Tyre maintenance in open cast mines


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Tyre maintenance in open cast mines

  2. 2. What is a tyre?  From a person on the street “A round, black rubber thing that holds my vehicle up!”  From a tyre expert “a visco-elastic toroid comprised of, high modulus flexible filaments, embedded in and bonded to, a low modulus matrix, which forms an anisotropic shell structure”
  3. 3. Function of Tyre • Carry a load • Guide or Steer the Vehicle • Transmit engine or brake torque • Absorb Shock • Roll • Last as long as possible
  4. 4. Understanding Tyre! RADIAL TYRE
  5. 5. Understanding Tyre! BIAS PLY TYRE
  6. 6. Radial vs Bias Ply RADIAL • More technologically advanced solution • Offers many performance advantages • More expensive to purchase but has lower cost per hour than bias BIAS PLY • No steel used in casing or Crown • Cheaper to purchase • Generally lower life potential • Higher cost per hour than steel braced Radial
  7. 7. What we expect from a tyre? • Load carrying capacity • Speed capability • Grip (during acceleration, braking and steering) • Handling (steering response) • Good ride (shock absorption) • Durability (long life, damage resistance) • Good appearance • At a low cost!
  8. 8. Common failures • Punctures • Cuts • Cut Separations • Turn Up Separations • Tread/Belt Separations • Heat Separations • Impact Breaks • Over Deflection Repairable Non-repairable
  9. 9. Factors affecting tyre’s life TYRE MAINTENANCE • Air pressure maintenance • Tyre matching • Rotation policy and scheduled changes • Alignment • Mounting procedures • Repair procedures • Workmanship and materials
  10. 10. Factors affecting tyre’s life MACHINE MAINTENANCE Poor mechanical condition of a machine affects the service life of the tires it uses.  faulty brakes can cause excessive heating of the wheels,  incorrect alignment of the steering wheels  poorly adjusted suspension, play in the spindles, the ball joints and the pivots  Absence of rock ejector
  11. 11. Factors affecting tyre’s life Fixed factors • Type of equipment • Weight distribution • Site speed • Haul lengths • Wheel position • Ambient temperature Variable factors • Underfoot conditions • Operator habits • Payload position • Utilisation of support equipment SITE CONDITIONS
  12. 12. Factors affecting tyre’s life
  13. 13. Tyre maintenance : Inflation Inflation supports and carries the load. Tires are designed and built to deflect in service. Inflation pressures are established to assure tires deflect properly. The pressures required vary with the load, speed and type of service.
  14. 14. Tyre maintenance : Inflation
  15. 15. Tyre maintenance : Inflation Over inflation can be as serious as under inflation. Over inflation over stresses the tire carcass. • Reduces the tire’s ability to envelope irregular objects in the travel path. • Causes a loss of traction. • Makes tires more vulnerable to spin cuts and shock load damage. • Reduces flotation in soft ground. • Produces a hard ride and vehicle vibration.
  16. 16. Tyre maintenance : Inflation An under inflated tire will deflect too much leading to excessive sidewall flexing. Under inflation typically results in: • Irregular or uneven tread wear • Sidewall radial cracks • Ply separation • Loose or broken cords inside the tire • Fabric carcass fatigue • Belt edge separation
  17. 17. Tyre maintenance : Inflation
  18. 18. Tyre maintenance : Tyre Matching Tire assemblies operated as a dual pair must: • Have the same outside diameter • Be from the same brand and type • Be of the same construction (both bias or both radials) • Have comparable inflation pressures( Within 1%) • tires with the same degree of wear i.e. comparable tread depths (if used tyre are used)
  19. 19. Tyre maintenance : Tyre Matching Some degree of tolerance is however accepted for difference in diameter of tires (or with differing levels of wear) mounted on the same vehicle. For loaders • 6% between the front and rear axles; • 3% between the two tires on the same axle. For rigid dump trucks • 3% between the left and right tires; • 1% between two dual tires. For articulated dump trucks • 2% between the front and rear axles; • 1.5% between the two rear axles; • 1.5% between the tires on the same axle.
  20. 20. 3% 6% LOADER Tyre maintenance : Tyre Matching
  21. 21. 3% 1% RIGID DUMPER Tyre maintenance : Tyre Matching
  22. 22. 1.5% 1.5% 2 % Tyre maintenance : Tyre Matching ARTICULATED DUMPER
  23. 23. Tyre maintenance : Tyre Rotation
  24. 24. Machine maintenance : Alignment Alignment refers to the angle formed by the wheels on the same axle. Toe-in and toe-out lead to accelerated, uneven wear of the tire on the shoulders. The outer shoulder in the case of toe-in and the inner shoulder with toe-out.
  25. 25. Tapered wear due to faulty alignment Machine maintenance : Alignment
  26. 26. Machine maintenance : Suspension Incorrect adjustment of the suspension can lead to the overloading of certain tires. Although the wear on the tires may seem visually similar to that of an alignment fault, there is a clear difference when you touch them: there are no sharp edges.
  27. 27. Machine maintenance : Rock Ejector
  28. 28. Site Condition: Underfoot Condition  Maximum grade not to exceed 7%.  Road width to allow two trucks to pass without spillage.  Regular cleaning of loading, dumping & haul roads.  Road crown or cross fall as flat as possible and still drain. Typical road crown is 2- 4%  Curve radii as large as possible. Haul roads should be super elevated to correspond to vehicle travel speeds.  Avoid waterholes/potholes as they could hide submerged tire hazards.  Do not overwater haul roads or work areas. Wet rubber cuts more easily than dry rubber.
  29. 29. Site Condition: Operator Habit The way machines are driven can significantly reduce the service life of the tires:  inappropriate driving: sudden acceleration, repeated heavy braking, cornering at high speed;  spinning of the drive wheels (scrapers during loading, loaders at the quarry face).
  30. 30. Site Condition: Payload Position Correct payload position
  31. 31. Site Condition: Overload Effect of the degree of overloading on the service life of a tire Overload (%) Reduction in tyre service life (%) 10 15 20 30 30 50
  32. 32. For Longer Tyre Life  Never turn front steering axle tires when the vehicle is standing.  Keep off windrows. These are often present when haul roads are being graded.  Do not drive on the berm of the road.  Do not drive over spillage.  Do not drive or back over rocks at shovel or dump areas.  Avoid tire spin.  Do not overload haulage trucks. Do’s & Do Not for Dumper Operator
  33. 33. For Longer Tyre Life  Control spillage and maintain a level working pad at loading areas.  Do not overload haulage trucks.  Properly center load in bed of truck.  Station a cleanup dozer at each loading area.  Properly match shovel or wheel loader to trucks being loaded. Do’s & Do Not for Shovel Operator
  34. 34. For Longer Tyre Life  Patrol haul roads and clean up spillage.  Fill depressions and dips in the road.  Main roads where haulage speeds are highest should get the most attention.  Two graders should work roads where haulage vehicles are wider than a single grader blade.  Create and maintain road crown to provide proper drainage.  Don’t leave high windrows. Tandem patrols help to reduce grader created windrows. Do’s & Do Not for Grader Operator
  35. 35. For Longer Tyre Life  Do not overwater haul roads or work areas. This can lead to unnecessary cuts in tire treads and sidewalls.  Water acts as a lubricant for rubber.  Wet rubber cuts more easily than dry rubber.  Some watering benefits grading operations.  Excessive watering of hard packed, smooth surfaces is a safety hazard. Vehicle control/safety is reduced on a slick, wet road surface. Do’s & Do Not for Water tanker Operator
  36. 36. For Longer Tyre Life  Do not overwater haul roads or work areas. This can lead to unnecessary cuts in tire treads and sidewalls.  Water acts as a lubricant for rubber.  Wet rubber cuts more easily than dry rubber.  Some watering benefits grading operations.  Excessive watering of hard packed, smooth surfaces is a safety hazard. Vehicle control/safety is reduced on a slick, wet road surface. Do’s & Do Not for Water tanker Operator
  37. 37. Storage of tyre Tires and tubes deteriorate rapidly if improperly stored. • Improper storage conditions include: • Direct sunlight. • Heat. • Air in motion. • Ozone. • Gasoline and oil. • Dust or moisture inside tires.
  38. 38. Storage of tyre New Tyres • Store vertically indoors in a cool, dark, dry, draft free area. If tires must be stored outdoors, they should be covered with opaque, waterproof tarpaulin. • Store away from electrical devices such as motors and switches. These are a source of ozone. • Do not store in rooms with or near gasoline or lubricants • Provide CO2 fire extinguishers in tire storage areas.
  39. 39. Storage of tyre Mounted Tyres • If tires are stored on a machine, it should be blocked up. Air should be released to 10 psi (.7 bar) or less. • Protect each tire with an opaque, waterproof cover. • Machines resting on tires should be moved once a month. This prevents deflection strain on only one part of the tire. • Do not use paint to preserve tires.
  40. 40. THANK YOU chandanchaman@gmail.com