Slow hydro's

Discussion in 'eXmark' started by Columbia Turf, May 16, 2002.

  1. Columbia Turf

    Columbia Turf LawnSite Member
    Posts: 99

    My oldest EXMARK, TT1448HP has a speed problem. I would guess this machine is 6-7 years old. (gosh, it has no hour meter)It had a new motor about 4-5 yearsago.The problem is, it doesnt have any ground speed. We have owned this unit since it was new. Can the pumps just wear out? I have complained to the dealer for a few years about thisproblem. I ran this mower yesterday and it seems it has gotten worse. Any Help???
     
  2. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Columbia,

    You've definitely got some wear in the pumps. Anything that's been running for 4, 5, 6 or 7 years is going to have wear. I doubt that this is your problem though. Most generally when I see a hydro that's lost ground speed over the years it's one of the following.

    Most common is engine rpm. Has it been checked? The 14 Kaw is a great engine but It's never been said that it has too much power and I've seen many of them loose some rpm's as they get older. Have the rpm's check and reset at your local dealer. I ran a TTHP with a Kaw this past winter with the same problem. The customer had not noticed a change in quality of cut but did notice the change in speed. Once the rpm was set the ground speed went back up and it did cut better as well. The change in the cut was gradual enough that he didn’t notice it.

    The next thing I see is usually belt slippage. This usually doesn’t effect both sides equally however. Most (not all) hydros have one particular grease zerk that gets forgotten and it's the one for the hydro belt tension idler. Pull on the cold start kit (the chain and ring on the RH side of the mower) and release it. It should snap back to full tension and you should feel no drag as it does. If you feel the pivot is a little stiff, unbolt it, clean it up with some every cloth, smear some grease on it and bolt it back in place. Then be sure to grease it once per week at the grease zerk. Normally if the pump drive idler isn't pivoting freely you'll notice the unit wants to pull slightly to the right on inclines or when pulling a riding attachment.

    How long has it been since you had a hydro filter change. If the filter is getting full or is getting plugged it can begin to starve the hydros for fluid. If the hydros aren't getting enough fluid they'll begin to slow down. Usually they'll get slower and slower the longer you run them as well until they finally stop. When that happens sometimes I get to sell you some more parts. Really expensive ones. The kind you don't want to buy so if it's been more than 12 months go ahead and have the hydros serviced.

    Check these things and let me know. It's possible the problem is in an adjustment or in the wear from the pumps but less likely.

    Thanks

    Terry
     
  3. Columbia Turf

    Columbia Turf LawnSite Member
    Posts: 99

    I think we have tried all of these sources. 1) Engine rpm, When the new motor was put on this was checked. It has been checked since then also. It is a unit with a choke/throttle cable all in one. (I dont particularily like this)I will try to have this checked again.
    2) Bet slippage, I happen to know about this grease point. My crews do sometimes forget about it however. During the winter months, I do as you suggest and take it all apart. It doesnt seem to help the ground speed.3) Filter, Changed once a year.
    I would like to get to the bottom of this. Should I consider rebuilding the pumps or wheel motors??? Do they make "kits" for either?? I dont want o buy any of those ""PARTS"" you are thinking about. I know they can get expensive really quick.
     
  4. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Columbia,

    Sounds like we've covered all of the most common issues and everything looks great. That just means we can move on to the not so common items.

    The good news is that a walk behind doesn't carry that much weight and so you don't get that much wear in the hydro components with the Mobil 1. I wouldn't suggest pulling the pumps apart. I just would be surprised if that was the problem. We use this same pump on nearly all of the riders and get thousands of hours out of them. With the maintenance your doing it would be unlikely you've got much wear internally.

    The next step is to look at the linkages. It is possible that you've gotten some wear in the linkages, motion control lever etc. that is not allowing you to fully "stroke" the pump forward. If this is the case you may be able to adjust this out however I get nervous when operators begin adjusting the hydros. Not always but far more often than not the problem either gets worse or a whole series of new problems are created. This is better left to your dealer.

    The other things we can look at are things like tires. As the tires wear they get smaller and the unit slows down. We should also make sure we're not comparing the old to the new. A few years ago we increased the forward and reverse speeds by about 1-mph.

    Last but not least we should find out just how fast your going. Here's what you do. Mark of a 100-foot run, get yourself a stopwatch and a calculator. Get a run at the starting line so your certain your up to speed before you hit the line. At that point start your stopwatch and stop it when you cross the finish line. You may want to have someone run along side and run the stopwatch. Not only will it be more accurate but possibly safer and all the other guys on the crew will get a kick out of watching the new guy chase the lawnmower. One other suggestion would be to do this on a hard surface and make sure there isn’t a lot of pedestrian traffic as well.

    The calculation is as follows distance (feet)/time it takes to go that distance (seconds) X .6818 = speed (miles per hour).

    So if it took you 9 seconds (it'll take you a lot longer) the formula would look like this:
    100/9 X .6818 = 7.58 mph

    Top speed of your unit should be about 5.3 mph

    Hope that helps.

    Thanks

    Terry
     

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