A Crémone or "Crémone Bolt" is a type of decorative hardware used as a locking device to fasten a pair of

casement window A casement window is a window that is attached to its frame by one or more hinges at the side. They are used singly or in pairs within a common frame, in which case they are hinged on the outside. Casement windows are often held open using a c ...

s. A knob or lever handle is linked by a

rack and pinion rack and pinion is a type of linear actuator that comprises a circular gear (the '' pinion'') engaging a linear gear (the ''rack''). Together, they convert between rotational motion and linear motion: rotating the pinion causes the rack to be d ...

to a pair of half-round rods or "surface bolts" which slide over the outside surface of the door or window and extend into sockets at the head and sill of the opening. The gear mechanism operates the two vertical rods at the same time; one rod extends up into the door head, and the other extends down into the door sill. The device is similar in appearance to an "

espagnolette An espagnolette is a Lock (security device), locking device, normally mounted on the vertical frame of a French door or casement window. A handle or knob is connected to a metal rod mounted to the surface of the frame, about a metre above the floor ...

" lock, but uses a half-round rod. Shown from the rear, the parts of the crémone bolt gearbox (1) includes the lever or knob (3), which rotates the pinion gear (4), engaging the pair of rack gears (2), which push the two half-round bars (5) upward and downward at the same time (only the bottom bar is shown), into the sockets.

References

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