994D - Seleccion de Llantas

8/16/2019 994D - Seleccion de Llantas

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TIRETIRESELECTION GUIDE

TIRE USE AND SELECTION CRITERIA

994D



994D

DETERMINING PROPER INFLATION PRESSURES

CALCULATING TON-MILE PER HOUR (TMPH)



994D

DETERMINING PROPER INFLATION PRESSURES

CALCULATING TON-MILE PER HOUR (TMPH)


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SIZE - These factors should

be considered when

choosing the correct tire size

for the 994D:

• whether overall width from

outside to outside of tires isless than the bucket width

(tire protection)

• the 994D’s operating loads

• whether taller tires are

needed for extended dump

clearance, 195/240 ton (177/218

metric ton) size trucks

• existing loader tire inventory

STRENGTH - strength indexindicates the tire’s ability, or

inability, to carry a given load

at a given speed. The

earthmover tire industry uses

three different strength index

systems: ply ratings for bias

tires, star ratings for radial

tires, or ISO load index and

speed symbols.

SPEED CAPABILITY - tire

type, tread pattern and tread

depth have direct influence

on the tire’s speed capability.

Not fully understanding and

respecting speed limitations

will cause heat-related

separations, and ultimately,

premature tire failures.

TIRE TYPE - the 994D tire

typically features a cut

resistant/ultra abrasion/roc

service tread type. These

compounds are generally

suited for work machine

applications and slowermoving transport machines

where there is a risk of

cutting, hacking and

penetrations. For transport

machines, compounds are

changed to increase speed

capabilities, but tread

abrasion and cut resistanc

is reduced.

TREAD PATTERN - the more

open tread design permits

greater average speed

capability. The larger tread

lug volume on wheel loade

tires holds more heat. The

greater amount of tread lug

volume reduces speed

capabilities, but improves

tread life.

TREAD DEPTH - wheel

loader tires typically are

rated as L4 (Rock Deep

Tread) or L5 (Rock Extra

Deep Tread). The deeper

tread reinforces and protec

the tire, but reduces the

speed capability.

GENERAL TIRE

CHARACTERISTICS

994D TIRE SELECTION

This guide is designed to help you evaluate

your choices and decide which tires will best

meet your production needs. Used in conjunction

with the advice and know-how of your Caterpillar

dealer and your local tire supplier, it can be a

powerful management tool in getting the most

from your wheel loader operations.

TIRE FACTORS

Three major factors need to be considered

when making tire selections: tire characteristics,

the machine, and the jobsite.

When selecting tires for the 994D, factors

other than tire characteristics must be considered.

The machine and job site characteristics are also

important because the wrong situations can lead

to excessive wear and decreased productivity. By

following the standards and guidelines set forth in

this manual, you will be better equipped to make

the appropriate tire selection for your application

and job site.


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USING INFLATION TABLES

The following information (shown in Table 1) demonstrates use of the tire manufacturers’ inflation tables. Pressures

for each application may need to be varied from those shown and should always be obtained from the tire suppliers.

Tire Load Capacities (Per Tire) Cold Inflation Pressures

Manufacturer/Model Load Kg 450 480 510 550 580 620 650

MPH KPH Load Lb 65 70 75 80 85 90 95

Bridgestone/Firestone Static * 257,500/117,000 268,500/121,750 279,500/126,500 291,000/132,000 304,500/138,000 315,500/143,000 326,000/148,00050/80-57 SRG DT LD 5 8 * 161,000/73,000 167,800/78,000 174,600/79,000 182,500/82,500 190,250/86,250 197,000/89,400 204,000/92,500

Bridgestone/Firestone Static * 295,000/134,000 308,000/140,000 321,000/146,000 333,000/151,500 345,000/157,000 357,000/162,000 368,500/167,500

49.5/85-57 SDT LD 5 8 * 187,000/85,000 195,000/88,500 203,000/92,500 211,000/96,000 218,500/99,500 226,000/103,000 233,500/108,000

Bridgestone/Firestone Static * 305,500/134,500 319,000/145,000 332,000/151,000 345,000/157,000 357,500/162,500 369,500/168,000 381,500/173,500

53.5/85-57 SDT LD 5 8 * 193,500/88,000 202,000/92,000 210,500/95,500 218,500/99,000 226,500/103,000 234,000/108,000 241,500/109,500

Goodyear Static * 267,000/121,000 277,500/125,500 288,500/130,500 300,000/138,000 314,000/142,500 326,500/148,000 333,000/151,000

52/80-57 HRL D/L-4G 5 8 * 171,000/77,500 182,000/82,500 185,500/84,000 193,000/87,500 201,250/91,250 204,000/92,500 210,500/95,500

Michelin Static(front) * 264,600/120,000 274,680/124,595 284,760/129,167 299,880/136,026 312,500/141,750 325,000/147,420 337,680/153,150

55/80R57 XMINED2 10 16(rear) 146,630/66,500 152,300/69,083 157,973/71,657 186,478/75,514 173,600/78,745 180,600/81,920 187,600/85,100

5 8 * 176,400/80,000 182,700/82,873 189,000/85,730 198,450/90,017 207,000/93,895 215,285/97,653 308,000/139,700

LB/KG

Table 1 For further explanation, see “Importance Of Proper Inflation Pressure”.

Bridgestone/Firestone50/80-57L4

Bridgestone/Firestone49.5/85-57 SDT LD L5

Bridgestone/Firestone53.5/85-57 SDT LDL5

Goodyear52/80-57 HRL D/L-4

Michelin55/80R57 XMINED2


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The 994D comes with standard 36 or 44 inch (92 or 113 centimeter) center-

mounted rims. The center-mounted base design reduces deflection and stress levelsin critical areas such as the flange and base back sections. The Caterpillar rim is

more durable and weighs less than competitive rims. Finite element analysis shows

stress levels are 15 to 20

percent less in critical

areas than in other rim

designs. Cat rims are

machined and shot-

peened in critical flange

and seat areas to further

reduce stress.

THE MACHINE

The 994D comes with standard 36 or 44 inch (92 or 113 centimeter) center-

mounted rims. The center-mounted base design reduces deflection and stress levelsin critical areas such as the flange and base back sections. The Caterpillar rim is

more durable and weighs less than competitive rims. Finite element analysis shows

stress levels are 15 to 20

percent less in critical

areas than in other rim

designs. Cat rims are

machined and shot-

peened in critical flange

and seat areas to further

reduce stress.

THE MACHINE

Flange

Rim Base

Lock Ring

Bead Seat Band

Mounting Ring

CAT CENTER-MOUNTED DESIGN RIM


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GROUND PRESSUREThe following shows a ground pressure comparison of the various

tires available for the 994D wheel loader. The 994D has lower ground

pressure than competitive wheel loaders using the same tires. The lower

pressures of the 994D equal longer tire life and better flotation in soft,

underfoot conditions.

THE MACHINE WEIGHTThe importance of accurate vehicle weight cannot be

overemphasized. Without it, precise tire loads cannot be known and

without precise tire loads, overload or underload conditions can occur,

possibly causing problems. The Front Axle Weight table shows typical

empty machine weight and distribution. Actual machine weights may

vary depending on optional equipment, including tires and chains.

Contact Contact PressureArea (empty) (loaded)

in.2 /cm2 psi /kg/cm2

Goodyear 52/80-57 1,958/12,625 59/4.1 95/6.7

Bridgestone/Firestone 49.5/85-57 2,480/16,000 47/3.3 75/5.3

Bridgestone/Firestone 53.5/85-57 2,862/18,460 41/2.9 65/4.6

Michelin 55/80R57 3,162/20,400 37/2.6 59/4.1

Bridgestone/Firestone 50/80-57 1,869/12,060 62/4.4 100/7.0

Front Axle

TIRE PROTECTIONAnother important aspect is protecting tires with the proper size

bucket and/or wings. The Tire Protection table below shows the amount

of tire protection available depending on tire and bucket sizes.

Also available are low- and high-profile bucket wings that add 24 in. to overall bucket width.

Tire 49.5/85-57 53.5/85-57

Bucket Width (in./mm) 222/5650 245/6220 222/5650 245/6220

Width Over Tire (in./mm) 207/5265 207/5265 215/5449 215/5449

Bucket Protection Per Side (in./mm) 7.5/192 19/478 3.5/101 15/386

EMPTY STD. MACHINEMACHINE W/RATED PAYLOAD

Operating Weight (lbs./kg) 421,600/191,200 497,600/225,700

Axle Split (% F/R) 55/45 75/25

Front Axle Weight (lbs./kg) 231,880/105,160 373,200/169,275

994D RIMPULL

CONTROLThe 994D features a

rimpull control and left pedal

operation that allows

operators to match rimpull to

working conditions, which

greatly improves tire life. Four

different settings allow your

operators to match rimpull

levels to job conditions with a

simple turn of the dial.

Std. Lift, 23 yd. 222 in. Bucket, 53.5/85-57 tires


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COST PER HOUR EXAMPLE:Suppose the current tire life average on a 994D in a coal mine application is 6,000 hours. The price of Brand X is $35,000

per tire or $140,000 total. This equates to an hourly tire cost of $23.00.

Now suppose a local Brand Y dealer contacts the customer about replacement tires for the 994D. The price of these

tires, though, is about 40 percent higher than Brand X’s, but they come with a guarantee of 10,000 hours. Is this a good

investment for the customer?

The total price for Brand Y’s tires is $200,000 (40 percent higher), but expected tire life is 10,000 hours. The hourly tire

cost is $20.00: a savings of $3.00 per hour. So it is a better investment. In fact, in this example, a Brand Y tire life in excess of

at least 8,700 hours would result in savings when compared to the Brand X tire.

This example provides an economic analysis

standard 994D with tires only, versus the addition

chains. If current tire life without chains is 2,500

hours and considering the listed assumptions, fro

axle cost would equal $20/hour. To achieve the

equivalent breakdown point by adding chains, tir

must equal 3,751 hours. Front axle tire cost woul

decrease with tire life in excess of 3,751 hours.

TYPICAL TIRE LIFETire cost for the 994D varies widely because of tire life ranges. Typical Tire Life table summarizes

ranges currently achieved with the 994 wheel loader. These hours are derived from numerous customer

surveys and represent typical tire life estimates in different applications. Tire life varies from site to site

based on tire selection, vehicle and jobsite management.

Application Location Tire Life

Coal Mining North America, Australia, South Africa 5,000-10,000 hours

Metal Mining North America, Brazil, Australia 3,500-8,000 hours

Diamonds Botswana 6,000 hours

ECONOMIC ANALYSIS

Equivalent Front Axle = Fr

= 3,751 hours Tire Life w/Chains ( $20- $6.67)

The loading area’s surface and condition are important factors on tire life. Imbedded or loose rocks

increase cutting or impact breaks. Poor drainage leads to mud and chuck holes. These result in tire

spinning, fast wear, cuts and increased fuel usage. Environmental problems such as heavy rain, heavysnow and a wide range in ambient temperatures can also affect tire life.

THE JOBSITE

BIAS PLY TIRES• Manufactured with multiple nylon plies• 1-4 bead bundles are used on each side

• Plies run at an acute angle to the centerline• Fabric or steel breakers are added under the tread for

reinforcement and bruise resistanceRADIAL TIRES• Single ply of high-strength steel cords run at a 90-degree angle

to the tread centerline• High ply turn-up around the bead strengthens the sidewall and

improves response to steering commands• 2-6 steel belts are placed under the tread• Radials deflect more than bias models, providing better traction,

flotation and mobility

TIRE CONSTRUCTION: BIAS PLY VS. RADIAL


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99 D TIRE CHAIN ECONOMIC ANALYSIS

ASSUMPTIONS: STEPS:Tire Cost = $25,000 each or $50,000/axle 1. Tire life without chains is 2,500 hours

Chain Cost = $30,000 each or $60,000/axle 2. Tire cost is $50,000/2,500 = $20/hour

Fixed Chain Life = 9,000 hours 3. Tire life break-even point:

Front axle chain cost = $60,000/9,000 = $6.67/hr tires versus tires with chains

CHAINS–COSTThe use of chains is

difficult to justify except

under a few conditions.

When tire life is

extremely poor for

various reasons, chains

can reduce total tire

and front axle costs.

Care should be taken to

assure rolling diameters

still conform to SAE

standards. The

additional weight of

chains may:

• increase fuel

consumption

• slow the machine,

reducing productivity

• increase wear on

power train

components, raising

operating costs.

In high operating

cost applications, the

savings with using

chains may offset the

cost and effects of their

additional weight. For

some tires and chain

selections vehicle

modifications are

required.

re should be

taken not to exceed the

Gross Vehicle weight

rating of the machine

when adding chains and

other attachments.

$40.50

$39.00

$37.50

$36.00

$34.50

$33.00

$31.50

$30.00

$28.50

$27.00

$25.50

$24.00

$22.50

$21.00

$19.50

$18.00

$16.50

$15.00

$13.50

$12.00

$10.50

$9.00

$7.50

$6.00

$4.50

$3.00

$1.50

$0.00

1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 9000 10000

2 3

1 4

Tires with Chains

Tires w/o Chains

Front Tires Only

C o s t P e r H o u r

Tire Cost

Chain Cost

Fixed Chain Life

$25,000 ea.

$30,000 ea.

9,000 hr.


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The 994D tire suppliers provide specific maximum

speed limit recommendations for empty tramming

applications (i.e. face to face, face to shop, shop to

face). As with TMPH, these speed limits help prevent

tire overheating while the 994D is in motion. The

following summarize these recommendations.

GOODYEAR - 52/80-57 HRL D/L 4-G

For a maximum tram distance of 7.5 miles

(12.1 kilometers), limit the empty loader speed

to 4.25 mph (6.85 kph) (1st gear) if the loader has

been operating. If the loader has been down for

two or more shifts it can be driven at 8 mph

(12.9 kph) (2nd gear) for up to one hour.

OTHER TIRE SPEED INFORMATION

Allowable Working Speeds

for Empty Machine Tramming Only

Construction Standard Conditions: Ambient Temp = 100˚ F (38̊ C)

3 miles

(< 1.61 km) (1.61-4.83 km) (>4.83 km)

Nylon/Steel 15+(24+) 8(13) 5(8)

Nylon/Nylon 15+(24+) 10(16) 5(8)

Case 1: Ambient Temp = 80˚ F (27˚ C)

Nylon/Steel 15+(24+) 10(16) 5.5(9)

Nylon/Nylon 15+(24+) 15(24) 6(10)

Case 2: Ambient Temp = 40˚ F (4˚ C)

Nylon/Steel 15+(24+) 15+(24+) 7(11)

Nylon/Nylon 15+(24+) 15+(24+) 7.5(12)

Note: These speeds are with OTD = 153/32nds. Maximum working speeds

change for different ambient temperatures and tread depths.

Firestone - 49.5/85-57 and 53.5/85-57 SDT


9/13

MISCELLANEOUS INFORMATIONRETREAD

Tires for possible retreading must have more tread

left than on completely worn tires to protect the casing.

Tires damaged by heat and bursting, as well as damaged

on the bead, can neither be repaired nor retreaded. Only

cutting and cracking of tires are repairable. Retreading

should not be considered for high speed, overloaded or

under inflated tires. The best recapping candidates are

tires which had fast tread wear. Reports state retread

prices are 60 percent of new and carry the same warranties

Life of retread tires is about 90 percent of new.

TIRE MATCH - (PER SAE J2204)

Tires on the same axle must have a circumference/diameter

within three percent of each other. Circumference/diameter

between front and rear axle tires must be within six

percent of each other.

Michelin - 55/80 R 57 XMINED2Unrestricted Allowable Average Speed >5.0 mph (8km/h)

For each hour time period, the 994D/XMINED2 may trave

a total distance of five miles, with no maximum speed limit.

All average speed limits are based on one hour of travel.

Note: On reaching the allowed time, the 994D must be parked for the rest of the hour.

Maximum Time Allowed Total Distance CoveredSpeed At Maximum Speed In One Hour

(mph/kph) (minutes) (miles/kilometers)

5/8 indefinite 5/8

6/10 50 5/8

7/11 43 5/8

8/13 37 5/8

9/14 33 5/8

10/16 30 5/8

11/18 27 5/8

12/19 25 5/8

13/21 23 5/8

14/23 21 5/8

15/24 20 5/8


10/13

IMPORT N E OF PROPER INFLATION PRESSURE

WHY SUCH LOW INFLATION PRESSURESIN THE REAR TIRES?

Low inflation pressures make the front tires not work ashard; the rear tires’ greater traction and enlarged footprintwill contribute to the total work done by the loader. Inaddition, spinning will be reduced, decreasing treadwearand the tire’s susceptibility to related cuts and damages.These factors will extend front tire life.

The rear tires will operate with reduced casing tension.If a tire is overinflated (or underloaded), its casingexperiences higher levels of tension, making it moresusceptible to related damages such as shock or impactruptures A “softer” tire can more readily envelop the

objects, such as rocks, that might otherwise damage orweaken the tire’s casing.

IN SUMMARY, LOWER INFLATIONPRESSURES OFFERMANY ADVANTAGES:

• increased traction through a smaller rolling radius andlarger footprint

• prolonged life of all tires through increased tread wearand reduced cut and impact damages

• improved repairability and treadability • reduced rim and wheel breakage • reduced machine and repair cost • reduced loading area maintenance

LOADER FRONT AXLE LOADSThe first step to assure proper tire inflation is to calculate

the maximum weight the loader’s front axle can experience. I

inflated for this condition, the front tires will not be overloademaximizing the life. The maximum front axle load occurs whe the loader tips and the rear axle loses contact with the grounThe front axle bears all the loader’s weight and the load whiccaused the tip. This tip occurs in the static condition. Load iexpressed as:

Maximum Front Axle Load =Static Tipping Load + Loader Operating Weight.

Referring to the inflation pressure tables, under staticconditions (or static front for Firestone), find the load and thecorresponding cold inflation pressure at which the front tiresshould operate.

EXAMPLEOne 994D equipped with 53.5/85-57

(L-5) tires and a 23 yd3 (21 m3) bucket Operating weight = 421,600 lbs.

(191,200 kg)

Straight static tipping load = 275,100 lbs. (124,760 kg)

Maximum Front Axle Load = 275,100 lbs. + 421,600 lbs.= 696,700 lbs. = 348,350 lbs./tire

124,760 kg + 191,200 kg =315,960 kg = 157,980 kg/tire

LOADER REAR AXLE LOADSCalculate the maximum rear axle load the loader will

normally experience. Anytime material is in the bucket, weigwill be transferred forward; the maximum rear axle load occuwhen the bucket is empty. For the 994D, the empty axle weigdistribution is approximately 55 (front) and 45 (rear).

Refer to the inflation tables to determine rear tire inflationpressures. The maximum rear axle loads will occur when the

loader is moving, 5 mph (8 kph) or slower is typical for the 994Most tables do not include the lower loads experienced on th994D’s rear axle. Therefore, consult with tire manufacturers.

EXAMPLE (CONTINUINGPREVIOUS EXAMPLE)Operating weight = 421,600 lbs. (191,200 kg)

Maximum Rear Axle Load = 45 percent of 421,600 lbs.189,720 lbs. = 94,860 lbs./tire

45 percent of 191,200 kg =86,040 kg = 43,020 kg/tire

UNDERINFLATION.An underinflated tire will deflect too much. A tire that is too underinflated can cause:

• excessive sidewall flexing • spotty or uneven tread wear • sidewall radial cracks • ply separation • loose or broken cords inside tire • fabric carcass fatigue

OVERLOADING

Overloading tires will lead to premature tire failure. Ifinflation psi is not adjusted for heavier loads, failures willoccur: tread and ply separation, disintegration of thecarcass and inner liner, radial sidewall cracking andexcessive chafing.

Adjusting tire pressures to compensate for overloadswill exceed the carcass strength, causing impact breaks,cuts, rapid wear and fabric fatigue.

When encountering excess loads, cold inflationpressures must be increased to compensate for higherloads. For each one percent increase in load, the inflationpressure must be increased by two percent. Tiremanufacturers should be consulted for proper tire inflation pressures.


11/13

TON-MILE PER HOUR (TMPH)*

A tire generates internal heat as it rolls and flexes. Over time, the tire can develop enough heat to exceed the rubber vulcanizing temperature (as low as 93˚ C or 200˚ F) and reverse the vulcanizingprocess. The tire can then lose strength and fail. The heat generated

within a tire at the rated pressure depends on:

• ambient temperature• weight the tire carries• tire construction• speed the tire travels

The Ton-Mile per Hour (TMPH) formula predicts the tire temperaturebuildup. The TMPH system rates tires according to the amount of workpossible from a temperature standpoint. It utilizes the product of load xspeed to derive a temperature buildup index.

Available tires for the 994D have a Tire TMPH rating from 125 to 280,depending on the tire construction and type. The Tire TMPH can bematched to the Site TMPH using these relationships:

Site TMPH = Average Tire Load x Average Shift Speed

Average Tire Load = Empty Tire Load + Loaded Tire Load2

Average Shift Speed = Round Trip Distance (miles/kilometers)x Number of Trips per ShiftTotal Hours per Shift

If the Site TMPH exceeds the Tire TMPH, tire failure can occur.

LOAD AND CARRY TMPH EXAMPLE

Standard lift rated bucket payload = 38 tons (34.5 metric tons)Operating weight = 211 tons (191 metric tons)

Empty weight distribution (front/rear) = 55/45%Loaded weight distribution (front/rear) = 75/25%

Empty (211 tons/191 metric tons)

Front (55%) = 116 tons/axle (105 metric tons/axle) = 58 tons/tire (52.5 metric tons/tire)

Rear (45%) = 95 tons/axle (86 metric tons/axle) = 47.5 tons/tire (43 metric tons/tire)

Loaded (249 tons/225.5 metric tons)

Front (75%) = 187 tons/axle (169 metric tons/axle) = 93.4 tons/tire (84.5 metric tons/tire)

Rear (25%) = 62 tons/axle (56 metric tons) = 31.2 tons/tire(28.2 metric tons/tire)

Average Tire LoadFront (58 + 93.4/52.5 + 84.5) = 75.7 tons/tire (68.5 metric tons/tire)Rear (47.5 + 31.2/43 + 28.2) = 39.4 tons/tire (35.6 metric tons/tire)

*Tire manufacturers may use different terminology for TMPH

For wheel loaders, the front tires are always more heavily loaded than the rear tires. For TMPH calculations, use the heaviest load conditions. this case, it is 75.7 tons (68.5 metric tons).

As an example, assume a 994D is being considered in a hopper loadinapplication. Distance between the stockpile and the hopper is 150 feet.Potential cycle time for the 994D is one minute. The total shift time is eighhours and assume a job efficiency of 83 percent (the 994D works 50 minutper hour).

Number of trips per shift = 8 hrs x 50 min per hr/1 min per trip = 398 trip

Round Trip Distance = 150 ft. x 2 = 0.057 miles5,280 ft./mile

45.7 m x 2 = .0914 km1000 m/km

Avg. Shift Speed = Round Trip Distance (miles) x Num. of Trips per shifTotal Hours per Shift

Avg. Shift Speed = .057 miles x 398 trips = 2.84 mph8 hours

.0914 km x 398 trips = 4.55 kilometers8 hours

Site TMPH = Avg. Tire Load x Avg. Shift Speed = 75.7 tons (68.5 metric tons) x 2.84 mph (4.55 kph) = 215 TMPH for the Site (311.7 TKPH)

Tire TMPH for the 994D ranges from 125 to 280. A tire should be selectedwith a Tire TMPH rating greater than 215.

TRUCK LOADING TMPH EXAMPLEAs in the previous example, the average front tire load is 74.1 tons.

Distance between the muckpile and the truck is 2.2 tire revolutions or 8feet (26.8 meters). Potential cycle time for the 994D is 0.67 minutes (40seconds). The total shift time is eight hours and assume a job efficiencof 83 percent (the 994D works 50 minutes per hour). Assume there arealways plenty of trucks available to load.

Number of trips per shift = 8 hrs x 50 min per hr/0.67 min per trip = 597 tri

Round Trip Distance = 88 ft. x 2


12/13

www.CAT.comPrinted in U.S.A

© 1998 Caterpilla

PRODUCTIVITY YOU CAN FEEL. Choosing the correct tires is vital to achieving top productivity for

your jobsite conditions. This guide is an important resource in getting the most from your wheel loader tire investment. You

and your operators will feel the productivity as you get more done, faster throughout every shift. And you’ll feel it on your

bottom line, with lower replacement costs and less downtime. See your Caterpillar dealer today to put this productivity to

work in your operation.

AEDK0267


13/13

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994D - Seleccion de Llantas