Talk:Scotch yoke

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[edit] General Comments For Discussion

IMHO the article is too engine and piston centric. I still think all engine related info should stay although in a separate section than the scotch yokes basic attributes. --DieselDude (talk) 20:36, 29 January 2008 (UTC)


[edit] Restored Disadvantage

On second thoughts restored disadvantage, added comment on roller fluid bearings.

[edit] Removed Disadvantage

The disadvantages are:

  • Rapid wear of the slot in the yoke.

This disadvantage exists because of sliding friction. This disadvantage does not exist when used with roller, or fluid bearings. With these bearings the only friction is rolling friction.


[edit] Mechanical Inconsistency

So it's an advantage that the piston would dwell longer at Top Dead Center and a disadvantage that it dwells less at Bottom Dead Center? The whole idea of the mechanism is that it has a piston on either end--SOLIDLY AND PERMANENTLY CONNECTED. Quite, obviously, the dwell at top and bottom are IDENTICAL. Sorry Homebuilding (talk) 02:54, 13 January 2008 (UTC)

The article is correct, the advantage and disadvantage is compared with a conventional crank and slider. I'll add that in. Greg Locock (talk) 03:26, 13 January 2008 (UTC)


The increased dwell around TDC is an advantage? According to these two articles it isn't so in real Otto cycle engines

http://sciencelinks.jp/j-east/article/200609/000020060906A0236528.php

Abstract: "In a reciprocating internal combustion engine, the Otto-cycle allows for maximum thermal efficiency with a same compression ratio, which means complete combustion in a moment at top dead center, which is practically impossible. In view of this fact, it can be considered that a slower transition of the piston speed near top dead center would promote combustion during that period. This, in turn, would increase the in-cylinder pressure and degree of constant volume thereby improving thermal efficiency. To prove this, an engine in which the piston can be displaced moderately to achieve ideal constant volume combustion was prepared and experiments were carried out. As anticipated, while the degree of constant volume increased, the thermal efficiency did not improve due to increased heat loss. Subsequently, further experiments were carried out using a direct injection, stratified charge engine which allows selective reduction of heat loss, and a high thermal efficiency was attained"

http://sciencelinks.jp/j-east/article/200623/000020062306A0851764.php

Abstract: "In the previous study, the authors found that by moving the piston slowly around top dead center, degree of constant volume increased, but thermal efficiency was not improved due to increased heat loss. Consequently, direct injection stratified charge combustion was tested to selectively reduce heat loss, and an improvement of thermal efficiency was achieved at this time. Moreover, when pre-mixed spark ignition combustion is completed in a short time with quick combustion, increasing the piston speed around top dead center rather than moving the piston slowly was found favorable to improve thermal efficiency."

So it may work better with a true diesel cycle but not with a premixed charge. --DieselDude (talk) 22:25, 23 January 2008 (UTC)

Excellent work. Do you want to put those refs into this article? I guess they should go into the Bourke page as well. Greg Locock (talk) 00:53, 24 January 2008 (UTC)
I'll try and add them. Its going to cause a flood of edits and undo's when edited in and added to the Bourke Engine :-/ --DieselDude (talk) 22:33, 25 January 2008 (UTC)
No it isn't. He's been banned permanently. Greg Locock (talk) 22:47, 25 January 2008 (UTC)
You missed a / in the closing of the ref tag —Preceding unsigned comment added by Greglocock (talk • contribs) 22:58, 25 January 2008 (UTC)
I corrected it, but I don't know how to remove duplicate references. --DieselDude (talk) 23:08, 25 January 2008 (UTC)

[edit] Removed Link

No information on scotch yoke on link.