TM 5-3820-256-10
NOTE
Normally, the hydraulic cylinder is used for the initial breaking of the joint. After that, use the rotary table
to unscrew the pipe, and use the break-out wrench as a back-up to hold the top joint of pipe from turning.
If a joint is extremely tight and the lower pipe turns inside the slips, use another pipe wrench to hold a
backup on the lower joint.
h. Pulldown/chain feed drive assembly. The chain feed drive transmits power to the roller chain that is fastened to
a chain pulldown. The chain pulldown is located in the mast. When the chain feed drive is operated, the chain
pulldown applies downward pressure on the water swivel. The downward pressure is transferred to the drill string
components below the water swivel, to increase the bit cutting force. When additional cutting force is needed,
operate the chain feed drive as follows:
(1)
Make sure the pulldown power control (5, figure 2-9) is in the OFF position.
(2)
Select the pulldown transmission high/low lever (3) to either the HIGH or LOW speed, whichever is most
suitable for the drilling conditions.
(3)
Move the pulldown power control (5) to ON.
(4)
Observe the hydraulic pulldown pressure indicated on the pulldown pressure gage (1).
(5)
Turn the pulldown control knob (2) and holdback control knob (4) to obtain the required pulldown pressure.
(6)
To stop the pulldown chain feed drive, move the pulldown power control (5) to OFF and shift the
transmission control lever (3) to NEUTRAL.
NOTE
If operation will be resumed, control knobs (2 and 4) may remain set for the selected pressure. To
resume operation, perform Steps 2 and 3.
(7)
When pulldown operations are complete, rotate the pulldown and holdback knobs (2 and 4) fully
counterclockwise.
i.
Air line conditioner.
(1)
Look through the air filter sight glass (2, figure 2-10) to see if moisture has accumulated in the bowl. If so,
use the valve handwheel (1) counterclockwise to close the shutoff valve before draining moisture.
(2)
Open the filter draincock (3) to release the moisture accumulation from the bowl. Close draincock when
bowl is empty.
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