What is this flat for?

[david_r]

I'm rebuilding a couple hydraulic cylinders. In addition to the wrench flats on the clevis end of the rod, there is a 0.1 flat machined the entire length of the threads. At first, I thought that this was there so that the clevis clamp bolt could pass through when the flat is lined up with the bolt hole. But the bolt hole on this clevis doesn't intersect the rod threads.

I went ahead and put it on the rods since they were already in the vice but I don't know what it's for. So, what is that flat for?

TIA

David

[Leigh]

Hi David,

Sounds like an anti-rotation flat, to keep the rod in position.

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Leigh W3NLB

[tattoomike68]

If the tube and end was ported weird it may need that. It must have been a shaft made for that porting.

[This message has been edited by tattoomike68 (edited 03-07-2006).]

[david_r]

Leigh,
That's what I thought at first. But there isn't anything to keep it from rotating.

Mike,
It's external to the tube. The threads for the rod clevis have the flat milled on them. All the way from the end to the step up to the full diameter.

[Leigh]

<font face="Verdana, Arial" size="2">Originally posted by david_r:
Leigh,
That's what I thought at first. But there isn't anything to keep it from rotating.</font>

The original mount may have had a D-shaped hole.

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Leigh W3NLB

[mark61]

Could it be that rod was common to several cylinders and one of the end/clevis had a set screw that would tighten upon the flat?

[LES A W HARRIS]

david_r,
In the dim recesses, I recall a lockwasher similar to a bearing lockwasher, except with a "D" hole; the nut is torqued, then a tab on the external castelations is bent in onto a flat of the nut, which stops the nut from backing off.
Les H.

[pcarpenter]

David-- you wrote:

"Leigh,
That's what I thought at first. But there isn't anything to keep it from rotating."


How about a wrench :-)

Shock absorbers that only have a threaded stem mount on top are made this way. What if you had to apply a substantial amount of force to remove a clevis, and the ram started to rotate? You would need a way to hold the ram without boogering it up.

Paul