the forward movement of the lever B, the pawl meets the first tooth of the rack the lever moves forward in the slot and tilts the pawl which subsequently trips over the teeth but prevents return movement until the lever is moved in the opposite direction to reverse the pawl. The pawl is held in engagement with the roller and quadrant teeth by a spring H. In a modification the lever B is pivoted directly to the pawl carrier and has lost motion between lugs on the pawl carrying end thereof. The application of the invention to the brake operating mechanism forming the subject of Specifications 144,793 and 201,305, to enable a variable brake pressure to be applied and released by hand in stages, is shown, in Fig. 9, the locking gear being mounted on the rock shaft 8 of the previous arrangements. The pawl carrier E is looselv mounted on the shaft 8, the fixed toothed segment A being concentric therewith. The roller K is carried by a lever B<1> which is pivoted at b<1> to a crank or projection, which may be the cam 39 of the arrangement described in Specification 201,305, secured to the rock shaft. The lever B<1> is also connected by a link L to another crank M turning with the rock shaft. When the brake is " full off " the roller K is held in position as shown at one end of the arcuate slot e in the pawl carrier bv the turning effort of the spring 41 upon the cam 39. the initial actuation of the brake hand levers (not shown) causing the rock shaft to rotate the floating lever B<1> and pawl carrier E simultaneously until the pawl D strikes the first tooth of the quadrant, the subsequent action being as described with reference to Figs. 1 and 7.