Hydraulic Expanding Arbour works by axially drawing the mandrel back using the machines drawtube after placing the expanding sleeve over it and securing it into place with a pin. This action forces the two tapers to interface and the mandrel to expand by pulling the expanding sleeve farther back onto the mandrel. It is utilised as a core around which pieces can be bent or other materials can be forged or moulded, or to support a partially machined item while it is being finalised.