Bad Ideas explained: http://www.furaffinity.net/journal/321008/ Includes index.

Ponyplay with power steering and power brakes.
-or-
The reins go to THOSE bits.

Picture a team of two "ponies' (who do not need to be equine at all. And maybe even shouldn't be equine, since this is ponyplay). They face roughly away from you, so you see their backsides. They are harnessed and bound to the traces of the wagon/carriage/what-have-you. They are, aside from the harnesses, nude. They do not have the usual bits, but are ball-gagged instead.

The driver, female of course, can urge her team on with the whip if need be. Or if she just feels like it. But how to steer and brake? There are reins. One rein per "pony" - and each rein ends up around his scrotum (this method requires 'stallions'). Pull on a rein and that pony WILL get the hint to slow down... and thus there is a turn in that direction. Pull on both and both slow or stop.

Odd how the route seems to have so many stop signs...