Abstract: A block heater for the cooling fluid of an engine block has a main body with a surrounding flange at the front face for engaging into an aperture in the block. A clamping element attached to the rear face can be actuated by a screw which is rotated from the front face to pull the clamping element into engagement with the inside surface of the block to cooperate with the flange in a clamping action. The clamping member cooperates with the screw to be pulled forwardly. The rear face of the clamping member has a countersink around the threaded bore therethrough and the screw has a bore in the end face thereof so that a portion of the screw material can be worked into a flange surrounding the end of the screw to engage into the countersink portion. This arrangement prevents reverse rotation of the screw from releasing the clamping member for discharge into the engine compartment.

Abstract: A heating element for an air flow comprises a channel shaped bracket including a base and side walls at right angles thereto within which is mounted a pair of mica sheets arranged parallel to the base and at right angles to the sides and connected to the sides by ribs longitudinally of the sides with transverse slots within which the sheets slide. Each sheet is wrapped with a heating wire formed into helical coils so that each side of the sheet carries a plurality of parallel helical coil portions with connecting portions wrapped over the edges of the sheet. The sheets are symmetrical and one is inverted relative to the other. Each sheet carries at ends thereof a male and a female connector of the blade and receptacle type so that the blade of one sheet engages into the receptacle of the other sheet.