Boom-bounce problems aren't confined to deck pours where the pump boom's reach is extended with slick line. When the boom is extended horizontally for placing slabs on grade, it moves down on the forward piston stroke of the pump and up on the return stroke. The bouncing motion makes the discharge hose flail about, which can cause injury to nearby workers.
The pump operator can help to minimize boom bounce during machine setup. Outriggers should be completely swung out and telescoped down so they're firmly in contact with the support surface, whether it's the ground, pavement or timber lagging. After leveling the machine, operators should ensure that there are no gaps between any outrigger pad and the surface.
Throttling down the pump is another way to reduce boom bounce, but it also reduces concrete output and slows the pour. A better option is to use a pump that evens out the concrete flow and provides smoother operation. Special hydraulic systems and very long-stroke cylinders on some pumps reduce boom bounce, make the pump run quieter and deliver more concrete per stroke.