German Type Worm Drive Hose Clamp consist of a band. Often galvanized or stainless steel. Into which a screw thread pattern has been cut or pressed.One end of the band contains a captive screw.
The clamp is put around the hose or tube to beconnected.With the loose end being fed into a narrow space between the band and the captive screw. When the screw is turned, it acts as a worm drive pulling the threads of the band. Causing the band to tighten around the hose (or when screwed the oppositedirection, to loosen).
Screw clamps are normally used for hoses 1/2 inch diameter and up. With other clamps used for smaller hoses.