At 10:38 AM -0800 12/2/97, \"Dick Green\". wrote:
>That's an interesting idea that should work in theory. I haven't dissected
>the motor/limit switch circuitry in the tower relay box yet, so I don't know
>exactly how it works. I suppose the limit switches are normally open and
>feed 110VAC to cutoff relays when actuated. OTOH, they could be normally
>closed and the motor supply runs through them until they are actuated (but
>it's hard to believe that they would send the high-current motor supply up
>the tower and through the limit switches.) Ever since I decided to get this
>tower, I've been wondering what would happen if one of the limit switches
>failed. Does anybody know?
My US Tower HDX-72MDPL came with factory-installed limit switches, but
without the remote control. In my two-year-old tower, the limit switches
are located at either end of the cable drum, not on the vertical tower
sections. The switches are NC with the motor current running through them.
As the drum turns, a worm driven cam moves slowly across the face of the
drum guiding the metal cable as it lays down across the drum. As this cam
approaches either end of the drum, it trips one of the limit switches,
breaking the motor circuit.
The wire between the motor and all the various switches is standard 3-wire
14 guage stranded. I can scan a photo of this arrangement if it would help.
Dick Flanagan W6OLD CFII Minden, Nevada DM09 (South of Reno)
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