Brakes – Operators – Speed-responsive
Reexamination Certificate
1999-08-31
2001-11-13
Schwartz, Christopher P. (Department: 3613)
Brakes
Operators
Speed-responsive
C188S031000, C188S082700, C074S57700S, C187S360000, C187S374000, C187S351000, C187S367000, C192S043100, C192S116500
Reexamination Certificate
active
06315089
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a safety device for racks that are vertically adjustable while controlled by an overhead rotating shaft. More specifically, the invention is directed toward a clover mechanism mounted on a rotary shaft to be used with an unbalanced free-fall dog that precludes rotation of the rotating shaft upon excessive acceleration, such as after catastrophic failure of the control mechanism for the rotating shaft.
Typically, overhead racks are used in commercial settings to conserve space within the facility. A typical rack is approximately fifty feet long (sixteen meters) and can be raised and lowered by a double chain motor that is attached to a rotating shaft. A flexible strap may wrap around the rotating shaft thereby shortening the amount of strap hanging below the rotating shaft and raising the rack. As an example, a bicycle rack consists of numerous hooks extending therefrom to hold bicycles from their front or rear wheels. The rack is raised and lowered as needed to load, view or remove the bicycles from the rack.
When a chain or belt breaks or dislodges from the gear or rotating cylinder, the rack can come crashing down. There are presently safety mechanisms to be used in association with the gear or rotating cylinder, such as the double chain in case one chain breaks or dislodges. Also, with a long rotating shaft constantly being placed under excessive stress, the shaft may fail in rare occasions.
A need exists to provide additional safety features for racks attached to rotating shafts and the like. The utilization of a construction that locks upon rapid or uncontrolled rotation of the rotating shaft is a desirable complementary safety feature.
Accordingly, it would be desirable to provide a safety lock device that is activated by rapid force on an arm of an unbalanced free-fall dog that pivotally reacts and locks before the rack drops a significant distance.
In connection with the foregoing objectives, it would also be a goal to have a safety device that allows the rack to freely move up and down at a slow rotative speed relative to the rotating shaft.
Moreover, it would be significant in the industry to provide a safety mechanism that can be attached to the rotating shaft at a location away from the chain, gears or other driven mechanisms.
It has therefore been found beneficial to produce an unbalanced free-fall dog that functions in conjunction with a clover mechanism that is mounted on the rotating shaft. Further aspects and benefits of the invention will be appreciated by those practicing the operation of rotating shafts.
SUMMARY OF THE INVENTION
The invention may be described as a safety lock device including a clover mechanism mounted on the rotating shaft to be used with an unbalanced free-fall dog that precludes rotation of the rotating shaft upon rapid acceleration or excessive speed of the rotation of the shaft. The present invention is a safety lock device primarily for use as a means for stopping the rotation of a rotating shaft upon which items are hung, such as a bicycle rack.
Additionally, the invention provides for a safety lock device that is activated by rapid force on an arm of an unbalanced free-fall dog that pivotally reacts and locks before the rack drops a significant distance. The free-fall dog is pivotally mounted wherein a pin acts as a fulcrum upon which the free-fall dog may teeter in an unbalanced seesaw motion. At opposite ends of the fulcrum are a locking finger and the arm. The free-fall dog is unbalanced such that the arm contacts the clover mechanism as it rotates while the locking finger does not contact the clover mechanism at slow rotating speed. At a slow rotative speed, the arm is only slightly deflected. With great acceleration, the arm is deflected farther from the clover mechanism thereby causing the locking finger on the opposite side of the fulcrum of the free-fall dog to be pivoted into the clover mechanism. The locking finger, which upon sufficient force to the arm, is injected into the gap between two protuberances of the clover mechanism by a reactive force to the force asserted on the arm that exceeds the force caused by the unbalanced state. A contact surface on the locking finger engages an engagement edge of the clover mechanism to lock the clover mechanism, which prevents further rotation of the rotative shaft. Thus, the downward movement of the items attached to the rotating shaft is stopped.
The safety lock device allows the rack to freely move up and down at a slow rotative speed with respect to the shaft because only the arm of the free-fall dog contacts the clover mechanism while rotating slowly. The locking finger of the free-fall dog (the shorter end of the seesaw) does not contact the clover mechanism unless a sufficient force is exerted on the arm (the longer end of the seesaw).
The safety lock device can be attached to the rotating shaft at a location away from the chain, gears or other driven mechanisms. Also, more than one safety lock device may be placed on a long rotating shaft. After any cause that makes the rotating shaft rapidly accelerate, the safety lock device of the present invention will preclude rotation of the portion of the shaft to which it is attached.
Another desirable result attained is the ability to unlock the safety lock device by rotating the clover mechanism in the reverse direction from the locked position.
Further objects, features and advantages of the present invention will become apparent from the following description and drawings.
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Fink John
Schilling Harry E.
Conte Robert F. I.
Lee Mann Smith McWilliams Sweeney & Ohlson
Morgan Marshall Industries, Inc.
Pezzlo Benjamin A
Schwartz Christopher P.
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