Patent GB-515428-A (GB)
Title: A safety device for mobile fire fighting ladders, masts and the like
IPC: B66C23/90
Filed: 1938-05-31
Abstract: 515,428. Ladders scaffolding. HUMBOLDTDEUTZMOTOREN AKT.-GES. May 31, 1938, No. 16247. Convention date, May 31, 1937. [Class 20 (ii)] [Also in Group XXI] In a safety tilting device for fire escape ladders, masts and the like, of the kind in which the tilting moment of the ladders, during - erection, is measured and applied for putting the ladder gear out of action, means is provided for varying the action of the measuring devices in accordance with the angular position of the ladder relatively, to the longitudinal axis of the vehicle, so that the erection of the ladder is stopped at an earlier point if it is being erected in a direction transverse to the axis. As shown in Fig. 2, a plate 7 in the rotary part 3 of the turntable, which carries the ladder-supporting structure 5, 6, is supported on two knife edges 8, 9 and is held there-against by springs and levers 12, 14 and 13, 15 constituting respectively measuring devices for rearward and forward tilting of the ladder. If the ladder tilts forwardly, it leaves the knife edge 9 and raises the lever 15, thereby raising a rod 29. The latter, through linkage 34, 35, 55, 58, moves a bolt 59 to allow a piston 60 to move, and close the passage 63 in the hydraulic operating gear of the ladder. Similarly, rearward tilting releases the piston 60 through the lever 14, rod 36, and linkage 37, 39, 41, 42. As the turntable 7 rotates on the fixed bed 2, it operates gearing 19, 22 and a cam 23 to move the lower end of the rod 29 along a slot 30 in the lever 15, so that a given movement of the lever 15 produces a greater movement of the rod 29 when' the ladder has been turned to a position transverse to the vehicle. The pressure of the springs 13, 15 is variable by screw caps 16, 17. The end of the rod 41 is movable along a slot 38 in the lever 39 by means of a rod 44 and 'a lever 45 rocked by a cam 47 which is rotated in conformity with the extension of the ladder. Thus the action of the measuring device 12, 14 is influenced by the degree to which the ladder is extended. Further, the cam 47 engages a lever 48 the position of which is controlled, through a rod 49, by the angle of elevation of the ladder. The lever 48 controls a lever 51 which is connected by a rod 52. to the rod 29 and by a rod 53 to a plate 54 of the stop gear. By this arrangement, the measuring device 13, 15 is influenced simultaneously by the angular position of the ladder and by its degree of extension and elevation. The locking device 74 for the vehicle springs is connected to linkage 73, 72, 71 adapted, when the locking device is not engaged, to raise the rod 36 and so put the ladder gear out of action. The variation of the action of the measuring device 13, 15 may be obtained by variation of the tension of the spring 13 or the ratio of the lever 45. In a modification, the variation of the action.of the device 13, 15 is obtained by means of a roller on the part 7 and a cam surface on-the fixed part 2 of the turntable. The contour of the cam surface is variable automatically according as the ground struts of the vehicle are, or are not, extended to support the vehicle laterally. The Specification as open to inspection under Sect. 91 describes also another modification, in which the spring of the measuring device 12, 14 is a leaf spring, and that of the device 13, 15 a torsion spring, the knife edge 8 being arranged in front of the leaf spring and the knife edge 9 between the two springs, whereby a greater spring resistance is opposed to forward, than to backward tilting. In another modification, Fig. 7, (Cancelled), the fixed part 2 of the turntable is supported on four ball-headed pins 95, 97 on the vehicle chassis 93, 94 and is held against tilting by springs 100, 102. If the ladder tilts, for example; forwardly the rear end of the part 2 rises, causing a lever 109 to depress a rod 118 to stop the ladder gear. The pins 95, 97 are so spaced that tilting of the ladder, when it is directed transversely of the vehicle, imparts an increased movement to the rod 118. The levers 107, 109 may be connected by intermediate levers for actuating the rod 118. The various springs 100, 102 may vary in strength. This subjectmatter does not appear in the Specification as accepted.