James Waldby wrote:

Some other posts have said to just use a switch rather than switch +
relays; 20A 12V DPDT center-off switches are readily available, eg
http://www.parts-express.com/pe/show...number=060-376 or page
89 of http://www.delcity.net/delcity/docum...9_switches.pdf
if 20A is enough for the tarp motor. Of course if the limit switches
aren't heavy enough to switch the motor, you'd need relays anyway.

Those are A.C. rated at 20A. A switch rated properly is a different
animal altogether. Bigger and more expensive.
Can you tell me the part number for a DPDT center off switch capable of
handling locked rotor current, cheaply?

Using the relays allows one to use relatively light gauge wire to connect
the control panel to the motor and the limit switches, as you implied.

Note that in the dropbox/tarp.JPG diagram, the K3 and K4 coils are
shown backwards. Hooked up as shown, the internal diodes or the
wiring to them would burn up on first use.

Good catch! Thanks, James! Corrected version is posted.
http://metalworking.com/dropbox/tarp_a.JPG
http://metalworking.com/dropbox/tarp_a.txt


--Winston