If you have a sensor on your lift, you don't really need to use as much air for the light lift - when enough air pressure is in the piston to lift the load to the desired point (or when it's moving at the desired speed), just shut it off. When lifting one tote it might be 13psi and for six it might be 60psi. Much simpler physically and programmatically. You will need to use a 3-position "closed center" valve. They are available
here, among other places.
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