On most Sky wheels, the boom drive motors and the shaft speed reducers were mounted in line (or next to each other). The spring grid couplings are the shaft couplers between the two. These type of couplers act as a shock absorber to dissipate the initial thump of the motor starting up, reducing wear on the speed reducers and bull wheel cables as these do not utilize soft start controls.
There were 2 0r 3 Sky wheels built with the motors mounted underneath the speed reducers, and coupled with pulleys and V-belts. These in my opinion were a better setup because you could change the rpm's of the booms by using different sized pulleys, this puts the wheels in a slightly different phase in relation to the booms on each revolution giving a much more exciting ride than the other setup.
All Skywheels should be yeller.