Deck Vibration

nandillion

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I have a 42 inch black yardman (model 13AN772G729) with severe deck vibrations. I have removed blades and deck still vibrates. Visual inspection indicates that the blade spindles are true.
Any ideas as to what could be causing the vibration?
Also the mower deck hangs very low, even on the highest setting it cuts very short.
 

bertsmobile1

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The late model deck mounting is very secure and rarely gives much trouble, just make sure that the pins on the rear mounts are through the holes and fully home.

Pull the bonnet off and engage & dissengage the PTO a few times watching the engine.
If it looks like it is shaking, check the mounting bolts for tightness & chassis for cracks eminating from the mounting holes.
Have a close look at the engine pulley. check that the center bolt is tight and that the pulley spins true

If all is well then pull the deck off.
Flip it upside down and check the 4 legs of each spindle housing for cracks.
While it is upside down grab the tip of each blade and try to rock it up and down, you should not be able to .
Pop some 2x4" on the ground and flip the deck back right way up.
Slip the belt off and spin each spindle looking & listening for rumbles.
Do the same with the two idler pulleys also check them for flat spots, even the slightest flat can make the deck dance

Also check your belt carefully for splits and more particular for missing bits. these will also bounce the deck a bit.

As for the deck height, you adjust it by moving the lifting rod to a lower hole then balancing left right with the slip joint on the left side of the deck.
If that nut comes loose the left side will drop quite a bit and this will also make the deck shake a bit.
Once you have it level left right the songle draw bar at the front will need to be shortened to keep the right attack around 5mm.

This set up is prone to excessive wear at the hole where the lift rod connects to the lift bar and also at the other end of the lift bar where it pivots on the tractor body.
I am forever welding them up & redrilling the holes
 

nandillion

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The problem is solved. Thanks for your input.
The problem was with the left hand pulley which had moved half a notch on the spline on the spindle and not evenly such that the pulley was slightly off center and creating a slight out of balance. This probably happened when a rock was hit.

Low deck was corrected by putting the lifting rods on the right holes and tightening the front draw bolt.

Thanks again.

The late model deck mounting is very secure and rarely gives much trouble, just make sure that the pins on the rear mounts are through the holes and fully home.

Pull the bonnet off and engage & dissengage the PTO a few times watching the engine.
If it looks like it is shaking, check the mounting bolts for tightness & chassis for cracks eminating from the mounting holes.
Have a close look at the engine pulley. check that the center bolt is tight and that the pulley spins true

If all is well then pull the deck off.
Flip it upside down and check the 4 legs of each spindle housing for cracks.
While it is upside down grab the tip of each blade and try to rock it up and down, you should not be able to .
Pop some 2x4" on the ground and flip the deck back right way up.
Slip the belt off and spin each spindle looking & listening for rumbles.
Do the same with the two idler pulleys also check them for flat spots, even the slightest flat can make the deck dance

Also check your belt carefully for splits and more particular for missing bits. these will also bounce the deck a bit.

As for the deck height, you adjust it by moving the lifting rod to a lower hole then balancing left right with the slip joint on the left side of the deck.
If that nut comes loose the left side will drop quite a bit and this will also make the deck shake a bit.
Once you have it level left right the songle draw bar at the front will need to be shortened to keep the right attack around 5mm.

This set up is prone to excessive wear at the hole where the lift rod connects to the lift bar and also at the other end of the lift bar where it pivots on the tractor body.
I am forever welding them up & redrilling the holes
 

zbuilder

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Can you please explain "off center". I don't understand how a pulley can be off center when it assembles over a shaft with liitle to no slop. Unless the bushing or bearing is worn, the belt contact faces should always be on center (concentric) with the I.D. I'm asking because I have a similar problem with a brand new Husqvarna 42" rider just purchased 2 weeks ago (July 2020). When I engage the blades the idler pulley is vibrating which makes the deck & the steering wheel vibrate pretty noticeably.

Thanks

The problem is solved. Thanks for your input.
The problem was with the left hand pulley which had moved half a notch on the spline on the spindle and not evenly such that the pulley was slightly off center and creating a slight out of balance. This probably happened when a rock was hit.

Low deck was corrected by putting the lifting rods on the right holes and tightening the front draw bolt.

Thanks again.
 
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Rivets

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