Brake Drum Query

[David HorsleyParticipant]

Fitting a new front brake cylinder yesterday with the help of my friend (a Rolls Royce-trained engineer), he asked me why the taper on the hub had a thin radial groove about half way along the taper that didn’t seem to have any apparent purpose but looked like it was part of the design.

I couldn’t answer that question – can anyone else, please ?

[ChrisParticipant]

Hi David

You mean a groove around the circumference inside the bore of the hub, halfway along? I don’t have a groove in mine but, in general the hub should only contact the stub axle  shaft at the inner and outer ends of the taper – not along the whole length. Since the taper on the axle shaft is a linear taper, the hub is the part that has to have a more complex profile. I guess the groove is something to do with the machining process that enables the areas at the two ends to be machined and checked without interference from the relief in the middle bit. Or something like that.

Chris

[Author]

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