Importance

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Abstract

A telescopic kelly bar assembly for use in drilling large excavations. The kelly assembly consists of a lower outer bar section, at least one middle bar sections and an upper inner bar section. Each bar has its own driver that either rests on top of the next size larger bar or is engaged to the rotary. The driver that is engaged on the rotary depends on which bar is the extended bar in the shaft excavation, since the driver that is engaged to the rotary is the driver of the bar that is extended in the shaft. The entire assembly is suspended by a swivel attached to a multi-part traveling block. When a bar is driven it is either driven by its driver via the rotary or by the next size smaller bar within the rotary. Lugs are added on the inside of the outer and middle bars at the top. If a round cross-section is used, the inside lugs transmit torque when fully extended from one bar to another. A thick ring is welded to the bottom of the middle bar and upper inner bar. The inside lugs and the bottom rings also act as stops to hold the bars together when hanging extended. Slots or holes located near the tops of the bars are used to receive pins. These slots and pins can hold all or some of the bars together. They also are used to hang the bars from the rotary. The bars can also be extended by removing the pins.

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First Claim