1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
  2. ALL NEW MEMBERS READ THIS FIRST!! Thank you for joining Heavy Equipment Forums! If you are new to forums we communicate with "Threads", please search our threads to see if your topic may have already been answered and if not then click "Post New Thread" in the appropriate forum. This will allow all of our members to see your question and give you the best chance to be answered. After you've made a number of posts you will graduate to Full Member status where you'll see a few more privileges. Following these guidelines will help make this the best resource for heavy equipment on the net. Thanks for joining us and I hope you enjoy your stay!!

tire change

Discussion in 'Wheel Loaders' started by komatsukid, Sep 30, 2009.

  1. komatsukid

    komatsukid Well-Known Member

    Joined:
    Jan 11, 2007
    Messages:
    228
    Occupation:
    loader operator/plant forman
    Location:
    michigan
    The loader I use is a Cat 980g series 2. At the begining of the season we replaced both front tires leaving the rear tires at 15 and 5 percent tread. Yesterday the tire that was about 15 percent blew. We replaced it with a new tire. My question is will having three new tires and one bald one damage the machine?
     
  2. JDOFMEMI

    JDOFMEMI Senior Member

    Joined:
    Jan 4, 2007
    Messages:
    3,074
    Location:
    SoCal
    It will put a lot of stress on the drivetrain, and cause premature wear in the differential, planetaries, and the drop box. Not a good idea to run that way long.

    Running as you were, with new fronts and worn out rears was doing the same kind of accelerated wear on components.
     
  3. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    10,171
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    I've worked for companies who's colors were bare steel and rust and never was ever able to quantify any accelerated wear on drive trains. Differentials are made to allow differences in spin from side to side. Wheel loaders always seem to work the drive line wind up out. Unless you are many inches different I wouldn't even expect to see a problem.

    If you are wondering then work the machine for a couple of hours then pick up the front end off the ground with your bucket and see how much the fronts turn as they get free.
     
  4. JDOFMEMI

    JDOFMEMI Senior Member

    Joined:
    Jan 4, 2007
    Messages:
    3,074
    Location:
    SoCal
    John

    Not to get into an argument, but checking to see if the front tires are "wound up" is not telling you if they are being stressed. I have been the guy with rust colors and mismatched tires, and I can tell you there is a price to pay.

    If you really want to know, get a thermal temp gun and check component temps. Check planetaries, diffs, and drop box temps and look for overheating. If any of these is hotter than the rest, it is a problem brewing.

    Also, on the tire size difference, if you are doing a basic loader cycle, loading trucks or a hopper, and spending as much time in reverse as in forward, it will be less trouble than if you are cosistently going forward, like stockpiling, or other load and carry work.

    The loader is a 980G, so the tires are sufficiently large enough to make a big difference. Depending on the tire, a new one has 3 to 4 inches of tread. That is 6 to 8 inches larger diameter than the 5% tire he has left. A 29.5 X 25 tire is ABOUT 6 foot tall. 8 inches of height difference is equal to 26" difference in travel on the ground at that size. That means for every revolution, the worn tire is going to be skidded over 2 feet. This constant stress WILL shorten the life of the drive train. I have been there and paid that bill. If you can find any way to afford it, replace that tire so they match. you will have to anyway sooner or later, and it will save headaches from developing elsewhere.
     
  5. Gavin84w

    Gavin84w Senior Member

    Joined:
    Mar 29, 2007
    Messages:
    554
    Location:
    Australia
    SEPD0430 is the media number for Cats recomendations, give your local dealer a call and quote this and read and understand it and go from there.

    Some mismatch is OK but there are limits. Good maintenance management and monitoring will get you through to wear out with a bit of swapping around.
     
  6. DigDug

    DigDug Senior Member

    Joined:
    Dec 11, 2005
    Messages:
    577
    Location:
    Maine
    Run it. The pig is making up the difference whether you are turning a corner or your tire height is different . I wouldnt say its best practice , but your not hurting the machine.
     
  7. RWeb

    RWeb New Member

    Joined:
    Oct 1, 2009
    Messages:
    1
    Location:
    New Zealand
    It's basically the same as a car - as they recommend having front two tyres being the same and back rears being the same. Ideally having them all the same type and put on at the same time is preferred. The tyre shop for example wouldn't allow me to put a directional tyre where the other front tyre was non-directional (even though it was only for a temporary measure)

    I hate the cost of the tyres for my CAT - being in NZ and far away from the rest of the world, everything gets more expensive...though our dollar is rising against the Yen/US

    -------------------------------------------
    Vegetable Garden + Home Garden = My Garden
    WLB
     
  8. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    10,171
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    JDOFMEMI,
    I don't doubt that there will be more stain against the drive train components. However I'm quite sure that for any machine built now days that is a negligible factor. I have not found any specifications from manufacturers stating the normal operating temperatures for drive train components.

    What I was stating is that I have never been able to find any way to show that wear rates for the rest of the drive train were increased. I have also never been able to attribute a failure in the drive train to mismatched tires.

    I will say the other tires out may wear out faster from slippage. The rusty machine crowd usually doesn't have the money to replace tires in sets, particularly now days, so you do what you have money for and suffer the consequences.
     
  9. JDOFMEMI

    JDOFMEMI Senior Member

    Joined:
    Jan 4, 2007
    Messages:
    3,074
    Location:
    SoCal
    John C

    I have not seen published temperature numbers either, and I think it is because of the different operating conditions. What I have is 20 years of seeing what each machine runs in its normal enviromant. When I see a planetary, diff, or drop box run 40 degrees hotter than normal, or than the others, I am looking for a reason.

    I have seen this kind of temperature change by the changing of tires to ones that do not match close enough. The damage depends on the kind of surface you are running on. The slipperier it is, the less of a problem you will have.

    I have had to replace differentials and planetaries that were worn to the point of breaking, as well as had loaders spit out the center driveshaft largely related to mis-matched tires. I have seen it for many other reasons as well. I agree with the lack of being able to afford buying matched tires, and have been there plenty of times in that same 20 years. I have also paid the price for it sometimes, and gotten by with it others.

    A differential will allow different wheel speed side to side, but with a loader or RTD, it is the front to rear that makes the biggest difference. There is no differential action in the drop box to allow different wheel speed front to rear. A newer machine will fare better, but an old, already worn one will be more likely to have the gears pushed out of alignment due to bearing play, and result in broken or chipped teeth.

    While you may be quite sure this will not cause problems, I am offering hard experience that says it does, and I have paid the price for it several times.

    I will let the komatsu kid who started the thread decide what to do from here. We can agree to disagree and each do it our own way without any hard feelings.
     
  10. Diagonal Brace

    Diagonal Brace Well-Known Member

    Joined:
    Jan 9, 2006
    Messages:
    176
    Location:
    Winnipeg Manitoba Canada
    level Rubber

    Gavin84W says it best. If Cat already has a spec they are probably not far off the mark.
     
  11. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    10,171
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    Never any hard feelings on an honest disagreement and good points from all.

    We'll catch something else in the future that we will agree on for sure.

    Thanks!
     
  12. Gavin84w

    Gavin84w Senior Member

    Joined:
    Mar 29, 2007
    Messages:
    554
    Location:
    Australia
    Jerry is 100% on the money, Cat have a doc that tells you the % difference allowed, when you run outside that and have your diff, final drives, driveshafts all achieve short life do you think if you go back to the manufacturer they will look after you?

    Cars are a diiferent deal for the most part as they are not 4 wheel driven in most cases.

    Try something one day if you run a wheel loader and have someone lift the front tyres off the ground and see how much unwinding will occur if you run radically different tyre sizes and think how that wind up is transferred through the drive line. When you have had the pleasure of doing centre bearings and driveshafts on 992C,s in the field you may eventually understand
     
  13. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    10,171
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    Gavin84w,
    Manufacturers don't publish specs for your benefit. Their lawyers make them do it to limit liability.

    Say you have a loader in warranty which blows up a differential. The wonks don't troubleshoot the failure looking for manufacturer's defects. They are looking for reasons to deny the warranty claim.
     
  14. surfer-joe

    surfer-joe Senior Member

    Joined:
    Mar 25, 2007
    Messages:
    1,403
    Location:
    Arizona
    Long experience with large loaders and tires leads me to support JDOFMEMI. Another way to check rotation is to paint a couple of lines on the two tires to a side, them move the machine forward and watch to see if the lines stay in alignment.

    Mismatched tires increase tire wear rate, increase fuel consumption, and of course, cause a lot more internal gear and bearing wear. Can't be helped, except by keeping tire sizes as closely matched as possible.

    I appreciate that small operators may not be able to afford to replace all four tires at one time, but they can and must do better work at matching used tires to avoid a potential very expensive repair and replacement of drivetrain components. Not to mention the downtime and loss of production.

    Motor graders also share this trait on the drivers. Mismatch the tire sizes and experience the fun (not) of repairing or replacing drive chains and possibly other damaged components.

    So, komatsukid, yes, your machine will experience problems with the tire setup you describe. One simply can not predict how soon. On a newer machine, still within warranty, the manufacturer would note the discrepancy in tire sizes and deny the claim.

    Good Luck!
     
  15. Gavin84w

    Gavin84w Senior Member

    Joined:
    Mar 29, 2007
    Messages:
    554
    Location:
    Australia
    So i own a loader and i want to know what sort of difference i can run beetween tyres so i dont destroy the driveline and my Cat dealer can provide me with a guide so i don,t blow up stuff and cost me lots of money and they are not publishing that for mine or any other customers benefit? Right, now i get it.
     
  16. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    10,171
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    You can jam a wheel loader into a hard bank of dirt, pull down on the bucket loading the front tires fully at maximum torque and then usually spinning the backs. You then pull out of the bank at max torque in reverse turning the machine one way or the other and either roading the machine to a dump point or short turn to dump into a truck.

    So you mean to tell me after taking that kind of beating for many thousands of hours, that a ten percent difference in tire size will suddenly cause a final drive, differential or drive line to wear out and break. I don't buy into the theory. Yes it would be better practice to have tires close to the same diameter. I'll tell you right now the front tires will wear out much faster than the rears and I've seen in excess of thirty percent differences in diameters end to end before we swapped the fronts to the rear and ran another 2,000 hours. To put it bluntly, I've never had a failure that I could relate to that difference of diameters in the tires.

    Is the machine going to turn into scrap iron because the tires are not the same? I would want to see imperical evidence and test results before I'll be convinced of the imminent problem. I also look at the original question another way. The questioner wanted new radial tires and was looking for ammunition to use in his quest for what he wanted. I'm not ready to give it to him.
     
  17. Gavin84w

    Gavin84w Senior Member

    Joined:
    Mar 29, 2007
    Messages:
    554
    Location:
    Australia
    John, how does the rear spin when the fronts are fully loaded to max torque? In a Cat loader the torque, drive or whatever you want to call it comes equally out of the driveshafts on each side of the drop box so i don,t get how the rears can spin.

    At the end of the day i have seen and worked for busted a$$ contractors who do whatever they want and go outside accepted practices and think they get away with it. If they really kept good records and ran to known machine life cycle costings they would scare themselves, they get away with it through falsifying information and talking BS. This earthmoving game is such a small world and it filters out very quickly.

    Some similar stuff to that also filters through here onto the board and if there is one thing i hate it is people who bang on about this or that because there are a lot of people watching these boards and trying to learn to which us guys with a bit of background should try and pass on what we know and what is right.

    Flame away
     
  18. Chris5500

    Chris5500 Well-Known Member

    Joined:
    Oct 23, 2009
    Messages:
    217
    Occupation:
    Plant Mechanic
    Location:
    Australia
    Gav's right here, no two ways about it, you have equal torque out of the transfer case with no differential action between the front and rear differentials, if the rears were to "spin" you would need atleast one of the front tires to "spin" also.

    Specifications are there for a reason and should be followed kids! A bit off-topic here, but to satisfy your curiositites and to show how serious the specs are, here are the specs for a WA1200-3 (I tried to make it as simple as poss!):

    Front to rear allowable tire radius differential (<90mm)
    Rear to front allowable tire radius differential (<40mm)

    Radius of new front tire (bucket emtpy): 1781mm - Ratio F/R: 1.000mm.
    Radius of new front tire (full bucket): 1716mm - Total of -65mm deflection - Ratio F/R: 0.950mm.

    Radius of new rear tire (bucket empty): 1781mm - Ratio F/R: 1.000mm.
    Radius of new rear tire (full bucket): 1806mm - Total of +25mm deflection - Ratio F/R: 0.950mm.

    Allowable tire wear:

    Tread depth: 136.5mm.
    Allowable tire radius wear: 116mm (85% of tread)
    Tire radius at allowable tolerance: 1665mm (bucket empty)

    Front (New) and Rear (Allowable wear (worn)):

    Bucket empty - New front: 1781mm Allowable rear wear: 1665mm Ratio F/R: 1.070mm.

    Full bucket - New front: 1716mm Allowable rear wear: 1690mm Ratio F/R: 1.015mm.

    Front (New) and Rear (Allowable wear (worn)): *After loaded condition F/R are the same:

    Bucket empty - New front: 1781mm Allowable rear wear: 1691mm Ratio F/R: 0.977.

    Full bucket - New front: 1716mm Allowable rear wear: 1716mm Ratio F/R: 1.000mm.

    When the radius differential front to rear is equal to 0.925mm (1.5 times new):

    Bucket empty - Front: 1665mm Rear: 1705mm Ratio F/R: 0.977mm.
    Full Bucket - Front: 1600mm Rear: 1730mm Ratio F/R: 0.925mm.

    Front (Allowable wear (worn)) and Rear (New) (Usually this combination will never happen):

    Empty bucket - Front: 1665mm Rear: 1781mm Ratio F/R: 0.935mm.
    Full bucket - Front: 1600mm Rear: 1806mm Ratio F/R: 0.886mm.

    Enjoy the block of text.

    P.S. How's your loader there komatskid? :D