Cable percussion (cable tool) drilling is the oldest, simplest, and most reliable
technology available of borehole drilling, at the least capital cost.
It will drill any material and requires no mud, pits, pumps, chemicals,
DTH hammers or compressors, yet will drill rock.
The method uses tools suspended on a wire rope, which are lifted and dropped to
break up and remove material from the bottom of a hole. A variety of tools can
be used. Clay cutters and stubbers allow rapid drilling in clays and in sands
having some clay content, to remove solid plugs of material. Other bits perform
in harder materials.
This non-invasive and sensitive borehole drilling method, allows discovery,
testing and development as drilling proceeds. It is an appropriate method for
water wells, environmental drilling, site investigation, remediation, and prospecting.
At only 400 Kg, this machine can be man-handled to places inaccessible to heavier
equipment.
Designed for drilling contractors & NGOs, it is also a useful means of locating
hand dug wells.
The presence or absence of boulders can be quickly discovered, in addition to the
depth, quantity and quality of groundwater, thereby eliminating the often high
failure rate with randomly sited dug wells.
Forager-55 trailer-tripod cable percussion borehole rig shown opposite drilling
in UK for a private water well with 1250 Kg winch & 10 hp diesel; £15,000
package c/w basic drilling tools.
Forager drilling is simple. It requires no additional materials, auxiliary pumps,
mud chemicals or additional engines to operate.
The single engine, and the winch with two levers, does all the work. The only
other input that may be required in some materials is a little water. This is a
small amount, to form a slurry with crushed or broken material, allowing it to be
bailed out of the hole. For clay cutter drilling no additional water is necessary;
hence the description as 'dry drilling', although an occasional cup of water to
wet the cutter may be a help.
Using a clay cutter in glacial till (drift)
The method will drill in any material from soft sands and clays to hard rock like
granite. The standard rig is entirely mechanical with no hydraulics, electrics or clutch.
Setup is quick, and as the frame is light, is all done by hand using the balanced
weight of the machine to help push up the tripod. This is a one-man job with no
need for mechanical assistance.
The shell & auger drilling method is non invasive. It does not cause modifications
to the strata - it is simply removing material from the hole. This is similar in
effect to the traditional pick & shovel hand digging method which was used to
excavate open pits and wells.
The Forager drilling system is based on a high quality free-fall winch, which
hoists and then lets fall a set of drilling tools to break up and recover materials
to create a bored hole.
Tools can include clay cutters, stubbers, rock crushers,
bailers and drive sampling tubes.
Clay cutters and stubbers take advantage of the property provided by the winch and tools
in free-fall to cut a core, or plug, in any cohesive material (clays and sands with some
clay content), which is removed from the tools at ground level.
Rock crushing tools
break up hard materials which can be removed with a bailer after adding enough
water to form a slurry.
Water extracted by bailing gives a good indication
of the yield, and water quality at any level, without having to install pumps.
The machine is well balanced and can conveniently be wheeled by hand between sites
without using a towing vehicle - including while carrying the drilling tools. The
winch can be utilised to haul the rig to more difficult places, crossing streams
etc. as the engine is sufficiently level to be run while the rig is folded and
on its road wheels. Being able to 'walk' the rig between village sites can save
considerably on the need for and cost of transport in support of a drilling
programme. This facility also enables drilling to take place where there is no
normal vehicular access. The rig, together with tooling, is canoe portable.
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FORAGER CABLE PERCUSSION RIGS
Rugged high quality rigs with very low inputs - quick one man set-up and
operation; they cover the entire range of materials, with nothing extra to buy
if the ground is harder than you thought. Machines are permanent, long life and
maintanable, using high quality components.
At their heart is the engine & winch combination; we use our own highly successful
design of clutchless freefall drilling winch and good quality engines.
They are suitable entry-level equipment for contractors and NGOs producing typical rural water
wells for hand pumps. Faster and cheaper than hand digging for rural development
programmes - not stopped by boulders, and a profitable commercial investment for
drilling water wells, site investigations, window sampling, remediation wells and
other environmental drilling. Can be used for setting drive points, hydraulic
(jet) percussion drilling, peizometers & insitu testing, geothermal drilling, and
prospecting.
SPECIFICATION for FORAGER-1250 'STANDARD' BUILD
Winch single line (bare drum) pull: 1250 kg (2750 lbs)
Weight of drilling tools: 250 Kg (550 lbs)
Drum capacity: 110m (360 ft) of 10mm dia. wire
Speed of hoist on a bare drum: 38m/min. (125 ft/min.)
Tripod frame hoisting capacity 5,000 Kg (11,000 lbs)
Height under top sheave 4.575 mtrs. (15 ft.)
Lister-Petter diesel engines standard, but also other diesels
PICTURE RIGHT:
Forager-55 drilling in chalk below superficial clays having placed 25m of 6" temporary casing - for water
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FREE-FALL WINCH
The main component of this drilling system is the Consallen F-1250 free-fall wire
winch, providing a bare drum single line pull of 1,250 Kg (2750 lbs) at a hoisting
speed of 38m/min. An overload protection device is fitted.
The winch is clutchless, being based on an internal epicyclic gearbox, and is operated
and controlled entirely by two external brakes. A foot pedal operates the
drum brake and a hand lever controls a second brake, which causes the drum to reel in
when applied. Relaxing the hoist lever allows the tool string to fall freely
for maximum impact in the hole. The foot brake can be locked 'on' with simple
catch.
The hydraulic version of the winch has power limited by relief valve, and
several other safety aspects are possible, unavailable on mechanically
driven machines. Fine infinite control of both hoisting and lowering operations
can be done safely and with confidence, without affecting the free fall capability.
Casing jacks may also be operated from the system using plug-in connections to the
proportioning control valve.
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TOWING
The rig, when folded, can easily be towed by a small car or pickup. The balance of the
machine means that it can be wheeled easily by hand.
Shown here with the Lister-Petter diesel engine option, with crank handle starting.
This is mechanically driven by belts from the engine.
HYDRAULIC POWER
The rig shown here has an hydraulicaly driven winch; ready for towing,
with the power pack on the operator's platform. During use, the power pack is
dismounted and removed from the immediate area of operations, eliminating
vibrations, noise and exhaust fumes.
Alternative sources of power include take-offs from other hydraulic equipment.
The power pack shown weighs 71 Kg and has wheels for easy movement on site.
The KIT - for local completion
For certain overseas purchasers the drilling machine is available in kit form.
It is supplied partially completed, with sub-assemblies ready for welding
to locally supplied rectangular and square hollow section (box section tubes).
Completion of the rig requires simple and commonly available skills and equipment
for hand cutting and welding. We have a separate CD which illustrates the work
required and the components supplied, which will be sent on request.
The advantages of this approach are that cost of the kit is less than would be
the case for equipment completely finished in UK, the freight cost is reduced,
and the import cost is less for self-coloured components than for bright galvanised
items.
Some additional information on the Kit version of the rig is shown on the
Price List for which a link is provided:
