GB1480969A - Retractable door stop - Google Patents

Abstract

1480969 Retractable door stop; magnetically operated fastenings CURTAYNE INDUSTRIES PTY Ltd 2 April 1975 13432/75 Headings E2A and E2X A retractable door stop mechanism comprises a housing 3, adapted to be set into the ground, or floor, at a desired point adjacent a door 10 to be restrained, a plunger 2 mounted in a cavity in the housing and slidable with respect thereto between a retracted position, at which the exposed top surface of the plunger is at the intended ground, or floor level, and a projecting position at which the upper portion of the plunger stands proud of the housing to provide the door stop, and first and second mutually attractive magnetic members 1, and 8 one of which is associated with the plunger 2 and moves from its retracted position to its projecting position when the other member is located close above it. According to the invention also an air vent leads upwardly to atmosphere from the cavity in the housing to allow air to pass freely between the cavity and atmosphere during the movement of the plunger which is a clearance fit in the cavity, a bias urging the plunger to its retracted position in the cavity when the housing is mounted in its operating position and a stop means 7 carrying the second magnetically attractive member and adapted to be located on the door 10 in a position so as to pass over the plunger when the door is opened and to raise the plunger, by 'magnetic attraction between the members 1, 8, to its projecting position at which is restrains further opening movement of the door. As shown, a spring 4 holds the magnet 1, with a slack fit, in the upper end of the plunger 2 and normally supports the latter with its upper surface flushwith that of a closure flap 5 screwed at 12 to the housing 3 which is secured, by screws 6, into a hole into the ground, or floor. A magnetic holder housing 7, which accommodates the second magnet 8 with an opposed pole facing the magnet 1, is secured to the door 10, the housing having a buffer 9 against which the plunger 2 can strike when the door is opened. The housing 7 may carry a drop latch, not shown, and the housing 3 may include extra venting openings in the form of part-circular recesses in the inside rim of the cap 5, and a hole and a channel 11 in the side of the plunger. The plunger 2 may be lubricated, e.g., with molybdenum disulphide. The stop mechanism, which may be made of non- rusting material, e.g. stainless steel, brass, and plastics such as polypropylene, except the magnets 1, 8 which can be ceramic permanent magnets, can be overridden by holding down the plunger 2. One, or both, magnetic members may be electromagnetic and controlled by switching. A number of magnetic members or a magnetic member of greater area than the magnetic member 1 in the plunger, may be incorporated in the housing 7.