I am building a lift using 4 threaded spindles and sprockets to travel 12 feet. The motor needs to have 56 mount as it will be mounted vertically (Shaft down) attached to a sprocket that drives a chain to the 4 supporting sprockets. The load (1,000 lbs, 250 lbs at each corner) will be lifted by rotating 4 sprockets each turning at about 1800 RPM, traveling up a (2 inch) threaded shaft at 4.5 turns per inch for about 144 inches between 10-20 seconds. I believe (based on my novice calculations) I will need: (4.5 turns = 1 inch, need 650 turns for 144 in, 650/20 seconds = approximately 1900 RPM.) I think I will end up with a 3-phase motor as I will need to have an inverter to control the start and stop speed. My crude guess (I am a software guy, so I don't really know about Mechanical Engineering) is that I will need 1.5 HP based on life experience. Is there anyone who can help me find the answer to: How much torque (and HP motor) I need to turn four (4) 4.5 inch (outer diameter - 2 inch threaded inside) sprockets each lifting 250 lbs at about 1800-1900 RPM? Thank you very much for your input.