Cam Gear Removal

[Chuck Woolsey]

:frown:Hello everyone,
I am working on a Hermle rack and snail movement for a Grandfather clock. The clock is a Howard Miller and they have marked the movement with their own numbering system. My question deals with removing the cam gear for activating the chime train, in the past I have been able to place an old hand nut on the threaded section of the center shaft and gently taping the nut to drive the cam gear off the shaft. However with this movement the center shaft is nearly 44mm in length and I fear damaging the shaft. I know there is a better method for removing this gear, will someone instruct me on his or her method to help out a rather new repairperson?
Thank you in advance.

Chuck Woolsey
NAWCC#155704

[Chuck Woolsey]

:frown:Hello everyone,
I am working on a Hermle rack and snail movement for a Grandfather clock. The clock is a Howard Miller and they have marked the movement with their own numbering system. My question deals with removing the cam gear for activating the chime train, in the past I have been able to place an old hand nut on the threaded section of the center shaft and gently taping the nut to drive the cam gear off the shaft. However with this movement the center shaft is nearly 44mm in length and I fear damaging the shaft. I know there is a better method for removing this gear, will someone instruct me on his or her method to help out a rather new repairperson?
Thank you in advance.

Chuck Woolsey
NAWCC#155704

[LaBounty]

Hi Chuck-

The cannon pinion/chime release cam is rather tightly affixed to the center shaft and isn't something that is usually removed. There are several risks in removing it; damage to the threads on the center shaft, which you've already realized; the shaft could become crumpled, since it is so soft; or the cannon pinion may become too loose to tighten up when re-seated.

However, assuming you have an extreme situation in which you must remove it, you might try using two screwdrivers of the same size, wedge them on either side of the center shaft under the cannon pinion. Twist the screwdrivers in opposite directions paying particular attention to the evenness of the force you are applying to the cam. You will be using the plate to pry against, of course, and should realize you may leave marks on the plate and cam which will have to be cleaned up. If you use progressively larger screwdrivers you should be able to get it far enough up the center shaft for it to become loose. And if not loose, then at least not so tight that you risk damaging the shaft getting it off with your usual method.

Good luck with it! But I have to reiterate that normally the risk in removing the cannon pinion on Hermele movements is too great to warrant the effort.

David.

[Chuck Woolsey]

:biggrin:David,
Thank you so much for the prompt reply, I have learned a valuable lesson when it comes to Hermle movements. Thankfully I had not attempted to remove the chime release cam before asking wiser minds (no damage done). One last question, should I leave the gathering pallet plate affixed as well or can it be removed?
Thanks again for the help.

Chuck Woolsey
NAWCC#155704

[gre406]

Chuck.. The gathering pallet bearing point is unfortunately a common place of wear in many clocks and has to be removed to install a bushing. There are many types and sizes of "hand pullers" that do this easily. Just be sure to use the right size and be careful not to bend the shaft.

http://userweb.nni.com/gre406/handpullers.jpg

Geo
NAWCC#78594

[LaBounty]

Hey Chuck-

Geo is absolutely right. The gathering pallet must come off to do pivot polish and bushing. The gear puller I prefer is kind of expensive, comes in two sizes, and is available from Timesavers (http://timesavers.com/). They are parts #19958 and #20780. Great tool!

David.

[Chuck Woolsey]

:biggrin: Thanks Geo,
I just wanted to be sure before I continued on with the repairs.
Yours and David’s advice are greatly appreciated.
Regards,

Chuck Woolsey
NAWCC#155704

[lpbp]

Many Repairmen don't work on Hermle movements, they replace with new ones, which are better quality, and cheaper than working on them. Exact matches are available from many parts houses.

Larry Pearson, FNAWCC #35863 L138
candidate for Director