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So I'm assembling a pull up bar and its assmebly instructions look like this

enter image description here

In the parts list it mentions only one type of spring washer (quantity 4).

But it actually came with two types of washers (quantity 4 each), type1 and type2.

Am I supposed to use both of them? And in what way? Any help would be appreciated!

isherwood
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Da Mike
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    Lock washers have been proven to not provide any benefit at all, it's amazing to me that they are still produced and used. NASA had this to say about them: “The typical helical spring washer … serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lockwasher of this type is useless for locking.” – jesse_b Apr 02 '20 at 17:44
  • @jesse_b A source (link) for this information would be nice to add, if possible. – gnicko Apr 02 '20 at 17:54
  • @GregNickoloff: [here](http://hillcountryengineering.com/wp-content/uploads/2011/10/Split-Lockwashers-Separating-Myth-from-Truth.pdf) or [here](https://engineerdog.com/2015/01/11/10-tricks-engineers-need-to-know-about-fasteners/) is a start but if you just google "Do lock washers work" you will find a ton of tests and data showing they do not. – jesse_b Apr 02 '20 at 17:56
  • @jesse_b: I get it. But the thought is that someone already "googled" that to get here. For "completeness", etc. You quoted NASA so you should provide a link back to the source.... All good. – gnicko Apr 02 '20 at 18:12
  • @GregNickoloff I don't have a link handy, but I do recall reading in some NASA design standards that lock washers are explicitly disallowed. – Tristan Apr 02 '20 at 18:37

4 Answers4

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They gave you four lock washers instead of 4 locking nuts. No problem. Install the bolts as shown in the instructions. Then install a flat washer on each bolt followed by a lock washer and then the nut. Tighten as specified.

enter image description here

Picture Source

Michael Karas
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JACK
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  • Picture attribution link is supposed to be provided unless you happened to create that yourself. – Michael Karas Apr 01 '20 at 21:14
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    @MichaelKaras Sorry about that. I thought the WikiHow in the lower right of the picture did that. – JACK Apr 01 '20 at 22:24
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    On a tangent, a lock washer basically does nothing close to a lock nut. Do regular checks with this pull up bar, because your lock washers will loosen MUCH faster than a real lock nut. Replace with a real lock nut if you can; you don't want to break your neck over $10 worth of nuts. [Info about lock washers](https://engineerdog.com/2015/01/11/10-tricks-engineers-need-to-know-about-fasteners/) – Nelson Apr 02 '20 at 06:41
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    Or any second "jam" nut torqued into the first nut would lock it quite well also., – StayOnTarget Apr 02 '20 at 16:19
  • @Nelson If I don't have a real lock nut, would you advise using just the flat washer? – Da Mike Apr 02 '20 at 19:41
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    @DaMike The lock washers will be fine, I've used them in heavy machinery for 55 years and never had a problem. You will find them in probably every car built. Maybe NASA doesn't like them but you're not mounting your bar in the space shuttle. Looking at the position or your bolts if the nuts should ever loosen up you'll feel it long before they fall off. you should be doing regular checks on a bar like this anyway. – JACK Apr 02 '20 at 22:57
  • @JACK I'm not against lock washers in general. I'm against REPLACING a lock nut with a lock washer. Their performance is not the same. I don't think you went around, took out existing lock nuts, and replaced them with a lock washer for 55 years and encountered no problems. – Nelson Apr 04 '20 at 18:10
  • @DaMike Adding a second nut like UuDdLrLrSs mentioned would work too. For nuts to fail catastrophically is a little rare, so it won't suddenly break on you, but it will get loose, and you need to stop using it when it is loose. The pull up bars also don't need to fail catastrophically to hurt you. If it shifts suddenly when you're hanging on it, it can loosen it off the door frame, or slam you to the frame of the door, or you slip off and smash your head into something. Read the instructions for safety checks. – Nelson Apr 04 '20 at 18:16
  • @Nelson LOL No I did not.... but I would hope the lawyers got with the manufacturers and made them retest the differences between the two locking devices... stay safe out there. – JACK Apr 04 '20 at 19:24
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Put the flat washer on first then the split lock washer and finally the nut.

Michael Karas
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The advice from the German military shock testing establishment is to NEVER use any washer except a flat one.

It is the bolt that should be under tension and the bolt that provides the force that keeps the joint together. Spring washers, split washers and crinkle washers will eventually yield and the tension in the bolt will be lost. The joint WILL open up. At best the nut will fall off, at worst the bolt will experience shear or bending moments and fail.

JimS
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  • It would be good to have a source for this information if possible. – gnicko Apr 02 '20 at 17:52
  • That's very true for structural applications where the bolts are close to their capacity. However, for a pull-up bar even a single bolt with loose nut should be able to support the weight of a person. Though just to be safe, it's of course better to have a lock nut there. – jpa Apr 02 '20 at 18:01
  • Some of the contents of your statement seems to be accurate but others don't make any sense. For example, bolts are often in shear, that's what they are designed to do, and that is completely separate from the nut or even how tight the bolt. – Ack Apr 02 '20 at 18:21
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They are normally installed so the split-ring "lock" washer is against the nut, and the flat washer is between the split-ring washer and the surface. This is to prevent damage to the surface. It appears they did not provide any flat washers, is that correct?

It appears they provided locking nuts, the kind with a piece of nylon or fibrous material in it. So you should be good.

However, I'd like to add some content about split-ring "lock" washers.

Both the Germans in the (I think) 1930s and NASA in the (I think) 1960s determined that split-ring spring washers, aka split-ring "lock" washers, actually speed the loosening of a nut under vibration when no other method is used of locking the thread in place.

This link contains quotes and a chart from the NASA paper. The chart on the last page is quite illuminating. http://hillcountryengineering.com/wp-content/uploads/2011/10/Split-Lockwashers-Separating-Myth-from-Truth.pdf

If you want a deeper read, here is the 100 page NASA Fastener Design Manual. https://ntrs.nasa.gov/citations/19900009424

Polymorph
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