Alamo Industrial Versa Series Operator's Manual page 182

The cutter shaft will run out of balance if:
1. Wire, rope, string, rags, etc., around the cutter shaft, are holding the knives in a folded back position.
Remove such foreign objects and be sure all knives are free to swing to the extended position.
2. Knives are missing or broken. Replace missing or broken knives.
3. Knife hanger lugs are broken off shaft. This condition usually results from continued operation in contact
with large hard objects where the knife hanger lugs themselves are hitting the hard objects. Lugs should
be replaced using arc welding equipment so as not to direct too much heat in one area of the shaft.
4. Cutter shaft ball bearings are worn enough to have radial "play" in them. Replace ball bearing and other
worn parts to eliminate "play".
5. Shaft is bent. The shafts are straight within a couple of thousandths of an inch when they are made. It is
possible that they will become bent in use, such as if the shaft is hooked on a stump while the tractor is
moving forward at a good speed.
6. Shafts are operated at improper speed. Rotating shafts have what is known as a natural period of vibra-
tion. The same is true of the cutter shafts on the Flail Mowers.
The actual speed at which the harmonic will occur will vary with each mower and each installation. To avoid
this harmonic vibration when operating the mower, it may be necessary to adjust the engine speed of the
tractor up or down.
Some units have a harmonic vibration which occurs below the nominal operating speed. On these units, it will
be noticed that there is always a little vibration at a particular RPM as the mower is being sped up to operating
speed. This occurs as the shaft passes through its normal harmonic vibration point. As long as the mower is
opened at the proper speed, then harmonic vibration will not be an issue
VERSA 03/09
© 2009 Alamo Group Inc.
MAINTENANCE
Maintenance Section 4-18
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