Multistage Screw

I am looking for a multistage screw to extend to about 16ft. Each section should be no more than 4ft. The supporting load is only 500lbs. I am looking to replace a telescoping pully type mast. Joycedayton does not make anything like this. Does anyone know of any other manufacturer? A worm gear system for the drive is what I had in mind. I am open to suggestions for alternate mast systems than fit the same profile requirements. Joycedayton refered me to a chain drive system that can push as well as pull....Thx