Sneaky Pete

Interesting in deed. Martin, Scott and Johnny.....hmmm. All share the same language skills.

jhonnydivine

sure I'm not the bearing guru... but it is a topic that I have deepened both for helicopters and for cars and I wanted to contribute.
I'm happy to have found the guru of humor!
bye

prosled8

One HUGE difference being longevity of these types of engines. Snowmobiles is where my 2 stroke experience comes from. Good luck getting 5000 miles out of a high performance 2 stroke. Rebuilds are MUCH cheaper than 4 strokes but you are doing them much more often. Of course running 180-200hp/ltr of displacement at 8000 rpm definitely shortens life cycles. Rarely do you see roller bearings fail in these though. It is much more common to replace a couple of top ends (pistons, rings, re-nik'ed cylinders) before the lower end bearings are of any concern.

Newer designs of 2 strokes for sleds have eliminated fuel mix in the crank case. They directly feed lube oil to mains and rods remain splash lubricated. This change was based more on new direct fuel injection technology than a need to change oiling for the lower ends.

So, yes, 2 strokes use ball bearings that see ridiculous forces with minimal lubrication but, engines like that do not last.

Schnell Gelb

yr quote; "it is a topic that I have deepened both for helicopters...."
Helicopters ?
But I know a helicopter mechanic who contributes here and he is a very sharp guy.
So establish your cred.
Which helicopters ?
Mil or civil, piston/turbine,
maintenance/inspection certification /
FAA or other?
It seems from your syntax/vocab that it probably is not U.S. based?

jhonnydivine

i'm italian.
man, I meant helicopter models, the ones racing.

dporto

Really?

jhonnydivine

still i don't understand what do you want to me!
I am an engineer and I love the mechanics. do you not like my post?
it's not my business.
i want to partecipate because i read a lot about this topic.
i have think that the goal of the forum is this.
maybe i make mistake
peace!

jhonnydivine

what?

jhonnydivine

they are the same but smaller. it's a ****ing hobby.

Schnell Gelb

Snr. Divine,
This may break your heart.
Your interest in toy helicopters fails to qualify you to advise us on roller bearings. Hopefully you have some more advanced credential to offer?

jhonnydivine

Master's Degree in engineering and anyway, I said that I improved the topic for both cars and both helicopters model. I work with the engines every day. if you want to talk about serious things, if you can, we will talk.

Schnell Gelb

I am impressed - if you can apply the theoretical knowledge to our issue.
Sorry if we are harsh initially but many fools apply for the position of bearing expert.Here is your chance to ascend to stardom.

What does your Masters Degree in Mech Eng suggest to help us with the IMSB issue ?
Here is the Executive Summary of the issue we are discussing:
1. Are the technical objections to substituting a roller bearing (with thrust flanges) for a deep groove ball bearing valid ?
2. Which of the inherent limitations of the roller bearing would be the probable cause for rejecting it as a retrofit solution- and why ?
3.Can you propose a method of resolving any/all of the limitations of the roller bearing for the IMSB retrofit?
BTW - most of what I know about flat engines ,I learned as a boy with a Lancia Flavia -in Roma at the sfasciacarrozze.

jhonnydivine

if i understand the first question, i think that,bearings in this type of engine must support two different forces: radial + axial. different other engines a winning choice could be given by the tapered roller bearings TwinLine, because respond well to the forces even if they lose in perfect swing.in the middle, the radial ball bearings, with two rows.
less resistant to the forces but run better

dporto

While Snr. Devine may very well be a qualified/brilliant engineer, I foresee his English language skills being a major impediment to any useful discourse on this forum.

jhonnydivine

ok! bye