How A Clock Works
The power source, main spring OR weight, provides the power to move the gears or wheels in the gear train.
There's a lot of power stored here, so we must have some way to control it's release.
That control is provided by the escapement. This anchor assembly acts like a switch to slowly meter the release of power one tooth at a time through the escape wheel.
The rate at which this escape wheel turns is controlled by the pendulum, the timing source.
The length of the pendulum determines the rate at which it swings back and forth. Longer pendulums swing slower.
The escapement also provides power through the crutch to keep the pendulum swinging. The escape wheel controls how fast all the wheels in the wheel train turn.
The gear ratios in the wheel train are selected so that one arbre somewhere in the clock turns exactly once per hour to display the time in minutes. That's where we put the big hand on the clock.
In order to display both hours and minutes the motion works divides the hourly rotation of the minute hand by twelve to move the hour hand once around the dial once for every twelve rotations of the minute hand.