Conrod question

[ArkSeaJumper]

What happen my new conrod??????????

[JK]

What's this? A minature engine?

[ArkSeaJumper]

It is a small generator engine conrod, around 150kw.

This is a bright new conrod, it comes cast like this, with bolts torqued up and all, you have to 'Brake' the big end in two, hopefully it goes along the line.

[JK]

I was showing it to one of my co-workers, he had heard about this new method. I wonder how much the manufacturers save per conrod by not machining the flanges.
Interesting picture and I'll know the answer when one of the Chiefs call saying he received defective rods.

[The Dieselduck]

You gotta be kiddin me. How the hell are you suppose to be sure that the torque is accurate when the seating of the cap may be off a little. Sounds like someone is being sold a bill of goods.

There must be some paperwork from the manufacturer explaining this (you could share), otherwise, like JK said, I would be sending it back.

Oh I just noticed, this is my 500th post, jeez, how time flies.

[JK]

This is a bright new conrod, it comes cast like this, with bolts torqued up and all, you have to 'Brake' the big end in two, hopefully it goes along the line.

I'm just trying to picture this....obviously it is scored somehow and you smack it with a big hammer and cross your fingers.

[ArkSeaJumper]

When we have a problem with these generators now we just lift out the engine and put in on of our 'Spare' engines. then we bring it back to our workshop to recon.

The first time this happened the engineer arrived up in the office with the conrod and asked how the fuck this was meant to work.

I had the dubious pleasure of breaking the first one, of course we had only ordered 6 for the overhaul.
I put it in the vise, big end down and smacked the top of the little end with the heal of my hand. It breaks quite easily.
I don’t know how they cast these with the weak point, but it must be much cheaper to make.
I hope they don’t start this on bigger engines.

[JK]

I'll bet the saving isn't passed on though!

( I edited your original post to fix the picture. It was a little fuzzy)

[Detri Mental]

Believe it or not this actually makes a stronger connection than the smoothly machined parting surfaces we are used to. The irregular fracture pattern holds the rod pieces together and actually ensures that they do not misalaign.

GMs new LS series V* engines are all manufactured this way, and I think the Swiss have been doing it for a number of years also.

[Dieseldame]

Curious about the "manufactured" weakness - how do they make sure the weakness is so localized I wonder???

DD

[ArkSeaJumper]

That part I haven’t figured out yet. And thinking about it makes you a little nervy snapping them.

[Big Pete]

Hi Guys,

I can see how the surface roughness of the fractures surfaces ensure perfect alignement when the rod is re-assembled.
For the fracture to fit together perfectly when the rod is re-assembled it must be a "short", brittle fracture, this implies that the cast material is not at all ductile, at least in way of the planned fracture line.
I would be very interested in how they do it.

Big Pete

[Dieseldame]

Okay, this technology is called fracture splitting and its been around for a while in other fields but only recently adapted for use in the manufacture of connection rods. I found a technical article about it but when I tried to up load it I got a message "The extension pdf is not allowed".

DD

[Dieseldame]

The paper on the fracture splitting method I previously mentioned can be found at http://www.yamaha-motor-india.com/about ... /gr_09.pdf.

DD

[TxMarEng]

Who manufacturers this engine? Chinese perhaps?