Machines used for excavation in hard rock include rippers, jackhammers, drills, compressors, and pneumatic equipment. Rippers are claw-like devices on bulldozers that break rock into rubble. Jackhammers, also called pneumatic drills, combine a hammer with a chisel to smash rock. Compressed air powers jackhammers and other pneumatic tools. Air compressors pressurize air to transmit power through hoses to construction machines.

1. EXCAVATION IN
HARD ROCK
Prabhanjan Thorat
prabhanjanthorat@gmailcom

2. EXCAVATION IN HARD ROCK
 Machines are used for excavation in hard rock includes
1. Rippers
2. Jackhammers
3. Drills
4. Compressors and
5. Pneumatic equipments

3. Ripper
 The ripper is the long claw-like device on the back of the bulldozer.
 Rippers can come as a single (single shank/giant ripper) or in groups
of two or more (multi shank rippers).
 Usually, a single shank is preferred for heavy ripping.
 The ripper shank is fitted with a replaceable tungsten steel alloy tip.
 Ripping rock breaks the ground surface rock or pavement into small
rubble easy to handle and transport, which can then be removed so
grading can take place.

4. Rippers
 Crawler tractors can be fitted with rear mounted rippers with various
configurations and linkage designs for depth control and adjustment
of the tip’s attack angle.
 Because of the power and tractive force available with large tractors,
penetration depth of a rear ripper on such machines can be as great
as 4 to 5 ft.

5. Parts of Ripper
 The vertical member of the ripper that is forced down into material to
be ripped is known as shank.
 A ripper tooth is fixed lower, cutting end of the shank.
 The tip is detachable for easy replacement, as it constitutes the real
working part of the ripper and receive all the abrasive action from the
rock.

6. Types of Rippers
 There are three types of ripper attachments available:
1. Fixed Radial
2. Fixed Parallelogram and
3. Parallelogram linkage with hydraulically variable pitch.
 Curved and straight types of shanks are available for the ripper.
 Straight Shanks are used for massive or blocky formations.
 Curved shanks are used for bedded or laminated rocks, or pavements, where a lifting action will
help shatter the material.

7. Types of Rippers
1. Fixed Radial:
With radial type ripper linkage, the
beam of the ripper pivots on link arms about
its point of attachment to the dozer;
therefore the angle of tip attack varies with
the depth of shank is depressed.
This may make it difficult to achieve
penetration in tough materials.

8. Types of Rippers
1. Parallelogram:
The parallelogram type ripper
maintains the shank in a vertical position and
keeps the tip at a constant angle.

9. Types of Rippers
1. Parallelogram with variable pitch:
The parallelogram with variable pitch
type ripper the operator can control tip
angle.

10. Factors affecting
effectiveness of Ripper
 Down pressure at the ripper tip
 The tractor’s usable power to advance the tip; a
function of power available, tractor weight, and
coefficient of traction.
 Properties of the material being ripped; laminated,
faulted, weathered and crystalline structure.

11. Percussion Drills
 Percussion drilling accomplishes disintegration of the rock by hammer
impacts to the bit at the same time a rotating motion is applied to
the bit.
 The percussion drill bit is literally hammered into the rock, it smashes
the rock to pieces.
 These drills may vary in size from handheld units such as
jackhammers to large crawler mounted rigs.

12. JACK HAMMER

13. Jack Hammers
 Also called as pneumatic drill or demolition hammer
 It is a pneumatic or electro-mechanical tool that combines a
hammer directly with a chisel. It was invented by Charles Brady King.
 Hand-held jackhammers are typically powered by compressed air, but some
use electric motors.
 Larger jackhammers, such as rig mounted hammers used on construction
machinery, are usually hydraulically powered. They are usually used to break
up rock, pavement, and concrete.

14.  A jackhammer operates by driving an internal hammer up and down.
 The hammer is first driven down to strike the back of the bit and then back
up to return the hammer to the original position to repeat the cycle.
 The bit usually recovers from the stroke by means of a spring.
 The effectiveness of the jackhammer is dependent on how much force is
applied to the tool.

16. Types
 Pneumatic
 Electromechanical or electropneumatic
 Hydraulic

17. Pneumatic
 Also known as a pneumatic drill or pneumatic hammer
 It is jackhammer that uses compressed air as the power source.
 Air supply usually comes from a portable air compressor driven by a diesel engine.
 Reciprocating compressors were formerly used.
 The unit comprised a reciprocating compressor driven, through a centrifugal clutch,
by a diesel engine.
 The engine's governor provided only two speeds:
1. idling, when the clutch was disengaged
2. maximum, when the clutch was engaged and the compressor was running
 Modern versions use rotary compressors and have more sophisticated variable
governors. The unit is usually mounted on a trailer and sometimes includes
an electrical generator to supply lights or electric power tools.
 Additionally, some users of pneumatic jackhammers may use a pneumatic
lubricator which is placed in series with the air hose powering the air hammer.
 This increases the life and performance of the jackhammer. Specific lubricant is
filled in the pneumatic lubricator. Furthermore, air compressors typically
incorporate moisture into the compressed air leading to freeze-ups of the
jackhammer or air hammer in cold weather.

18. Electromechanical or electro pneumatic
 Variety of sizes from about 12 lbs - 65 lbs.
 Require an external power source, but do not require a compressor.
 Although in the past these tools did not have the power of an air or pneumatic
hammer, this is changing with newer brushless-motor tools coming close to the
power of a pneumatic tool and in some cases even matching it.
 Electric powered tools are useful for locations where access to a compressor is
limited or impractical, such as inside a building, in a crowded construction
site, or in a remote location.
 Electropneumatic tools use a variety of works for attaching chisels.
 The connection end size is also related to the breaking energy of the tool.

19. Hydraulic
 A hydraulic jackhammer, typically much larger than portable ones, may be fitted
to mechanical excavators or backhoes and is widely used for roadwork, quarrying
and general demolition or construction groundwork.
 These larger machine mounted breakers are known as Rig Mounted, or Machine
Mounted Breakers. Such tools can also be used against vertical walls (or ceilings
for that matter), since the vehicles involved are massive enough and powerful
enough to exert the forces involved without needing the help of gravity in
operating the tool.
 Pneumatic or hydraulic tools are particularly likely to be used in mines where
there is an explosion risk (such as underground coal mines), since they lack any
high-power electrical circuitry that might cause a triggering spark.
 Hydraulic breakers usually use a hydraulic motor driving a sealed pneumatic
hammer system, as a hydraulic hammer would develop a low strike speed and
transfer unacceptable shock loads to the pump system.
 Advances in technology have allowed for portable hydraulic breakers. The
jackhammer is connected with hydraulic hoses to a portable hydraulic powerpack:
either a petrol or diesel engine driving a hydraulic pump; or a mini-
excavator or skid-steer via a power take-off driveshaft to the machine's hydraulic
system.
 Hydraulic power sources are more efficient than air compressors, making the kit
smaller, cheaper or more powerful than a comparable pneumatic version.

20. Glossary of terms
 Bit – This is a portion of drill which contact with rocks and disintegrates
it.
 Burden – Horizontal distance from a rock face to the first row of drill
holes or the distance between rows of drill holes
 Coupling – a short, hollow steel pipe having interior threads. Coupling is
used to hold the pieces of drill steel together or to the shank. Percussion
energy is transferred through the steel; not the coupling. Therefore
coupling must allow the drill steel to butt together.
 Cuttings – The disintegrated rock particles that are removed from a hole.
 Drifter – It is an air operated percussion type drill similar to jackhammer;
that is required mechanical mounting.

21. Bits (chisels)
Bit types include:
 Spade - provides flat finish for concrete or edging in asphalt or dirt
 Flat tip - allows direction control or finer edge finish
 Point - general breaking
 Stake driver - drives concrete form stakes
 Scabbler - finishes surface smooth or for cleaning prior to bonding
 Flex chisel - flexible metal blade (attached to shank with bolts) for tile
removal and scraping
 Bushing tool - multiple carbide points for cleaning up seams and knocking
down rough spots in concrete

22. Working of jackhammer
 When the valve is in the
position shown here, air enters
through the thick yellow hose
at the top and follows the
thinner paths shown in yellow,
pushing the piston (red)
downward and smashing the
hammer (green and gray) into
the ground.
 As the piston moves down, air
flows back up through one of
the pipes and pushes the blue
valve over to the right, so the
air now follows the brown paths
and exits.

23. Working of jackhammer – Cont….
 Drilling unit consists – Hammer, drill steel and bit
 Compressed air flows through a hammer, it causes a piston to reciprocate at a
speed up to 2200 blows/minute.
 Energy of piston is transmitted to a bit through a drill steel
 Air flows through a hole in the drill steel and the bit to remove the cuttings
from the hole and to cool the bit.
 Drill steel is rotated slightly following each blow so that the cutting edge of
the bit will not strike at the same place each time.

24. Suitability of jackhammer
 With or without pusher leg (Pneumatic powered) for hole length upto 3.5m and
dia. 32-38mm – Medium hard rock to hard rocks, small output, small size
horizontal mine openings and pin holes for services.
 Hand held – Funnel chamber excavation, shaft sinking, winzing in all and types
of rocks
 Electric breakers from Kennards come in 10kg, 15kg and 33kg models. - They
can be used for small to medium demolition projects like tile lifting, bitumen
cutting and digging clay.
 The 10kg option is light enough to work horizontally but still break up concrete
with a thickness of 50mm.
 The largest model will break concrete of up to 100mm in thickness, and has
the equivalent impact of a 28kg pneumatic hammer.

25. Suitability of jackhammer – cont…..
 A jack hammer trolley is ideal for easy removal of lino and floor tiles, and has
built-in shock absorption and an anti-vibration device to ensure the job isn't
harder than it needs to be.
 Pneumatic jack hammers are suitable for all drilling purposes in underground
and open-pit mining due to their low weight and high stability, however, they
need expensive power supply. (Small Scale Mining)
 The electric hammer should be considered as an alternative to pneumatic
systems in small mines with only few working places. Its low Input of primary
energy needed and environmental soundness are marks of the electric
hammer, however, high cost of installation of electric power supply should be
considered in the case that it is not available.

26. Jack hammer drill bits

27. AIR COMPRESSORS
 Air compressors are devices used to provide efficient
power to construction tools and machinery.
 Air compressors can be operated by internal combustion
engines and their ability to pressurize air enables power
to be transmitted via pipes or hoses.
 Air compressors are commonly used for transmitting
power to rock drills, jackhammers, air motors, pumps,
and many more types of construction equipment.
 The use of compressors enable workers to bore holes,
cut materials, crush rock, pour vibrated concrete, and
are constantly used in countless other construction
applications.

28. Features/How it Works
 In order for air to transmit power, it needs to be compressed or increased
to a higher pressure. When air is compressed it is given energy that can
provide power for machinery, usually through the use of pistons pushing
the compressed air back and forth.
 Boyle’s law indicates that the volume of gas (such as air) increases when
the pressure is decreased at a constant temperature. Because of the
nature of compressed air, it is inevitable that some energy will be lost in
the process.
 This loss of pressure is caused by the friction of air as it travels through
pipes or hoses, therefore making the size of the pipe/hose a primary
factor in maximizing energy.
 Several air compressors are usually used in conjunction with one another
to create a distribution system that carries the compressed air as power to
different points. The air is then conceived as energy for a mechanical
tool.

29. Types of Compression
Temperatures
 Adiabatic compression occurs when the volume of air changes without a
necessary change in heat temperature.
 Isothermal compression occurs when the temperature does not change
but there is a change in the volume of air.
 Intercoolers are used in between the stages of compression to help
reduce the air temperature and remove moisture from the air.
 Aftercoolers allow compressors to cool the air after it is discharged. If
moisture is not removed from the air, it runs the risk of freezing in the
process of expanding, sometimes causing the oil used to lubricate tools to
wash away and become less effective.
 Air Receivers are also used to equalize the pulsations being produced
from the compressor. This removes any water and oil vapors that have
accumulated during the process.

30. Distribution System
 A distribution system is installed to make the most of compressed air for
large-scale construction applications.
 When compressed air travels from its point of origination to the tool in
question, the pressure drops, causing a loss of power. The distribution
system aims to reduce the loss of power using pipes that are large enough
so that pressure does not extend more than 10 percent of the original
pressure amount. Shorter hoses can be used, which means less pressure
escaping.
 When a project requires a significant amount of compressed air per
minute, an air manifold can assist with this.
 Air manifolds have pipes that are much larger in diameter and allow
compressed air to pass through different systems without the fear of
“friction-line loss”.

31. Types
 Compressors can come in many different types with select features. They
can be either stationary or portable.
 Stationary compressors are best used for applications that endure long
periods from a fixed site, whereas portable ones are used on sites where
there is constant movement.
 Portable compressors are made so with the use of rubber tires, steel
wheels or skids and are powered by gas or diesel engines. The most
common type of portable compressor used for construction projects is the
rotary screw compressor.
 Compressors can provide a flow of power that is intermittent, also known
as positive-displacement, or a continuous flow of power, which is seen
in centrifugal and axial flow (for fluids).

32. Positive-displacement
Compressors
 Rotary Screw Compressors
Rotary screw compressors are the most common compression systems used
for automobiles. They consist of two helical rotor screws to push gas (air)
into a small environment. The air is compressed when it enters the confined
space allotted for it. The advantages of this type of compressor are its light
weight, compactness, and low maintenance. It is best suited for
applications that involve air-powered tools that require a more uniform
flow of power.
 Reciprocating Compressors
Reciprocating compressors achieve compression with pistons that
reciprocate inside tandem cylinder(s). This type of compressor is used when
high compression ratios are needed without a high flow rate. Reciprocating
compressors usually power devices that require lower speeds.

33.  Rotary Vane Compressors
Rotary vane compressors have blades located inside the
rotor that slide in and out of pockets. The Rotor blades
are what achieve compression. Rotary vane compressors
can have multi-stages, where the preferred pressure is
produced after several stages. It can also come in
portable or stationary compressors.
 Scroll Compressors
Scroll compressors have spiral vanes to compress air. In
this scenario, one of the vanes are stationary while the
other moves, creating an energy of compressed air.

34. DRILLING
EQUIPMENTS
DRILLS
PERCUSSION
DRILLS
ABRASION
DRILLS
FUSION
PIERCING
DRILL BITS
DETACHABLE
BITS
FORGED BITS

35. DRILLING
 DEFINITION- The process of making a
hole in hard materials such as rocks and
earth.
 COMPONENTS –
 Drill- Type of tool which holds the drill
bit and rotates it to provide axial force
to create a hole.
 Drill bits- Cutting tools used to create
cylindrical holes.

36. TYPES OF DRILLS
 PERCUSSION DRILLS
1.JACKHAMMER OR SINKERS 2.TRIPOD DRILLS
3.STOP HAMMER 4.DRIFTERS
5.CHURNS OR WELL DRILLS 6.PISTON DRILLS
7.WAGON DRILLS
 ABRASION DRILLS
1.BLAST-HOLE DRILLS 2.SHOT DRILLS
3.DIAMOND DRILLS
 FUSION PIERCING

37. PERCUSSION DRILLS
 Jackhammer or Sinkers- Air operated drill,
mainly used for drilling vertical holes.
 Tripod drills- Mounted on tripod to provide
sufficient stability,used for very hard rocks.

38.  Stop hammers- Thrust end to hold the drill against the work and usually
used for “up” holes.
 Drifters- Similar to jackhammer, but so large that it requires
mechanical mounting.

39.  Churns or Well drills- Reciprocating
Drill consisting of a long steel bit
mechanically lifted and dropped
to disintegrate the rock.
 Piston drills- Drill rod is securely
fastened to the piston and travels
the full length of the piston stroke.
 Wagon drills- Drifter mounted on a
mast supported by two or more
wheels used to drill holes at any
angle from down to slightly
above horizontal.

40. ABRASION DRILLS
 DEFINITION- Grind rock into small
particles through abrasive effect of bit
that rotates in hole.
 TYPES-
1.Blast-hole drills
2.Shot drills
3.Diamond drills
 Blast hole drills- Rotary drill consisting of
steel pipe drill stem on bottom of which
is roller bit that disintegrates the rock as
it rotates over it.

41.  Shot drills- Rotary drill whose bit consists of a steel pipe with a
roughened surface at bottom.
 Diamond drills- Rotary drill whose bit consists
of metal matrix consisting a large number of
diamonds disintegrating the rock while rotating.

42. FUSION PIERCING
 Recent development in drilling holes for blasting purpose.
 Produced by burning a mixture of oxygen and flux bearing fuel, such as
kerosene at the end of a blow pipe.

43. DRILL BITS
 TYPES OF DRILL BITS-
 Detachable bits- Removable from the drill when required.
 Forged bits- Made up of single length of drill steel and are available
at several shapes.

44. DRILLING PATTERNS
 Selection of drilling pattern varies with the type
and size of the drill’s used, depth of hole, kind of
rock, quantity, rapidity of the explosive & amount
of steaming.

45. BLASTING
 DEFINITION- The process of
breaking rocks into smaller
pieces by use of explosives.
 TYPES OF EXPLOSIVES-
 Explosives based on chemical
nature
 Explosives based on availability

46. EXPLOSIVES BASED ON CHEMICAL NATURE
 High or detonating explosives-
Process is extremely rapid, almost
instantaneous.
 Low or deflagrating Explosives- Low
velocity of burning and produce
pressure by progressive burning.

47. EXPLOSIVES BASED ON AVAILABILITY
 Powder explosives- Slow burning , slow acting and low strength
explosives made either from potash nitrate or sodium nitrate.
 Disruptive explosives or Dynamites-
Available in various sizes and
strength. Approximate strength
is specified as a percentage of
ratio of weight of nitroglycerine
to the total weight of a cartridge.

48. DETONATORS
 DEFINITION- Cylindrical metal shells close
at one end having 6.8 mm dia & 50 mm
height.
 The ignition of detonator is done by
blasting fuse or electric ignitors.
 Following is required for electric
ignition:
1. Detonator.
2.Power source-dynamo.
3.Circuit line-iron or copper wires.
4.Electric ignitor-comprising 2 supply wires
detonator shell and priming charge.
5.Line testing apparatus-galvanoscope or
measuring bridge.

49. FIRING CHARGE
 common practice to fire several holes using
parallel circuit,series circuit or combined parallel
and series circuit

50. FUSES
 Fuses are required to ignite
explosives.
 They are in the form of a small rope
of cotton with core of continuous
thread of gun powder.
 The rate of burning is about 1
cm/sec.
 They enable the person firing the
charge to move to a safe distance
before the explosion takes place.

51. BLASTING CAPS
 DEFINITION- Small explosive
device used to detonate a
larger, more powerful explosive
such as dynamite.

52. TOOLS FOR BLASTING
1.Dipper 2.Jumper
3.Priming needle 4.Scraping spoon
5.Tamping bar
 Dipper- Used to drill hole to the required depth.
 Jumper- Used to make blast hole & more effective in boring a nearly
vertical hole.
 Priming needle- Used to maintain the hole while tamping is done & is in
the form of a thin copper rod with a loop at one end.
 Scraping spoon- Used to remove dust of crushed stone from blast hole.
 Tamping bar- Used to tamp the material while refilling a blast hole.

53. PROCESS OF BLASTING
1.The blast holes are made and
cleaned by using the tools.
2.The charge of explosive placed
at the bottom.
3.Remaining portion is filled
with clay and tamped.
4.Fuse is inserted, kept
projecting 15-20 cm above the
rock surface.
5. Thereafter free end of fuse is
fired by detonator.

54. Transporting and handling of explosives
1. Dynamite and detonators should be
kept separately when storing and
transporting.
2. Vehicle carrying explosives should
carry a warning sign and operated with
care.
3. The smoking or the carrying of
matches and lighteners etc., should
not be permitted on or around a
vehicle transporting explosives.
4. Wiring on motor-truck used for moving
explosives should be heavily insulated.
5. Explosives should be stored in dry
ventilated bullet proof and fire
resistant magazines, away from
buildings and roads.

55. Thank you