1. 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

2. 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.

3. 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

4. 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

5. 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.

6. 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

7. 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

8. BRIDGESTONE TYRE

9. 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

10. 27XR49 TYRE (USED IN 85T DUMPER)
BRIDESTONE OTR TYRE
27XR49 TYRE
(USED IN 85T DUMPER)
1A : Standard Structure
E : Earthmover

11. 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.

12. 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.

14. 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.

15. Principles of Construction
The Bias tyre
and
The Radial tyre

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

17. 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

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

19. 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

20. 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.

22. 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.

24. 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.

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

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

30. 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.

32. 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)

33. 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

34. Radial tyre
Bias tyre

35. 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.

36. 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

37. 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

38. 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

39. 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

40. 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.

41. 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

42. 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

43. 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

44. 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.

45. Excess loads will result in reduced tyre performance

46. 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

47. 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.

48. 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.

49. 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.

50. OTR TYRE CARD

51. 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.

52. 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.

53. 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.

54. 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

55. 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.

56. 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.

57. 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.

58. TYRE DEPTH GAUGE

59. DEPTH MEASURING MARK

61. BRIDGESTONE
MICHELIN

62. 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.

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

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

65. Improving Performance Increasing Profitability
Extending tyre life
Improving Performance
Increasing Profitability

66. THANK YOU