[fsmith61]

Hi Anthony,
I will be changing the bellville washers for the tool retention
on a Toyoda FHN50II NM6027
I have ordered the washer set from Toyoda...Is there a service
manual with instructions for changing these out..... any
information with the orientation, number of,
and stacking direction of the washers would be a great help...

[sagespecialized]

I have done a few of these...
Pull the drawbar and take a measurement of the total stack up length at compression, write it down.
I lay a big piece of cardboard out to draw on. As you take each washer off take note of the concave/ convex side and draw it's orientation on the cardboard, your essentially making your own blueprint as you pull each washer and denote the concave/ convex side. when your done it should look something like:
))((()))(()))((())) etc...When you have all the washers back on tighten the nut until you reach your stack up length that you wrote down initially and you should be good to go. We did grease each washer during reassembly also.

There is no manual that I know of for this info.

Good luck.

[neilw20]

sagespecialized.
I note you have shown stacks with ((())(()))(((
Did you really mean that one lot only had (( instead of ((( ?
For many bellville washer sizes above a certain thickness stacking more than in pairs can reduce the fatigue life.
This is from a manufacturer spreadsheet calculator I use.
See attached. You fill in the yellow fields your self.
I have found safe deflection deflection limits to ensure service life is as required.
The accuracy of these calculations have not been verified, but match closely to any measurements I do.

[fsmith61]

Thanks for taking the time to comment.

I have found many of the washers broken and
impossible to make a diagram to reflect the direction
and number of washers.
I think this is common, we have seen broken washers
when other machines need them changed out.
The other machine manufacturer had step by step
instructions from a service manual for the procedure.

I was hoping the Toyoda guy would help or at least
comment, I may not have posted correctly.

[neilw20]

Give me following and I will see how it calculates.

1. ID:
2. OD:
3. Thickness:
4. Relaxed height:
5. Number of washers:
6. Compressed height of whole stack:
7. Relaxed Height of whole stack:
8. Expected number of cycles:

Fill in as many as possible, or use the ,XLS calculator I posted.
If the washers are breaking, some limits are being exceeded.

[sagespecialized]

The drawing I drew was an example of how I document which direction and how many washers stack up that way. It was not correct in how many were stacked etc...that needs to come from inspecting each washer as it comes off the draw bar and noting it accordingly..

[neilw20]

The reason I posted the calculator was to assist figuring why they are failing.
1 too many cycles.
2 squeezed past their rated value.
3 poor stacking arrangement can lead to reduced life.
4 inadequate lubricant.
Any or all of the above.
Look for microscopic cracks ID and OD. Cracks radiate from punching burrs.
Never mix old and new.
Never mix different batches.
Only run dry if single stacked.
More than double stacked will reduce fatigue life.

[dpuch]

I have replaced these on our FA-400 machines. What I know is that the stacks are ALWAYS the same number in a set. If you have 3 ((( then all the stacks in each direction will be of 3 washers. There will not be any stacks with a different number. Doing so would result in the smaller stacks completely flattening before all the others and cause it to fail much sooner.

On our machine the stacks were something like this (from memory, so may not be exact)
)))((()))((()))((( | )))((()))((()))((( | )))((()))((()))((( || )))((()))((()))((( | )))((()))((()))((( | )))((()))(((
Sets of )))((( x3 with a flat washer between each group. A thick larger washer in the middle, and the final group was only x2 sets.

Bottom line expect all stacks to be of the same number of washers, and this sets the force of the spring. The number of stacks sets the travel the spring can compress.
Use the spreadsheet posted above to verify what you observe taking the drawbar apart matches the specified force and travel needed to operate.