Abstract: A plurality of air blowers spaced with each other are disposed along a side wall of a clean tunnel, thereby outer air is supplied into a tunnel zone by way of a filter. A clean air produced within the tunnel zone is circulated by disposing air outlets and a suction port in a zone of each blower. Thus, a constant clean air flow can be circulated without raising the temperature of the clean air within the clean tunnel.

Abstract: Articles are transferred in a coverless casing while avoiding contamination. The casing is disposed in a first tunnel zone and attached to, but isolated with separator, from a driving assembly located in a second tunnel zone. Air openings exist between the separators through which a column connects the casing to the driving assembly. Blowers force air through a filter into the first tunnel zone, where it flows through the air openings into the second tunnel zone, then is withdrawn through an air outlet. This air flow keeps the first tunnel zone clean by not permitting contaminants from the second tunnel zone to enter the first tunnel zone.

Abstract: In electrodes for seam welding machines and the like, electric current paths from a transformer to an electrode shaft are established not as through an electrode frame, cover plate and others, but directly through contact means which is connected at one end thereof to the transformer and abuts at another end upon a free end of the electrode shaft coaxially thereof.