I've made this back in 2018 as a replacement for the broken one.

Lawnmower is LUX-TOOLS B&S 750 EX DOV, I believe the cogwheel is for the gearbox-to wheels junction.

I didn't have a printer, so I can't provide the print parameters.

I've tested it in ABS - it broke. The weak part are the 7 big teeth at the top of the cogwheel, if printed flat.

Later I've tested with Nylon, PETG and carbon-fiber filament and they seem to hold up.

Designed in Fusion 360