Hey,
Jax Rhapsody I first I thought that that is not right, but then I thought back to one of the bike shops that I worked in had a number of trikes in for repairs and I had to put them outside each day we opened up and put them away each day when we closed shop. I got to ride a lot of these trikes.
I think you are right. Almost all of the non-Schwinn trikes were one wheel drive. And when you pedal them they don't go straight. The old Schwinn Town and Country had a differential. For me that meant that I could not ride it tipped up on two wheels like the other trikes. Whichever wheel left the ground, that is the wheel that the differential sent the power to, and that wheel would spin. I remember thinking that even though I didn't like the one wheel drive idea, that Schwinn, that seem to have spent far more money on their version of the trike, had essentially no-wheel drive. Why would they do that?
Perhaps it was to get the trike to track straight when your pedaled.
This makes sense now. If the wheel is pushing your trike forward and it is 16 inches from the center line of the bike, the bike is going to want to turn. If we turned it around and pretend to put a brake on only one rear wheel, the bike will again pull to the side with the brake when we slow down with the brake.
If we were to make a trike with a solid rear axle, we would not have this problem when going straight, but we would have problems when turning because our inside wheel will want to turn less than our outside wheel.
Wow, the design trade-offs of a trike rear axle.