Half hour strike

[ed]

I have a 30 day pendulum wall clock. It normally struck on the hour and the half-hour. All of a sudden the half-hour strike quit working. I can see the hammer rise but it will not fall. The hour strike seems to work fine. Any suggestions that a non-clockmaker could accomplish that would fix this. All suggestions will be appreciated. thanks

[shutterbug]

Maybe At the next hour, does it strike during the warn (when it sets up for the strike)? It would be a single strike about 5 minutes before the hour. Then, when the hour strike completes, is the hammer raised?

[Richard T.]

We really need pictures to help us know what you really have. The maker of the clock and the type of striking mechanism the clock has, whether it is a count wheel for both hour & half hour, or a "passing strike" on the half hour. It could be a rack and snail. We need to know. Also a photo of the hammer set up would help.

Looking forward to seeing photos of your clock.

Best,

Richard T.

[shutterbug]

30 Day clock - pretty sure we're talking rack and snail. I'm guessing a slight adjustment on the gathering pallet will do it, but we do need some further info. to be sure. If it were a passing strike, the hammer would eventually fall, just at the wrong time.

[bangster]

Right. Rack & snail. Half-hour strike triggered by a half-higher lobe on the center cam that drops the rack just one tooth on the half hour. My guess is that wear or something prevents it from providing enough lift to release the rack. It's a place to start looking.

Depending on how handy you are, you can probably fix it yourself. We can help you through it. First, remove the hands. Next remove the dial. Next, if you can, post us a pic of the front of the movement.

[Mike Phelan]

Right. Rack & snail. Half-hour strike triggered by a half-higher lobe on the center cam that drops the rack just one tooth on the half hour. My guess is that wear or something prevents it from providing enough lift to release the rack.

Many of these modern clocks simply don't drop the rack at all but raise the rack hook sufficiently to unlock the striking at warning. Same with roulants.
Otherwise, it would need an extra lever or a dodgy shorter tooth to allow the rack to fall by one tooth.

[ed]

Thanks for all of the above. The mechanism is definetly "rack and snail". There is what looks like a two arm lever arangement with the two arms attached to each other and offset at a small angle. One arm rides the snail and the other with the rack (looks like a gear sector ?) makes contact with the gathering? pallet. I have found that if I press down slightly on the lever combo when it is time for the half hour strike that the rack will go down one click. The hammer will then fall as normal. If the angle between the two arms changed slightly the arm that rides the snail would not let the rack lever fall that one click for the half-hour strike. My intuition is that if I can decrease that angle very slightly (the same effect as pushing down on the combo) that might solve the problem. I will wait for any input before I do anything. Thanks for any help anyone can provide.
ED

[shutterbug]

Don't do anything until you're sure. Look at the gathering pallet pin, and see if it is interfering with the rack fall (it could be getting in the way during the warn run). Then check to see what might be interfering with the levers dropping. Look things over and let us know what you find.

[Heritage-Clocks]

You first sad that you watch the hammer rise but it doesn't fall. Well that would mean the the hammer is rising during warning. You need to adjust the gathering pallet. Or advance the star wheel that picks up the hammers. You want the star wheel to drop the hammer and the warning wheel to lock out just there after. If the tail on the rack needs adjustment. Then adjust it so just one tooth on the rack is received by the gather pallet. But the hammer shouldn't even move when the clock goes into warning, either for the hour or half hour... Plus secure the hands onto the movement when you test all this. It will put the snail in it's true position. Make sure you have no slop in the rack so it can move in and out while activating. < This will change how it lands on the snail. Some of those tails are pretty small and there isn't much length for airier. And check that you haven't got a bent pallet pin. Or a loose pin. Check every thing that is involved.....

H/C

[ed]

Every thing looks normal to me, but I am not a pro. I have noticed that the wheel with the three pins that do the actual lifting of the hammer comes to rest in a diffferent position depending on whether it is in the hour-strike mode or in the half-hour strike mode. After the hour-strike mode I can move the hammer by hand about one-half inch, after the half-hour strike mode I can only move the hammer by hand about one-quarter inch. Could the fix be as simple as moving the minute hand a fraction of a turn in the counter-clock wise direction. I seem to recall that this is the recommended process for some clocks. It may only be recommmended to get the 'chime' count in sync with the position of the minute hand. I have always set this clock by going in the clock-wise direction and waiting for the strikes to complete before moving on. I may put the clock back together and ignore the fact that it does not have a half-hour strike anymore. You guys on this message board are incredible. Thanks again. ED

[bangster]

Many of these modern clocks simply don't drop the rack at all but raise the rack hook sufficiently to unlock the striking at warning. Same with roulants.
Otherwise, it would need an extra lever or a dodgy shorter tooth to allow the rack to fall by one tooth.

I think that's what I meant to say.

[shutterbug]

Could the fix be as simple as moving the minute hand a fraction of a turn in the counter-clock wise direction.

I don't think that's going to help anything in this case. I think the gathering pallet is going to be the answer, but we need you to do some observing of what exactly is happening on the half hour that's different from the hour. Then we'll be able to give you some reasoned advise

[ed]

Thanks to all of the above. I decided to give up on the half-hour strike fix in fear that I would mess up the main functions of the clock. As I had the clock laying horizontal re-assembling it I tried the strike mechanisms again and both worked. That might be a clue to someone but not for me. Don' t know if I will try to fix it again. I will keep watch on this thread if anybody has any ideas.