From: NONONOmisc07@fmguy.com   
      
   In sci.electronics.repair, on Mon, 3 Feb 2025 17:45:03 +0000,   
   liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote:   
      
   >N_Cook  wrote:   
   >   
   >> Only made a preliminary check o this 1KW pump and float switch in a   
   >> sump, prior to dismantling ad exploring further.   
   >> Sump full of water but no pump action. Moving the float about made no   
   >> differece. Tapping the pump casing made the pump work until the float   
   >> switch dropped to the cut off point.   
   >> Refilling the sump and again no pump action until tapping the casing and   
   >> again stopping properly. I cannot see what in the way of sticky motor   
   >> brush or loose/corroded contact inside the motor housing could produce   
   >> this symptom.   
   >   
   >You haven't said what sort of motor it is, but if it is a commutator   
   >motor with brushgear, the fault could be worn-down brushes to the point   
   >where one of them is almost-but-not-quite touching the commutator.   
   >Tapping the motor gives some sort of contact and then the vibration of   
      
   If it's a motor with brushes:   
   I had a convertible, a car, and the motor to put the top up or down   
   often would not start.  I had to open the trunk and whack it with lug   
   wrench to get it going and once going it was always enough for 1/2   
   cycle, up or down, but often didn't work for the next half-cycle. The   
   longer this went on, the harder and the more times I had to hit the   
   motor.   
      
   I decided it must be the brushes and the real hardware store I went to   
   had a cabinet with several drawers and 20 or 30 sizes of brush. Somehow   
   I knew the x-section and I bought 2 brushes.   
      
   When I got the motor out and apart, I had the right size brush, but the   
   woven copper leads in the ones I'd bought were half or less of the   
   x-section of what had been in there. I didn't think the new brush leads   
   could take the current, because the frame for a full size convertible,   
   or even a compact, is heavy, and the mechanical advantage isn't too good   
   either for part of the travel, so the motor uses a lot of current.  But   
   the motor was out, I couldn't put the top up or down, and it was   
   summertime.   
      
   So I got some tinfoil, which is USA talk for aluminum foil, from a roll   
   used for cooking, wadded it up and stuffed it under the original   
   brushes, without interfering with the springs that were already there,   
   and my motor was good as new for years to come, until the rest of the   
   car wore out.   They still had plenty of length before they would be   
   gone altogether, they just needed to be pushed against the armature, and   
   the tinfoil took up about a half-inch.   It took only one or two square   
   inches for each, iirc.    Except that I probably didn't return the   
   brushes I'd bought, the whole repair cost 2 or 3 cents.   
      
   Better than 800 pounds!   
      
      
   >the motor allows it to touch the commutator often enough to keep it   
   >running.  This will give a fireworks display around the commutator and   
   >will do considerable damage if it continues.   
   >   
   >If it is not a brush motor, a similar thing can happen if the terminals   
   >have become loose.  The sudden shock torque as the motor starts is   
   >enough to make contact and vibration will keep it running; then the   
   >contact is lost again after the motor has stopped.   
   >   
   >The first things you need to check are what type of motor it is and   
   >whether the supply is reaching the terminals in the connection box on   
   >the motor casing.   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)