Alamo 02983328C General Information on Flail Mower Vibration

MAINTENANCE

AXTREME 03/09 Maintenance Section 4-17

MAINTENANCE

General Information on Flail Mower Vibration

EXCESSIVE VIBRATION

Vibration is a MONSTER and if allowed to continu e unchecked, can cause the complete break-u p of a machine

in a very short time.

A properly operated Flail Mower will produce very little vibration. If vibration does occur, the mower should be

stopped and the trouble corrected, as warranty does not cover failures resulting from continued operation after

something happens to cause the mower to vibrate excessively.

Vibration is caused by a rotating part which is out of balance. This could be the cutter shaft or, on those mod-

els having a universal slip joint assembly drive shaft, from the dr ive shaft.

If the two extrem e end s of the drive sh aft, (the yoke s plines which fit on the tractor power take off shaft and on

the mower gear box driven shaft), are not parallel, vibration will be evident.

This is because of the mechanics of a universal drive wherein the rotational speed thru a universal joint is not

uniform. If the ends of a universal drive shaft are parallel, the uneven rotation effect is cancelled out and the

machine being driven will be driven at a uniform rate of speed. However, if the ends are not parallel, the

uneven rot ation effect may be multiplied, resulting in a sp ee ding up a nd slowin g down of the entire mo we r sys-

tem (gear box, extension shaft, pulleys, belt, and cutter shaft) each revolution. This effect can be readily

noticed if the mower, while running, is raised to an extreme height on the tractor lift.

For smoothest operation, the tilt of the mower shou ld be adjusted (on a 3-p oint hitch, by adju sting th e length of

the top link between the tracto r an d the mower ) so that the ends of the d rive shaft are parallel when the mower

is down in operating position. Raising the mower, while running, to extreme heights on the lift should be

avoided.

To check wher e the vibration is originat ing, first be sure the ends of the universal drive shaft are parallel. Then,

if vibration is still present, remove the drive belt and run the mower. If vibration is still present, it most likely is

coming from and cause d by a b ent d rive shaft. If so, the shaft sh ould be r epla ced o r str aigh tened . If th e vibra-

tion is gone - the drive portion of the mower is running smoothly - then the vibration is probably coming from

the cutter sh aft (it could be a pulley out of balan ce or a faulty belt with a varying cross section, but this is not

likely).

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 co ntinued operation in co ntact

with large hard obje cts where the knife hanger lug s themselves are h itting the hard object s. Lugs should

be replaced using arc welding equipment so as not to direct too much heat in one area of the shaft.

4. Cutter shaf t ball bearings ar e worn en ough to h ave radial "play" in them. Replace ball bearing a nd other

worn parts to eliminate "play".

5. Shaft is ben t. The shaft s are straight within a couple of thous and ths 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.