Sprag-type clutches are well known by those skilled in the art. These clutches are often used since they have a freewheel mode desirable to some. These clutches, however, have numerous disadvantages including very tight and expensive to manufacture tolerances that required for them to operate properly. For example, the diameter and concentricity of the races is required to be exact for the clutches to work. In addition, sprag-type clutches often have insufficient capacity, and the sprag is prone to skidding or flipping over, resulting in a history of poor durability for these clutches. Negative experiences in the industry with these clutches have led manufactures to cease offering freewheel clutches in the marketplace, with limited exceptions.
Other types of freewheel clutches are known to those skilled in the art. For example, U.S. Pat. Nos. 5,718,114 and 5,852,932 teach a mechanism comprising an outer race on an inner circumferential side of a stator. The outer race includes a first side face being formed with first teeth. The mechanism also comprises an unrotatable inner race assembled on a stationary shaft. The inner race includes a second side face, opposite the first side face, formed with second teeth which can prohibit the outer race from rotating in one direction by meshing with the first teeth. The inner and outer races move axially with fluid pressure so that the first teeth and second teeth can be engaged and disengaged. A structure to adequately align and initiate engagement of the first and the second teeth is absent from these inventions. As a consequence, excessive wear on the teeth, noise and/or vibration may result.
In light of the disadvantages found in the prior art, it is desirable to provide a robust, economical freewheel clutch that can be located within the confines of current torque converters.