| 摘要 |
A ball dropping assembly (350) for dropping one or more objects, such as spherical balls, (5,5',5") into a wellbore (7). The assembly comprises a sea t (330) for retaining a ball before it is released. The assembly may also comprise a ball feeding channel (380) for feeding additional balls onto the seat. A ball retaining lever (40) is provided to selectively receive and retain balls onto the seat (330), and then to release the balls individually into the wellbore (6). In one embodiment, the assembly is attached to a side bore (4) in fluid communication with a main bore in a cementing head (105). The ball-retaining lever (40) rotates into the bore (6) when releasing a bal l (5'). When a plug (8) is released into the bore from a cementing head (105), the plug (8) will trip the lever (40), causing the ball-retaining lever to rotate back towards the ball-retained position. Thus, the ball dropping assembly also serves as a plug release indicator.
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