DONIMALAI IRON ORE MINE NMDC LIMITED DONIMALAI IRON ORE MINE OFF-THE-ROAD TYRES BY T.HARISH A.M (MECH) TOKEN NO: D2623 SERVICES MECHANICAL

Off-The-Road Tyre Definition: Off-the-road tyre made with premium casings and durable compounds, these tyres are built for heavy loads, solid traction and outstanding resistance to punctures.

Industry Standard Off-the-Road tyres are designed and produced to meet the commonly accepted international standards, those set by the TRA (Tyre and Rim Association) in USA, ETRTO (European Tyre and Rim Technical Organization) in Europe and/or by the JATMA (Japan Automobile Tyre Manufactures Association) in Japan

General Information Classification Effective Tyre Use a. Uses and Characteristics of OTR Tyres b. TRA Classification c. Tyre Structure Classification by Service d. Structure and Functions of OTR Tyre Effective Tyre Use Proper Tyre Selection Proper Tyre Use Tyre Maintenance

1a. Uses & Characteristics of OTR Tyres The Characteristics which Off-the-Road tyres must possess differ somewhat according to the function they must serve and the type of vehicles on which they are mounted. These differences are outlines in Table.

Type/Service Function Vehicles Main tyre Characteristics required Earthmover Transporting Dump trucks, Coal haulers, Scrapers, Trucks Heat resistance, Cut resistance, Wear-resistance, Shock burst- resistance Grader Grading, Leveling Graders Traction, Maneuverability, (Directional- Stability) Loader and Dozer Loading and Dozing Shovels, Loaders, Bulldozers Wear resistance

1b. TRA Classification Off-the-Road tyres are classified by TRA as follows, and the names of the patterns of the corresponding Bridgestone OTR tyres are described below. TRA Classification E=Earthmover Tread Type Radial Tread pattern E-1 Rib E-2 Traction VKT,VFT,VHB,VGT E-3 Rock VKT,VFT,VGT,VMT E-4 Rock Deep Tread VELS,VRLS,VALS E-5 Flotation VSJ

BRIDGESTONE TYRE

1c. Tyre Structure classified by Service and designated by Bridgestone Each Bridgestone tyre has a Bridgestone code number on it, so that it may be easily identified and serve the function for which it is made. Service BS Code No. Structure Earthmover Service 1A 2A 3A Standard Cut-resistant Heat-resistant

27XR49 TYRE (USED IN 85T DUMPER) BRIDESTONE OTR TYRE 27XR49 TYRE (USED IN 85T DUMPER) 1A : Standard Structure E : Earthmover

TYRE SIZE The size of each tyre is indicated by nominal width and rim diameter in inches and mm. Radial structure is indicated by the letter “R”. For some tyre the aspect ratio is indicated by percentage. Example: 27XR49 tyre used in dumper. 45/65-45 tyre used in loader.

1d. Structures and Functions of OTR Tyre Components Radial tyre consists of six primary components ; Belts, Tread, Sidewalls, Inner liner (Tubeless Tyres), Plies & Beads These six components are primarily responsible for the tyres fundamental characteristics.

Function of the tyre component Belts Minimize tyre deformation Strengthen the tread Prevent damage from cuts and shock. Tread Excellent traction Longer serviceability Higher resistance to cutting Sidewalls Cushion the ply from shock and cutting, and to flex & bend Inner liner It keeps the inflation pressure constant. Ply This layer maintains the inflation pressure of the tyre in supporting the load. Beads Fit the tyre perfectly on the rim, preventing the tyre from slipping out of the rim contour while the vehicle is in motion.

Principles of Construction The Bias tyre and The Radial tyre

The Bias Tyre A casing made of several plies positioned in a criss-cross manner This is a single piece construction

The Radial Tyre + A casing made of a single ply of steel cords A crown consolidated by a belt made of several plies Sidewalls and tread are independent from one another

OFF-THE-ROAD RADIAL TYRES The advantages of Off-The-Road radial tyres

The advantages of Off-The-Road radial tyres are: Greater resistance to cut penetration Greater resistance to wear High speed durability and greater loading capacity Stronger traction Better riding comfort Better fuel consumption

a. Greater resistance to cut penetration Multi-plies steel belts act as shields which provide resistance to puncturing. This means reduction in downtime for repair or replacement as well as greater safety when driving.

b. Greater resistance to wear Less distortion of triangular motion tread. Greater stiffness of the tread supported by strong steel belts restrains the movement of the tread for superior resistance to wearing.

c. High speed durability and greater loading capacity The movement of heat in the tyre will increase while the vehicle is in motion. Excessive heat built-up in the tyre is one of the biggest factors of tyre damage. The radial tyre provides great resistance to heat due to rigid tread, advanced construction, and no friction between plies. Consequently, it enhances safety and reduces heat.

d. Stronger Traction Uniform distribution of weight on ground with stiffer tread provides stronger traction than bias tyres. Operator can drive steadily and reliably.

e. Better riding comfort Operator feel less discomfort from up-down acceleration. Radial tyres offer more comfortable riding because of flexible sidewalls.

f. Better fuel consumption One of the factors most influencing fuel consumption is rolling resistance. Rolling resistance is caused by deflection of the tyre. Low consumption of fuel is achieved by minimizing rolling resistance through steady contact with the ground which results from rigidity of the tread.

Radial tyre Better mobility Better steering Preservation of road surfaces and tracks Reduced risk of puncture (lower pressure on the ground) Even and slow wear Better endurance for the casing (reduced overheating)

Bias tyre Reduced endurance of the casing (extreme overheating) Higher risks of perforation (higher ground pressure) Extreme abrasion of the center of the tread Less evenly distributed ground pressure Stamping and rutting effect on soft surfaces Reduced mobility Less reliable steering

Radial tyre Bias tyre

2. Effective Tyre Use In order to permit the effective utilization of tyres, all tyres must at first be selected properly according to the operating conditions and the type of vehicle on which they are intended for use, and then mounted, used and maintained properly.

Selection of the proper tyre Proper use of tyres Proper maintenance Effective use of tyres Reduction of tyre damage Prolonged tyre Serviceability Reduction of tyre costs Minimization of downtime

3. Proper Tyre Selection Make, model Maximum capacity of load Maximum speed and horsepower Tyre size, star rating and ply rating Type of Vehicle Climate Roads Operating speed Operating load Operating Conditions Serviceability expected Heat and cut resistance Recap ability Maneuverability Customers requirement Performance expected Correct tyre size, star rating and ply rating, type, and tread pattern Correct specifications of tyres Correct inflation pressures Selection of proper tyre

4. Proper tyre use To get the most out of tyres, tyres should be used correctly. The following points must be observed. Factor Person responsible a. Correct inflation pressure Tyre mechanic b. Specified load Shovel operator c. Prescribed vehicle speed Vehicle Operator d. Proper vehicle maintenance Maintenance team e. Full haul road maintenance Haul road operator staff

4a. Correct air inflation pressure Tyre serviceability depends on maintaining the correct inflation pressure, and this function is the responsibility of the tyre in- charge and his staff. Use the inflation pressure recommended by the tyre manufacturer. Ex: 85T Dumper (27 X R49) tyre Cold inflation pressure : 100 psi Hot inflation pressure : 110 psi

Tyre damage analysis Maintenance of correct inflation pressure is absolutely necessary. Excessively high or low inflation pressure may result in damage to tyres and drastically shorten serviceability of tyres. Typical damage to tyres resulting from improper inflation and road conditions is shown in the table.

Cuts, Cut burst Measure cut depth Inspect air pressure Serviceable Rock pierce in rubber Remove object. Repair if necessary. Inspect air pressure. Swelling tyre This is normally not -repairable. Scrap tyre. Unserviceable

Rubber chunks out Improve road conditions Rotate or Reverse tyres Avoid rough driving. Serviceable Minor / Severe Cracks Continue to use. Ensure adequate pr. Inspect. Tyre burst from shock or cutting. Scrap tyre. Unserviceable

4b. Specific Load The load on each dumper must be kept within the limits specified for the dumper. Overloading should be avoided. Problems caused by overloading listed in table. Phenomenon Resulting damage Excessive generation of heat Damage from heat Increased stress on sidewall Ply separation Excessive tread movement Abnormal abrasion Increased tension of cord Cut and shock burst Increased stress on beads Bead damage

Correct loading Avoid unbalanced loads. Protect tyres from falling stones during loading. When loading with a shovel, maintain the prescribed rate of loading, and keep weight distribution in mind.

Excess loads will result in reduced tyre performance

4c. Specific Speed. The speed of a vehicle is determined by the operator. For the most efficient, safe and economical use of vehicles and tyres, the operator should keep within the proper speed for his vehicle. Phenomenon Resulting damage Higher heat generation inside tyre Heat damage Increased abrupt braking Chipping, Bead damage Obstacles on the road Cutting, Cut burst, Bead damage Sharp cornering Irregular wear, Quick abrasion, Bead damage

5. Tyre Maintenance Company spends lakhs of rupees each year to replace Off-the-road tyres. Studies show that most of these replacements are needed because of cuts and impact injuries. If all men associated with tyres work as team then physical damage to tyres can be reduced.

5a. Tyre maintenance team work Establish a regular inflation programme. Conduct a daily hot inflation check of all tyres on machines in operation. Record and analyze problem areas on a daily basis. Leaking tyres should be repaired immediately. Calibrate pressure gauges on a monthly basis. Inspect and inflate to recommendations.

Establish a sound rim cleaning programme Establish a sound rim cleaning programme. The air seal on tubeless tyres depends on clean rims. Use new ‘o’ rings on each tyre change. Always use a valve cap. This provides positive air seal. Remove imbedded rocks and loose tread rubber to prevent cut separation. Maintain a detailed tyre performance record system and a complete scrap tyre analysis.

OTR TYRE CARD

5b. Shovel Operators team work Areas around shovels can produce a large percentage of cut tyres because of : Poor cleanup of dumper loading area. Bucket spillage. Not centering load in dumper bucket. Overloading resulting in spillage. Failure to call dozer for leveling and clean up of dumper loading area.

5c. Dumper operators team work Operator education means much more than learning to drive a dumper. Operators can make a major reduction in tyre expense by following these simple rules: Avoid jack-rabbit starts and locked-brake stops. Slow down on sharp turns. Avoid backing over rocks at the shovel and dump areas.

Analysis of cut tyres indicates approx Analysis of cut tyres indicates approx. 30% are damaged at night between the hours of 9:00 pm and 5:00 am. This is caused by poor visibility, inadequate lighting and sleepy operators. Operators should make a walk around check of tyres at start of shift and at least every two hours, watching for cuts and low inflation. Keep windshields, rear view mirrors and headlights clean for good visibility.

5d. Dozer Operators team work Spillage from end of blades in road or dump areas to be avoided. Cleated tracks cut up haul roads and expose rocks which can damage tyres. Wheel Dozer operators can perform very valuable service in reducing tyre cuts. Avoid wheel spin. This cuts treads. oo

5e. Motor Grader Team work Good blading to remove all rocks from haulage areas. Never leave high windrows which contain rocks if dumpers must cross them. Haul roads must be without dips, because dips in haul roads, with 30 kmph speed of haulage dumpers can result in an increase of tyre dynamic load factors of 1.5 to 3 times the tyre load rating.

5f. Water Sprinklers team work Over watering is a detriment because it exposes rocks imbedded in haul roads, creating tyre cutting conditions. Wet rubber cuts up to 50% easier than dry. Slick surfaces in many operations and dumper operators can lose vehicle control from skids, wheel spin or ineffective braking.

How to measure tyre abrasion The degree of tyre abrasion can be determined by comparing the groove depth of the used tyre with that of a new tyre. The difference will indicate the rate of wearing. Mean tread depth to be calculated. Depth gauge is used to measure groove depth of tyre tread.

TYRE DEPTH GAUGE

DEPTH MEASURING MARK

BRIDGESTONE MICHELIN

Repairing and Retreading Only cutting and cracking of tyres are repairable. Tyres for possible retreading must have more tread left than that on normally worn out tyres for protecting the casing. An overheated casing is a very poor prospect for repairing. Tyres damaged by heat and bursting as well as damaged on the bead can neither be repaired nor retreaded.

AVERAGE TYRE LIFE FROM APR2003 TO AUG2010 : 9594 HOURS 27XR49 TYRE PERFORMANCE AVERAGE TYRE LIFE FROM APR2003 TO AUG2010 : 9594 HOURS

Tyre Cost Cost of 27XR49 tyre used in 85T Dumper Year Value 2010 Rs. 5,83,772 2005 Rs. 3,02,305

Improving Performance Increasing Profitability Extending tyre life Improving Performance Increasing Profitability

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