steam·roll·er 
(stēmrō′lər)
(stēmrō′lər)n.
1.
a. A steam-driven machine equipped with a heavy roller for smoothing road surfaces.
b. A similar machine with an internal-combustion engine.
2. A ruthless or irresistible force or power.
v. also steam·roll (-rōl′) steam·roll·ered, steam·roll·er·ing, steam·roll·ers also steam·rolled or steam·roll·ing or steam·rolls
v.tr.
1. To smooth or level (a road) with a steamroller.
2. To overwhelm or suppress ruthlessly; crush.
v.intr.
To move or proceed with overwhelming or crushing force.
steamroller