Anchor Escapement A particular form of escapement, invented after 1760, which when used with a long pendulum gives greater accuracy
to time keeping than previously achievable.
Arbor A shaft or spindle that normally holds a wheel and a pinion, but can
also hold lifting pieces, detents or bell hammers.
Balance Wheel A single spoked horizontal wheel that is pushed alternately
backwards and forwards by the clock wheel train, thus regulating its speed.
Bell Hammer Also known as the clapper, for
bell striking.
Centre Wheel The wheel on the centre arbor that carries the minute hand and whose pinion is driven by the
great wheel. The centre wheel rotates clockwise once per hour and two-handed thirty-hour clocks often have a centre wheel train.
Contrate
Wheel The third wheel of a going train with a verge pendulum escapement, with its teeth at right angles to the plane of the
wheel.
Count Wheel A disc or wheel cut with slots in its edge or with inserted pins. The slots or pins are increasing
distances apart and control the number of hours struck by the hammer. Also known as a locking plate.
Crown Wheel
The escape wheel of a verge escapement, cut with an odd number of teeth at right angles to the plane of the wheel. Each pointed
tooth has a vertical or near vertical acting face.
Detents Those arms and levers that control the locking and unlocking
of the striking train.
Escape Wheel The last wheel of the going train, the teeth of which impart impulse to the pallets
and thus maintain the pendulum in motion. In a verge clock the escape wheel is also the crown wheel.
Fly A rotating
brass flap that acts as an air brake to control the speed of the striking train.
Foliot An alternative to the balance wheel;
it is a horizontal bar with weights at each end. The weights can be moved out from the centre of the bar to offer some regulation.
Not found on English clocks later than 1600.
Gathering pallet A small steel piece (shaped like a nib) which, as it
rotates, gathers the rack, one tooth at a time, to bring it back to its resting position.
Going Train A set of wheels and
pinions driven by a power source such as a falling weight and regulated to rotate at a constant rate by an escapement. Also
termed "the watch".
Great Wheel The first wheel in a train, normally carrying with it (on the same arbor) the winding pulley
or barrel.
Hammer Counter A stiffly sprung steel part that attempts to bring the hammer to a halt just short of the bell
but in practice allows the hammer head to continue momentarily to result in a single clearly struck note.
Hammer Spring Normally a blade spring that acts on the hammer stem to make the hammer strike the bell when the hammer tail falls off a striking
pin.
Hoop Wheel The second wheel of a count wheel striking train with a hoop riveted to its side. The gap in
the hoop is responsible for locking the train after completion of striking.
Hour Wheel In a single- or two-handed clock
with a three-wheel going train, that part of the motion work that is driven by the pinion of report to rotate once per 12 hours and
carries on it arbor the hour hand. It is part of the motion work, and also known as the dial wheel.
Motion Work An
arrangement of wheels and pinions, normally situated behind the dial, that converts the rotation of the going train to that of the
one or two hands on the dial.
Pallet Wheel The second wheel of a rack striking train that carries the gathering pallet.
The pallet wheel can carry a pin to lock the train after striking or this can be carried out by the tail of the gathering pallet against
a pin the rack.
Pin Wheel The great wheel of the striking train. When it rotates, pins in its periphery act to pull
back and release the striking hammer.
Pinions of Report Pinions on the end of the great wheels which drive either the count
wheel or the hour wheel.
Plated Movement One where the wheels, arbors and pinions are held and pivoted between two plates
of brass separated by three or more pillars.
Posted Frame A type of frame that contains the clock movement, consisting
of top and bottom horizontal plates separated by four vertical posts at the corners.
Ratch A twelve-pointed star wheel,
situated on the hour wheel arbor, whose purpose is to raise the striking detents and thus let off the strike at the hour.
Second
Wheel That wheel whose pinion is driven clockwise by the great wheel and which drives the pinion of the escape wheel in
a three-wheel going train.
Striking Train A set of wheels and pinions driven by a power source such as a falling weight,
which when released by the motion work causes the hour to be struck.
Third Wheel That wheel whose pinion is driven by the
centre wheel and which drives the escape wheel pinion in a centre-wheel going train.
Verge Escapement The earliest form
of escapement in which two pallets spaced apart, and at about 90 degrees on the verge staff, are pushed alternately aside by the teeth
of a crown wheel to impart oscillating motion to a pendulum or a balance wheel.
Warning Wheel The third wheel of the striking
train carrying a pin in its periphery, that is held by the warning flap and then let go at the hour to release the train for striking.