A protective bellows protects a universal joint driven by a shaft, such as forming part of the front wheel drive mechanism of a motor vehicle. The bellows has a collar with an interior annular rib which, on completion of the fitting process, locates in an annular groove in the shaft. During the fitting process, a tube is forced between the interior peripheral surface of the collar and the outer surface of the shaft, via a channel in the rib and a channel in the material of the inner end of the collar which grips the surface of the shaft. Grease is pumped into the interior of the bellows through this tube. Further channels extend through the rib and the adjacent material of the collar, and allow excess air Pressure to be vented to atmosphere during and after the grease-filling operation.