BarrelWinding the clock wraps the line round it and lifts the weight. As the weight falls, it turns the barrel and the great wheel.
Great wheelDrives the pinion of the center wheel. It is fixed to the barrel through the ratchet and click.
ClickClockmakers call the pawl of a ratchet the click. It lets the barrel be wound without turning the great wheel, then holds it.
Center wheelIts arbor comes through the front plate and carries the minute hand. It drives the pinion of the third wheel.
Third wheelIn many clocks it drives the escape wheel's pinion directly.
Escape wheelThe pallets let it go one tooth at a time. This happens with each swing of the pendulum. Each time it moves, it gives the pendulum a small push.
PalletsThe anchor's two arms end in pallets. They catch and release the escape wheel's teeth in turn as the pendulum swings.
WeightIt is the power source. This one drives the going train. The other drives the striking train.
PulleyThe line runs from the barrel down round this pulley. Then it goes back up to the seat board.
Pendulum 5
CrutchIt hangs from the pallets' arbor behind the back plate. The fork at its end holds the pendulum rod, so the pendulum rocks the pallets.
Suspension springA short, straight spring of metal ribbon. The pendulum rod hangs from it.
Pendulum rodIt hangs from the suspension spring and carries the bob.
BobIt is lens-shaped, so from the front it is a disc.
Rating nutTurning it moves the bob up or down the rod. Raising the bob makes the clock run faster; lowering it makes it run slower.
Striking 6
HammerThe striking train lifts it and lets it fall on the bell. It falls once for each stroke.
BellIt sits on a stand above the movement. Some clocks strike a gong instead.
SnailIt turns once in 12 hours. It has a step for each hour. The step under the rack's tail decides how far the rack can fall.
RackJust before the hour it falls until its tail meets the snail. One tooth is then gathered up for each stroke of the bell.
Rack hookIt is lifted just before the hour to let the rack fall. Then it holds the rack as it is gathered up.
Gathering palletA pinion with one tooth. For every blow of the hammer it gathers up one tooth of the rack; after the last tooth, the striking stops.
Plates and motion work 7
Front plateThe wheels turn between this plate and the back plate. Their pivots sit in holes in the plates. The dial goes in front of it.
Back plateThe pendulum and the crutch hang behind it.
PillarsThey join the front and back plates. This makes a rigid frame for the wheels.
Seat boardA board across the top of the case. The movement rests on it, and one end of each weight's line is fastened to it.
Cannon pinionIt fits friction-tight on the center wheel's arbor. That lets the hands be turned to set the time. It drives the minute wheel.
Minute wheelIts own small pinion drives the hour wheel.
Hour wheelIt fits over the cannon pinion. It turns once for every 12 turns of it.
How this list was compiled: Every name checked on 2026-09-30, a name kept only where two of these use it. (1) W. L. Goodrich, The Modern Clock (1905, public domain), full text at https://archive.org/details/modernclockstudy00good : front and back plates, pillars, seat board, barrel, great wheel, click and ratchet, centre wheel, third wheel, escape wheel, pallets, crutch, suspension spring, pendulum rod, bob, rating nut, weight and pulley, cannon pinion, minute wheel, hour wheel, snail, rack, rack hook, gathering pallet, hammer, bell. (2) P. N. Hasluck, The Clock Jobber's Handybook (1889, public domain), https://archive.org/details/clockjobbershan00haslgoog : the same names except rating nut (it says the bob is raised and lowered by a nut on a screw). (3) Wikipedia, text only: Movement (clockwork), Wheel train, Pendulum clock, Anchor escapement, Striking clock, Pendulum. Wikipedia calls the rating nut the rate adjustment nut. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; no one maker's movement, nothing traced. Licence: own work
How it works
The movement of a grandfather clock is driven by falling weights and timed by a long pendulum. These four views name it wheel by wheel, and cover the parts of a mechanical clock in general.
Read the full guide
The going train
The weight's line turns the barrel and the great wheel. That drives the center wheel, which turns once an hour, then the third wheel and the escape wheel. The pallets let the escape wheel move one tooth for each swing of the pendulum.
The parts of a grandfather clock pendulum
The pendulum hangs from the suspension spring. Its rod passes through the fork of the crutch, which links it to the pallets, and carries the bob. The rating nut under the bob sets how fast the clock runs.
Clock running slow? Turn the rating nut to raise the bob; a shorter pendulum swings faster.
A striking clock has two weights and two trains: going on the right, striking on the left as you face it.
Questions and answers
What are the parts of a clock mechanism?
A power source, here a weight on a line round a barrel; a wheel train; an escapement, here the escape wheel and pallets; and a pendulum to keep time. The motion work under the dial turns the hour hand from the minute hand.
What is the movement of a grandfather clock?
The movement is the mechanism of the clock, as distinct from the case and the dial. Its wheels turn between a front plate and a back plate held apart by pillars, and it sits on the seat board at the top of the case.
What does the crutch do on a pendulum clock?
It is the arm that hangs behind the movement from the pallets. Its fork holds the pendulum rod, so each swing rocks the pallets, and each tooth the escape wheel passes gives the pendulum a small push back.
How does a grandfather clock know how many times to strike?
A stepped cam called the snail turns once in twelve hours. The rack falls until its tail rests on the snail, further at each later hour, and the clock strikes once for every rack tooth that has to be gathered up.