The lifting mechanism must resist the horizontal forces and have very little deflection when the load is at either end. the rail is very strong and has very very little deflection when supported from the center. There are no side forces.
We have a 10' long linear rail (~100lbs) which will have a 250lb load translating from one end to the other. The lifting device needs to cover a range of 1'6" to 3'6" and remain stable with the load at either end of the rail. Our first choice for operation would be manual (a crank, etc.), second...