Large convex washers for blade

[smhardesty]

OK. I guess I'll run this out there and see if I'm really off base. I got a mower in today and it had a pair of convex or domed washers holding the blade on. It's been a LONG time since I've seen a mower with this type of contraption. The way they WERE on, was one stacked on top of the other and both on the bolt side of the blade. I didn't realize what they were until I had the bolt and washers in my hand. I always thought those two convex washers were supposed to be mounted with one on each side of the blade, center of the dome out. Then, as you tighten the bolt, the outer edges of the washers start to squeeze together to create a miniature vise.

So, am I all wet, or is that the correct way to use those convex washers?

 

[Rivets]

Personally I would never mount two bevel washers either one on each side or stacked. My machine shop experience says when mounting a blade it should go, adapter, blade, washer and bolt, in that order. Any other way the second washer is defeating the purpose of using a bevel washer in the first place.

 

[Hammermechanicman]

Those are Belleville washers. You don't use them on both sides. You only use them on one side.

 

[Rivets]

Sorry, I used the old farts spelling.

 

[smhardesty]

Those are Belleville washers. You don't use them on both sides. You only use them on one side.

OK. Just searched for Belleville washers. Yes, that's exactly what these are. So, why would somebody have put two on? This isn't the first time I've run into these. It's been a long time, but I distinctly recall having had mowers come in my shop when I was in the biz several years ago and they had two of the washers on them. One was always on top of the blade and one on the bottom side. That's why I was thrown off with this one having two, but stacked on the bottom side. I think I might have just had two, or maybe three come in when I was in the biz before

Any idea what somebody would do that? Will two grip tighter if one on top and one on bottom? I'm just trying to figure why I happen to have run across more than one mower having two on the blade. This one is the first time I've seen two stacked on bottom? Any reason for doing that? I might actually have run across mowers that had been serviced by the same shop years ago and they did the double washer thing fir some reason. I'm just throwing ideas out for why I've seen more than one mire with two washers. Kind of weird.

Also, just how long ago did they stop using Belleville washers on mower blades? I never saw any while growing up and we went through a good number if push mowers on the farm.

 

[Rivets]

I doubt it was factory installed with the blade mounted between two washers. Probably a DIY guy who thought ”if one is good, two is better”. Think about it, if you sandwich the blade between two washers, you have a smaller surface contact area between blade and adapter. If you stack them you can no longer squeeze the washer, because it will double the thickness. Stopped seeing them when adapters changed by adding alignment pins and they found that split lock washers would work and they saved two pennys per unit.

 

[bertsmobile1]

Check to see if the threads are worn.
Most likely as others have said a DPO.
Some mowers do use multiple bevelle washers ( to my surprise ) the F2400 Kubota has 2 washers stacked together ( not opposed ) on the blades which I suppose was cheaper to use the lighter washers doubled than making a new thicker one .
Then again they are long thick & heavy blades that need to be kept onto the shafts.

 

[ILENGINE]

Actually murray would stack two belleville washers between the blade and the bolt. Some Kubota Z turns use the double belleville washer stacked between the blade and the bolt. Seem like there is a couple units out there that use one on top and on under the blade.

 

[smhardesty]

This has been a heck of a learning experience. I've read through all your comments and did a bunch of Internet research. In short, everybody is right. These things can be used in all sorts of different configurations, depending on what they were securing, and in some cases they recommend not using them. According to the image below, I think those two washers were SUPPOSED TO be stacked. If I'm reading that right, stacking two washers would pretty much double the gripping power of a single one. They wanted to be sure that blade was tight. That's just a guess. But, for whatever reason, I'm changing it back the way it was tomorrow, first thing.









.

 

[Rivets]

Now that I see that we are talking about large equipment and flipping the washers, my assumptions were not quite on. I thought the OP meant installing the washers cupped together straight to the adapter or shaft. Need to have more coffee before replying. Don’t remember ever seeing two washers used on Murray products. Sorry for my mistake.