Patent GB-776219-A (GB)
Title: Improvements relating to filing cabinets
IPC: G06K17/00
Filed: 1955-06-24
Abstract: 776,219. Filing papers. CRAIG MACHINE, Inc. June 24, 1955, No. 18250/55. Class 146(1). A filing cabinet comprises a housing, a series of drawers disposed one above the other in the housing, a carrier for the drawers mounted for vertical motion and electrical driving means for effecting the raising and lowering of the carrier, means for stopping the electrical driving means when one of the drawers is in a position adjacent to an opening in the housing and means for guarding access to the drawers, which, when pressure is applied thereto either by the hand of the operator or when a drawer is partially withdrawn or otherwise, renders inoperative the electrical driving means until the obstruction occasioning the pressure has been removed, thus safeguarding the operator's hand and avoiding undue strain in the operating mechanism. Two carriers 12 for drawers 14 are mounted counterbalanced relation on a pair of chains 32 in a cabinet 10 having openings 18 through which one drawer 14 from each carrier 12 may be slid by hand. Each chain 32 passes over idler sprockets 46 mounted on vertically adjustable supports 48 and a sprocket 44 on a shaft 42 driven from a motor 36 through a reduction gear 38 and chain 40. The gear 38 is of the worm gear self-locking kind so that when the carriers 12 are in position with two drawers 14 registering with the openings 18, disparity in the weights of the drawers will not cause a shift. Control unit. The motor 36 is started and stopped and the selected pair of drawers 14 brought opposite the openings 18 by operation of a knot 52, on a control unit 16, mounted on a shaft 54 to which is secured a, slip ring contact member 57 with three contact rings 58 against which bear brushes 59. A double contact switch 60 is mounted on shaft 54 to rotate therewith and has arms 62 each with a roller 64 bearing against a cam plate 66, mounted on a co-axial shaft 92, having a shoulder 65 to press the arm 62 to close a contact 63. The knot 52 is held in one of its seven possible positions by a spring-pressed ball 70 engaging in one of seven recesses 69 on a segmental plate 68 mounted on the shaft 54. As shown in Fig. 8, when one of the switch contacts 63 is closed, a circuit to the motor 36 is closed through either relay 74 or 76 which are energized to operate a throw switch 78 or 80 to start the motor in the required direction to move the carriers 12 towards the desired position. The cam plate 66 is moved at the same time to a new position by a sprocket 82 on shaft 42, chain 84, sprocket 86 andgearwheels 88, 90, the ratio of the gears being designed to rotate the plate 66 approximately 120 degrees when the carriers move from one extreme position to the other. As the roller 64 moves off the shoulder 65 on cam plate 66, contact 63 is broken and the relay 74 or 76 de-energized to stop the motor. A running condenser 94 and braking condenser 96 are connected across the fields of motor 36, a charge being built up on condenser 96 by means of a rectifier 98 in series so that when switch 78 or 80 is returned to open position, the condenser 96 unloads through the field of motor 36 causing the motor to stop rapidly and preventing oscillation of the mechanism. A modified control unit is described, comprising a servo system controlled by a bridge circuit. Guards. Each opening 18 has guard bars 20 along the upper and lower edges mounted on plates 106, 114 which move up and down respectively under pressure, the plates 106, 114 having slots 108, 116 engaged by pins 110, 118 on the cabinet 10 to limit their movement and springs 112, 120 to return them to normal position. Each bar 20 operates a limit switch 100, opening of any switch 100 breaking the circuit through the switch 60 so that the motor is stopped. Each plate 106 is directly connected to a rod 104 and each plate 114 connected to a rod 104 through a rod 124 and pivoted lever 122, the sliding up or down respectively of the rod 104 moving a ball 102 to open the switch 100.