Torque and Speed Relationships in Gears | Motor Driving Winch Through Geartrain

LECTURE 06
Here the relationships are derived for torque and speed between mating gears in terms of radius, diameter, circumference, and numbers of teeth. It is shown that there is a direct ratio between gear size and torque and a negative inverse relationship between gear size and torque. (The negative indicates that the rotational direction changes at each mesh.) The concept of pitch circles is presented as a way of modeling gear action as simple friction rollers. The idea is presented that gears must have the same pitch (number of teeth per unit of circumference or diameter) in order to properly mate. A problem is solved in which a known mass must be lifted at a specified speed by a specified spool diameter using a specified set of gears with specified numbers of teeth. The required torque, speed, and direction of rotation is determined for the motor that drives the geartrain. It is explained that the "lossless" assumption utilized in the example is a good starting point for understanding, but fails to account for torque loss that would happen due to friction in any real geartrain.
ENGR 122 Playlist (Engineering Problem Solving III):
• ENGR 122: Engineering ...
ENGR 121 Playlist (Engineering Problem Solving II):
• ENGR 121: Engineering ...
ENGR 120 Playlist (Engineering Problem Solving I):
• ENGR 120: Engineering ...
This lecture segment was recorded on March 26, 2018. All retainable rights are claimed by Michael Swanbom.
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Thank you for your support!

[@atexnik]

Thank you! I finally understood how small circle turns big circle with ease. It is all thanks to the fact, that they have equal opposite forces on the tangent at the point of contact. If we compare this to a Lever machine, then the small gear is effectively a "pusher" that applies force on a lever of distance r2 and its pivot point at the centre of the big gear.

[@TheBomPE]

I'm glad it helped! Thanks for watching!

[@abdelrahmanmohammed3561]

Absolutely brilliant. Clear, Simple and directly to the point. Thanks

[@TheBomPE]

Thanks for the positive feedback! I'm glad you liked it, and thanks for watching!

[@Chelsea2009FC]

Your voice was very soothing throughout the lecture, good video!

[@jerichoyang243]

thanks for uploading this video. one of the best video about gears and speed and torque.

[@TheBomPE]

I'm glad you found it useful! Thanks for watching!

[@jaw9570]

A simple and clear way to explain, thank you.

[@TheBomPE]

Glad you liked it! Thanks for watching!

[@GeorgeJMcConnell]

Yes, great instructional video. Can't wait to watch a few more.

[@TheBomPE]

I'm glad you liked it! Thanks for watching!

[@CharlieTechie]

I was having problems with this subject until I saw your fantastic video. Simple and clear explanations. Thank you very much for posting on KZbin and I am surprised that you have such few likes compared to views. You deserve more likes; teachers such as you are had to find. I subscribed to your channel. A question: what software program are you using for your whiteboard screen? I really like it.

[@TheBomPE]

I'm glad it helped! Thanks for the glowing review! My channel is still pretty young, and many of the views are probably students at the university where I teach, so they might not think to click like. Plus, there might not be that big of a slice of the general KZbin population that cares about this kind of thing. (Not enough cats in it.) Thanks for subscribing and helping to let others know about the channel. I use Microsoft OneNote to do the inking, and I use Camtasia to capture my screen. Thanks for watching, and I hope you'll check out my other videos too!

[@prasadakavoor773]

Loved it. Thanks for this!

[@skd5432]

wow....... a brilliant head start for any mechanical engineer..... 👍🏼

[@TheBomPE]

I'm glad you liked it! Thanks for the positive review!

[@zafaniamwando4634]

That was perfect especially your accent stay blessed bro

[@TheBomPE]

I am blessed, and appreciative of your support! Thanks for watching!

[@mikoajkahl9451]

great video!

[@TheBomPE]

Thanks, I'm glad you liked it! Thanks for watching!

[@arnaudzodehougan9624]

this video is fantastic. Which tool do you use to write on your tablet, thank a lot..

[@ncroc]

Very nice lecture. There is one thing that bothered me though. Can we set both the speed and the torque of the motor independently? There are those speed - torque curves which show that the amount of torque the motor will provide depends on the speed of the motor or does it? I've always thought once we determined the amount of torque required, we are stuck with whatever speed the motor will give us for that torque. Is that wrong? Are you trying to selecting a new motor that can provide the desired torque at the desired speed?

[@muhammedbakrkurt9428]

Thank you Sir, for your good teaching. I just have a small question. How can I learn this topic more detaily?

[@bowaleadeyemi4642]

Thanks alo

[@BoxerDogs]

1. For a shaft with one gear on it, If you increase the torque applied to the shaft, would that cause the shaft to rotate faster? Why? 2. If you make a shaft turn faster, would you need to apply more power or more torque?

[@negarhosseini6978]

thanks a lot

[@TheBomPE]

Glad to help!

[@joshuathames1233]

What software/tablet or computer combination are you using to do your presentations so you can draw and things as you go? I’m a first time first year tech school teacher and would appreciate knowing if you didn’t mind sharing. Fantastic job on all your videos!!

[@user-fh3jy6md3p]

Microsoft OneNote to do the inking, and Camtasia to capture the screen. Referenced from the first comment's reply.

[@johnboy4687]

Which calculator app are you using Sir ? I am trying to find a similar one on apple app store but with no luck...

[@michaelswanbom6023]

If you found this video useful, consider helping me upgrade the old tablet PC I use to create these videos! Thanks! www.gofundme.com/help-replace-my-2011-tablet-pc

[@sundayrewire3863]

Am working on Toyota avensis with 10pin gear not counting the least gear no trouble code found

[@gurpreetsingh-ty6gw]

If speed increase then friction of gears will be ?? Decrease or increase

[@jogasingh1516]

Great information. I know this is silly of me asking ,but is there a gearbox were speed and torque increase at the same time.in one to one gear ratio

[@TheBomPE]

If a gearbox has a 1:1 ratio, then it's input speed will not be different from its output speed. As for torque, it would take an input of energy to have more torque output than is put in. You might think about a power steering system as an example of this.

[@jogasingh1516]

@@TheBomPE Thank u for your kind input.will look into power steering box for idea

[@husnainhyder6713]

Dear Sir Lecture was great you have cleared a lot but one quick question you have shown the force on each gear along tangent line and applied newtons third law but what about Normal force won't their be any normal force between two gears please help us in this matter Thank you

[@TheBomPE]

Real gears do exert normal components of force as they transmit torque. I ignore this component in this lecture because it isn't relevant to computing gear ratios for speed and torque, and I'm teaching freshmen in this video. In my higher-level classes we discuss implications of the normal components of force, such as bearing reactions or shaft flexure. For instance, you might be interested in this video: kzbin.info/www/bejne/hoTZmKForbujoLc Thanks for watching!

[@husnainhyder6713]

@@TheBomPE Thanks alot God bless you

[@fourseasonsportyli7414]

the angular speed (rpm) of 15 teeth and 47 teeth are the same as well as the torques on the two?

[@TheBomPE]

That's correct. They are actually a single body since they are rigidly joined. For this body to be in equilibrium, the torque input has to be the same as the torque output.

[@daneshmandalmandal765]

Sir can u clear my doubts that 9.81 standard acceleration?how did u get 2.54cm/100?

[@dr.davidbannerf.e.s.6217]

What is the total change in forces acting upon two people sitting across from each other on a spinning Marble ride....that is traveling around a Circular Track?? One person is on the side of the Marble that is forcing them to be spun with the SAME direction of the Ride itself....while at the same time, the other person on the other side of the Marble is being spun OPPOSITE the direction of the Ride itself. The ride itself is moving in Non-Uniform Motion around a Circular Track. The spin speed of the Marble forces the two people to switch positions every 12hours that goes by.... Every 12hours one of them is being spun WITH the direction of the ride going around it's circular Track, while the other person 180degrees on the other side of the Marble ---- > is being spun the OPPOSITE direction of the ride going around it's circular Track. These are in fact Additions and Subtractions to the total Forces acting upon those Two people, whilst they are on that Spinning Marble Ride. The diameter of the Marble is 8,000miles. The speed of rotation is 1,000miles in one hour. The forward velocity and forced turn Momentum of the Marble ride, attached to the Central Pivoting Arm that the Marble ride is tethered to, forcing it go around in a Circular path ---- > 67,000miles in one hour. The Diameter of the Locked circular Track the Marble ride is going around with a Velocity of 67,000miles in one hour, is 186,000,000miles (93 million mile radius to Central Pivoting FULCRUM Point in the Center of the Sun).

[@dr.davidbannerf.e.s.6217]

Now apply Physics and REALITY ---- > And then walk away from the Globespell entirely.

[@tomasm2945]

HI, I have a gearing ratio math problem that I would appreciate your assistance. Is there someway I can message you privately as its a project I am working on?

[@PeterCroughsTongeren]

I don't get where the 9.81 m/s² comes from (39 minutes into the video). F = m . a 24 inches is 60.96 cm or 0.61 m (rounded). So it should be 79 kg x 0.61 m/s² = 48,19 N(ewton) So in my opinion, your result is wrong.

[@TheBomPE]

You are welcome to that opinion. I can tell you that it is incorrect.

[@PeterCroughsTongeren]

@@TheBomPE ok fine.. teach me... how do you get your figure?

[@TheBomPE]

@@PeterCroughsTongeren Weight is the force felt by a massive object due to gravitational acceleration. On earth, gravitational acceleration is roughly 9.81m/s^2. Calculating weight from mass using gravitational acceleration happens so frequently in engineering that after a while it is typically just done without explicit explanation or justification.

[@PeterCroughsTongeren]

@@TheBomPE Thank you for your answer and I'm ashamed not have recognized the freefall velocity. But I still think you're off. The question was (correct me if I'm wrong) "What force do we need to apply to move the weight at a ration of 24 inches per second). When I apply your answer to a = F/m you get of course 9,81 m/s or 981 cm or 386 inches per second. So with your result when a force of 774.99 N is applied to the weight of 79 Kg, the weight has already moved 386 inches after one second and not the 24 inches we were looking for. But probably I must have missed something in the question. Thanks for being a good sport and taking the time to react.

[@funy0n583]

why does he go into such depth about how gears physically interact in the beginning but then he says stuff like "non concurrent force systems"

[@TheBomPE]

Perhaps he knows about these topics and he enjoys helping others learn as well? As a colleague of his often reminds students: learning doesn't suck. When you are done scoffing you should try it out.

[@funy0n583]

@@TheBomPE im just saying if you know what non concurrent force systems means you probably know how gears interact. im not scoffing at anybody its just this seemed like a pretty simple lecture until i was hit with such an alien series of words

[@TheBomPE]

I see. If you want to see this lecture in context, you might look at the series of lectures: ENGR 122: Engineering Problem Solving III: kzbin.info/aero/PL1IHA35xY5H52IKu6TVfFW-BDqAt_aZyg You might learn why it is handy to have a shorthand way of saying "an arrangement of forces where the lines of action of the forces do not all intersect at a single point."

[@funy0n583]

@@TheBomPE thank you this is actually very helpful. sorry about the misunderstanding