From: liz@poppyrecords.invalid.invalid   
      
   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   
   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.   
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)