HLVH 2 speed motor doesnt like low speed anymore
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  1. #1
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    Default HLVH 2 speed motor doesnt like low speed anymore

    I have a beautifully restored 1989 HLVH restored lathe. Reground ways, repainted and each nut screw and washer went over and made like new. I dont use it every day so it may sit and just look pretty for a bit. But when I need it...I need it.
    So lately the low speed setting on the motor does not want to start. It seems like it tries to get the chuck spinning (a quality 6 jaw) but lacks the torque. I can push start it to get it spinning then it takes off. Or start up with the high speed then just swap to low speed and it runs. But from zero rpm it wont start on its own in low speed.
    Here may be a few clues.
    Its a 480v 3ph machine. I power it with 220v single phase at my house (not too many homes come with 480v 3ph) . Run through a step up transformer and dynamic phase converter. This system has worked great for many years. But alas lately the low speed has lost its ooomph.
    A dirty contact....bad low speed winding in the motor???
    The lathe sits in my garage in Southern California so its dry, and always pretty constant temperature..around 70. In summer sometimes 90F.
    Any help from hardiinge aficionados would be greatly appreciated.

  2. #2
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    I would start with the three voltage measurements from phase to phase at the input of the lathe control box with the motor off. They are probably not equal, but should be not terribly unbalanced. Then repeat that check with the motor running in high and then low and compare results One possibility is a bad capacitor in the phase converter. You should also check the overload relays and heaters in the lathe control box. You can measure the phase to phase voltage at the wires feeding the motor between the motor and the switching unit when running in high and low. You can also check the resistance phase to phase on the high and low motor windings.

    I have a Snyder commercial phase converter and a three phase transformer between the converter and the 440V lathe. The lathe runs, but I don't use it at all because the bed was worn when I got 32 years ago.

    Larry

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  4. #3
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    dynamic phase converter ? rotary or actually static? if static i.e. uses caps. not a motor. then you may have killed your expensive hardinge motor.

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    I would start with a close inspection of the contacts on the high/low drum switch.
    Burned / missing or worn down. Are possible causes.

    Bill

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    Quote Originally Posted by hitandmiss View Post
    I would start with a close inspection of the contacts on the high/low drum switch.
    Burned / missing or worn down. Are possible causes.

    Bill
    I have also seen where the cotter pin on the handle falls out. I may be way out there on this one, it's been 25+ years ago I worked on one. But I see to recall the Heaters need to be exchanged. On Hardinge's I think they were black and screwed to the drum switch switch inside the electrical cabinet..??

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    No its dynamic. Theres a motor sitting on top of the transformer acting to swap phases.

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    No its a dynamic phase converter. It almost does seem like a starter capacitor is failing on the low speed circuit. But then again the phase converter doesnt care about high speed low speed. It just feeds volts per amps


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