Problem with date wheel on longcase clock

[oakcircle]

Several weeks ago, the date hand on my longcase clock began advancing only intermittently. Without thoroughly investigating the cause, I adjusted the hand and date wheel relationship. I finally realized the problem was actually the pin that advances the wheel had retracted and was not reliably engaging the wheel. I was able to push the pin back out for full engagement, but now I can't get the hand to advance properly. Depending on how I adjust the hand and wheel relationship, the date advances between 1 1/2 to 2 days.

The date wheel I have is like the attached photo, and the pin is attached to a gear that rotates counterclockwise to push the date wheel forward.

I have guessed that the initial engagement of the pin should start by barely clearing the tip of the "previous tooth" and traveling down the "backside" of it, so I've oriented it that way several times. However, this results in 1 1/2 day advancement.

Could someone please help advise me on where the pin should begin engagement with the date wheel?

 

[Tinker Dwight]

Usually there is a spring lever to keep it from over rotating
and will snap it back 1/2.
Tinker Dwight

 

[Randy Beckett]

It sounds likely that the pin is now engaging the intended tooth a little too deeply, causing it to stay in contact with it too far, indexing it 1 1/2 teeth. This would position the wheel so that on the next rotation, the pin would catch the tip of the 2nd tooth instead of the next one in line, and advance 2 teeth. Tinker is right, that the more modern clocks have a spring loaded lever that positions the wheel so that it will engage the pin properly on the next rotation, but I don't know about the older long case clocks.

 

[oakcircle]

It sounds likely that the pin is now engaging the intended tooth a little too deeply, causing it to stay in contact with it too far, indexing it 1 1/2 teeth. This would position the wheel so that on the next rotation, the pin would catch the tip of the 2nd tooth instead of the next one in line, and advance 2 teeth. Tinker is right, that the more modern clocks have a spring loaded lever that positions the wheel so that it will engage the pin properly on the next rotation, but I don't know about the older long case clocks.

Randy, You are describing exactly what happens. Since the gear with the tooth rotates counterclockwise, full engagement is when it is in the 6 o'clock position. Should I gently bend the tooth towards the center of the gear so it doesn't engage so deeply? Thanks for your help.

 

[Randy Beckett]

Randy, You are describing exactly what happens. Since the gear with the tooth rotates counterclockwise, full engagement is when it is in the 6 o'clock position. Should I gently bend the tooth towards the center of the gear so it doesn't engage so deeply? Thanks for your help.

I am hesitant to advise bending something without being able to see and study it. However, if this is the only way the engagement can be altered, you will likely need to. I would expect this to be a fine adjustment, with very little difference between 2 teeth advancing and no teeth advancing.

Just to be sure we understand each other. You did mean to say to bend the pin rather than the tooth didn't you? Or maybe I don't have the mechanism pictured properly.

 

[dAz57]

Generally the early longcase clocks don't have a spring on the date wheel, they do on the moon dials but not the date.

If the date wheel has 31 teeth like the one shown then there is a 24 hour wheel driven from the hour wheel to flip this over, more commonly the date wheels have 62 teeth and is advanced every 12 hours by pin on the hour wheel.

By your description the pin that flips the date wheel is too deep in the teeth, you will have bend it back so it only moves the date wheel one tooth at à time

 

[bdgtfb]

my 1780 longcase movement doesn't have a date wheel retainer but does on the moonroller as you stated. my question is what stops the date from advancing/reversing once the pin moves past the engagement position?

 

[dAz57]

date indicators are either a disc or a ring, there is enough friction that the disc will only move as far as the pin pushes it, with the ring version, it sits on 3 L shaped retainers on the back of the dial, some setups have a 24 hour wheel where the pin on that moves the ring once per day, others only have the pin on the hour wheel and moves the date disc 1/2 a day at a time.

so the answer is friction, moon dials are more free turning and do need a jumper spring fitted

 

[Tinker Dwight]

It also make it so one can easily correct the date
when the pin isn't engaged ( at the end of the month ).
Tinker Dwight