Question...

[minh-thanh]

Question...
I'm probably the one asking the most questions on this forum
I seem to have read somewhere that there is a relationship between the sizes as shown in the picture
Can anyone help me understand more ?
Thank you !
And how should I rename this topic to match its meaning? that will make it easier for others to find if they are in need of information..

 

[GreenTwin]

The total travel of the crosshead equals 2xW.

The piston rod needs to be long enough for the rod end to clear the gland on the bottom cylinder head.

I think the shorter H is in length, the larger the angle between W and H.

As H becomes infinitely long, I think the rod angle approaches zero.

A large rod angle makes for a rougher running engine ?

These are my guesses.
The folks who know engine design will have to check me on all of this.


Edit:
That is a really nice looking engine !
.

 

[Nikhil Bhale]

Hi,

W is crank throw; one half of stroke,
H is Con rod length,
L is the piston rod length. it is stroke + piston length + TDC clearance +BDC clearance + clearance between rod and gland.
I am assuming this engine is similar to modern 2 stroke marine engine

Regards

Nikhil

 

[minh-thanh]

@Nikhil Bhale
I know that
What I'm looking for is: for example, what should be the minimum con rod length compared to half the stroke? if it's too short, the pressure on the crosshead is huge
@GreenTwin

Edit:
That is a really nice looking engine !
.

Yes, it's a really nice engine and also one of the engines I'm designing

 

[Andrew Stroud]

I have seen the suggestion that the connecting rod is 2.25 - 2.5 x the stroke (2W on your drawing) for a slow speed crosshead engine. L is determined by 2W + the needed clearances as mentioned previously so no need to include in any relationship between conrod and stroke.

 

[minh-thanh]

I have seen the suggestion that the connecting rod is 2.25 - 2.5 x the stroke (2W on your drawing) for a slow speed crosshead engine. L is determined by 2W + the needed clearances as mentioned previously so no need to include in any relationship between conrod and stroke.

Thank you !