On 4 wheeled vehicles the front wheels need to incorporate a self adjusting mechanism to take up brake pad wear. This usually isn’t a problem as this is built into piston operated brake callipers.

 

On 3 wheeled vehicles the front wheel(s) must have either an automatic or manual means of adjustment to compensate for brake pad wear.

 

The rear axle on either 3 or 4 wheeled vehicles must incorporate either an automatic or manual means of adjustment to compensate for brake pad/shoe wear.