TM 5-3820-276-10-1
OPERATOR MAINTENANCE
THEORY OF OPERATION
SCOPE
This work package describes the theory of operation of the Water Well Drilling System (WWDS) major
components and systems.
WATER WELL DRILLING RIG (WWDR)
The WWDR is designed to operate in worldwide drilling conditions for mud and air drilling applications. The
WWDR is capable of drilling a 12.25 -in. (311.15 mm) diameter hole to a total depth of 2,000 ft (609.6 m). The
WWDR starts its drilling operation by engaging the Power Take Off (P.T.O.) drive (transfer case), which is
powered by the Caterpillar (CAT) C-18 (630 hp) diesel engine. Activating P.T.O. provides the hydraulic power for
raising the derrick, powering the tophead rotation, and lowering and raising downriggers. The on-board air
compressor is then activated by mechanically shifting the transfer case during air drilling operations only.
AIR DRILLING
The WWDR on-board air compressor (1,250 cfm/350 psi) (35.40 cmm/24.13 bar) and the Portable Air
Compressor (PAC) (1,170 cfm/350 psi) (33.13 cmm/24.13 bar), are functionally tied together through an auxiliary
air compressor connection on the WWDR that directly feeds the drill string with air. The combined high pressure
air is transferred through the rig-mounted plumbing through the tophead drive and down the inside of the drill rod.
This pressurizes a down-hole hammer and bit combination that hammers the consolidated (rock) formation into
fractured/cut up small pieces. A volume, Cubic Feet per Minute (CFM), of air lifts the cuttings to the surface
between the Outside Diameter (OD) of the drilled hole or casing and the outside of the drill rod. The cuttings flow
to the top because the diameter of the drill bit is larger than the OD of the 4.5-in. (114.3 mm) drill rod. The annular
space between the drilled hole or casing and the 4.5-in. (114.3 mm) drill rod creates up-hole velocity because the
air flow is restricted, forcing the cuttings to the top of the hole.
MUD DRILLING
With the use of the Mud Cleaning System (MCS) and its on-board triplex mud pump, the high pressure/volume of
drilling fluid (mud) is transferred from the MCS to the rig mounted plumbing through the tophead drive and down
the inside of the drill rod. The drill rod powers a rotating drill bit which cuts the unconsolidated (sand, gravel, soft
rock, or a combination of all listed) formation and brings the cuttings to the surface between the drilled hole or
casing and the side of the drill rod. The annular space between the drilled hole or casing and the 4.5-in. (114.3
mm) drill rod creates up-hole velocity because the drilling fluid (mud) flow is restricted, forcing the cuttings to the
top of the hole.
WATER WELL SUPPORT VEHICLE (WWSV)
The WWSV is utilized as a support vehicle and operates in conjunction with the WWDR, MCS, and PAC. The
WWSV carries up to 2,500 gallons (9,463.53 L) of water from site to site. The water is used for air drilling (water is
injected into the drilling rig for dampening the dust and lubricating the hammer). The water is also used to make
the drilling fluid/mud for the mud drilling method. Water is pumped from the WWSV with an on-board water
transfer pump to the 1,000 gallon (3,785.41 L) tank mounted on the MCS. The WWSV can carry additional drill
rod needed to complete the hole and the casing used for unconsolidated formations. The WWSV carries a welder/
generator and acetylene torch kit (the welder/generator is used to weld steel casing or power small tools and the
acetylene torch kit is used to cut the casing to length). The welder/generator shall have a threshold capacity of
operating at 8,000 Watts continuously. The welder/generator shall be able to provide AC/DC power for Metal Inert
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