Ball bearing and a continuously variable speed transmission of belt type

摘要

A ball screw in a continuously variable speed transmission has an axially immovable pulley half (2) and axially movable pulley half (3) both mounted on a rotary shaft (4). The axially movable pulley half (3) is moved by a ball screw (20) so as to infinitely vary the belt wrapping radius and thus the transmission speed. A nut (22), forming one part of the ball screw (20), is immovably secured in both axial and rotational directions. A screw shaft (21), forming the other part of the ball screw (20), is movable in both axial and rotational directions. The screw shaft 21 is connected to the axially movable pulley half (3). The axially movable pulley half (3) is axially moved by rotating the screw shaft (21).