To close and tension a hose clamp, the two end portions of a clamping band, which overlap one another, are provided on surfaces that face one another and have toothed areas which are held in reciprocal engagement by a holding device. The toothed area of one end portion is formed on the outer face of a tongue, the width of the tongue being less than the full width of the band. The holding device has a raised area that is formed in the other end portion and bears the other toothed area on the inner face thereof. The raised area begins spaced from the free end of the other end portion with an outwardly projecting step that has an opening for the tongue to pass through.

A hose clamp includes a band and a worm drive mechanism. The band has a set of slots located between a first and second circumferential end of the band. The worm drive mechanism is connected to the band and causes radial contraction of the band to tighten the band. The worm drive mechanism includes a screw that engages the set of slots for radial contraction of the band. A clamping-pressure-restoring construction is provided in order to maintain a seal between the hose clamp and an underlying hose during use of the hose clamp and when the underlying hose experiences size expansion and contraction due to, for example, temperature fluctuations.