GB481946A - Improvements in or relating to the control of aircraft brakes - Google Patents

Abstract

481,946. Controlling aircraft wheel brakes. BENDIX, Ltd., and ROBERTS, G. P. Sept. 21, 1936, No. 26580. [Class 4] Aircraft fluid-pressure wheel-brake operating-gear of the kind providing for simultaneous or differential operation of the port and starboard brakes comprises valves mounted with their axes parallel in a casing and actuated by two separate cam or lever members pivotally mounted on a rocking lever and extending in opposite directions from the pivot, means operated from a hand control being provided for rocking the lever to advance both cams into engagement with the valves and further means operated from the rudder bar being provided for rocking the cams simultaneously about their pivot to advance one cam and retract the other to actuate the brakes differentially. Valves 1, 2, actuated by tappets 4, 5, Figs. 1 and 2, and controlling the supply of compressed air to the brake motors on each side of the aircraft are arranged in a casing 3 with their axes parallel but staggered to enable the tappets to be engaged by cam levers 6, 7, arranged on a shaft 8 of which the axis is at right-angles to the axes of the valves, and, in operative position, is disposed in a horizontal plane intermediate the horizontal planes containing the valve axes. Shaft 8 is carried by a lever 14 freely. pivoted in a shaft 12 and angularly adjustable by manual control means. Cam levers 6, 7 are each formed as bell-crank levers with horizontal arms 9 coupled by link 10 to a lever 11 fast on shaft 12 which is operatively connected to the rudder controls. The bell crank levers are centralized by the action of a spring loaded plunger 22 which engages a semi-annular projection 26 formed on shaft 12. The hand control means comprise a cable 15 passing through a conduit 40 to a pin 28 on a lever 27 mounted on the hand control wheel 33, Fig. 4. Lever 27 is guided in a slot formed in a domed cap 39 and pin 28 is guided in a slot 29 in a bifurcated lug 30 projecting forwardly from an angularly movable disc 31 mounted on boss 32 of the handwheel. The inner end of lever 27 is formed as a cam surface such that initial movement of the lever from position A to position B produces only small movement of cable 15, sufficient to move lever 14 from the position of Fig. 6 to that of Fig. 9, in which, with the' rudder neutral, both cams contact the valve tappets but neither tappet is depressed, whilst during movement from position B to position C a pin 36 carried by the lever engages a notch 37 formed in lug 30 and serves as a fulcrum for the lever causing lever 14 to move into a position such that with the rudder neutral both tappets are fully depressed. The slot in the cap 39 is formed with a bayonet catch which is engaged by angular rotation of lever 27 and disc 31 when the lever is in the " parking " position C. In order to permit of differential control of the brakes with the lever in position C conduit 40 is located at the valve end by an initially compressed spring 45, Fig. 12, which is adapted to compress to a greater degree to permit axial movement of the conduit on rudder operation, whereby one tappet remains depressed and the other is allowed to move outwardly as lever 14 is eased backwards. Each cam lever is formed with a boss 6a, 7a, Fig. 2, which limits the outward movement of the tappet not engaged by a cam as shown in Figs. 9 and 12. Specification 13738/36 is referred to.