US Patent 8205685 Housing and gearbox for drill or driver

A power tool with a handle housing, a motor, an output member and a cassette. The handle housing that defines a handle. The motor is received in the handle housing. The cassette is received in the handle housing and includes a transmission housing, a multi-stage transmission received in the transmission housing, and a rear thrust washer. The transmission housing has a first end with first and second circumferentially extending channels formed therein. The rear thrust washer has a body and first and second lock members that extend radially from the body. Each of the first and second lock members is received in an associated one of the first and second circumferentially extending channels.