Help problem with power to clutches on Russian Lathe

[tim-tbl]

Help!

I have a a 1975 stanco lathe with electrically operated drive clutches.
The clutches are desined to receive a 12 volt supply to operate the coil, however they are only receiving 8 volts so do not have the power to operate properly. Ive checked the transformer voltages and they all appear to be fine, but I am really at a complete loss as to where the 4 volts have gone, if anybody could point me in the right direction I would appreciate it.

Thanks Tim

[fkaCarel]

To put it cynically: Russian machines were'nt produced to function, they were made to fullfill quota. So be reasonable, if it ever worked, it's a plus. So start with putting 12V at the clutch and see if it works. Then trace the line of switches, relays and wires and if possible, replace with European parts. Take a cynical approach and mumble: "eta govno". (Russian for: It's s**t).

Carel

[MotorFly]

Bad contacts or something like that...

[Stevenpats]

Check across the coil, and from each lead to ground. You should have a reading of 20 ohms or something like that, could be more or less. If you have continuity to ground from either lead the coil is probably bad. Some are potted in a gear or some type of actuator . I worked on a boring machine with clutch problems(I am electrician) but turned out it was stuck in one direction, no electrical problem. Look for a capacitor, sometimes they are wired at the controls or at the coil to help smooth out and bring up the volts a bit.
s

[tim-tbl]

Russian bits don't look like Euoropean bits(female russian shotputters), there are 2 capicitors on the board but I am not sure how to check them, as for the coils they are all showing a continuity of about 20 ohms, but that problem may affect one of the coils but not all four, but you are right they are a nightmare cos everything is in Russian and I don't speak it or read it, strangely I also have a Poreba lathe(polish) and that never goes wrong, the contacts are alright because the joy stick is only reading 8 volts aswell.

[fkaCarel]

Did you check the transformer output with the coil switched off, and after that the coil voltage in the switched on state? That could be an explanation. If the Polish and Russian lathe are comparable (also communistic: one design for all, or better a half design) than there is also the possibility that electrically everything is OK, but that the clutch is worn to the point, that it is too far away from the coil. The airgap must be minimal. It is possible that the coil could'nt stand 100% use, so they lowered the voltage to fix that.

Carel

[tim-tbl]

No I havent checked the transformer under load, I will do that in the morning, Ill let you know what happens.
Cheers Tim

[Al_The_Man]

I have worked on Stanco's and was not really impressed with the electrics, The function switches resembled something that was used in the west in the '40's.
If they are the same as the clutches used on the the mills, there is some brushes that operate on slip rings to the clutches and they eventually wear down and cause problems (high resistance).
If you have 12v at the source and only 8 volts on the clutch then this may be the problem.
Al.

[tim-tbl]

The machine is horrible, but I inherited it and have had to make it work, I had the clutches rewound and the pressure plates replaced a couple of months ago, on all four clutches, The power is coming out of main board at 8 volts, but there are bits on the board that I don't know what they are, because I have never seen them before on any other sort of machine, The transformer has 3 outputs from 415v-240volts(control)
110v(don't know) 40volts(fast travis motor I think) but no 12volt and although there maybe another transformer in the control panel somewhere, but I don't know.