How Do I Convert DC Motor To Reverse With SPDT Switch?

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John Swift:
Hi Joe ,

how much smaller do you need it ? it just fits my screen

John

attached picture at 70% of original size

edit
PS -- settings for my scanner my needs adjusting , had to install the software to scan the image

reinstalled windows a few days ago ,, expect it to take a few more days to get thing back to normal

Chuck in E. TN:
Try right clicking the picture and choose open in a new window. Works for me.

Chuck in E. TN

snub:
Thanks to all for your help.
The original switch is momentary contact. There were no limit switches in the original setup, so if one motor was working faster than the other it would still be trying to rotate while waiting for the other one. And this is what chewed up the drive gears.
There was a switch to let you know when the buckets were fully open. It was connected to a light on the dashboard that blinked until they were open.

Since I will only be using one motor ,and based on what worked before, do you think that I would need to use limit switches?

DMIOM:
hi,

If you do use limit switches and can get two normally-closed ones, and they are of sufficient rating to carry the motor current, you can arrange them as in this sketch, with bypass diodes. When you motor up to the stop the limit switch interrupts the current BUT the diode will allow the reversed polarity to motor you the other way back away from the stop

Dave

John Swift:
Hi snub ,

with motors that powerfull , I'd fit limit switches ( one at each end of travel)

or if that's not easy, try adding a wirewound resistor in series with the motor to limit the torque

as a starting point, measure the motor current before you hit the end stops
and divide 3 by your answer to get a resistor value that drops 3 volts

with the engine running the motor now runs on about 10.5V
both the torque and stall current will now be reduced

to find the maximum current with the motor stalled
divide 13.5 v by the sum of the motor resistance and your added resistor
the wattage rating for your resistor is given by I squared R ( I = stall current, R = added current limiter resistance)

John

PS could you use a mechanical torque limiter as used in battery operated drills and screw drivers ?

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