Abstract: A method of defrosting a refrigerating circuit for use in cooling a vehicular chamber comprises two steps. In a first step a frost formed at an outer surface of an evaporator of a cooling unit is defrosted by directly leading discharged gas to the evaporator. In a second step a frost formed at elements of the cooling unit except the evaporator is defrosted by making air in the vehicular chamber pass through the heated evaporator. In this manner, the cooling down characteristic in the vehicular chamber is improved and compressor durability is preserved.

Abstract: An axial mode helical antenna includes a metal belt member disposed around the reflector of the antenna in order to permit use of reduced diameter reflectors and, therefore, to produce a small helical antenna having increased directivity.

Abstract: An electromagnetic clutch is disclosed comprising a rotor and an armature plate with improved frictional surfaces. The armature plate is disposed to face the rotor with a predetermined axial gap. The rotor or the armature plate is provided with a contact surface which contains spiral concaves and projections with a predetermined pitch. This surface has a layer of metal plating with a hardness lower than that of the magnetic materials which make up the rotor and armature plate.

Abstract: A pneumatic control apparatus for an interchangeably operable pneumatic device in which both the shut-off reversing valve for selectively supplying a flow of compressed air to the pneumatic device and a pressure reducing valve for restricting the pressure to a determined pre-selectable value, are located in a single housing.