A Chain Hoist
The chain hoist would have to have some kind of hook sticking out to hook the cars' hook-wires. See figures 1 and 2. The chain I selected after a long process of dealing with—and getting samples from—many different companies, was nearly 10' of Dupont Delrin 500 acetal resin chain (#70001 from Grandt Line Products, Inc.; I got several sprockets from them as well); it's 5/32"-wide, 1/16" tall, has eight links per inch, and links can be clipped into place without tools. The size was perfect to lay on top of N-scale track and yet not rub the underside of my coaster cars. I got a One Touch Selectable Gear Box through Edmund Scientific. It came with a 3-volt motor but a phone call revealed that I could go up to 6 volts, so I got a 6-volt DC, 250mA power adaptor, built the gearbox kit with motor, and calculated a decent hoist speed.
Let's see: a 7000 rpm motor does 117 rps and the gearbox had a selectable 119:1 speed reduction selection. So I could get the speed down to one rotation per second for the (20-tooth, .848"-diameter, .125" shaft size) sprocket that drove the chain. The circumference (3.1416 x .848) would therefore equal the inches per second the chain traveled up the hoist incline, or 2.66". This turned out to be about right. When I carefully twisted loops of Anchor black annealed #28 wire around the installed chain in several places (see figures 1 and 2) and tested the car-hook grabbing potentials, I found, after a few adjustments, that the cars would be picked up and hoisted to the top and let go, and would then travel down the coaster track. Note: obviously, the cars had to be released just after they reached the apex of the hoist track and were starting the decline—see our various photos.
In constructing the track, I made the last few feet have barely any decline so that the cars would slow down and hit the hoist ramp very gently so they wouldn't derail. The position had to be just right so that the cars' hook-loops would be grabbed by the hoist-chain hooks as they went by. Like every other part of this project, many adjustments had to be made—including redoing the lowest few feet of track—in order for things to work right.