The brakes on a riding lawn mower are almost in two categories. We often use the transmission as a brake to slow us down or allow us to slowly let us down a hill. The go pedal or the handle for our hydrostatic transmission does a lot of work to keep the lawn mower under control.
On the other hand, the brake pedal is to bring us to a stop quickly or to hold the lawn mower and keep it from rolling.
The riding lawn mower brake is often a small disc brake that is mounted on the transmission. When you depress the brake pedal, it pushes a small brake pad against the disc to stop the transmission from rotating.
This type of brake has a few problems if not property maintained. One problem is that they almost never get adjusted as the brake pad is wearing out. So you must push the pedal down further as the brake pad wears out.
Another problem is that grass clippings, mud and twigs can get thrown up in the brake and cause it to stop working.
Lastly, a fluid leak in the transmission can cause the brake pad to get wet and lose its friction ability on the brake disc and not allow the disc to stop rotating.
Check all these items out carefully and make the repairs necessary to resolve your riding lawn mowers brake problem.