Why does putting a carriage on rails make it much easier to pull? As in, how were the first trams such an improvement from omnibuses when the same weight was still being pulled?

Question

Why does putting a carriage on rails make it much easier to pull? As in, how were the first trams such an improvement from omnibuses when the same weight was still being pulled?

In: 520

Answer 1

Bumps use up energy.

When you roll over a bump, you are lifting the entire carriage a tiny amount. That energy has to come from somewhere. You get some of it back on the other side of the bump but not much of it.

Air filled tyres are better than solid for the same reason. Going over a bump the tyre deforms a little but that loses a lot less energy than lifting the entire vehicle.