Two speed traction drive pulley system

Abstract

A two speed pulley assembly comprised of a sheave, a brake member, an output member, and a brake. The sheave receives a rotational input and also includes a series of carrier arms which cooperate to define a circle which is coaxially with the sheave. Rollers are rotatably supported on said carrier arms. A braking member is rotatably supported relative to said sheave and includes portions defining a first raceway in contact with the rollers. An output sleeve is also rotationally supported relative to the sheave. The output sleeve includes portions defining a second raceway in contact with the rollers. The brake inhibits rotation of the braking member when engaged while permitting rotation thereof when disengaged. Mounted between the sheave and the output sleeve is a one-way clutch bearing. The clutch bearing engages when rotation of the sheave attempts to or begins to overrun rotation of the sleeve. During use, the sheave drives the output sleeve through the rollers at a rotational rate greater than that of the sheave when the brake is engaged. When the brake is disengaged, the sheave drives the output sleeve through the one-way clutch bearing at a one-to-one ratio. In this way the present invention provides two different driving speeds from a single belt pulley assembly thereby increasing the electrical output of an alternator at low engine speeds. Alternatively, the input and output member may be reversed to provide a speed reduction mechanism.