Abstract: [Problem] To provide a rotor unit that may effectively prevent detachment of a magnet with a holder while absorbing dimensional errors of a rotor main body and the magnet. [Solution] In the rotor unit according to the present invention, the holder mountable on the rotor main body prevents the magnet from being detached from the rotor main body. The holder includes an elastically deformable insertion arm extending from a flat-plate like holder main body, a hook portion provided on a free end side of the insertion arm, an elastically deformable magnet pressing arm extending from the holder main body, and a magnet pressing portion provided on a free end side of the magnet pressing arm. The rotor main body includes a hook hole into which the insertion arm is inserted, and the hook hole is provided with a locking portion in which the hook portion is lockable.

Abstract: A position of a reservoir hole of a hollow piston of a hydraulic tensioner is downside of a centerline or center plane of the piston to increase the oil retention within the internal reservoir during engine shutdown, reduce start up noise and decrease air from accumulating within the internal reservoir.

Abstract: A hydraulic tensioner for an internal combustion engine for tensioning a span of a chain or a belt has a piston with an internal reservoir connected to a high pressure chamber through a check valve assembly. The check valve assembly has a disk seat received within the hollow bore of the body of the piston having at least one passage connecting the internal reservoir to the hydraulic pressure chamber; a check valve retainer coupled to the disk seat; a check valve disk received between the disk seat and the check valve retainer moveable between a first position and a second position, and a check valve spring received between the check valve disk and the check valve retainer.

Abstract: A hydraulic tensioner for an internal combustion engine for tensioning a span of a chain or a belt has a piston with an internal reservoir connected to a high pressure chamber through a check valve assembly. The check valve assembly has a disk seat received within the hollow bore of the body of the piston having at least one passage connecting the internal reservoir to the hydraulic pressure chamber; a check valve retainer coupled to the disk seat; a check valve disk received between the disk seat and the check valve retainer moveable between a first position and a second position, and a check valve spring received between the check valve disk and the check valve retainer.