Energy-absorbing span lock system for drawbridges
AssigneeSteward Machine Co., Inc.
InventorRobert L. Cragg
Life of this patent
Estimating the term…
Abstract
An energy absorbing span lock system for drawbridges, such as a double-leaf bascule leaf span. A retractable and extendible connector mounted on one leaf of the span engages a receiver on the other leaf. Resilient energy absorbing shoes in the receiver accept the connector and allow relative deflection between the leaf ends caused by vehicular traffic.
Claims21
For use in combination with a drawbridge having at least one span with a free end structure moveable with respect to a complementary structure, span lock apparatus for releasably interlocking the free end structure with its complementary structure in a manner providing a shear connection therebetween, said apparatus comprising:
- a connector mounted on one of the structures, said connector having a shear member extendable and retractable relative to said one structure;
- receiver means mounted on the other of the structures for receiving an extended portion of said shear member and for aligning and interlocking the structures when the drawbridge is closed;
- and
- first resilient means mounted on said receiver means for resiliently engaging opposed upper and lower surfaces of said extended portion of said shear member;
- whereby shear loads applied to the span are resiliently accommodated.
In a bascule bridge having at least one moveable leaf structure, an energy absorbing span lock system for releasably interlocking the moveable leaf with a complementary structure, comprising:
- a connector mounted on one of the structures, said connector having an extendable and retractable portion for spanning between said structures;
- a receiver means mounted on the other of the structures for receiving the extendable and retractable portion of the connector and for aligning and interlocking the structures when the bridge is closed;
- and
- resilient means mounted on said other of the structures for resiliently engaging opposite upper and lower surfaces of the extendable and retractable portion;
- whereby shear loads can be transferred across the structures in a manner that absorbs shocks and accommodates wear.
In a bridge having at least one moveable span structure with a free end portion adapted to be juxtaposed with another structure to form a load support surface, and a releasable shear connection between the structures for limiting relative motion therebetween, the improvement wherein the releasable shear connection comprises:
- a shear connector member carried on at least one of said structures,
- actuator means for selectively extending and retracting said shear connector member,
- receiver means on the other of said structures for receiving said shear connector member when extended;
- and
- resilient means disposed between said receiver means and upper and lower surfaces of said shear connector member for accommodating motion of the shear connector member caused by loading of the span while transferring shear loads from one structure to the other,
- whereby shock loads on the span and wear on the shear connector member can be accommodated.
Dependencies are inferred from the claim text.