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Catherine L. Gibbon: Improvements in Street Railway Construction, 1892

The Wedge

This piece was an automatic lock of true wedge shape with "harpoon" points. Once driven through the mortise holes in the chair and rail and over the tie-bar, the wedge locked the entire structure and itself in, binding the rails vertically while permitting them to expand and contract. The only way to force the wedge out was to compress the harpoon points with a tool and drive it out.

tie-bar and wedge
Click image for larger view of tie-bar and wedge. (741K) (From Gibbon Catalogue)