Чел, ты сделал модель кшм неправильно, у тебя неправильное соотношение хода поршня (фломастера) и длины шатуна. Bro, ar ratio is wrong, connecting rod must be smaller
@@rickhill3071 the scotch yolk would never work in internal combustion engine , whether it was on the crank shaft or inside the piston , combustion forces would drive the yolk to the side , binding it half stroke , where as normal crank shaft connecting rod and rist pin and piston , everything is rotating on a center line .
In the first arrangement, the horizontal distance between the pen and the mountng point, is constant. In the second arrangement the horizontal distance is not constant, because the piston arm rotates.
The other way to consider it is the distance from the pinion to the marker is constantly changing in the first while the distance in the second is fixed.
The crank mechanism graph is bigger and hence, this mechanism has more torque/power than the scotch yoke mechanism and I think this is why it is being used in a car engine rather than the scotch yoke
So cool. As a Physics grad I can say thanks. Definitely learned something here from a mechanical engineer. I always assumed that bottom configuration would give a sine wave, but clearly it wont - at least not a perfect one.
I agree, my physics professor back in college used to say both devices would give the same oscillation, they don't; that's why I made this video, to show him wrong, 20 years later.
@@bettafish541 what do you mean? Clearly, theoretically they don’t give the same oscillation, assuming that the CAD model is correctly drawn. That’s the whole point of the animation, to show the theoretical difference 🤷🏼♂️
Old textbook Youngson early 1900s on steam engine slide valves gives good treatment for determining the effect on steam engine slide valves and the effect on length of connecting rods - he called this angularity of connecting rod, which changes valve timing in upstroke vs. downstroke of double acting steam engines (most are). Still applicable to preserved and newbuild steam engine people who take indicator diagrams on their engines. (We still use Watt's formula IHP = PLAN/33,000 here and there is a difference between upstroke and downstroke due to the connecting rod angularity effect on steam distribution). Interesting video.
Absolutely beautiful representation. Kudos Edgar Torres. I hope you build a physical proof that also demonstrates this as well as record a video of the final outcome.
Here is the equations for moving the pen. First pen h=r*cos( alpha)+l Second pen h=sqrt(r*r*sin(alpha)-l*l)+r*cos(alpha) Where: alpha is the swing account r is the radius followed by the connection l is the length of the arm that connects the pen. As can be seen from the equasions, the position of the pens must be different.
The second pen is: r*sin(alpha)+sqrt(l²-r²*cos(alpha)²) In the limit as l approaches infinity, the square root term approaches l, and the two curves become identical. This is because a longer arm doesn't need to tilt as much to cancel out the cosine component of the wheel.
@@JeffACornell 1)Yes r*r ... 2)You hawe right. L^2 > r^2 l=c r=a c^2=a^2+b^2 Sury 3) ( imaginary numbers ... ) For the mine it was so simple that I simply decided that is widely known. 4) The important thing is that the description of the movment is completly diffrent .
Do these two mechanisms, in reality, produce slightly different sine wave graphs as shown in the animation? Is one a pure sine wave, and the other not so?
Exactly, that is the purpose of the animation: to show the differences. The Scotch Yoke produces a pure sine oscillation, the other doesn't. You can see more for this topic (including the equations) at: laksh04.medium.com/kinematic-comparison-of-scotch-yoke-with-single-slider-crank-mechanism-7cdb27935e74
@@etorrex Thank you so much! This is not just interesting, but helpful. I teach calc-based intro physics and need to cover this idea. Great animation, and vey helpful link! Thank you again.
Cam with connecting rod takes more length than with out connecting rod scotch mechanism regarding performance both are same take it easy comparison animation wise in one page s wonderful note diameter of cam is equal to stroke length in both cases thanks k.sakthidoss. Good excellent demo
And which one is now sinus? I would think it's the top one because it does just transfer the up/down motion onto the paper and no sidways motion. Am I right?
In high school physics i remember a very low tech but effective way of producing visual SHM from a turning wheel. Bike wheel, stick glued perpendicular to radius, then the wheel as a bike rider would see it, backlit in front of a cloth like a shadow puppet. The same teacher also made a graphic model non stable stationary point with a piece of cardboard thumbtacked to a backboard with a rubber band attached to either side of the stationary point. The point was to show the difference in a real world machine between the unstable stationary point at the apex (slope = 0) of a "hill" parabola and a stable stationary point (slope =0) at the bottom of a valley parabola
So does this mean that the top arrangement is more efficient cus its more direct and the curve on the oscillations are more straight compared to the lower 1 that has a rounder curve that kinda means it travels more in the same amount of time?
Thank you, Anwar. Excellent idea, Fourier series is one of my favorite topics (I teach that to my acoustics students), let me see what I can create to explain the topic. Best regards.
I wonder, is it possible to represent the bottom one as a sum of two sinusoids? One for the main crank and the other for the pin that couples the two arms?
It depends on the situation. How much stress the linkages are under, how well they're lubricated, etc. If we ignore friction. The blue wave is having to move the pen faster over a longer path to reach the same point at the same time as the red wave, which wastes energy. But the red linkage looks heavier than the blue linkage which will take more energy to accelerate in general and is subject to repetative shear/bending stress, unlike the blue which is mostly just axial stress.
Out of curiosity for the engineers out there. Which system is cleaner? I would imagine one performs better at high speeds. What about under heavy loads? Or even under variable speeds and/ or variable loads? I wish I had taken physics classes in high school sometimes.
The differential equation for the slider crank has a mass singularity at 0 deg and 180 deg wheel angles, you can see it intuitively since it has a tendency to lock up at those angles. It will also be more sensitive to out of plane misalignment.
@@dennisbernstein6831 It occurred to me also, and that is why I was concerned about heavy loads. I'm not an engineer and I don't know the associated language used to describe these things, but I had a feeling the rotating model would probably fare better under real world conditions. Thanks for your answer.
Thank you for this video. Sorry but... What am I supposed to see, I don't see any difference? (I don't have good eyes too.) Maybe the curves are not exactly identical?
Hi Luc. Indeed that is the case, the curves are not exactly identical (the difference is notable on a big screen, but if you are watching the video on a smartphone you may not notice the difference.) This video is to show how despite what entry level physics teachers may tell you about slider-crank mechanisms producing pure sine waves, this is in fact, not the case. The Scotch yoke mechanism would be the one producing the pure sine wave.
although the pattern is the same equaling the same way that doesn't mean that they're so equal. first off if you apply rotation power to the wheel primarily and have that then move the piston lever you need to measure the wheel rotation and see if one of these two methods has more friction than the other does. The second consideration is that a train is powered by pressure on this arm rather than by the wheel spinning and the arm pressing on the wheel would be significantly different between these two methods because of what would happen to power due to leverage in the bending of the elbow. Again there are some matches to the movements but in the real world of linear movement translated into rotational movement, friction and leverage will be slightly different between these two models. .
The classic 'piston' mechanism is the same length as the scotch yoke when fully extended or retracted, but the arm hinges when at any other position, making it effectively shorter than the scotch yoke. That's what causes this effect.
Animation good connecting rod with cam length s more length that pt note put another as corect ion thanks for u r effort this as a machine maker i welcome u
The discrepancies in oscillation represent the variation of speed overtime of the wheel from one mechanism to another. In the bottom scheme, this discrepancies of speed can be observed when one point turn reach one of the boundarie of the metallic bar, or says differently, when the wheel reach half of his turn. This can be explained by the mechanical effort of the mettalic bar to move from left to right, each time one boundaries (left or right) is reach, the discrepancie happen. The top scheme use two metallic bar and allow a more constant speed with less energy loss.
Nothing to do with any of that. It's a simple result of the upper mechanism only translating movement on one axis (left and right), while the lower translates movement on two axes (left and right, up and down) due to the lever being a fixed length between pinion and marker. The wheels are both moving at the same constant rate with no variation.
If both mechanisms were driven by one input then they would lock and the difference in velocity between the two would be more obvious than with the two mechanisms being driven separately !
Before Copernicus they added more circles. Imagine doing that to a steam locomotive. Impractical yes, but how many would be needed to produce a sine wave? Too many for me to think about.
The slide mechanism has far too much slack dwell time for a shaft driving application, that’s why it is seldom used. But it works decently if the wheel is the driving force and only light switching forces are needed.
Has anyone actually designed a crank and conrod concept like the top example illustrates for a engine? It seems like it would be incredibly smooth but may have wear problems for longevity? Would be interesting to see in an engine
"Bourke engine - Wikipedia" en.m.wikipedia.org/wiki/Bourke_engine Using a rollerbearing in the Scotch yoke results in the halving of the experienced contact velocity, and a drastic reduction of friction.
This is the perfect graphical explanation of the secondary imbalance of internal combustion engine. Very good.
Which makes me wonder - has it been tried to use the Scotch Yoke in an internal combustion engine? I think that would be interesting to know.
@@rickhill3071 have a look at a big ship engine.
Чел, ты сделал модель кшм неправильно, у тебя неправильное соотношение хода поршня (фломастера) и длины шатуна. Bro, ar ratio is wrong, connecting rod must be smaller
@@rickhill3071 the scotch yolk would never work in internal combustion engine , whether it was on the crank shaft or inside the piston , combustion forces would drive the yolk to the side , binding it half stroke , where as normal crank shaft connecting rod and rist pin and piston , everything is rotating on a center line .
@@rickhill3071 this sounds like a project for the Garage54 channel to do on a Lada engine.
In the first arrangement, the horizontal distance between the pen and the mountng point, is constant. In the second arrangement the horizontal distance is not constant, because the piston arm rotates.
Thank you. I was trying to understand what was different.
Thanks a lot
Thank you very much for the explanation.
The other way to consider it is the distance from the pinion to the marker is constantly changing in the first while the distance in the second is fixed.
The crank mechanism graph is bigger and hence, this mechanism has more torque/power than the scotch yoke mechanism and I think this is why it is being used in a car engine rather than the scotch yoke
So cool. As a Physics grad I can say thanks. Definitely learned something here from a mechanical engineer. I always assumed that bottom configuration would give a sine wave, but clearly it wont - at least not a perfect one.
I agree, my physics professor back in college used to say both devices would give the same oscillation, they don't; that's why I made this video, to show him wrong, 20 years later.
@@etorrextheoretically they would, but with realistic clearances it would be different, even more so after it wears down
@@bettafish541 what do you mean? Clearly, theoretically they don’t give the same oscillation, assuming that the CAD model is correctly drawn. That’s the whole point of the animation, to show the theoretical difference 🤷🏼♂️
@@Utube2ItubeDie Frage ist, welche Kurve ist der genauere Sinus ?
@@stg9210
Genau!
Old textbook Youngson early 1900s on steam engine slide valves gives good treatment for determining the effect on steam engine slide valves and the effect on length of connecting rods - he called this angularity of connecting rod, which changes valve timing in upstroke vs. downstroke of double acting steam engines (most are). Still applicable to preserved and newbuild steam engine people who take indicator diagrams on their engines. (We still use Watt's formula IHP = PLAN/33,000 here and there is a difference between upstroke and downstroke due to the connecting rod angularity effect on steam distribution). Interesting video.
Absolutely beautiful representation. Kudos Edgar Torres. I hope you build a physical proof that also demonstrates this as well as record a video of the final outcome.
... you do it, stop trying to manipulate people into doing work YOU want done 😂😂
@@TheLifeOfKane sshhhh. He might still do it
Beautifully illustrated 🔥🙏🤗
Here is the equations for moving the pen.
First pen
h=r*cos( alpha)+l
Second pen
h=sqrt(r*r*sin(alpha)-l*l)+r*cos(alpha)
Where:
alpha is the swing account
r is the radius followed by the connection
l is the length of the arm that connects the pen.
As can be seen from the equasions, the position of the pens must be different.
Thank you.
The second pen is:
r*sin(alpha)+sqrt(l²-r²*cos(alpha)²)
In the limit as l approaches infinity, the square root term approaches l, and the two curves become identical. This is because a longer arm doesn't need to tilt as much to cancel out the cosine component of the wheel.
@@JeffACornell 1)Yes r*r ...
2)You hawe right.
L^2 > r^2
l=c r=a
c^2=a^2+b^2
Sury
3)
( imaginary numbers ... )
For the mine it was so simple that I simply decided that is widely known.
4)
The important thing is that the description of the movment is completly diffrent .
Pineapple pen....
Do these two mechanisms, in reality, produce slightly different sine wave graphs as shown in the animation? Is one a pure sine wave, and the other not so?
Exactly, that is the purpose of the animation: to show the differences. The Scotch Yoke produces a pure sine oscillation, the other doesn't. You can see more for this topic (including the equations) at: laksh04.medium.com/kinematic-comparison-of-scotch-yoke-with-single-slider-crank-mechanism-7cdb27935e74
@@etorrex Thank you so much! This is not just interesting, but helpful. I teach calc-based intro physics and need to cover this idea. Great animation, and vey helpful link! Thank you again.
They aren't the same because of rod angularity which produces second harmonic. A rod infinitely long would have none.
Cam with connecting rod takes more length than with out connecting rod scotch mechanism regarding performance both are same take it easy comparison animation wise in one page s wonderful note diameter of cam is equal to stroke length in both cases thanks k.sakthidoss. Good excellent demo
Чудесная синусоида. + трапеция Акермана.
And which one is now sinus?
I would think it's the top one because it does just transfer the up/down motion onto the paper and no sidways motion.
Am I right?
Red is sinus
Straight shaft, therefore the Scotch yoke, at the top
In high school physics i remember a very low tech but effective way of producing visual SHM from a turning wheel. Bike wheel, stick glued perpendicular to radius, then the wheel as a bike rider would see it, backlit in front of a cloth like a shadow puppet. The same teacher also made a graphic model non stable stationary point with a piece of cardboard thumbtacked to a backboard with a rubber band attached to either side of the stationary point. The point was to show the difference in a real world machine between the unstable stationary point at the apex (slope = 0) of a "hill" parabola and a stable stationary point (slope =0) at the bottom of a valley parabola
very useful to understand simple harmonic motion
So does this mean that the top arrangement is more efficient cus its more direct and the curve on the oscillations are more straight compared to the lower 1 that has a rounder curve that kinda means it travels more in the same amount of time?
ขอบคุณการอธิบาย การแปลเปลี่ยนกฎการเคลื่อนที่วงกลม ให้เป็น ไซด์เวฟ อย่างชัดเจน..
Its excellent animation. Can it be used to explain harmonics or Fourier series?
Thank you, Anwar. Excellent idea, Fourier series is one of my favorite topics (I teach that to my acoustics students), let me see what I can create to explain the topic.
Best regards.
The lenght of the connecting rod is changing on the hinged rod. What is mysterious about this ?
The shaft on the top cannot run lik the bottom one because it is a solid shaf and fix in to two solid bearings
Nice animation, can I ask what software was used to produce it please?
Thank you, ManNo60. This video was made with an animation software called Blender: www.blender.org
@@etorrex cool animation, I would love to see some behind the scenes footage of how this animation is done.
Me gusta 👍 y estoy considerando tomar la idea presto para mi proyecto gracia por ser tan humilde permitirnos ver tu idea
should the blue line match the red, if the rod is infinitely long?
Yes, it would.
How about mounting the disk on the with the pen attached to wheel above the paper?
Are they even rotating at the same speed to produce similar results? What else moves the pen
Hi,
How to to select motor and gearbox for this mechanism based on load
Please let me know What CAD PACKAGE IS USED TO DEVELOP this?
please put the governing equations for both cases in your video, then it would be a great educational tool
Ok, what's the equatins for both cases?
Wow! Such a HUGE difference! 😏😏
I wonder, is it possible to represent the bottom one as a sum of two sinusoids? One for the main crank and the other for the pin that couples the two arms?
Not just possible, necessary. You can't accurately describe it with just one.
If paper is run in as pen wheel manner then will it draw circle if yes then small can be drawn?
Nice video 👌🏼
An analysis would be good. (Of the blue function in particular.)
I have 2 power hacksaws, one standard crank and the other a scotch yoke. The scotch yoke one definitely runs smoother!
So which is better for what purpose?
Ah yes, using a digital computer to simulate an analog computer just to flex on them
Sir, what CAD package or Modelling package is used for this.
Could someone tell me Which one of these is efficient?
It depends on the situation. How much stress the linkages are under, how well they're lubricated, etc.
If we ignore friction. The blue wave is having to move the pen faster over a longer path to reach the same point at the same time as the red wave, which wastes energy. But the red linkage looks heavier than the blue linkage which will take more energy to accelerate in general and is subject to repetative shear/bending stress, unlike the blue which is mostly just axial stress.
Could you please tell us which software did you use?
Made in Blender. www.blender.org
So which obes better? Im confused
What software did you use to model this? This is so cool!
Thank you. I used Blender. blender.org
Out of curiosity for the engineers out there. Which system is cleaner? I would imagine one performs better at high speeds. What about under heavy loads? Or even under variable speeds and/ or variable loads? I wish I had taken physics classes in high school sometimes.
Tô be honest they look so similar that it probably must be the same, although the second one looks more cheaper
The differential equation for the slider crank has a mass singularity at 0 deg and 180 deg wheel angles, you can see it intuitively since it has a tendency to lock up at those angles. It will also be more sensitive to out of plane misalignment.
@@dennisbernstein6831 It occurred to me also, and that is why I was concerned about heavy loads. I'm not an engineer and I don't know the associated language used to describe these things, but I had a feeling the rotating model would probably fare better under real world conditions. Thanks for your answer.
Same. Difference of math and rounding error is magnified by the square.
You are exactly correct.
I wonder if the difference in the waveform can be heard if those waves are made into sounds...
Nice demonstration, would be better if you add equations for both motions.
Thank you for this video. Sorry but... What am I supposed to see, I don't see any difference? (I don't have good eyes too.) Maybe the curves are not exactly identical?
Hi Luc. Indeed that is the case, the curves are not exactly identical (the difference is notable on a big screen, but if you are watching the video on a smartphone you may not notice the difference.) This video is to show how despite what entry level physics teachers may tell you about slider-crank mechanisms producing pure sine waves, this is in fact, not the case. The Scotch yoke mechanism would be the one producing the pure sine wave.
@@etorrexNow I understand. Thank you!
Great. Which software did u use?
Is this cosine error, or abbe error?
Think about the distance between the pen and the rotating point.
los venden en amazon?
Apenas los vamos a pasar a producción.
@@etorrex ya se lo había pedido a santa
Which one better?
no puedo parar de verlo....
The difference is so subtle. Is there a way to make it more apparent?
shortening the connecting rod
If I was still taking Vicodin, I'd probably be building one of these by now. I never got into tinkering so much in my life, before or since.
Shouldn’t the lines cross at the center?
Would be cool to have a third one with a y component slot!
mecanismo biela manivela corredera, de cuantos grados de libertad????
So, which one is which?
So it pulls fast but pushes slow, leading the whole curve to sag a bit in every position.
Great minds solve the same idea.
I would assume that in the limit as the crank rod length goes to infinity, they would become the same
although the pattern is the same equaling the same way that doesn't mean that they're so equal. first off if you apply rotation power to the wheel primarily and have that then move the piston lever you need to measure the wheel rotation and see if one of these two methods has more friction than the other does.
The second consideration is that a train is powered by pressure on this arm rather than by the wheel spinning and the arm pressing on the wheel would be significantly different between these two methods because of what would happen to power due to leverage in the bending of the elbow.
Again there are some matches to the movements but in the real world of linear movement translated into rotational movement, friction and leverage will be slightly different between these two models.
.
I like this!
🔆
Isn't it just that their is more deflection in the bottom one since the force to move the pen is applied at a different point
The classic 'piston' mechanism is the same length as the scotch yoke when fully extended or retracted, but the arm hinges when at any other position, making it effectively shorter than the scotch yoke. That's what causes this effect.
I didn't understand what this wanted to say. I'm not sure what is different both systems.
Animation good connecting rod with cam length s more length that pt note put another as corect ion thanks for u r effort this as a machine maker i welcome u
It's weird that the blue line is "outside" the red line on the left, but "inside" on the right.
Easy you can visually see the short end U turn for a quick pullback that transfer to paper.
I'm thinking there is a longer dwell time at each end of the slide in the above mechanism resulting in a wider red curve.
Brilliant..👍👍👍👍👍
The discrepancies in oscillation represent the variation of speed overtime of the wheel from one mechanism to another. In the bottom scheme, this discrepancies of speed can be observed when one point turn reach one of the boundarie of the metallic bar, or says differently, when the wheel reach half of his turn. This can be explained by the mechanical effort of the mettalic bar to move from left to right, each time one boundaries (left or right) is reach, the discrepancie happen. The top scheme use two metallic bar and allow a more constant speed with less energy loss.
Nothing to do with any of that. It's a simple result of the upper mechanism only translating movement on one axis (left and right), while the lower translates movement on two axes (left and right, up and down) due to the lever being a fixed length between pinion and marker.
The wheels are both moving at the same constant rate with no variation.
Интересно было бы посмотреть мгновенный спектр. Жаль, что вы этого не показали.
I'm just a backyard mechanic hack. I prefer the yoke design.
Do the same for ross yoke Stirling linkage 😅
If both mechanisms were driven by one input then they would lock and the difference in velocity between the two would be more obvious than with the two mechanisms being driven
separately !
Before Copernicus they added more circles. Imagine doing that to a steam locomotive. Impractical yes, but how many would be needed to produce a sine wave? Too many for me to think about.
how was this made?
With Blender. www.blender.org
The slide mechanism has far too much slack dwell time for a shaft driving application, that’s why it is seldom used. But it works decently if the wheel is the driving force and only light switching forces are needed.
I think slider-crank is the perfect sinus.
In material science they told us 2pi is 6 so this is close enough.
How can we neglect friction tho ? 😢
Sinus vs cycloid?
Cool!
But how does it affect machinery
Has anyone actually designed a crank and conrod concept like the top example illustrates for a engine?
It seems like it would be incredibly smooth but may have wear problems for longevity? Would be interesting to see in an engine
"Bourke engine - Wikipedia" en.m.wikipedia.org/wiki/Bourke_engine
Using a rollerbearing in the Scotch yoke results in the halving of the experienced contact velocity, and a drastic reduction of friction.
@@AtomicHermit thank you :)
I'd imagine space would be a problem since it takes up far more space.
At Oshkosh they had Burke engines with Scotch yoke
Read valve two Pistons double and the . exhaust will be blue flame .
A close-up of the two traces would have been helpful..
Eso lo saben hacer los Ingenieros Mecánicos, los envidio
Esta bonita la bicicleta
The blue line is probably more accurate as their is less restricted motion.
Please give me the simulation on Matlab
donde puedo comprar uno como esos?
Good
Yes the crank is sin^2
The Scotch Yoke seems to involve more reciprocating mass.
It's all in the wheels mechanism
I don't get it. It seems pretty much the same oscillation to me.
Useful
The more components, the more precision required.
Oddly satisfying
The upper mechanism oscillation is a perfect sinus wave, but the lower one in not.
In which method one get more oscillation in less force?