AG-Meier 5' Mohawk Brave mower too much vibration

[RedRock]

Whenever I hit a sandy bump in the terrain I'm mowing, my 5' Mohawk mower starts to vibrate like crazy. So bad that it seems to strain the PTO at that point. Typically, this vibration will not subside until I throttle down to idle, and/or disengage the PTO until the mower blades come to a full stop. Then I spin up again to full RPM from a stop and the vibration is gone...until I hit the next high spot or extra dense patch of grass. This goes on and on and has become quite frustrating. I've stopped and checked to make sure both blades are extended-check, *stump jumper is not warped-check, gearbox is properly greased-check.

It seems to me that the spinning of the blades is always fine until you hit the slightest slowdown, in the case of a small sandy berm or other obstacle, small green stump, etc. it simply won't stabilize until I wind it completely down and start over again.

I've had my Mahindra dealer check it out twice now (second time with my Mahindra 2816 driving it) and they claim it doesn't do it, I'm not sure if there encountering anything in their test field significant enough to cause a brief slowdown.

I'm at my wits end with this now, have spent over $300 in hauling and inspection costs and still no resolve. Has anyone ever had an issue like this? Do I have a lemon mower? The *stump jumper has a slight warp opposite of where the blades attach but other than that there are no obvious signs of damage to blades or the carrier. Is it possible the vertical axle is loose enough or bent just enough to get out of balance only when disturbed a bit? ...and somehow spinning it down and back up again gets it in a stable groove temporarily?

 

[tree farmer]

Sorry, I can't offer any remedies to this, but you're not alone and possibly it's just the nature of the beast. I bought a used 5' Mohawk around 20 years ago that always did the same thing as yours when I hit a clump of bunchgrass or a large mole hill. I think I had every nut and bolt out of it at one time or another trying to find a cause for its violent shaking. I was fearful of it grenading my tractor every time it happened. The only thing I could figure out was that it had a fairly small diameter stump jumper plate. This made it necessary to have longer, blades on it, which were much heavier than those on most 'hogs'. When the blades hit something they tended to fold over one another, throwing it way out of balance. It did the same thing to a lesser degree when starting it up. I paid $300. for it, used it for about 17 years 'til the deck finally rusted through, gave it to a scrap collector and bought a new 6' Montana rotary 3 years ago. Never had to repair or replace anything on it, so I think I got my money out of it.:thumbsup:...Dan.

 

[johnrex62]

I cannot offer any resolution to this either, but I got a 5' Ag-Meir Mowhawk Brave and have not encountered that issue. I have backed over a pile of grass clumps that bound the blade to the point of shearing the shear bolt and I have scalped berms and hit hidden saplings big enough or numerous enough to slow my blades without actually shearing. I notice a bit of shaking with the more severe blade "stall" that lasted until the blades were back to speed, but never any vibration under any other scenario.

My cutter has performed well beyond expectations and has cut stuff I should never have attempted, including a metal fence post disquised as a giant bloodweed clump. It twisted the post into a pretzel and sliced off one of the three sides and spit the sucker out the back before I could react and still cuts. No nicks or gouges in the factory blades yet, though I don't know why not.

 

[Mikeeemo]

Check for free movement of the blades.
The blades should not bind in any way.

I had to install shims on the shoulder bolts of my mower to gain the free movement needed.

The vibration can cause damage to the gear box, if it is allowed to continue.

You can get stress fractures in the output shaft.

The shoulder bolts have to be TIGHT.
400 - 600 ft lbs on avg.

 

[RedRock]

Thanks for the responses.... my dealer tells me they still can't get it to vibrate for them so I'm going this week to see if I can show them. Transport and check out fees are starting to add up. I'm really frustrated with this now. I'm tempted to cut my losses and try to sell it to buy a different one, but how do you do that on a clear conscience.