Patent ID: 7255546

Claim:
A spindle for a vane motor having a power stroke and an exhaust stroke and being eccentrically mounted in a cylinder for unitary rotary motion, said spindle being eccentrically mounted relative to said cylinder and including a plurality of vanes having a working face and being motivated by impinging pressurized air admitted thereto on said working face through apertures in the cylinder during said power stroke and said cylinder including a circumferentially outer periphery, said vanes mounted in complementary axial slots formed in said spindle for reciprocal motion, said vane having a top edge and a bottom edge, said top edge being straight and said bottom edge being contoured and said bottom edge being disposed in said complementary slots, means for increasing the area of said working face of said plurality of vanes by undercutting said spindle adjacent to said slot where said pressurized air impinges on said vanes and said undercuts includes three axially spaced undercuts wherein the space between said axially spaced undercuts extend to said outer periphery wherein said undercutting defines a plurality of axially spaced undercuts and being in the same direction of said slot.