This is a replacement part for the parking brake cam gear fitted to several model zero-turn lawn mowers. This will replace part number 70392, which is the right hand side. My part will replace either the left or right side gear - just flip it over.

There is a safety switch on these mowers that will shut the engine off if the mower is moved out of neutral with the parking gear engaged. If that safety switch malfunctions, or if it's overridden, then the teeth can be sheered off as seen in the photos. So long as the safety switch is functioning as designed, then this plastic piece will be a sufficient replacement for the pot (cast) metal original.