GB539462A - Improvements in and relating to wheeled jack - Google Patents

Abstract

539,462. Lifting-jacks. TRIGGS, W. W. (Yale & Towne Manufacturing Co.). March 11, 1940, No. 4544. [A Specification was laid open to inspection under Sect. 91 of the Acts, Oct. 28, 1940,] [Class 78 (iii)] [Also in Group XXXII] A wheeled jack, more especially for converting a two-wheeled hand truck temporarily into a four-wheeled truck, comprises a main frame member 18 supported on the axle 16 carrying the wheels 13. The crutch member 19, which is. formed with guides 20 V-shaped in plan leading to a recess 21 engaging the downwardly-projecting pin 22 on the truck, is pivotally supported on the frame 18 by two pairs of links 25, 27 forming a parallelogram. The handle socket 15 is pivoted at 23 on the crutch member 19, the shaft 23 also carrying a pawl 32 adapted to co-operate with a notch 35 on the frame. A holding hook 47 is pivoted on the main frame at 28 and is controlled normally by a dog 38 pivoted on main frame at 37 and controlled by a rod 47 placed under compression by a spring enclosed in the handle. In the position shown in Fig. 3, the compression of the spring holds the dog against the spur 48 of the holding hook and thus maintains the latter with its recess 49 in contact with a projection on the handle socket, and supports the handle in its raised position of rest. A downward pull applied to the handle first disengages the socket from the holding-hook and then causes projections 30 on the socket to contact the rear links 27 and swing them upwards, thus elevating the crutch. When the full lift has been effected, the pawl 32 arrives opposite the notch 35 and falls by gravity to engage it. The handle can then be released while the crutch is held in its elevated position by the.pawl. To lower the platform, the handle must be moved back to a position nearer the vertical than that shown in Fig. 3, so that a pin 55 on the socket engages the surface 56 on the holding-hook and swings the latter clockwise until the heel 48 becomes disengaged from the dog 38. The holding-hook then falls further by gravity until the projection 57 is arrested by the stop 32a on the pawl. In this position of the parts the handle can be used to haul the loaded platform from place to place. When the handle is swung downwards again beyond the point required for elevating the platform, the lifting-hook is re-engaged with the member 50 as shown in Fig. 6, the pawl 32 is raised from the notch 35 and is held in the raised position by the member 57. In consequence the pawl does not reengage the notch when the handle is manipulated to lower the crutch member.