Tyre maintenance in open cast mines

TYRE MAINTENANCEIN

OPENCAST MINES

CHANDAN CHAMAN

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”

Function of Tyre

•Carry a load

•Guide or Steer the Vehicle

•Transmit engine or brake torque

•Absorb Shock

•Roll

•Last as long as possible

Understanding Tyre!RADIAL TYRE

Understanding Tyre!BIAS PLY TYRE

Radial vs Bias PlyRADIAL

• 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

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!

Common failures•Punctures

•Cuts

•Cut Separations

•Turn Up Separations

•Tread/Belt Separations

•Heat Separations

•Impact Breaks

•Over Deflection

Repairable

Non-repairable

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

Factors affecting tyre’s lifeMACHINE 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


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


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.



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.


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


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)

Tyre maintenance : Tyre MatchingSome 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.

3%

6%

LOADER


3%

1%

RIGID DUMPER


1.5%

1.5%

2 %

Tyre maintenance : Tyre MatchingARTICULATED DUMPER

Tyre maintenance : Tyre Rotation

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.

Tapered wear due to faulty alignment

Machine maintenance : Alignment

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.

Machine maintenance : Rock Ejector

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.

Site Condition: Operator HabitThe 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).

Site Condition: Payload Position

Correct payload position

Site Condition: Overload

Effect of the degree of overloading on the service life of a tire

Overload (%) Reduction in tyre service life (%)10 1520 3030 50

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


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


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


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


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

Storage of tyreTires 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.

Storage of tyreNew 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.

Storage of tyreMounted 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.

THANK YOU

[email protected]

Technology

Tyre maintenance in open cast mines