US 2004/0201005 A1Published application

Fail-safe device for raising/lowering articles

OwnerPeter Stoneinventor

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Abstract

A failsafe device for raising/lowering articles includes a frame and a fastener for attaching the frame to a ceiling or wall to elevated an article above the floor. A pulley or sheave is mounted on the frame about a substantially horizontal axis when the frame is mounted on the ceiling or wall. A cable is entrained over the pulley and has a substantially vertical lifting cable portion attachable to the article to the lifted and a substantially vertical pulling cable portion arranged to be pulled downwardly by a user to elevate the article and raised upwardly to lower the article. A cam is mounted on the frame on one side of the pulling cable portion and has a cable engaging surface. The cam is movable between a cable releasing position and a cable locking position, the cable engaging surface including a first engaging portion normally spaced a fixed distance from the pulling cable portion to form a clearance gap in the cable releasing position and a second engaging portion bridging the clearance gap a distance equal to least the fixed distance for substantially instantaneously arresting the cable and preventing movement of the pulling cable portion upwardly toward the pulley and corresponding downward movement of the article. A pusher is mounted on the frame for always applying a force on the pulling cable portion in the direction of the cam for urging it across the clearance gap into contact with the first engaging portion only when tension in the pulling cable portion is decreased relative to the tension in the lifting cable portion, continued contact between the pulling cable portion causing the second engaging portion to bridge the clearance gap as it moves from the releasing to the locking positions until a tension is applied by the user to the pulling cable portion with a force that substantially corresponds to the weight of the article. A biasing spring urges the cam to move to its rest position out of contact with the cord when a force is applied to the pulling cable portion.

A failsafe device for raising/lowering articles comprising a frame, attaching means for attaching said frame to a support surface above a predetermined height to which the article is to be selectively elevated;

low friction deflection means mounted on said frame about a substantially horizontal axis when said frame is mounted on the support surface;
a cable entrained over said low friction deflection means which has a substantially vertical lifting cable portion attachable to the article to the lifted and a substantially vertical pulling cable portion arranged to be pulled downwardly by a user to elevate the article and released upwardly to lower the article;
cam means on said frame on one side of said pulling cable portion and having a cable engaging surface, said cam means being movable between a cable releasing position and a cable locking position, said cable engaging surface including a first engaging portion normally spaced a distance Δ from said pulling cable portion to form a clearance gap in said cable releasing position and a second engaging portion bridging said clearance gap a distance equal to at least Δ for substantially instantaneously arresting said cable and preventing movement of said pulling cable portion upwardly toward said low friction deflection means and corresponding downward movement of the article, and pushing means on said frame on an opposing side of said pulling cabled portion in relation to said cam means for continuously applying a force on said pulling cable portion in the direction of said cam and for urging said pulling cable portion across said clearance gap said distance Δ into contact with said first engaging portion only when tension in said pulling cable portion is decreased relative to the tension in said lifting cable portion, continued contact between said pulling cable portion and said cable engaging surface causing said second engaging portion to bridge said distance Δ while said cam means moves from said releasing to said locking positions until a tension is applied by the user to said pulling cable portion that substantially corresponds to the weight of the article;
and biasing means tending to urge said cam means to disengage from said cord when tension is applied by the user to said pulling cable portion to thereby promote unlocking of the cord when said pulling cable portion is pulled by the user.

1 more element

Abstract

Claims48