Abstract: Disclosed is a pulley that comprises a metal bearing with an elastomeric material on its outer rim molded into a polymeric wheel, where the coefficient of thermal expansion of the polymeric wheel is at least 1.0.times.10.sup.-6 cm/cm/.degree.C. greater than the coefficient of thermal expansion of the metal bearing. The pulley is made by applying an elastomeric material to the outer edge of the metal bearing and molding the polymeric wheel around it. The use of the elastomeric material prevents slippage between the metal bearing and the polymeric wheel.

Abstract: Disclosed is a piston having a cylindrical body made from a thermosetting molding compound. The body has a central well and a molded-on metal cap having sides that extend downward over the exterior of the body and into the well. There is insulation under and in contact with the metal cap.

Abstract: Disclosed is a method of making a wheel assembly such as a pulley with a bearing. A wheel is molded from a material that shrinks when its temperature falls from a temperature above 100.degree. F. to room temperature. The wheel has a circular opening at its center suitable for holding a circular bearing. The diameter of the circular opening when the wheel is at a temperature above 100.degree. F. is greater than the diameter of the circular bearing and is less than the diameter of the circular bearing when the wheel is at room temperature. The bearing is positioned inside the opening when the wheel is at a temperature above 100.degree. F. The wheel is cooled to room temperature and shrinks around the bearing, thereby fixing the bearing to the wheel. Also disclosed is a wheel assembly made by this method.

Abstract: Disclosed is a molding apparatus which includes(A) a mold for making an undercut part which includes coring sandwiched between top and bottom cavity halves, where the coring is divided into three or four sections; and(B) a press for(1) separating the coring from the top and bottom cavity halves; and(2) separating the sections from each other.