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| Illustration 1 | g06416199 |
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(1) Mast As
(2) Rotary Drive | |
The mast assembly (1) pivots on a fabricated support frame, which extends upwards from the machinery deck. The mast assembly is constructed of rectangular tubing. Two large displacement hydraulic cylinders move the mast 90 degrees to a vertical drilling position from the horizontal 'at rest' or travel position. The mast assembly accommodates two standard drill pipes joined together, plus top and bottom subs. The carousel can carry another 5 drill pipes efficiently. The mast can be locked in the vertical position and in 5° increments up to 30° off vertical. The locking assembly ensures mast stability when drilling in the positions the mast is locked in. There are two mast lengths available for the MD6250
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| Illustration 2 | g06260281 |
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(3) Locking Cylinder
(4) Proximity Switches (5) Locking Pin | |
The mast is positively locked on both sides by two separate cylinders (3) and pins (5). The mast lock is controlled from within the operator station and is monitored by two proximity switches (4). Locked and unlocked positions are indicated on the touchscreen via the control system. The mast is locked by one locking cylinder on each side.
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| Illustration 3 | g06260569 |
| (6) Mast Raise Cylinders | |
The MD6250 utilizes hydraulic cylinders to raise and lower the mast. The mast raise cylinders (6) produce lifting force during the extension of the cylinder when raising the mast from the horizontal position.
As the mast continues to rise, the load on the mast raise cylinders increases until the center of gravity passes over the pivot pins. Once the mast passed the pivot point, negative force is applied to the cylinder.
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| Illustration 4 | g06260305 |
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| Illustration 5 | g06364466 |
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(7) Pipe rack
(8) Pipe rack swing cylinder | |
The pipe rack (7) swings from the parked position to the load position under the rotary drive when an extra pipe is needed. There are two pipe rack swing cylinders, one at the bottom of the mast, and one at the top The pipe rack swing cylinders (8) place the pipe rack into position. The operator controls the functions in the cab.
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| Illustration 6 | g06260325 |
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(9) Carousel lock cylinders
(10) Pipe pots (11) Carousel breakout plate (12) Indexing cylinder | |
The carousel assembly carries extra pipes in the drill pipe pots (10) for multi-pass drilling. The carousel pivots on the carousel axle and is supported by an upper and lower bearing cap. The carousel lock cylinders (9) retract allowing the indexing cylinder (12) to move the carousel to the next position. Drilling can only be performed when the carousel is in the parked position.
The two locking cylinders work in opposite directions. One locks the carousel so that it does not rotate involuntarily. The other allows the pipe rack to move out of the parked position. When the pipe rack needs to be rotated, the pipe rack lock / unlock button in the operators area. This will disengage the park lock and engage the swing lock.
The carousel park position switch sends a signal to the drill system display to indicate carousel position. If the carousel moves out of the parked position, the hoist and pull-down function will be disabled. When the carousel is in the load position, reduced pull-down pressure is introduced to protect the carousel during drill pipe changing operations. The pipe is held in position by a slot in the upper and lower carousel break out plate (11).
Hydraulically Operated Break Out Wrench (HOBO)
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| Illustration 7 | g06260310 |
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(14) Swing cylinder
(16) HOBO wrench (17) Rotate cylinder (18) Clamp cylinder | |
The HOBO wrench is mounted on the outside left of the mast structure and is used to loosen the pipe joints without excessive loads being placed on other pipe handling components. The HOBO wrench (16) has three hydraulic cylinders including the swing cylinder (14), rotate cylinder (17), and clamp cylinder (18). The swing cylinder swings the HOBO inward toward the mast and drill pipe. The clamp cylinder tightens the jaws around the drill pipe. The rotate cylinder rotates the drill pipe to loosen a threaded joint. If correct drilling operational procedures are followed, the HOBO should only occasionally be required to unscrew the drill pipes.
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| Illustration 8 | g06260329 |
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(19) Deck wrench cylinder
(20) Deck wrench | |
The deck wrench (20) is mounted at the base of the mast on top of the drill deck. The deck wrench is used to hold the drill pipe down a hole while the joint above is broken while drill pipe-changing procedures are taking place. The jaw of the wrench is shaped to engage the flats near the top of the drill pipe. The deck wrench is mounted inside the mast structure on top of the deck. The deck wrench cylinder (19) actuates the deck wrench to engage or disengage the drill pipe. The deck wrench is extended to engage the drill pipe by pressing the left joystick forward with the bottom left button depressed while the trigger is in the centered position. Pushing the left joystick forward with the bottom right button depressed while the trigger is in the centered position will put the deck wrench in the park position.
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| Illustration 9 | g06260332 |
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(21) Safety arm cylinder
(22) Safety arm | |
The pipe safety arm (22) is used to prevent a drill pipe from falling out of the mast if accidentally unscrewed from the top. The safety arm is moved with a safety arm cylinder (21) for loading and unloading drill pipes. The pipe safety arm is controlled from the operators cab by the switch that also controls the winch.
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| Illustration 10 | g06364471 |
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(24) Travel sheaves
(25) Pull-down slider block (26) Hoist/Pull-down cylinder (27) Hoist slider block (28) Pull-down cables (29) Hoist cables (30) Hoist cable adjusters (31) Crown sheaves (32) Lower sheaves (33) Cable tensioning cylinders (34) Pull-down Cable Adjusters | |
The hoist/pull-down cylinder (26) has a double rod design. The hoist / pull-down cylinder consists of two hollow piston rods joined in the center at the feed cylinder piston. The hoist/pull-down cylinder is installed under tension in the mast and secured with a large nut and washer at each end.
Hydraulic oil travels through the center of the two hollow piston rods, down to the cylinder piston, which is ported to direct the oil into the cylinder barrel. The cylinder barrel travels along the length of the fixed hoist/pull-down cylinder rods.
The hoist slider block (27) and pull-down slider block (25) contain two traveling sheaves (24) each. The slider blocks and are bolted directly to the hoist/pull-down cylinder barrel and travel with the hoist/pull-down cylinder barrel as it moves up and down the hoist/pull-down cylinder rods.
Hoist/Pull-down Cables and Sheaves
Two hoist cables (28) are attached at the top of the mast to hoist cable adjusters (30), directed around the two traveling sheaves in the hoist slider block attached to the hoist/pull-down cylinder, around the two crown sheaves (31), and down the mast to attach to the top of the rotary head.
Two pull-down cables (29) are attached to at the bottom of the mast to the pull-down cable adjusters (34), directed around the two traveling sheaves in the pull-down slider block attached to the hoist/pull-down cylinder, around the two lower sheaves (32), then up the mast and attached to the bottom of the rotary head.
The auto cable tensioning circuit provides a small pressure / flow to cable tension cylinders as drill pipe string is hoisted from ground position to parked position at the end of each hole. This ensures only the slack created in drilling process is removed by tensioning system and that excessive force is not applied to cables.
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| Illustration 11 | g06364476 |
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(35) Winch
(36) Winch rope (37) Drum (38) Drive motor | |
The winch (35) consists of the drive motor (38), drum (37), and winch rope (36).
The winch is hydraulically operated from the operator station with either a lever or a tethered remote.
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| Illustration 12 | g06260556 |
| (45) Pipe positioner | |
The function of the pipe positioner (45) is to stabilize and guide the drill pipe when drilling and during travel to prevent excess movement of the pipe. The pipe positioner consists of the main support arms and the roller guide assembly, both of which are connected to hydraulic cylinders.