Patent ID: 7493971

Claim:
An expandable downhole tool for use with a drilling assembly in a wellbore, comprising: a tubular body; at least one moveable arm disposed within said tubular body and being radially translatable between a retracted position and a wellbore engaging position; at least one piston comprising a cam portion that mechanically supports said at least one moveable arm in a radially outward direction in said wellbore engaging position when an opposing force is exerted; wherein said at least one piston is axially translatable in response to a differential pressure between an axial flowbore within said tool and said wellbore; a sliding sleeve biased to isolate said at least one piston from a fluid flow in said axial flowbore and said pressure differential, thereby preventing said at least one moveable arm from translating between said retracted position and said wellbore engaging position; and a port in fluid communication with said flowbore and said at least one piston.