Plate compactors fall into one of three categories: single plate compactors that move in only a forward direction, reversible which move in forward and reverse, and high performance/heavy-duty plate compactors. The handle of a plate compactor plays a key roll. It can be mounted in the center or back of the unit. It can be a swinging handle allowing for easier maneuverability. And it could also be an anti-vibration hadle for increased operator comfort. Equipment is a key element in paving and pavement maintenance.
When hovering, hummingbirds hold their bodies upright and flap their wings horizontally in a shallow figure-8. As the wings swing back they tilt flat for a moment before the wings are drawn. Most hummingbirds flap their wings about 50 or so times a second.
Hummingbirds have been clocked at close to 30 mph indirect flight and more than 45 mph during courtship dives. Migratory ruby-throated hummingbirds have no problem flying 18 to 20 straight hours to cross the Gulf of Mexico, powered by their fat stores and given a bit of help from winds.