|gerry madden||26/07/2021 17:31:57|
|201 forum posts|
Chaps, I haven't progressed far on my tower clock project because I keep thinking of doing things differently. My latest wobble is this. The design is an 8-day and it needs something like an eight foot weight drop for this. Not only does 8 days come around far too frequently for my liking, but finding a convenient 8 feet drop is challenging too.
One way of getting rid of the weight might be to drive the thing with a virtually stalled motor. The stall-torque could increased by a very high ratio gearbox, perhaps a fine worm and wheel or epicyclic.
Motors used as 'torque generators' are often used in automotive power-assisted steering systems so the idea is not new. But I haven't seen this in a clock before so just wondering, if it has, are there any good recommendations to be had on the best type of motor to use ? I think the internal heating could be easily controlled or limited with speed controller. ...or just a big resistor!
Any thoughts or comments would be appreciated on the practicalities of this idea ?
104 forum posts
Wildings tower clock book contains a description of electric winding for the clock. Not sure how easy it is to find a copy of the book these days?
6010 forum posts
So many options around the remontoire concept a stalled motor seems like a blatant eco-hostile fire risk system. I thought the electric steering systems were just using an electric hydraulic pump with the rest as per normal.
|John Haine||26/07/2021 19:04:27|
|4106 forum posts|
If you look on the Frodshams website they briefly describe the electric drive for Clock B. This has a motor driving a worm and wheel with the wheel on the axis of the hour hand. The weight of the motor exerts a torque on the arbor that drives the clock and there's a mercury tilt switch that detects when the motor has drooped a bit below the horizontal and drives the motor to lift it to just above.
|John Haine||26/07/2021 19:08:54|
|4106 forum posts|
Or use a stepper motor to drive the axis through a spring coupling, step the motor with pulses from the pendulum derived by an opto interruptor. Put a bit of preload on the spring, the stepper keeps it wound.
|Peter Cook 6||26/07/2021 20:33:44|
|156 forum posts|
Smiths of Derby do a patented auto wind system (AW10) for heritage tower clocks. The system is in effect a remontoire which winds the weights at frequent intervals reducing the drop needed, and eliminating the need to wind manually. There are details on their website which might give you some ideas.
There is also a good paper by Mark Frank on tower clocks (speech_final_web.pdf (my-time-machines.net) which discusses various remontoire systems for tower clocks - from page 23.
Edited By Peter Cook 6 on 26/07/2021 21:03:34
|vic newey||26/07/2021 20:39:25|
97 forum posts
Are you sure you need an 8ft drop? you don't leave an 8 day clock for 8 days before you wind it, the weight would reach the bottom and stop the clock on the 8th day so you wind it every 7 days.
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