no recoil

+1 here, I've just read the complete thread where I started out with it all whistling over my head and ending up with knowing a little about how a clock works, I recently bought a 1940's ish pendulum wall clock which quietly ticks away in the hall and I admit to watching it trying to see what makes it tick.

Martin P

Hi, this old thread is currently of great interest to me. The question I would like answering is this and it may well be more targeted at those familiar with clocks and / or physics;

does the recoil transfer any energy to the escape wheel. it is argued by some that turning the E.W backwards which impacts on the time train down to the weight that this energy is then added to the forward driving impulse as the anchors pallets slide off the E.W's tooth.

I have asked this on a watch forum, many readers but no replies. I have google this but get nothing firm.

My take is as the force exerted turning back the E.W at the point of the anchors maximum travel is latched by the force in the pendulum. There can be no impulse force acting at this stationary point. but as the pendulum then starts its fall due to gravity the E.W helps it on its way but is there additional energy to what there would be ordinarily at this point due to recoil. Or on the other hand has it been used up resisting and bringing the E.W to a stop.

The issue to me is many writers have stated recoil is a disadvantage due to wear and wasted energy. Whilst wear is obvious is wasted energy, not if the recoil helps propel the anchor?

Chris

Oh dear. Recoil happens as the anchor drives the escape wheel backwards just after the impulse. If there is a seconds hand attached to the escape wheel arbor you see it move backwards a little just after it jumps forward. The impulse is delivered at that jump forward. The train is, somewhere, absorbing energy from the pendulum - how much goes where depends on many factors such as play in the pivots and various other things. Some might even slightly raise the driving weight. With luck most of the recoil energy will be delivered back to the pendulum, but if things are worn and or inaccurate maybe not. The level of escapement error is also determined by the recoil (amongst other things) so wear etc that changes the recoil changes timekeeping.

The Graham deadbeat escapement has no recoil as its name implies, so no energy is extracted from the pendulum by recoil.

Harrison's Grasshopper is very good at returning the energy especially if it has a remontoire, and recoil is an important aspect of his clocks' operation. Many gravity escapements inherently have recoil, in that the pendulum picks up a weight before it reaches maximum swing, "recoiling" it, then the weight is taken off the pendulum at a lower level by a stop and is then returned to the higher level by some sort of mechanism.

Edited By Chris TickTock on 29/02/2020 16:36:02

No.

I agree with John.       No

Roy

Edited By roy entwistle on 29/02/2020 20:04:22

Excuse me Sirs, would EW be Escapement Wheel, if yes I'm beginning to understand.

Martin P

Well Guys,

That is my thinking but I am unsure of the arguments supporting the case as quite evidently others seem to be. For a start thjere is backlash in the time train so a tiny kick back may not do anything. Also we are presuming a weight driven clock and not a spring so can a tiny shift back add to the forward movement. Also when the anchor comes to rest it initially still has to overcome inertia. I am yet to be persuaded that recoil adds to the forward momentum...but I could be wrong as believe me themathmatics involved fly very high.

chris