Patent ID: 7557568

Claim:
A fluid pressure equipment with a position detecting mechanism comprising: a housing; a piston and a magnetic device moving synchronously in the housing by the action of fluid pressure; and a magnetic sensor mounted to the housing, for detecting the position of the piston by sensing the magnetism from the magnetic device, wherein the magnetic device is mounted to the piston and includes a pair of ring shaped yokes made of a magnetic substance and having central holes, and at least one permanent magnet disposed between the yokes, and the magnet is disposed in a state that the north pole and the south pole of the magnet point at both sides of the yokes respectively, wherein the piston is divided into a first piston portion and a second piston portion respectively located at opposite axial sides of the magnetic device such that the magnetic device is positioned in a space between the first piston portion and the second piston portion, wherein the first piston portion further comprises a central cylindrical portion extending in the axial direction of the piston at the center position of the side surface adjacent to the second piston portion, the cylindrical portion passes through the central holes of the yokes and contacting the second piston portion to fix the axial length of said space.