On some highwheel or hard tire safety bike pedals there are usually keyed type washers on the outer bearing adjusters with a simple flat formed into the hole diameter that matches the milled flat on the pedal axle. This washer is designed to keep the bearing adjuster from turning while the nut is being tightened up. If your pedals are missing these washers they are easily made. Just use a regular washer and gas weld part of the washer i.d. You can use a Dremel tool and small files to bring it to shape.