Old woodies and flywheels question

For those of you who may not know, old wooden coasters had chain lifts that used enormous belt-driven flywheels (some of them 12' to 14' in diameter) as part of the chain's motor.  At some point, the flywheels disappeared and more compact motors were used on new woodie installations.  I'm not sure what how the flywheels contributed to the whole chain lift system (actually, I'm not familiar with the inner workings of chain lifts and their motors to begin with), I guess that is a whole separate issue...

What I would like to know is, when did this "change" come about?  I know that the Phoenix and Lincoln Park Comet, both built in the mid-to-late 1940s, have flywheels, but I'm not sure if the last PTC coasters (Racer, Screamin' Eagle) or Bill Cobb's earliest creations have them or not.

I don't know when the change came about, but I do know what the flywheels were for...

The flywheel is connected to a belt, which is connected to a drive pulley on the drive motor. The center shaft of the flywheel is connected to the chain drive sprocket.

The electric drive motor runs at about 3,400 RPM, and probably has about a 6" pulley shaft on it. The flywheel is, say, 12' in diameter. That means the belt speed, based on the 6" pulley, would be 89 ft/sec. That would rotate the flywheel at about 141 RPM. Connect that to a 18" chain wheel, and you have a chain wheel running at 141 RPM, which works out to about 11 ft/sec, which is not at all unreasonable for a coaster lift chain. The belt had the added advantage that it could provide an effective clutch if anything else in the mechanism jammed up.

These days, it's easier to just use a 25:1 or so reducing gearbox and a torque converter (fluid clutch) to do the same thing.

--Dave Althoff, Jr.