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ELSR question again

jwatts

Hot Rolled
Joined
Apr 19, 2006
Location
Missouri, USA
I had some trouble a few weeks ago with the spindle not starting with the ELSR lever on my 43 round dial. I was told to check the microswitches in the housing on the headstock, and both of them tested fine. After putting everything back together I realised that the lever on top of the housing had been in neutral the whole time, and moving it to right or left fixed the problem (I felt more than a little stupid). I went back to it this past weekend, and once again, no go, this time I know the lever was not in neutral. My first thought is that it is likely either the microswitches (although they tested fine a few weeks ago) or the contactors in the DC panel. My real question is what might cause both forward and reverse to go out at the same time? It just doesn't make much sense to me for either both of the microswitches or both the contactors to go out at the same time. I won't be able to look at it again until this weekend, but any suggestions would be greatly appreciated.
 
Check the output from the exciter. I had intermittent problems with the controls not working till I found one of the brushes in the exciter was worn down too far and only contacting part of the time.
 
The elsr controls on the round dial have an interesting design, with typical Monarch over-engineered mechanical interlocks and switching designed to prevent someone from inadvertantly turning on the spindle when the lock is supposed to be engaged.

I'd suggest disassembling the ELSR and making sure that everything is working as it is supposed to. Maybe its just a matter of understanding how it works and making sure it is lubricated.

there is a large babbit spiral gear at the tailstock, which wears over time and may need recasting eventually. The spiral causes the ELSR rod to move in a forward direction (towards the headstock) when the lever is thrown. The forward direction engages the mechanical interlocks. There is also a button that sticks out on the bottom left front of the ELSR casting. If it is pushed in, it locks the ELSR rod in the off position, and prevents someone from engaging the spindle by accidentally pushing a lever.

-Dave
 
With only square dial experience on ELSR, there are 3 micro switches, 1 fwd, 1 rev and 1 drive, the wiring is in series, such that the drive switch and a direction switch must both be closed to connect the relays in circuit, and energize the motor. No drive switch closing, no fwd or rev.
 
The three separate microswitches in the ELSR unit take the place, logically, of the drum switch in the headstock.

As such:

1) one is N.C., and it remains so, unless the shaft is other than center position; in other than center position, the contacts open and the M-G START or CONTROL START switch, with which it is in series connection, is inhibited, while

2) two are N.O., and remain so, unless the shaft in an extreme position; in an extreme position, FWD is selected, or REV is selected; these selections are only effective if the M-G/CONTROL is already STARTed.

The wiring diagram for the square dial machines make no special distinction as to non-ELSR or ELSR, excepting to show a drum switch for non-ELSR and three separate switches for ELSE.
 
Thanks for the info guys, that gives me some things to look for when I get at the lathe this weekend. The ELSR mechanism seems to be working properly, meaning that it moves axially as it should when I select forward or reverse. I'm far from sure, but I think there are only two microswitches on the round dial. At least there were only two in the housing on the front of the headstock.
 
Macona, thanks so much. A few taps on the exciter housing with a plastic mallet and all is right again. The brushes and commutator both look to be in good condition. I think the 65 year old springs have just lost a little of their springiness. Thanks again.
 








 
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