Which mechanism to use to move the heliostat.
There are a number of different escapement mechanisms invented. From very delicate to very robust. One sturdy one is gravity escapement used in bell-towers.
Key to the animation: The two “gravity arms” are coloured blue and red. The two three-legged escape wheels are also coloured blue and red. They work in two parallel planes so that the blue wheel only impacts the locking block on the blue arm and the red wheel only impacts the red arm. In a real escapement these impacts give rise to loud audible “ticks” and these are indicated by the appearance of a * beside the locking blocks.
The three black lifting pins are key to the operation of the escapement. They cause the weighted gravity arms to be raised by an amount indicated by the pair of parallel lines on each side of the escapement. This gain in potential energy is the energy given to the pendulum on each cycle. For the Trinity Clock a mass of around 50 grams is lifted through 3mm each 1.5 seconds – which works out to 1mW of power. The driving power from the falling weight is about 12mW, so there is a substantial excess of power used to drive the escapement. Much of this energy is dissipated in the acceleration and deceleration of the frictional “fly” attached to the escape wheels.