Thor Forums

[Beacher]

Originally Posted by Chance

With dollies that have surge brakes (or electric for that matter), it would seem that maximum stopping power would be limited by weight from toad's front wheels only; hence the maximum toad's braking contribution would be roughly from 50% to 65%. ..

No. Not quite.

The net effect of the toad load to the coach occurs at the hitch ball.

The hitch ball does not know or care how many wheels behind it have braking force or stopping power. Only the dolly knows! The hitch ball certainly does not only give 50% to 66% credit for stopping the toad due to only two wheels with brakes. The dolly applies a 100% braking contribution for the toad's rolling mass using it's two wheels. As far as the hitch ball is concerned, it doesn't know if there is a dolly or 4-down toad connected, as long as it stops properly.

In order for a tow dolly's two wheels to stop the weight of the toad, (regardless of it's size), it has to apply enough braking force. With hydraulic surge brakes, if you load a small vehicle on the dolly, it applies a small braking force, and with a large vehicle it applies sufficiently more, all automatically. Electric brakes require an electronic brake controller which can be preset to anticipate the mass of the toad, based on inertia.

If you have ever made an emergency stop while pulling a properly configured tow dolly, TT, 5er, or boat you know that the stopping distance is just as good as the coach by itself, (if not better, due to the rolling resistance helping to slow down, like an anchor or drag chute).