Tag axle for truck camper rigs

EYEMLOST wrote:
PLEASE CORRECT ME IF I'M WRONG;

If tag/trailer axle's wheels/tires spin independently, wouldn't that eliminate tire scrubbing?


My HMMWV trailer is that way; with torsion bars for suspension.

No, each tire moving independently reduces or eliminates scrubbing for single axle setups, where the inside tire needs to cover a shorter distance in a turn than the outer tire. That still applies to each axle independently here, but you introduce another pivot point that essentially requires the tag axle to drag sideways in order track with the drive axle. Since tires don't roll sideways (they aren't spheres, though that would be interesting), you end up with scrub.

Next time you see a tandem axle fifth wheel making a sharp turn, watch the rear axle. It's extremely obvious in that setup. Note that each wheel has its own hub assembly and the rotation happens there, so each tire can move at a different speed than its partner.

You don't need torsion axles, by the way, to have each wheel turn at independent speeds. Just about every setup does that - and that's also why they have open diffs in most cars.