Patent GB-1390891-A (GB)
Title: Apparatus for transferring objects
IPC: A61G1/02
Filed: 1973-03-27
Abstract: 1390891 Endless conveyer belts; invalid lifting devices DIAMONDHEAD CORP 27 March 1973 [5 April 1972] 14752/73 Headings B8A and B8H A projectable surface or apron 50 for transferring a patient to and/or from a bed or ambulance has a main conveyer belt 18, a separate take-up means 48d-48g below the apron 50, a main brake 102 (Fig. 9A), and an auxiliary brake 104. The belt 18 extends over the apron surface 18 around a back guide beam 26 and around rollers 84, 86, and 118 of a reciprocable take-up carriage 86. A belt 34 extends around a second apron 32 and is in contact with the lower run of the belt 18. The belt 34 is fixed at 44 to a fixed frame table portion 24. The aprons 32 and 50 are connected together on each side of the apparatus by a respective member 56 which is formed as a sliding guide member relative to a main side frame 22. The member 56 also connects the aprons to a drive chain 66 (Figs. 3 and 8) for projecting the aprons. The latter is driven by a motor (80) (Fig. 2, not shown) which is coupled to a drive shaft (78) (Fig. 4, not shown) which carries at each end respective sprockets 76 engaging the chains 66. The carriage 88 comprises side frames (13a) (Fig. 14, not shown) connected by upper and lower transversely disposed box beam members 150, 150 (Fig. 8). The frames (13a) carry mountings for sprockets 92 (Fig. 3), each respectively engaging one of the drive chains 66. Also connected to the side frames (130) are spherical bearings for respective ends of the belt guide rollers 84, 86 (Figs. 8 and 9A). Flexure of each of these rollers is prevented by a set of three pairs of small rollers 146 bearing at spaced intervals along the rollers 84, 86, and carried by brackets (148) (Figs. 14 and 15, not shown) on the box beam members 150, 150. The carriage sprockets 92 are also each in engagement with a respective fixed chain 96 (Fig. 3) to provide the equivalent of a rack-and-pinion mechanism. Guide rollers 94 and 95 constrain the chains 66 and 96 to maintain engagement with respective segments of the periphery of the respective sprockets 92. Thus on energization of the motor (80), as well as the aprons being projected by movement of the brackets 56. The carriage 88 is driven along by the interaction of the rack chains 96 and the sprockets 92. The main brake 102 comprises a fixed brake lining surface 110 (Fig. 8) on a lower horizontal surface of the back guide beam 26, and a moable brake lining surface 112 (Fig. 18) carried by a brake beam 114. The latter is normally biased downwardly by springs 160 but may be lifted into operative position to grip the belt 18 between the linings 110, 112, by the action of cams 190, 190, on a cam-shaft 126. The latter is chain driven by a motor (234) (Fig. 2, not shown). The beam 114 is pre-stressed to an arcuate configuration in order to result in a more uniform braking pressure. The auxiliary brake 104 comprises an arcuate brake pad 116 (Figs. 8 and 18) against which the belt 18 is forced when the belt guide roller 118 of the belt take-up means is deflected rearwardly by the action of cams 208, 210, on the cam-shaft 126. The roller 118 is prevented from bending under braking load by the action of a set of rollers similar to the rollers 146 (Figs. 14 and 15). Control of belt tracking.-This is effected by the action of the roller 118 being deflected in slightly obliquely relation by the cams 208, 210 (Figs. 19A to 22B, not shown). This is made possible by the differential phase relationship of the cams 208, 210, on the shaft 126, coupled with an electronic control circuit (Fig. 26, not shown) and belt edge engaging sensors (218) (Figs. 16 and 17, not shown) co-operating with micro switches (228), (230). The angular setting of the cam-shaft 126 is determined by control of the drive motor (234) of the cam-shaft 126. This depends on a particular combination of electric switches: (a) The particular setting of switches operated manually on a control panel (252) (Figs. 1 and 25, not shown). These switches control the drive motor for outward and inward unloading action, and outward and inward loading action. The motor 80 is stopped automatically at the end of each of these operations by one or other of micro switches 214, 218 (Fig. 3). Two further switches or the panel (252) control a motor (258) which raises or lowers the apron assembly 14 on a wheeled base (10) (Fig. 1, not shown). These latter two switches have no interaction with the operation of the motor (234). (b) The switches 228, 230, which respond to belt tracking. (c) Reed switches (240), (242), (244), and (246) (Figs. 23, 24, and 26, not shown), which together with magnets (248) (250) mounted at 90 degree phase difference on the cam-shaft 126, define the four operational positions (at 90 degree equal phase intervals) of the shaft i.e. track left, neutral (no braking or tracking action), track right, and brake. Belt tracking is also adjustable by the variation of shims (288) (Fig. 16, not shown) which enable the alignment of the back guide beam 26 to be altered. Operation.-In conveying a patient to a bed &c. (Fig. 9A) the load out button (256e) (Fig. 25, not shown) is depressed, and in addition to the drive motor 80 being energized, the main brake is applied. The button (258f) is then pressed in order to retract the apron assembly (Fig. 9B, not shown), and during this operation the auxiliary brake 104 is engaged and the main brake is disengaged. The carriage 88 moves outwardly and takes up the surplus length of belting. In extending the apron to a position from which a patient can be conveyed from a bed (Fig. 9C, not shown), the button (256a) is pressed. The main brake is applied and the axiliary brake is released. To convey the patient from the bed (Fig. 9D, not shown) the button 256b is pressed, the auxiliary brake now being released and the main brake being applied. The circuitry (Fig. 26, not shown) ensures that any tracking correction for the belt 18 takes place only during those phases of operation when the auxiliary brake is inoperative i.e. during retraction of the apron after conveying a patient to the bed, or during extension of the apron to a position in which a patient is to be unloaded from the bed.