Ridgeway grandfather clock running slow even after adjusting pendulum

[Brucethedude]

Hi, I’ve been working on a 1987 Ridgeway Grandfather clock (451-033 94 cm) that runs slow. It’s losing about 15 seconds every 15 minutes. I have adjusted the pendulum all the way up and it still never changes. I have even ran it only on the time chain without the strike and gong. I have cleaned and oiled the clock and made sure there’s no build up of grease. If anyone could give me some ideas as to where to look to fix this issue I would appreciate the help.

 

[Dick Feldman]

Bruce,
Clean, oil and adjust are not necessarily curative measures, especially if the root issue is wear. Have you checked the movement for wear? Can you send a picture of the rear plate of the movement? How old is the movement/clock?
If you are convinced that shortening the pendulum is the correct solution, the rate (timekeeping) can be varied by shortening the suspension spring and/or the pendulum leader or the pendulum.
Do you have a Timetrax or another timer? What is the actual BPH rate compared to that rated for the clock movement? Have you listened to the escapement with a beat amplifier? Is there scuffing, etc. going on that might slow the pendulum. Your video shows good amplitude. How much over swing is there in the escapement?
Good luck,
Dick

 

[wow]

Dick. Good to see you back. Haven’t seen your posts lately.

 

[Willie X]

Need photo of the back, to include leader and suspension spring.

Have you ever seen this movement/pendulum combo keep time? More often than you may think, a clock will have the wrong movement, or the wrong pendulum.

Willie X

 

[Rod Schaffter]

Have you ever seen this movement/pendulum combo keep time? More often than you may think, a clock will have the wrong movement, or the wrong pendulum.

I concur with Willie; looking at the video, the pendulum seems long for that case. As an example, it were the pendulum for a 60 BPM clock on a 66 BPM movement, it would lose about 27 seconds every 15 minutes; less if one cranked the bob up...

Good Luck, Rod

 

[Willie X]

You can use a piece of soft wire and tie the pendulum a couple of inches higher on the leader. Or, if this is not doable, remove the pendulum's top piece and use a wire as a temporary replacement, 2 to 4 inches shorter. This is a sure fire way to see what length the pendulum will need to be.

The pendulums, for a any particular movement are often the same, except for the length of the top pieces. The top pieces can usually be modified easily.

Willie X

 

[shutterbug]

Have you tried raising the lyre grill part of the pendulum? That might make a significant difference on time keeping. You could also conceal a little weight high up on the pendulum - maybe behind that upper leaf on the rod. You're trying to raise the center of oscillation a bit.

 

[Willie X]

24 minutes per day, that's going to take at least one inch and probably another inch to re-center the rating nut. So, about 2 inches will be a good place to start. This is close to what Rod mentioned. Willie X

 

[PatH]

Is the bob actually moving up when the rating nut is turned?

 

[RJSoftware]

One other possibility is the hands/clutch is too loose. There are different styles of clutch, but the function is same. The clutch allows you to change time by slipping so that gears of time train can remain stationary, but yet is still grip enough to push the separate gears that move hands ( called motion works) forward to keep time.

The one big clue if the clutch is too loose is if it takes little to no effort to turn minute hand forward. When a clutch is too loose it can work intermittent sometimes hands stop sometimes not. If adjusting the minute hand leans towards feeling floppy in different positions, thats a good indicator. There should always be some resistance felt when advancing the minute hand. Whatever amount, it should be smooth and consistent.

Some typical types involve a cupped washer or pronged spring washer. Some even have a dedicated spring. They are mostly found on minute arbor. Sometimes you can reach in fully assembled movement with needle nose pliers and add more tension.

 

[shutterbug]

It would be good to see the suspension spring, the leader and the rating nut on the pendulum.