So he did. And it is. I misread. Actually, there is a star at both
ends of the mandrel shaft...a beefy one for the blade, another smaller
for the pulley.
Just going by memory - I'm not going to go drop my deck to look :) -
there are two pulleys on the left...one for idler, another for the
blade drive belt.
On my deck there is also a large washer *under* both the left and
right blade pulleys. It's location there is kinda counter-intuitive
as usually washers go between the nut and whatever is being held on
but the reason for it being under the pulley is to elevate the pulley
so it's hub is completely on the shaft's "star". (IIRC correctly, the
washer also creates sort of a broader base for the pulley to resist
wobble.) If the washer is missing (or on top) the pulley's hub only
partially engages the drive on the shaft. Which means it would strip
Normally, they use shear pins or keys on shafts that are gear/chain/direct
drive, so if you have an abrupt stoppage, you don't damage the engine or
transmission or gears. With belt driven components, they tend to rely on
belt slip for protection.
My Cub Cadet, for example, has a shear pin on the driveshaft between
the engine and the (hydraulic) transmission.
In contrast, the Cadet's attached equipment (mower deck, snow blower etc)
are belt driven, and have (at least) two slip points: the first one being
one or more belts (there are two belts between the PTO pulley and side
blades). The second being the PTO engagement clutch.
They don't necessarily slip much - if I run the blower into a
snowbank that's too much for the 12HP engine, the engine _will_ stall.
However, it takes several revolutions with loud squealing from the belts.
At least it's not instantaneously - which could do damage.
Cadets are built _tough_. This thing is from the early 70's, and
I use it almost like a bush hog at times. It had the bearing on the
main cutter blade wear out, the two idler pulleys that feed the
mower deck have destroyed their bearings twice each, and I've had
to replace the main mower belt several times (this belt is rather
fussy. Standard V belts aren't deep enough, and I screwed up once
and got too big a pulley which caused the belt to rub). The mower
deck has had to be unbent once. Aside from that...
On the Cadet, the side blades (it has three) are run by a long
belt (never replaced that I know of) from the center pulley, and
tensioned with a idler pulley on a spring.
In the OP's case, I'd:
1) Make sure that the deck isn't bent/distorted especially on the
side of the blade that destroys its spindles. It could be getting
restricted at the blade tip and very subject to jamming, or perhaps
the spindle mount is bent out of plane with the others.
2) See if he can slacken the belt a bit.
3) If it has a slippable engagement clutch, see about backing it
off slightly. Only slightly, otherwise he'll burn it out. You
only want it to slip on a stall.
Age and Treachery will Triumph over Youth and Skill
Can't say for sure but it sorta sounds like there is vertical wobble
at the star (shouldn't be). One thing sure, hitting a stick should
*NOT* cause what is happening...I regularly hit oak roots and fallen
branches - branches up to 2" in diameter - with no damage other than
dulling the blade which is always dull anyway. I don't mow, I thresh
I've never even had debris stop the mower unless it is physically big
enough and oriented so it gets kicked up and wedged in the blade
housing. In that case, the blade drive belt slips. And smokes if I
don't shut it off. You sure your belt isn't too tight and that you
are using the correct length (BTW, belts are a lot cheaper at auto
stores). No wobble in the pulleys? All the bearings good?
Steel is not just steel. Properly heat treating the correct type
of steel makes a huge difference in the longevity of a splined
Are your replacement parts aftermarket parts? Did Sears change their
supplier of parts? Can you swap left from right to troubleshoot this
id be sure your pinching the pully good when tightening the bolt, if
pully isnt getting pinched it will wear out inside.. maybe locktight it
and tourqe it.. then recheck after you mow each time to see if its
loosening. i had a pully on a deck kept comming loose,forget now what
tractor, i got a grade 8 bolt,red locktighted it and socked it down
tighter than it should be..fixed it. lucas
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