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tthp design questions

Discussion in 'eXmark' started by dobehap, Nov 2, 2003.

  1. dobehap

    dobehap LawnSite Senior Member
    Posts: 292

    Dear ExMark,

    I have few questions about my new 36" tthp.

    1. I have noticed a high pitch "dsing" on occasion when the machine is in usage.
    Upon closer examination, I figure the sound is comming from the pumps belt tentioner that on occasion comes in contact with the pulley. If you look at it from the side, the clearance between the tensioner and the pulley is very small. Is this a flaw in design, or is it normal? Or is this unique only to my machine?

    2. The manual blade engage lever. Lately I have noticed it to snap back (disengage the blades). I have checked the belt tension, and its withing the +/- 16th of the indicator, so its not that. The only thing that I have noticed is the shape of a rod that goes up to the lever, perhaps it need to be further bent for adequate leverage beyond the "center point" (if you know what I mean)

    3. Is there a "risk" of running the hydro pumps comletely open? What I mean by this is this: The machine was designed to use the pumps with set limits. I understand the limits are there due to ECS grips control, as well as good ballance between the forward and reverse speeds.
    What I want to know is- is there a risk of damaging the hydro pumps if I udjust the grips to go further down, allowing the pumps to go faster.
    I dont know if I made myself clear, but for instance- there is a very little play on how far down the pump moves when in reverse possition, because when you squese the handle- there is only so little space you have to squese and thats it. But if you manually move the pump in reverse, then you can see that it WILL go in reverse much faster.
    Just want to know if its safe. I want to increase the speed of my tthp.

    Overall, thanks for a great product.
  2. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258


    Wow! It's Monday and you’re going to make try to think first thing this morning.

    The blade engagement thing has me really thrown. You'll need to take the unit in and get that one inspected by the dealer. The only thing I can figure is that if the lever is a little loose or if it's slightly bent (happens once in a while in the welding process) that the linkage is getting hung up on the lever once in a while. The linkage could always lay against the tubing that acts as the pivot for the lever and the stop for the linkage.

    The pump drive thing is throwing me off a little as well. Is the chain making contact or is the idler arm or the spring?

    If it's the chain it's an easy fix that you can perform or have the dealer fix it when he's looking at the blade engagement. If the ring for the cold start kit (chain and ring assy) is one or two links too far out it will allow the chain to dangle and make contact once in a while. The simple fix is to mark the location of the ring or count the links and move it one link inward on the chain.

    As far as tweeking the control I would try it. What you’re describing is the dead band. This allows you to put the neutral locks on with out stroking the pumps into reverse. It also gives you that neutral location on the drive levers so you’re not hitting reverse when you don't want to.


  3. dobehap

    dobehap LawnSite Senior Member
    Posts: 292

    Your manual brake uses the same mechanism. You have your lever that pivots on the bolt. As you engage the breaks, you feel tension (it wants to spring back) but once over the "hop" it locks in there tight.
    As for the blade engage, it worked flawlessly for a month, its just starting to happen, and the only thing that makes sence is the rod that connects from the handle to the connecting coupler is bent, or it is easily bent....its almost as you should use a thicker gauge for the rod. I'll take it in to the dealer, but I have mixed feeling about it...we'll see.

    This was my first thought as well, and I played with those chains ...well I took the darn thing off to be sure. So its not the chain. The part that I'm talking about is the PART that has this chain attached to it. Now this part that has the chain attached to it comes in contact with the pulley that right above it. If you look at it, it has a 16th of an inch clearance. Therfore little vibration make it come in contact (metal to metal make a noise) It happens occasionally. Is this just a bad design, or its only my machine that has a defect. Please ask if I'm still not clear.

    Ok Terry you completely lost me here, First you say that you WOULD try it, then your explanation made no sence to me

    Side Note:
    I'm a little hesitant taking this to my dealer because my dealer is like 1 hour away from me, and the one time I dealt with him he was very frendly and nice, but as far as Technically goes, thats another story.
    So if I can do it myself, I would like to.

    Thank you.
  4. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    That's a typo on the last one. It should say I would NOT try it. Don't try to adjust, modify, tweak or tinker with the drive linkages. 99% of the time you'll only create a bigger issue that will take a qualified tech a good deal of time to correct.

    I went out and looked at the pump drive idler where the chain attaches. If your certain that is where the contact is being made it should be an easy fix but I'd still like you to take the unit in just in case. Chances are that the mount for the chain may be slightly "tweaked". It would be the first I've heard of but it is entirely possible. If that's the case it may have been that ways since day one. The reason I want it looked at is to make sure you don't have an issue with the pulley or the bearing in the pulley rather than with the arm.

    Is the blade engagement disengaging or simply doesn't have the same "snap" it used to?


  5. dobehap

    dobehap LawnSite Senior Member
    Posts: 292

    It doest both. The blade engagement disengages and doest have the snap to it. Preatty much at a point where the machine is not usable.
  6. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258


    I might have one more possible cause for what you’re seeing but you'll need to take to the dealer for repair if I'm correct.

    There is a possibility, in theory anyway that if the pivot for the clutching pulley came loose from the engine deck that it could generate similar symptoms.

    If you want my honest opinion the unit really needs to go into the dealership. Without being there to look at it and take things apart we’re just guessing from here.


  7. dobehap

    dobehap LawnSite Senior Member
    Posts: 292

    I will take the unit in,

    I will post updates.
  8. dobehap

    dobehap LawnSite Senior Member
    Posts: 292

    took the unit it,

    For the manual pto lever, they just re-bent the rod. I have no clue how it could possible just bend??? I'm always careful with it. If the metal has softened, them re-bending it will make it even weaker, ah, will see.

    For the high pitch noise, they could not hear it, since it happened very rarely. So nothing they did about that.
  9. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258


    I'm glad to here they found the problem.

    Generally when a linkage is bent it's not uncommon for the operator to not know how it happened. That's usually because they weren't around the machine when the linkage got bent.

    Most often you can trace these things back to the trailer. Often bent linkages occur either when the units aren't strapped down and they roll around or when the straps cross one of the linkages.

    Please let us know if you have any other issues.


  10. weedwoop

    weedwoop LawnSite Member
    Posts: 75

    I own a tthp 48" that about 6 years old and have been very pleased. I have however, had a problem with the blade clutch that is simular but a little different than what you guys are discussing. I can,t keep it in proper adjustment. I used the adjustment nut untill the rods bottomed out, cut the ends off one of the rods to get a little more and changed the clutch belt. What I figured is happening is that the bends that are in the rod, over time start to straiten and cause the rod to get longer. I replaced the rods with new and that helped for a while, but now even with the rod very tight i can't get the adjustment indicators lined up where they should be. Are there other parts or possably the whole clutch that should be replaced. The mower probably has about 1500 hrs. and has been very good to me so I would not mind spending money on it as long as I was sure it would correct the problem. Thanks.

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