This original STIHL drive pinion provides factory quality and is a key component of the self-propelled drive system on the wheels of your mower. Located on the right side of the drive shaft, this small gear directly transmits torque from the gearbox to the internal toothed ring of the wheel. Made of specially alloyed steel with high resistance to friction and wear, the original part guarantees smooth movement of the machine without slipping, overloading of the drive mechanism or accelerated wear of the inside of the wheel itself. When replacing the drive pinion, be sure to clean the shaft of grass deposits, soil and rust. Carefully inspect the condition of the key (wedge) and spring located inside the pinion, because they enable proper engagement when moving forward and free rotation when the mower is pulled backwards. Before assembly, lightly lubricate the shaft and the inner mechanism of the pinion with a dedicated grease to prevent seizing and ensure long, flawless operation of the drive. Key characteristics: Part type/size: Wheel axle drive pinion – Right (Pinion) Manufacturer: STIHL – original part Reference OEM number: 0000 640 2505 Compatible models: VIKING MB 455 / MB 455 E / MB 455 C / MB 455 M / MB 455 MM VIKING MB 505 / MB 505 E / MB 505 M / MB 505 MM / MB 505 KAT VIKING MB 650.0 V