This question's right up my street, I used to be an ice-skater :)

The *generic* name for it would be "(ice) resurfacing machine" but at Solihull we always used to call it a Zamboni. A company called Zamboni used to make them, I don't know if they still do... anyway, people here used to call all of them "Zambonis" whether they were made by them or not, it's a bit like "hoover" (a brand name which became generalised in the language).

But since we don't know if the one you're talking about was made by them, I'd go for "resurfacing machine". After people have been skating the ice will have lots of tracings etc. on it, and these need to be filled in - so the ice has to be resurfaced.

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Note added at 9 mins (2007-03-12 12:37:46 GMT)
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См. также:

"What is an Ice Resurfacing Machine?

Background

An ice resurfacing machine shaves the ice, removes the shavings, washes and squeegees the ice, and has enough carrying capacity to clear the ice surface in one run, making it completely smooth. Ice resurfacing machines are widely known by the brand name Zamboni."
http://www.answers.com/topic/ice-resurfacing-machine