Abstract: A forward/reverse change-over mechanism (3) of an automatic transmission comprises a forward clutch (5) inside a drum (7) with the base (7c) which rotates together with an input shaft (1). The forward clutch (5) engages by driving a piston (9) housed in the drum (7) by the oil pressure of an oil chamber (10) between a base (7c) and the piston (9). Projecting bearings (16) which seat the piston (9) are formed by press-forming at equal angular intervals concentrically with the axial center of the drum (7) in the base (7c). By installing a sensor body (18) which responds to the passage of depressions (17) formed underneath the bearings (16), the forward/reverse change-over mechanism (3) can be made compact and manufactured with a small number of parts and machining steps.

Abstract: A forward/reverse change-over mechanism (3) of an automatic transmission comprises a forward clutch (5) inside a drum (7) with the base (7c) which rotates together with an input shaft (1). The forward clutch (5) engages by driving a piston (9) housed in the drum (7) by the oil pressure of an oil chamber (10) between a base (7c) and the piston (9). Projecting bearings (16) which seat the piston (9) are formed by press-forming at equal angular intervals concentrically with the axial center of the drum (7) in the base (7c). By installing a sensor body (18) which responds to the passage of depressions (17) formed underneath the bearings (16), the forward/reverse change-over mechanism (3) can be made compact and manufactured with a small number of parts and machining steps.

Abstract: A method is provided for forming spline teeth on the walls of a press-formed sheet-metal article on which two peripheral walls of different diameters are disposed in a continuous manner via a step portion by means of a die with a plurality of steps of ironing surfaces, and a punch having a plurality of corresponding ironing surfaces. The punch is provided with a first punch and a second punch which are arranged in a split manner. The second punch first irons teeth on the larger diameter peripheral wall. While the first punch is next used to iron teeth on the smaller diameter peripheral wall, at least some of the pressurizing force on the second punch is maintained to avoid the creation of flaws in the step portion of the sheet metal article.