Can't get rotary mower blade to tighten

[thecoopers]

I would appreciate some direction.

Have a Kubota rotary mower (RCK60-29B).Mounts on a B2920 tractor.

Middle blade is causing a problem. It won't tighten and slips and causes noisy vibration. The other two blades are operating fine.

I have taken it off a number of times and reinstalled and can't get it to draw up tight.

The mower is seven years old. The blades have always tightened before.

Any thoughts?

 

[BruceP]

I cannot speak specifically for YOUR Kabota...but I suspect you may be missing some kind of specialized washer.

When I bought my G5200, it was a 'mess' and many little items were missing. I used the online exploded parts diagram and determined that there is a VERY special belleville washer which is used to keep the blades snug on the spindles.

A belleville washer is 'cupped' so it maintains tension when snugged down.

Perhaps you should check the online parts diagrams for your mower. You can zoom in to see all the components clearly.

 

[SDT]

I would appreciate some direction.

Have a Kubota rotary mower (RCK60-29B).Mounts on a B2920 tractor.

Middle blade is causing a problem. It won't tighten and slips and causes noisy vibration. The other two blades are operating fine.

I have taken it off a number of times and reinstalled and can't get it to draw up tight.

The mower is seven years old. The blades have always tightened before.

Any thoughts?

Both of my Kubota MMMs use two Belleville washers on the blade bolts.

Check yours.

Please tell me that you are not using an impact wrench to tighten the blade bolts.

SDT

 

[thecoopers]

BruceP,

Thank you for sharing your thinking.

This very well may be the problem as there are two washers with a cupped effect. I may be installing them incorrectly.

Although, I do believe I installed all the blades the same.

I will check.

 

[thecoopers]

SDT,

I think that your thinking and a previous post are telling me correctly what to do.

I am going to check and see what the washer installation looks like and compare it to the other blades.

Thank you.

 

[vic gerbasi]

same stuff on gf1800

 

[Dave_eng]

A blade needs to be properly centered to stay tight.

A blade which has operated loose will have worn the hole a bit and also the bolt and the blade is no longer being centered and will continue to come loose.

Time for a new blade and mounting hardware.

Dave

 

[GreensvilleJay]

re: Belleville washers...
---()--------

is the correct way
NOT
---((---------

Jay

 

[Dave_eng]

re: Belleville washers...
---()--------

is the correct way
NOT
---((---------

Jay

Suggest you read the info on this link. The orientation of the two washers works both ways to achieve two different goals. Nested provides 2 x the clamping force of one washer.

Opposed, as you are suggesting, provides twice the deflection but only the clamping force of one washer.

www.bellevillesprings.com/stacking-disc-springs.html

Dave

 

[saratim2020]

To keep bolted joints tight, we can choose from many methods. The most common is the addition of a locking device between the rotating part (nut) and the parts being secured (i.e. bus bars). That locking device often is a belleville washer. Such a device does not meet all locking device necessities, however. Enter, the Belleville washer. The Belleville is a disk spring that applies weight to the connection once you clamp down on it with the appropriate amount of force. The advantage of this washer is that it applies compressing pressure along a continuous arc pattern, instead of focussing it at one point the way a split-ring lock washer does. While you should use a belleville washer only at the nut end of the connection (normally), you can use Belleville washers in tandem. One at the nut end and one at the bolt head side. This is a common way to use these washers, especially when gathering bus bar. You can get it from Albany County Fasteners because it provides the best quality materials.

 

[SDT]

Suggest you read the info on this link. The orientation of the two washers works both ways to achieve two different goals. Nested provides 2 x the clamping force of one washer.

Opposed, as you are suggesting, provides twice the deflection but only the clamping force of one washer.

www.bellevillesprings.com/stacking-disc-springs.html

Dave

According to the Operator's Manuals for both of my Kubota MMMs, (( is correct, whereas () is not.

SDT

 

[mikester]

If the bolt/spindle isn't stripped, do you block the blade and use a torque wrench?

I slide a pice of pipe on the blade I'm working on and do the final torque by hand. If I block a different blade then the belt tension isn't enough to hold the other spindles in place for torquing.

 

[MOOTS]

Bolt, splined spacer, ((, blade, deflector cup.

That's the proper orientation on our F3680's, F2690's and ZD331.