Which of these is the name of a machine used to keep the surface of an ice skating or hockey rink smooth?

An ice resurfacer is a vehicle or hand-pushed device used to clean and smooth the surface of a sheet of ice, usually in an ice rink. The first ice resurfacer was developed by American inventor and engineer Frank Zamboni in 1949 in the city of Paramount, California. As such, an ice resurfacer is often referred to as a "Zamboni" regardless of brand or manufacturer.

Zamboni created a plant for making ice blocks that could be used in refrigeration applications. As the demand for ice blocks waned with the spread of compressor-based refrigeration, he looked for another way to capitalize on his expertise with ice production.

In 1939, Zamboni built the Iceland Skating Rink in Paramount, California. In order to resurface the skating rink, 3 or 4 workers had to scrape, wash, and squeegee the ice. A thin layer of water was then added for the fresh ice. This process was extremely time consuming, and Zamboni wanted to find a more efficient way to resurface the ice. In 1947, he built a machine that would shave, wash and squeegee the ice. This machine was mounted on an army surplus Willys Jeep chassis.