How do I check if my brake system is working properly?

If the tractor requires more than five (5) feet to stop at highest speed in highest gear on a level, dry concrete or paved surface, then the brake must be checked and adjusted. Park on level concrete, depress the clutch/brake pedal, engage the parking brake, disengage the transmission with the freewheel control, and try to manually push the tractor forward. The rear wheels must lock and skid; if they rotate, the brake needs adjustment or pad replacement. (Page 25)