That is positively the 2nd worst wiring diagram I've seen ( I'm in the
middle of an ancient DC motor control by Reliance.....)

I'd hazard a guess that the forward motor relay is KM2 and that is the
one that is sticking closed. Wait for the problem to occur, give KM2 a
smart rap with the fat end of a rubber grip screwdriver. The other
thought is that the main switch assembly is dirty, has a contact that is
hanging up. Cleaning with contact cleaner would be a good start.

Fred wrote:
Fred wrote:
Clausing 12x37 clone will not run backwards

Today, my 1994 Clausing 12x37 clone metal lathe has stopped turning
off with the lever switch on the apron. I can switch from forward to
neutral to reverse and hear relays at the front lever switch work each
time, but it keeps running forward. If I want to stop it I have to
hit the emergency button. This is at least aggravating. But, I can
get stuff done as long as I don't need it to run backwards.

My problem right now is I'm all set up to run backwards for a
threading operation that I'm uncomfortable running forward. The lathe
will only go forward and starts right up with the apron lever in the
neutral position when the start button is pressed. It still will not
start in the forward and reverse apron lever position, as it's not
supposed to. But if it's in the apron neutral position it will start
running forward when the start button is pushed. Cycling the power
off and back on does not effect this behavior.

It has happened before and not really been a problem. And, maybe I
can let the thing cool down and get these threads cut later tonight or
tomorrow. But, I need to eventually fix the problem.

There are several multi wire relays in the panel box on the back and I
suspect one of them is the problem, or the switch in the front
controlled by the apron lever. Its a pretty complicated bunch of wiring.

Please help, I do not know how to diagnose this?

Thanks,

Fred

The lathe worked fine yesterday morning and I was able to cut my
threads. After it got warm, it again would only run in forward.


After the machine has run awhile it cannon be cut off with the apron
lever switch will only run in forward (even in the neutral or reverse
apron switch position). I can push the button on the reverse relay and
get the motor running in reverse. I know this is not the preferred
method.

I found electrical schematics drawings that look like my lathe's wiring
and I have an voltage meter. How to I diagnose exactly what is going
wrong here?

I think I understand the switches, transformer and relays. And, how to
change the lathe to 220v. I do not understand what the "Heating Relay"
does.

I have posted a photograph of the electrical panel box and the schematic
drawing on my website.

http://ornamentalroseengine.com/download/lathe1.jpg
http://ornamentalroseengine.com/download/lathewire1.png

Thanks for any help.

Fred