[Levansic]

Good find!

Inertia comes into play when something experiences acceleration or a change in velocity. Usually the effects of inertia are noticed when starting or stopping movement. In the initial post, there is inertia of the original 1,000 lb. mass, and a rotational inertia of the screw and the motor. Reflection implies bouncing off of something, which has little to do with inertia.

With a linear rate of 6" per second vertical, the inertia is no match for the force of gravity, if the actuator was required to start or stop. Elasticity in the system will play a much greater role, and here is where inertia will have an effect.

Assuming no friction between the worm and the rack, the shaft needs a torque of approximately 510 oz.-in. to oppose gravity and only a little more at 60 rpm to lift the load. There are a few 2012 KoP motors/gearboxes that theoretically can supply this torque at those speeds. In the real world, there is friction, and elastic deformation of all components, which both increase the torque required. All of the real world drags likely dwarf the inertia of the motors, in this application.

-- Len