What is the name of the machine that masonry workers use to pat down the gravel base under concrete?

It looks kind of like a push behind lawnmower, it has a gas engine and a flat bottom it flattens or levels the gravel...

What is the name of the machine that masonry workers use to pat down the gravel base under concrete?
The machine you are thinking of is a vibratory plate tamper.





There are several brand names such as Wacker and Bomag.





A "jumping jack" compactor is a more upright machine that is used for compacting pipe backfill, not for compacting gravel base.
Reply:it has many names --whacker--thumper--impactor-compactor
Reply:depending in what country your in.UK its a whacker plate
Reply:it's called a tamper
Reply:there is a plate compactor.....i think that is what you mean....you can rent those





also there is a jumping jack....for serious compaction but not easy to level surfaces with