Educate me! How do gramophones regulate speed?

[shawnxu]

Hi everyone,

I recently got into mechanical watches and the concept of how time is measured which I understand is through the concept of an escapement and a balance wheel which keeps the energy from the main spring from unwinding out of control.

That got me thinking about the mechanics pertaining to gramophones. I have a HMV 101 myself but never really gave much of a thought to how it all works.

It seems like it works on a similar concept as a mechanical watch? There is a mainspring which is wound and the energy from it spins the turntable. I'm just curious to understand how exactly, in the context of gramophones, is the energy from the mainspring regulated to spin the turnable precisely to 78 revolutions per minute.

I've tried to do some google searches. From what I gather, correct me if I'm wrong, the 'governor' is responsible for this task?

Hopefully someone here will be able to educate me on this. I find all this really interesting and would love to understand more.

Next on the list is to understand how 78 records store sound haha but I'll leave that for another day.

Thank you so much in advance!

Cheers,
Shawn

[OrthoFan]

You're correct, it is the governor which "governs" the speed of the turntable.

On a spring-motor gramophone/phonograph, the turntable speed is controlled by the spinning governor, which interfaces--via a worm gear--with a gear on the turntable's spindle. As you adjust the speed knob, the leather (lubricated) friction foot, touching the governor's spinning disc attached to the weighted flat springs, moves the disc in or out causing the governor to spin faster or slower. This video shows how it works, and how to repair it:

(Double-click the video above or click this link to go to the video on YouTube.)

OrthoFan

[shawnxu]

You're correct, it is the governor which "governs" the speed of the turntable.

On a spring-motor gramophone/phonograph, the turntable speed is controlled by the spinning governor, which interfaces--via a worm gear--with a gear on the turntable's spindle. As you adjust the speed knob, the leather (lubricated) friction foot, touching the governor's spinning disc attached to the weighted flat springs, moves the disc in or out causing the governor to spin faster or slower. This video shows how it works, and how to repair it:

(Double-click the video above or click this link to go to the video on YouTube.)

OrthoFan

Ah... that's cool! Thanks so much for the link!:)

Best Regards,
Shawn

[Marco Gilardetti]

The name of the machine is Pickering Governor. It is very similar in principle to the Watt Governor, which is more often studied at high school, but while the Watt Governor uses gravity force to counteract the centrifuge force of the revolving masses, the Pickering Governor uses the elastic force of springs to which the revolving masses are connected. It thus doesn't need to be necessarily assembled in vertical position, and basically works in whatever orientation.