New postby Gerald (Ged) Pitchford » Thu Oct 23, 2008 6:25 am

A type of escapement used in early clocks and watches, sometimes called Crownwheel because of the shape of the escape wheel.
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Re: Verge

New postby Glyn Meredith » Tue Mar 09, 2010 4:58 pm

The 'verge and foliot' is the earliest real form of mechanical escapement. The crown wheel (c) is powered by a falling weight and moves a little way until it is in contact with an arm (pallet p) of the verge (v). The verge then spins, which momentarily releases the wheel until it comes into contact with the second pallet (q). This action is controlled by the 'foliot', a crossbar at the top end of the verge. The weights at each end of the foliot can be changed to alter the timing.

The pictures at Wikipedia help to explain it.

Verge_Escapement_Labelled.png (8.42 KiB) Viewed 6652 times
De_Vick_Clock_Verge_&_Foliot.png (8.26 KiB) Viewed 6290 times

The verge and foliot escapement was difficult to regulate, one cause being the expansion of the foliot mechanism with an increase in temperature.

The foliot escapement was later replaced by the balance wheel.
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