gb23 This is a robust heavy duty gearbox capable of 100hp at 540rpm. The input shaft is 44.45mm diameter with a standard 20 tooth PTO spline. The output shaft and mounting hub have a 16 tooth tapered spline for positive locking and drive. A seal protector has been fitted to the mounting hub to help prevent grass, wire or any other objects from penetrating the oil seal. The input shaft and bevel gear are coupled together by an involute spline to ensure concentricity and positive drive.