BenVanDeWaal's Lego Clock "Escapements"

[DLuders]

If you like Lego clocks, see BenVanDeWaal's YouTube Channel which has videos of various "escapements". The pendulum provides the motion to turn a ratchet wheel using various Lego Technic parts. Here are two examples:

-- "Galileo escapement (~Year 1637) with a 12-teeth escapement wheel....Impulse transfer is approximately tangential (i.e. with minimal friction), but unlocking is radial. Friction between the lifting pin and the unlocking lever can be eliminated by making the lever rotating about the pendulum arbor. Although unlocking friction can be made small, it may be variable, as a result of irregularities in the gear train, thus disturbing the pendulum motion in an inpredictable way.

The weight, 70g, drops 1.25 mm/s.

For construction details of the escapewheel see

".

-- "There is only 1 gravity arm, and 14 'pins'. The (yellow) pendulum and the (red) gravity arm rotate about the same, fixed, axis, but are well separated.

The gravity arm is lifted by the escapewheel (grey) and locked in its high position by a hook. In this position it is free from the scapewheel and its (Galilei) unlocking mechanism.

When the pendulum swings to the right, it unlocks the gravity arm from the hook and is then impulsed by the falling gravity arm.

The unlocking mechanism of the scapewheel acts as a banking pin for the gravity arm that stops falling down while the pendulum continues its swing to the left. Then the scapewheel is unlocked and brings the gravity arm back to its high position. This operation has to be accomplished before the pendulum comes back. It should not be too fast, however, to prevent tripping. Therefore, the scapewheel rotation is slowed down by a fly that rotates about a vertical axis (to control friction; upper left corner), without reducing its static torque.

At no moment the pendulum is in direct mechanical contact with the geartrain. Even if the geartrain's performance is affected by irregularities, this will have no effect on the motion of the pendulum."

[mahjqa]

I think the second one just broke my brain.

[KEvron]

at the risk of stealing ben's thunder, here's his latest escapement:

"The famous H1 marine timekeeper was made by John Harrison in 1730-1735. It's oscillator consists of two interlinked bar balances (rather than a single pendulum) or dumbbells that are angularly connected with cross-ribbons. The restoring force is provided by two helical steel springs, and so does not depend on gravity.

"In this Lego version the springs are replaced by two equal masses, suspended by threads of equal lengths, and at equal distances from the pivots, to the balance arms. The system of balances and masses is in equilibrium when the balance arms are parallel and vertical. When the upper part of the balances are moved towards each other, the upper mass goes down, and the lower mass goes up. The rise is always larger than the drop, which causes a restoring force, dependent on gravity (see below)...

"The pointer does not indicate time, but counts the swings."

not only is this an astonishing realisation, but it once again demonstrates ben's keen knack for innovation (equilibrium weights instead of springs!). i'm a wannabe; he's a real master.

KEvron

Edited March 5, 2012 by KEvron

[Burf2000]

These mechanism are simply amazing and once I have some time from building killer robots, I would love to give this a go!