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9 SUSPENSION EQUIPMENT.
ROTARY SWIVEL

The swivel is the changeover link which connects the
rotatable drill string to the suspension system. The swivel stem (or
body) is attached to the upper end of thekelly and they rotate
together. The weight of the drill string is supported by the oil
flooded thrust bearing within the housing and the whole assembly
is suspended by the hook and the swivel bail (Fig. 9.1).

Figure 9.1 – Types of swivel

There are three purposes of the swivel: to suspend the drill
stem, to permit free rotation and to serve as the passageway for
drilling fluid into the drill column. It is capable of supporting more
than 650 tons and rotating attached drill column at speeds up to
400 rpm without undue wear.
Often when a piece of equipment daily performs its task with
little or no attention, it is completely neglected. This sometimes
happens with the swivel. Realizing this and understanding the

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