gary's clocks

Animation- Escapement- (As in Fine Woodworking 1986)

animation escapement closeup

The Escapement wheel has 30 teeth.

Each tooth contacts the pendulum lever 2 times per rev.
A tick or a tock once every second.

The pendulum takes one second to travel from left to right.
2 seconds to return to where it started.

I've seen this escapement used in many clocks.

Setting up the tick tock arm to make an even beat can be tricky with this one.

Introducing the upside down Graham Escapement

upside down Graham Escapement

Many of you should be familiar with the Graham escapement.

This is the most popular and efficient escapement.

Visit a place that sells grandfather clocks.
Look inside the clock and you will most likely find this escapement.

But not with the tick tock deal on the bottom like this one.

I have a reason for placing the tick tock lever on the bottom....................

Think about pushing a kid on a swing set?

Where would you rather push?

Where the kid is sitting at the bottom of the chain or way up high at the pivot?

More on this idea to follow as the webpage is updated.

Consider this food for thought.

Compare Same pendulum with the force applied at the top and bottom

If you were trying to keep the pendulum moving where would you push?

Where do most of the clocks push on the pendulum to keep them in motion? (guess near the top) pendulum force compare

upside down escapement

Take advantage of pushing near the bottom of the pendulum

uside down escapement

Compare a heavy(10 pound) pendulum bob to a light one (1 pound)

Two identical pendulums except for bob weight are released at once.
The heavy one keeps going while the light one stops.

comp pend weights

Compare how the contact angle for an escapement influences output force

This animation is a simplification of what happens when the escape wheel contacts the tic tock lever.

All of the assemblies have these qualities in common

  • same force applied to upright lever in orange
  • the lever and tick tock arm have the same density
  • the coeficient of friction same for all

    What's different is

  • the contact angle varies from 67 degrees to 15 degrees.
  • different square blocks of weight were placed on top of the tic tock arms

    The blocks of weight were sized such that if they were made any larger or heavier the tick tock lever would seize.

    What you should observe is that the shallower angled arm can support more weight.

    This weight represents the impulse that would be given to the pendulum arm.

    The trade off is that the shallower angle does not deflect very much.

    In the 4 examples above the same amount of work is being done by all.

    Work is defined as W= Force X Distance.

    So the animations make sense.
    Move a small weight a large distance or move a heavy weight a small distance.

    In each of the examples if you were to multiply the weight of the block by the vertical distance it moves, you'd get the same result.

    More to come on this analysis as the Friction and Inertia factors are varied.

    escape angles

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