Abstract: An air duct is constructed with a rolling annular portion that is desirably formed of a series of hemi-toroid planar-cut surfaces. The rolling annular portion may include an inner portion and an outer portion constructed of different materials. The rolling annular portion permits relative movement within the air duct while minimizing disturbances in airflow.

Abstract: A positive crankcase ventilation (PCV) valve having a housing and a valve and spring assembly. The housing may be constructed of an electrically conductive material and include an electrode integrated therein. The valve and spring assembly is disposed within the housing. The valve and spring assembly may be constructed of a metallic or a plastic material. The housing receives an electrical signal from a power source via the electrode. The electrical signal applied to the housing causes an increase in housing temperature thereby preventing freezing of the valve and spring assembly within the PCV valve.