Johnston ES351 Mechanical Sweeper. "SIMPLE SOLUTION * BIG ADVANTAGE". The Johnston ES351 Mechanical Sweeper is the newest model from the world's largest manufacturer of street sweepers. It underscores Johnston's entry into the competitive 4-wheel chassis mounted sweeper class. Johnston's "Easy Sweep" Mechanical sweeper is matched with Freightliner's M2 chassis and together; they offer both superior performance and a level of comfort and drivability that any operator will appreciate.