17 replies to this topic

[Roll_Centre]

I got bored the other day in the shop, and decided to try and figure out how one would manufacture a rod end. After much thought and cutting a few of them open, I have a general Idea, but I was curious if anyone had a more exact idea about how to manufacture these things, it's been racking my brain for a while.

Thanks for your help guy's and cheers ...

[J. Edlund]

What type of rod end?

[Roll_Centre]

Standard issue spherical rod ends ...

[desmo]

I've wondered the same. Can't say I've given it much thought though.

[Chevy II Nova]

Curious question...

I have always wondered how the water jackets and oil galleys are cast into a block as well.

[McGuire]

Originally posted by Chevy II Nova
Curious question...

I have always wondered how the water jackets and oil galleys are cast into a block as well.

They don't have to be...check out the Mercedes-Benz M196 GP engine of 1955, where the cylinder "block" and head were built up from forgings and formed sheet steel.

[Greg Locock]

Internal cores made from sand stuck together with some funny resin. One of the tricks when designing a block is to ensure that a reasonably high proportion of the sand will get out of the block by the time it is fully machined.

I think rod ends are forged/swaged around the ball, but I don't know how the nylon layer survives that.

[desmo]

Originally posted by McGuire


They don't have to be...check out the Mercedes-Benz M196 GP engine of 1955, where the cylinder "block" and head were built up from forgings and formed sheet steel.

One engineer told me that maraging steel crankcase pieces explosion formed into dies and welded together at one time looked like a viable proposition for F1 cases as an alternative to cast Al alloy. John Barnard and Ferrari did steel cases for F1 around 10 years ago... not sure how they were made.

[Chevy II Nova]

Originally posted by McGuire


They don't have to be...check out the Mercedes-Benz M196 GP engine of 1955, where the cylinder "block" and head were built up from forgings and formed sheet steel.

I was referring to road cars.

[Crazy Canuck]

I always thought the bearing was press fit into the housing...not really sure though...

CC

[JwS]

Sometimes the ball is swaged into the housing, when the housing is a relatively soft material. When the outer race is harder steel it is often cracked to allow it to expand over the ball and then captured in the outer housing. If you look real close you can usually see the crack. I think some of the plastic ones are molded in place, others may be just pressed together. The outer race material and construction depends on how strong you need the rod end to be, especially in axial loading, a swaged rod end won't take much axial load without loosening up, the hard steel races will take quite a bit.
JwS

[dosco]

Here at work we have some aircraft-grade turnbuckles/tierods that have spherical rod-ends.

The sphere is actually removable(!!). The sphere has opposing flat faces. When rotated to the proper angle, the flats match with flats in the rod-end, and the ball falls out. Very cool.

[JwS]

The bigger mystery is how some deep groove ball bearings are assembled, yow! I guess they are pressed together too, I have seen some fully populated ones that amazed me. the ones with spacers are easier , once the spacer is out all the balls go to one side and it comes apart.
It is neat to see how some of this stuff is built!
JwS

[McGuire]

Originally posted by dosco
Here at work we have some aircraft-grade turnbuckles/tierods that have spherical rod-ends.

The sphere is actually removable(!!). The sphere has opposing flat faces. When rotated to the proper angle, the flats match with flats in the rod-end, and the ball falls out. Very cool.

Many spherical bearings and CV joints etc. are made this way (though with CV joints the tolerances are often so close that getting the balls and cage out of their race can be a parlor puzzle).

...On your usual three-piece spherical rod end (sphere, race, and housing) the race is typically swaged to the housing. If you look closely you will usually see a concentric staking ring rolled onto the flats of either the race or the housing... it's not so much when you think about it. Unless the rod end is mounted in double shear, a washer with an OD greater than the ID of the housing is called for.

[BRNDLL]

I just saw mention of something called DLC... Diamond Like Carbon coating.
The description was something to the effect of an extremely low friction (2-4 microns) layer with an incredible hardness (3K Vickers?) and good wear characterstics. It has been in developement since '94 and was necessary to reach the current 19K rpm in the modern F1 motor.

It has allowed Ferrari to run their titanium rods directly on the crankshaft with no big end bearings...

Can this be correct?
Unreal.

bb

[J. Edlund]

Originally posted by BRNDLL
I just saw mention of something called DLC... Diamond Like Carbon coating.
The description was something to the effect of an extremely low friction (2-4 microns) layer with an incredible hardness (3K Vickers?) and good wear characterstics. It has been in developement since '94 and was necessary to reach the current 19K rpm in the modern F1 motor.

It has allowed Ferrari to run their titanium rods directly on the crankshaft with no big end bearings...

Can this be correct?
Unreal.

bb

Yes it's true, well I don't know exactly how long it have been in development but otherwise it's true but note that the Ferrari part is a rumor not a fact. DLC on the piston pin can replace the small end bushing, which makes it possible to make the small end smaller and allow larger loads since there isn't any soft bronze bushing that can be deformed.

A scanned article about DLC can be found here (can be a little difficult to read):
http://hem.bredband....8/annat/dlc.pdf

[desmo]

Originally posted by J. Edlund


Yes it's true, well I don't know exactly how long it have been in development but otherwise it's true but note that the Ferrari part is a rumor not a fact. DLC on the piston pin can replace the small end bushing, which makes it possible to make the small end smaller and allow larger loads since there isn't any soft bronze bushing that can be deformed.

A scanned article about DLC can be found here (can be a little difficult to read):
http://hem.bredband....8/annat/dlc.pdf

Thanks for that Interesting stuff and it got me looking for more. After further reading that Ferrari rumor doesn't sound as implausible as it did the first time I read it.

[AS110]

The gym across the road buys them by the 100 lot - the wear rate is 10 times that of automotive use.They have to use nylon ends because of the noise issue in their weight gear.So called high quality joints - they are not impressed.