UNIT 2.1: Routine check before machines operation Unit Objectives At the end of this unit, you will be able to: 1. Learn about the tools and equipment used for routine check-up of the jack hammer. 2. Types of jack hammer bits. 3. Inspect whether right type of chisel bit is fitted and whether the bit/point is in good order or need replacing 4. Re-shaping of jack hammer bit. 5. Blasting in mining. 6. General spare parts of jack hammer. 7. Check pneumatic connection, fittings and hose joints for Pneumatic Jack hammers. 8. Carry out pre-operational inspection of jack hammer to ensure machine is in good order and all guards, handles and safety mechanisms are fitted and operational 9. Inspect electrical cable and junction points to determine whether the cable and plug is in good order or needs replacing; Check whether the electrical lead is connected to an approved safety switch. 2.1.1 Tools and Equipment for Routine Check Without proper tool, you cannot perform any maintenance and pre-operation check. The tools used for routine check of jack hammer are not a special set of tools but the tools which generally available in the bag of a mechanic. Following are some of the most common tools found the mechanic kit: Spanner Set Spanner is used to open/close nut-bolt assembly. There are different types of spanners available in the market like: Double Ended Spanner Figure 2.1.1.1 Double End Open spanner 41
Participant Handbook Single Ended Open Spanner Figure 2.1.1.2 Single Ended Open Spanner Ring Spanner Figure 2.1.1.3 Single Ended Open Spanner Slugging Open Spanner Figure 2.1.1.4 Slugging open end spanner 42
Slugging Ring Spanner Figure 2.1.1.5 Slugging ring spanner Adjustable Spanner Figure 2.1.1.6 Adjustable spanner Wrenches Set The Wrench tool is used to provide grip and mechanical advantages in applying torque to rotate objects like nuts and bolt. These wrench are available in multiple sizes and shape. When a person has a small or large job, they can find a great crescent wrench that will help them complete the job. The identifying factor of this wrench is the angled jaw that has a fifteen degree angle perpendicular from the handle. Socket Wrench 43
Participant Handbook Figure 2.1.1.7 Socket Wrench Allen Wrench Figure 2.1.1.8 Allen Wrench Pipe Wrench 44
Figure 2.1.1.9 Pipe Wrench Screwdrivers Set A screwdriver is a tool used for turning screws. It can be manual or powered. A simple screwdriver has a handle, shaft, and tip which interact with screw head to turn or rotate it. Slot Head Screwdriver Figure 2.1.1.10 Slot head screwdriver Phillips Head Screwdriver 45
Participant Handbook Figure 2.1.1.11 Phillips head screwdriver Torx Drive screwdriver Figure 2.1.1.12 Torx drive screwdriver Robertson Screwdriver Figure 2.1.1.13 Robertson screwdriver 46
Pullers To complete certain jobs correctly a mechanic will need a variety of pullers. There are various types of pullers which are discussed next. Ball joint separator Figure 2.1.1.14 Ball joint separator Bearing Puller Figure 2.1.1.15 Bearing puller Slide Hammer 47
Participant Handbook Figure 2.1.1.16 Slide Hammers Gear Puller Figure 2.1.1.17 Gear puller in use 48
Figure 2.1.1.18 Gear puller Voltmeter A voltmeter is an instrument used for measuring potential difference between two points in an electric circuit. Analog voltmeter An Analog meter provides readings by deflecting a pointer on AN analog scale. On most analog meters, there's a rotating switch that chooses between resistance scales across the meter face. 49
Participant Handbook Figure 2.1.1.19 Analog voltmeter Digital Voltmeter Digital voltmeter provides a numerical display of voltage by use of an analog to digital converter. An analog-to-digital converter (abbreviated ADC, A/D or A to D) generally, an ADC is an electronic device that converts an input analog voltage or current to a digital number proportional to the magnitude of the voltage or current. 50
Figure 2.1.1.20 Digital voltmeter 2.1.2 Bits of Jack hammer There are mainly two types of bits used for jack hammer. CHISEL BIT Below are the some types of chisel bits which are generally used in jack hammer. Moil or Bull Point Moil points, also known as bull points, come in lengths up to 240" long. These points may be used in demolition of concrete and for slag and refractory brick removal. 51
Participant Handbook Figure 2.1.1.21 Bull point chisel Narrow Chisel Narrow chisels have a standard tip on the end and come in lengths up to 240" long. These chisels may be used in demolition of concrete and for slag and refractory brick removal. Figure 2.1.1.22 Narrow chisel 52
3 Wide Chisel These chisels may be used in demolition of concrete and for slag and refractory brick removal. Figure 2.1.1.32 3 Wide chisel Wide Asphalt Cutter Asphalt cutters are made to cut through asphalt to expose under laying concrete and can also be used for stone removal. Figure 2.1.1.23 Wide Asphalt chisel 53
Participant Handbook Clay Spade Clay Spades are used to get through hard soil or ground. They are often used for utility work and installation of in-ground swimming pools. Figure 2.1.1.24 Clay spade chisel Ground Rod Drivers Figure 2.1.1.25 Ground road driver chisel 54
CROSS BIT The cross bits can be used under any rock drilling condition, it's hardly impacted by the model of drill rig and the rock performance. Cross bit is mainly used to dig through hard rocks and fissural rock. It is mainly used for digging into mine laneway and blasting holes in all drilling works matched with the taper drill rod. For different rock, we use the different type of alloy so that the life of bits can be extend. Figure 2.1.1.26 Cross bit of jack hammer The hole in the middle of Cross bit is generally used to clean the debris of rock and mining material at the location where jack hammer is being used. Water and other fluid through the hole of cross bit. 55
Participant Handbook 2.1.3 Re-shaping of Jack Hammer bit Depending on the size of the bit it may be cheaper to just go with a new bit, compared to the time and materials to reshape the chisel. If the bit of the jack hammer is less damaged then it can be reshaped with the help of grinder. The hand grinder usually takes more time to re -shape than electric grinder. So you can use electric grinder to spare your time for other works. Figure 2.1.1.26 Electric grinder When the chisel bit is not able to be reshaped with the help of grinder, then Heat Treatment process is used. 2.1.4 Blasting in mining As high producing underground mines are getting the primary choice of global mining corporations, it's affordable to say that such mines will also need construction of serious underground developments prior to and during ore production. As a result, long underground tunnels are very common to be seen in underground mines. To suffice the requirement to dig these long tunnels in a fairly shorter period of time, there is an increasing demand to use rapid and mechanized tunneling technologies like TBMs (Tunnel Boring Machines) and roadheaders Various drilling patterns have been developed for blasting solid rock faces, such as: Wedge Cut or V cut Blast holes are drilled at an angle to the face during a uniform wedge formation so that the axis of symmetry is at the centre line of the face. The cut displaces a wedge of rock out of the face within the initial blast and this wedge is widened to the full width of the drift in subsequent blasts, each 56
blast being fired with detonators of suitable delay time. The apex angle is as close to as possible to 60 This kind of cut is especially suited to massive size drifts, which have well laminated or fissured rocks. Hole placement should be carefully preplanned and also the alignment of each hole should be accurately drilled. Figure 2.1.1.27 Wedge Cut Pyramid or diamond cut The pyramid or diamond cut is a variation of the wedge cut where the blastholes for the initial cavity might have a line of symmetry along horizontal axis as well as the vertical axis. Figure 2.1.1.28 Pyramid or diamond Cut 57
Participant Handbook Drag Cut The drag cut is particularly suitable in small section drifts where a pull of up to 1 m is very useful. Figure 2.1.1.29 Drag Cut Fan Cut The fan cut is one-half of a wedge cut and is applicable primarily where only one machine is used during a narrow drive. usually the depth of pull obtainable is restricted to 1.5 m. Figure 2.1.1.30 Fan Cut Burn Cut 58
A series of parallel holes were drilled closely spaced at right angles to the face. One hole or more at the center of the face are uncharged. This is known as the burn cut. The uncharged holes are often of larger diameter than the charged holes and form zones of weakness that assist the adjacent charged holes in breaking out the ground. Since all holes are at right angles to the face, hole placement and alignment are easier than in other kinds of cuts. The burn cut is especially suitable to be used in large rock like granite, basalt etc. Figure 2.1.1.31 Burn Cut Sequence of detonation For both fragmentation and throw, blasting efficiency depends on the delay sequence of blasthole detonation. Delayed detonation improves loadability of the complete cut, contributes to a much better strata control and reduction of blast -induced vibrations. 59
Participant Handbook Figure 2.1.1.32 Bunch blasting with Nonel tubes and detonating cord Figure 2.1.1.33 Firing of Tunnel round the Nonel (after Olofsson) 60
2.1.5 Spare parts used for jack hammer Spare parts are used to replace faulty component of a jack hammer. Bushings Mechanical bushings are sleeve shaped lining which are used to reduce the friction and wear between mechanical elements. They also facilitate to constrain and restrain the motion of the elements. There are two types of bushing in jack hammer i.e lower and upper bushing. Figure 2.1.1.34 Upper and lower bushing Seal Kits Each Seal Kit contains seals in an assortment of different shapes and sizes to replace defected seals of jack hammer. These seals generally used to prevent leakage of fluid from cylinder. These seals also withstand high pressure, extreme temperature, and transverse forces within the cylinder. 61