Talk:Scotch yoke

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)


 * I agree. I was surprised to see issue about the piston: TDC, combustion, etc. War (talk) 16:32, 19 January 2012 (UTC)


 * Ok, I moved some things around but now I think it's even MORE obvious that the references to engine design should be removed. Perhaps if it was all consolidated into a section dedicated to engines. I suggest taking the Advantages and Disadvantages out completely and replacing them with two sections: "Otto Cycle Engine Use" and "Bourke Engine Use". The the Bourke engine fans can clean this these sections as they please.War (talk) 16:53, 19 January 2012 (UTC)


 * It's clear that the Scotch Yoke should have more discussion about it's use in actuators. The Bourke engine content is barely notable yet it makes up the bulk of the article. It's clearly not balanced at this time. I strongly suggest that other editors reduce and clarify the 'engine' stuff and add more information on it's use in actuators. War (talk) 17:25, 19 January 2012 (UTC)


 * Cut the Bourke stuff right down, for the one or two people who are interested there is plenty of material on the engine in its own article. It does not need to be duplicated here. Greglocock (talk) 21:29, 19 January 2012 (UTC)

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

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.

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)

Removed Link
No information on scotch yoke on link.
 * First commercial application: Scotch Yoke

One overseen Disadvantage
That pin on the connecting rod is held on one side only as compared to a throw on a crankshaft. Since the complete load is carried by that one side, it has more than double the dimensions of the same joint on a crankshaft using the same materials and running at the same speed. This added strength means more reciprocating weight, which would further increase the stress at that point. The strength of this one joint becomes one of the factors limiting the speed at which the output shaft can rotate. In the case of the Bourke Engine the pistons contribute also to the reciprocating load which increases to the square of the rotation. An inadequately dimensioned joint demolishes the machine given enough RPMs.

AdrianAbel (talk) 14:01, 20 December 2008 (UTC)

"That pin on the connecting rod is held on one side onl"

Is it?

Greglocock (talk) 22:34, 20 December 2008 (UTC)


 * No you're right. This "disadvantage" does not apply generally to the Scoth Yoke. Even the Bourke Engine holds the pin on both sides. You may delete the entire contribution. Holding the pin on just one side occurs in special designs. Sorry.


 * AdrianAbel (talk) 13:44, 25 December 2008 (UTC)
 * It depends whether the driving force is from the pin or the yoke. Where the yoke reciprocates and the drives the pin as in the Bourke Engine two or more bearings can hold the pin. To the contrary, if the pin is on the connecting rod and drives the yoke as in the animation in the main article, there's room for just one bearing. The stress of the pin at the connecting rod can well be enormous and must be accounted for in the design. Do you agree?
 * AdrianAbel (talk) 13:45, 7 January 2009 (UTC)

Applications - reciprocating vs linear - example?
Article mentions that a common use is for actuators in oil and gas pipelines. A picture (or diagram) of such a device would be useful -- particularly of the actual mechanism -- there is nothing at actuator yet.

The article implies that the mechanism is essentially for reciprocating motion -- certainly, the advantages and disadvantages would suggest that, and the animation too. If an actuator uses this yoke to connect a motor to drive a sliding valve open or shut (a linear rather than strictly reciprocating motion), then the disadvantages relating to friction would be barely relevant (for example). I think the article needs further work to clarify this.

EdJogg (talk) 10:22, 7 February 2009 (UTC)

animation
I would recommend the use of color to distinguish the two components of the linkage - it took me a few seconds to understand what it was doing (I thought one of the two ends of the piston was somehow connected to the rotating crank). —Preceding unsigned comment added by 146.6.203.239 (talk) 15:35, 6 July 2009 (UTC)

I have added an external link to my website showing working of scotch yoke mechanism. I hope you like it. (Vikithakar (talk) 18:00, 11 June 2011 (UTC))

This article is about Scotch Yokes, not Bourke Engine
Recent enthusiastic edits build on previous attempts to shanghai mentions of the scarcely credible bourke engine into this article. Could a non involved editor have a look and decide how much is appropriate? I would support massive reduction of mentions, but perhaps not complete eliminationGreglocock (talk) 19:40, 17 December 2011 (UTC)

Article has nothing on the history
There's no date of patent, no mention of the first use of the phrase "Scotch yoke", no mention of the first use of it in machinery, how it has varied with different engines over the generations.2604:2000:1383:8B0B:1C64:8308:33BC:E2D6 (talk) 19:16, 4 October 2020 (UTC)Christopher L. Simpson

The SyTech engine
The company behind this engine has released very comprehensive material on this series of engines (it is modular design with 2, 4 and 8 opposed cylinders). As it is a novel ICE that seems to actually reach the commercial market as a range extender, it would be nice with its own page (I personally don't know how). Even if it should not reach market, it has some very interesting features/design that should be documented for the future.

The youtube chanel "driving 4 answers" (a quite respectable chanel on ICE technology) has made a video on this engine (where he also compares it to an other scotch yoke engine in the works by the company Alfadan). 2A01:799:952:4500:5E97:9E2C:C6CA:CFA5 (talk) 19:38, 26 January 2024 (UTC)
 * Hmm. SyTech do seem to have a running prototype. That is rather a large step forward from the usual Solidworks animated engine. Nonetheless, 37% efficiency is not especially good, and flat fours aren't amazingly easy to package, and the vibration problem with this design is significant until you get to a flat 8. It's not a terrible idea, apart from the Scotch Yoke itself which is probably a durability nightmare. That may be solvable, but with only 500 hours running time on a mixture of prototypes, I'm dubious. What you'll actually notice is a complete absence of RS news on this. Greglocock (talk) 03:27, 31 May 2024 (UTC)