Lazer drive idler spring failures

Discussion in 'eXmark' started by rdsellen, Oct 13, 2007.

  1. rdsellen

    rdsellen LawnSite Member
    from Houston
    Posts: 8

    The drive idler pulley springs are failing on my Lazer CT (LCT4418KC / serial # 496517) due to fatigue cracking at the hook. I am on my third spring in less than 3 years. When I discussed with the dealer, he did't have any advice -- so I bought two more springs.

    Does anybody else have this issue? If so, please respond to this post so we can constructively bring it to Exmark's attention.

    My machine is in residential service and has 165 hours on it. It runs very well, and I follow all the rules on disengaging / engaging PTO at idle and half speed respectively. There is no noticeable noise or vibration. The failures are sudden and are all fatigue cracks at the hook. The belt is in great shape-- and is never damaged by the spring failure. I know Exmark does not want to hear this, but sure seems to me there is an issue with the metallurgy of the spring. I have the last old (broken) spring -- and would be happy to send it to Exmark for failure analysis.

    My dealer is a great bunch of guys -- but they didn't have much intererst in my spring issue -- but he sure had plenty of springs in stock -- hum. The dealer was skeptical that it was a part issue. I hope Exmark takes this seriously. I am starting to wonder if the spring vendor stopped stress relieving the part post fabrication? This would save a few cents -- but If so, this is darn shame for such an otherwise terrific machine.


    Russell D. Sellen
     
  2. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Russell,

    I approved your post to see if anyone else is having the same issue. I've also forwarded your post on to some of our experts here at the factory. I'll let you know what I find out ASAP.

    Later,
    Casey
     
  3. rdsellen

    rdsellen LawnSite Member
    from Houston
    Posts: 8

    Thanks for the support. I appears I may have to eat my words on the spring vendor's fabrication as the root cause of the failure. I have attached a digital photograph of the immediate area of the failure. Upon a cool headed review of the data, it appears that the spring has been very cleanly "filled" as if cut by a very fine bladed hack saw. It is very smooth and at a slight angle to perpendicular to the fracture. After being cut half way, the spring failed. This seems more plausible as the failures are aways on the front or fixed end of the structure vs on the idler end. It looks like the bolt that forms the fixed end support for the spring has a slot cut into it which must be with vibration cutting the softer spring.

    Is this support bolt a replaceable part? If so seems like we should give this a try and maybe even put some sort of Teflon wear sleeve over the bolt. Seems this would prevent future failures.

    What do you guys think and sorry for being a tad huffy. This thing is very inconvenient part to have fail in the north 40.

    Russell D. Sellen

    failed drive Idler spring upload.jpg
     
  4. rdsellen

    rdsellen LawnSite Member
    from Houston
    Posts: 8

    Dear Exmark and forum:

    The idler spring bolt which mounts to the frame has a groove cut about half way thru the bolt -- it was next on the list to fail. The idler end spring attachment appears to be cutting a groove into the slot which supports the other end of the spring. This level of wear seems odd for a residential machine with < 200 hours. The machine runs very smoothly at idle and full throttle. Of course, I have not checked the drive assembly for excessive vibration with the blades engaged.

    I would appreciate any help Exmark can provide in both fixing and preventing reoccurence of these issues. I expect we will need to replace the idler arm next.

    Thanks

    Russell D. Sellen

    Idler spring bolt.jpg
     
  5. rdsellen

    rdsellen LawnSite Member
    from Houston
    Posts: 8

    Dear Exmark:

    I have replace the bolt with a 3/8"x2" bolt. I added a steel sleeve and washer in an attempt to spread the forces over a larger area and thereby reduce the tendency to cut the bolt and spring.

    Please see attached digital photo of the assembly.

    I have more words to eat, my commentary on the level of vibration was from observing the fixed end of the spring which in fact does not vibrate. However, the idler end of the spring does vibrate with a peak to peak amplitude of about 3/8". The frequency is a linear function of engine RPM and pretty fast at full throttle. This is not surprising that this is cutting grooves in the idler arm and the bolt end. I do think the sleeve on the bolt end has stabilized this end for now.

    I have check for trash in the belt -- and have used compressed air to clean the webbed part of the belt and pulleys. I check the movement of the idler with the spring off and it moved very smoothly. I greased the idler fitting prior to reconnecting the spring.

    I am at a loss for what to do next. But if we don't do something, the sawing motion of the spring relative to the idler arm end will eventually cut this end and either the spring or idler arm will fail.

    Russell D. Sellen

    modified replacement idler spring bolt.jpg
     
  6. ECS

    ECS LawnSite Bronze Member
    Posts: 1,733

    I have a 52" Lazer HP. The first year (2005) I went through 8 springs and two bolts. My first spring went withing a week of purchasing the machine. Last year I went through a couple more springs. This year another one.
     
  7. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Russell,

    Breakage of the idler pulley spring can be attributed to numerous factors. A repetitive failure of this component would indicate there is more coming into play than just a faulty spring or otherwise. At the same time I can say that the plating of the spring does make the spring to become more brittle. You may wish to have your dealer contact the factory to obtain a raw spring without the plating, which may very likely correct the issue. The photo you had posted is typical of failures and does not indicate any specific cause.

    As mentioned previously, there are numerous factors that can cause the failure of the spring. These factors ultimately result in excessive stress/vibration of the spring, which results in spring failure. Your Exmark dealer has training and experience that can be beneficial in determining and correcting the cause of these repetitive spring failures. If you would like your dealer to take a look at the drive system and check for the presence of these causes, please have your dealer contact the service department so that we may review a "checklist" of items to be inspected, if needed.

    Exmark stands behind the products we manufacture and will provide full support to correct any problems that may be experienced. Aside from the spring problem, thank you for providing the positive feedback regarding your experience with our product. I'm sure we can correct the spring problem and make future use of your Exmark more "terrific" than the past.

    KC via Exmark Customer Service
     
  8. rdsellen

    rdsellen LawnSite Member
    from Houston
    Posts: 8

    Dear KC

    Thanks for your advice -- I think you are suggesting there is something not quite right with my machine IE go thru the check list?

    I have found only two or three similar posts with multiple spring failures -- so it must not be a weakness in the design or else everybody would be squawking. Per your advice, I will make an appointment with the dealer to go thru the check list. They are Triangle Lawn in Beaumont TX. I will print out the "spring string" and bring it with me.

    Was Exmark surprised at the condition of the bolt? IE chicken or the egg? (all your comments were on the spring). Also, since this seems to a problem peculiar to my machine or at least a pretty limited issue, should I be dealing directly with Exmark service via email vs the forum?

    Thanks again

    Russell D. Sellen
     
  9. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    rdselllen,

    I've always been an advocate that the usage of this forum is quite limited. We can answer simple, non-technical questions here, but if you have an odd-ball or major problem it is always best to work w/ your dealer or directly w/ us. So yes, I would recommend you to get in touch w/ our Customer Service department if the dealer can't get the situation worked out.

    1-800-667-5296

    Thanks,
    KC
     
  10. juspayme

    juspayme LawnSite Senior Member
    Posts: 299

    i have a 2000 25 60 with 2700 hours. i stock all the parts for quick reparis. last year i bet i went through 5 or 6 of those springs. this year i havent changed one. maybe a bad batch of springs. check your pully arm make sure it isnt bent up.
     

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