drop ball

drop ball

[′dräp ‚bȯl]
(engineering)
A ball, weighing 3000-4000 pounds (1400-1800 kilograms), dropped from a crane through about 20-33 feet (6-10 meters) onto oversize quarry stones left after blasting; this method is used to avoid secondary blasting.
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References in periodicals archive ?
Tenders are invited for Fitters Personal Protective Spectacles Fitted With Genunine Toughened White Glasses And Stainless Steel Perforated Side Protection For Eye Guaranteed To Withstand Drop Ball Test As Specified Under Is 5983/1980.
Freeman returned to the field and play restarted with a drop ball.
The ball went to a Tynte forward who placed it into the empty net, but referee John Dempster of Swansea disallowed the goal, ruling that the ball was dead once the spectator had entered the field of play and ordered a drop ball where the fan kicked it.
Bucks' best chance was denied following a Rovers' back pass - the referee had given the free kick, subsequently forgot, and instead awarded a drop ball.
I thought it was going to be a drop ball when the game restarted so I said to the lad we'd do rock, paper, scissors to decide who got possession.
Best had also struck the bar when he was meant to be giving the ball back to Doncaster from a non-contested drop ball after a head injury to Jason Shackell.
Best had earlier avoided a memorable moment of controversy when his attempted pass to Rovers goalkeeper Neil Sullivan, from an uncontested drop ball, struck the crossbar.
Unfortunately for us, it meant a drop ball in the box and they could get all their players back.
And he then enraged the Santos stars by awarding neither the goal nor the spot-kick and restarting play with a drop ball.
According to the laws of the game, the beach ball should have been considered an "outside agent" and referee Mike Jones should have disallowed the goal and awarded a drop ball.
And Black Cats boss Steve Bruce was thankful for referee Mike Jones' ignorance of the rule that states any interference in play by an 'outside agent' - a description which apparently covers beachballs - should see play stopped and restarted with a drop ball.
Murray and Howlett (1994) observed that hydraulic drop ball rock breakage technique produces cleaner rock fragmentation, very low levels of ground vibration, minimal fly rock and dust and negligible toxic fumes.