The DeWALT 90638422 Cordless Trimmer Motor & Pinion Assembly helps restore cutting power and smooth operation for compatible DeWALT cordless string trimmers. It works by converting electrical energy into rotational power while the integrated pinion gear efficiently transfers torque to the cutting head for dependable trimming performance. Made to replace a worn or damaged motor assembly, it helps restore reliable power output, improve cutting efficiency, and maintain consistent tool operation. This motor and pinion assembly provides a practical solution for supporting routine maintenance and extending the service life of your cordless trimmer.