I am building a 20X20 ft. steel building that has a roll-off roof, to be used as an astronomical observatory. The roof, when finished, will weight approx 1800 lbs and will be moved by an electric motor and gear reducer via single link roller chain onto an external support structure.

At present, the "trolley" on which the upper portion of the roof will be built is now completed and can be moved by hand. This structure includes the 20x20 ft. square frame supported by six vee grove rollers and weighs approx 600 lbs.

I attached an automotive type torque wrench to one end of the "trolley" and have found that it now takes 50 lbs pressure to initiate movement and roughly 35 pounds pressure to continue that movement. However, to test the effect of additional weight, I added 400 lb and again observed the torque requirement. Now it takes 80 lb pressure to start movement and 50 lbs to sustain.

These are the known pieces of information. My question is about the drive system required to move the completed roof structure.

I have 70 amp, 220 VAC, single phase, available to the building and am considering using a 1 hp, dual capacitor motor with a gear reducer producing circa 25 rpm output and driving a 3.5 inch sprocket to #50 chain.

Question is, am I headed in the right direction with the drive component selection or should I consider other options?

I am obviously not an engineer but certainly like to build. Any input provided will be more than appreciated and likely save me from going down an expensive "trial and error" pathway.

Many thanks, in advance.

Flinthill ■