Mounting Hubs
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The main advantage of using a mounting hub is it allows for the construction of a lighter weight timing belt pulley, since the mounting mechanism is a separate piece. Mounting hubs also reduce the expense of having multiples of the same belt drive pulley for different shaft sizes. Added to this if the bore or keyway of the hub gets damaged, the hub would be the least costly part to replace. Mounting hubs come in different styles including clamping style, floating hub style, taper-lock bushing style and QD flanged bushing.
Technical 
