The Basic 6 Step Escapement Inspection

Watch Escapement

Written By Alex Hamilton

Alex Hamilton is a watchmaker, collector of fine watches and writer of all topics in the study of Horology.

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When new to watch repair one can run into many problems with the function of a watch after servicing has been done. Although there can be multiple reasons for a watch’s poor performance, a large percentage can be traced back to the escapement of the watch. The purpose of this article is to give the new watchmaker a simple six-part check of the escapement functions which will eliminate all problems associated with the watch.

If your initial testing on the timegragher is showing the telltale signs of escapement faults, then it would be wise to use this checklist during your disassembly procedure to try to identify and correct issues prior to cleaning the parts. With that said, these steps can be used after the cleaning has been done. Prior to these checks it is important that the rest of the train is in the proper condition. A proper working mainspring and barrel, undamaged wheel teeth and pinions as well as the pivots being straight, with the proper side and end shake. These checks are done with no power to the mainspring.

Height Divisions or Relationships

proper watch pivot clearence

This basically refers to how parts interact with one another Dial up and Dial down. By checking the end shake of the escape wheel to the pallet jewels you can make sure that they stay centered in both the DU and DD positions so that the escape wheel teeth and pallet stones are interacting together properly.

Check the end shake of the pallet fork and make sure the guard pin is not rubbing on the impulse jewel. This can often happen because the end shake is different in the balance staff.

Check that the pallet fork slot interacts properly with the impulse jewel, both DD and DD. Make sure that the escape wheel is flat and round, the roller jewel is straight up and down in the fork slot and check that the guard pin interacts properly with the safety roller.

Now check your banking pins

Bent banking pin

There are three type of banking style, built-in, eccentric, fixed.

The Built-in style, found in more modern watches are formed into the plate and don’t ever require adjustment. Inspect the edges for damage as well as the contact area on the pallet horns or shank, depending on where the contact is.

With Eccentric and fixed banking pins you want to check that they are perpendicular to the plate and parallel to each other. If they are not parallel, the pallet fork has a larger swing in one position.  This will change the how the pallet stones are interacting with the escape wheel which will influence the rate between all positions. Check to make sure that the impulse jewel moves freely through the pallet slot. If the impulse jewel has any interference you will have to move the pins. Just remember when you move one pin, you need to move the other one equally. The easiest way to check this is with the pallet fork shank against the banking pin and check the total lock of the pallet stone to the escape wheel tooth.

Check your fork horn clearance.

Part of the safety system against shock, check the fork horn clearance on either side of dead point or line of center. Rotate the balance assembly 45 degrees on either side of dead point and check for the clearance. It should be equal on both sides. If its not make sure the pallet horns are not bent or recheck the banking pins to make sure the are equal on each side of dead point.

If the horns and banking pins check out, then there is probably a problem with the impulse jewel being out of perpendicular with the roller table or leaning to one side or the other.

Total lock

total lock

Now inspect the pallet jewels. This is done with the pallet fork shank resting on the banking pin. In a 18000 beat watch, total lock should equal 1/3 of the total length of the impulse surface of the pallet stone. High beat watches are much less. Once total lock is set then all the other functions of the pallet’s stones, drop, lock and slide, will be correct.

Safe lock

The final check is to go back and put power to the mainspring and check for safe lock.

Put the pallet in the lock position, pallet shank against the banking pin, move the balance assembly so the fork horn clearance can be checked.

Make sure the escapement does not unlock when the pallet fork comes in contact with the impulse jewel. When you release the pallet fork from this position, the angle of draw should take over and pull the pallet fork shank back to the banking pin.

This is called safe lock and should be checked on both sides. If the escapement loses it lock, then you need to increase the total lock must be increased until safe lock is achieved.

As you become more familiar with these checks and incorporate them into your normal routine, you will be able to catch a lot of problems before you put the watch on the timegrapher after assembly and lubrication.

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