OT (Kinda) - Motor Capacitor

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Model T Ford Forum: Forum 2012: OT (Kinda) - Motor Capacitor
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Friday, December 28, 2012 - 10:01 am:

I was working on making more spoke blanks for the T and my jointer has stopped working. I think the issue is the motor capacitor is shot. How does a person size a new capacitor for a motor? The motor humms when I turn it on, but does not turn over. I pulled the motor last night and checked the wire connections, the ground was a loose. I tightened it up. On the bench it would start up every time. I re-installed it, and it will not start.

I did not write down the motor spec’s, but it is a ¾ Hp motor, I think it is a 1750 rpm, wired for 110V. I will have to pull the motor to get to the motor’s data plate.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Cascisa - Poulsbo, Washington on Friday, December 28, 2012 - 10:08 am:

Jason,

The capacitor will be marked with its voltage and capacitance value - something like 22 MFD, 240 VAC.

A more common problem is dirty switch contacts on the centrifugal switch mounted in one of the motor endbells. Try cleaning these contacts before you buy any parts.

Be_Zero_Be in Leesburg, VA


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska, Denver CO on Friday, December 28, 2012 - 10:13 am:

Also check to be sure that the springs are not broken on the centrifugal switch.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Shirley on Friday, December 28, 2012 - 11:28 am:

I've been told that smoke is put into electric motors at the factory. If you let the smoke out they will no longer run, so don't let it humm for long. PS make sure the jointer turns free,not a bad bearing or something binding the cutter head.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Friday, December 28, 2012 - 11:37 am:

It runs on the bench because it has no load. The capacitor allows it to pick up speed as it starts. As Bob Cascisa says above, clean the switch make sure you hear the click of the springs as the drive engages, and then check the capacitor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, December 28, 2012 - 02:12 pm:

Bob - You can get new smoke at any Lucas parts distributor but it ain't cheap. And on top of that, you'll need the special new-smoke injector tool with pump.

Lucas Replacement Smoke.jpg


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Anderson, central Wisconsin on Friday, December 28, 2012 - 10:31 pm:

In a single phase motor the capacitor(s) offsets the voltage wave to induce repulsion for starting.
I'm assuming your motor is not capacitor run so the starting capacitor is probably in the area of 300mfd.


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