I need to be able to pull a blow molding clamp out of the machine onto a temporary frame for maintenance. The clamp weighs 20,000 lb but the starting force to get it moving is only 365 lb, so can I use a 1500 lb winch to pull the clamp out onto the roll-out frame? The clamp is sitting on 8 V-Grooved wheels and running on rails.
If your 365 lb force figure is right, then yes this will work. Make sure you are including force to accelerate as well as force to overcome rolling resistance and gravity if the rails aren't perfectly level. Also make sure you have a mechanism in pace to slow and stop the clamp - it's no good to get it moving if it keeps on moving and hurts someone.
F= m.a, it all depends on what acceleration you pull it with. So 20k/1500= 13.33 ft/s^2 roughly 40% of gravity acceleration. Use 60% of that as a conservative number. You could pull hypothetically unlimited load with any winch no matter how small the strength as long as the load is not locked in place, as dislodgement force could be very high, and your winch has spring loaded bracket properly adjusted to break the start jerking. Pulling is different than lifting! You deal more with friction than weight.
As an example NASA's 450 ton space station can be dragged to different orbit( called a boost) or to correct position for docking with the Shuttle by tiny rockets with a thrust of something in the order of hundreds of lb. force.