Patent GB-1321621-A (GB)
Title: Vehicle having a liftable body and braking apparatus therefor
IPC: B64F1/31
Filed: 1970-07-14
Abstract: 1321621 Movable gangways BOOTHE AIRSIDE SERVICES Inc 14 July 1970 [31 July 1969] 34190/70 Heading B7J [Also in Divisions B8 and F2] A vehicle such as a passenger transfer vehicle including a passenger-carrying body movable up and down guide posts normally at a predetermined speed has a brake for controlling downward movement in the event of operating failure in the form of a friction device normally rotating, and thus ineffective, but arrested, for braking, by engagement by a spring-loaded plunger released for such engagement by a sensor responsive to excessive downward speed of the body. An (aircraft) passenger transfer vehicle 10, Fig. 1, has wheels 12 and a chassis frame 11 including lifting posts 16, 17, up and down which a passenger pod 15 is guided by rollers 20 in bolsters 18 and 19 secured to the pod. The pod is raised and lowered by rotatable vertical screw shafts 27, 29, driven by a motor M through a gear-box 24 and shafts 25, 26; shafts 27, 29 engage captive nuts 35, 36, respectively, on the lower bolsters 18, 19, respectively. Two chains 43 are provided, one being secured to each upper bolster and trained over a double sprocket 57, Fig. 6, splined to a shaft 53 journalled in a brake housing 37, 50, fixed at the top of the appropriate lifting post 16 or 17. To the other end of the chain is secured a wheeled counterweight 45 accommodated inside the lifting post. Also splined to shaft 53 is a pair of braking races 59, 61, of which the left one, 59, is located by a split ring 65 engaging a counter bore 66 in it, and the right one, 61, is urged to the left by a compression spring 73 acting through a retaining ring 75, washers 72, a spur gear 71 and a ring 69. An adjusting nut 77 for spring 73 is provided. The outer surfaces 84, 85, respectively, of races 59, 61, respectively, are cone-shaped, and cooperate with cone surfaces 87, 88, respectively on the inside of a locking ring 81, Fig. 8. A spring-loaded plunger 103 is normally retained in the position shown in Fig. 6 by a trigger pin 110, so that the braking-race locking-ring assembly 59, 61, 81, may freely rotate within an internal bushing 83 in whichever direction the assembly is driven by the chain-operated sprocket 57. The spur gear 71 meshes with a pinion 130, Fig. 4, which is connected through a one-way clutch to a bevel gear so that the bevel gear is driven only when the pod 15 is descending. The bevel gear engages another bevel gear associated with a centrifugal cross-head 155. When the speed of descent is excessive, spring-loaded centrifugal pins 157, 158, protrude from the rotating cross-head 155 and one or other strikes a plunger block 175 Fig. 3, so as to withdraw trigger pin 110 from its aperture in the wall of plunger 103. The plunger 103 is then urged by spring 107 into one of four apertures 95, Fig. 8, provided in ring 81, thus arresting the ring, which in turn exerts frictional braking on races 59, 61. Plunger 103 may be re-set by slight rotation of ring 81 in the reverse direction, whereupon surfaces 99, 98, Fig. 8, move plunger 103 axially outwards. A roller 181, Fig. 6, associated with a switch 180 co-operates with a cam surface 185 on plunger 103 so that on inward movement of the plunger the motor M is de-energized.