Since it takes less energy to turn the big gear slowly than it would to turn the little one quickly, you are saving energy and making work easier by using gears. One gear can make another one turn faster, but it can also make it turn in a different direction. When you turn a big gear to the right, the little one will move to the left.
This is good for many machines where the direction needs to change in order for the machine to work. Some rides at an amusement park or fair use large gears which make them spin in circles like the spinning teacup ride at Disneyland. Huge wind turbines use gears to convert the slow motion of the blades into much faster motion to make electricity. They are used in clocks to make the minute and the hour hand go around. They are used in motors: big car motors, and little motors that make your toys move.
Turning the handle will make one of the gears move, and the other one will move in the opposite direction. You can also see gears on a bicycle. With some bikes, the wheels will move at different speeds when you pedal because of gears connected by a chain. Use this worksheet to help review the concepts of how gears change speed and direction.
You can make different gear patterns using this gear template generator. Home Science Tools offers a wide variety of Physics products and kits. Because every teacher-student situation is different, there is no one science curriculum that is best for every homeschool family Every year most homeschool families go through the difficult process of deciding what curriculum to use for the next year.
Shifts in education priorities, successes and trials from the previous year, maturing students, and Tasks such as pinching require tiny muscles in the hand to be strengthened. These small muscles often strengthen after larger muscles, those that What Do Archeologists Do? Anthropologists and archeologists study the origin, development, and behavior of Turning the big cog slowly will require less energy than it would to rotate the small one quickly; so by using cogs, there is saving of energy and making work easier.
It's also possible to increase the speed of a machine using cogs that have a different number of teeth. What happens is that when the big wheel is turned, then the little wheel has to rotate much faster to keep up but with less force. When two cogs slot into each other, the second normally turns in the opposite direction. This means that when one rotates clockwise, the other turns anticlockwise. This arrangement is used to turn the power of a machine through an angle.
Some of the machines used in our daily life would be impossible to operate without cogs. A car is a perfect example that has a box full of cogs.
So why are cogs needed in there? The car's engine works best at a minimum speed of about rpm, meaning if the speed go below that, then the engine would cut out. The problem of having the engine directly connected to the wheels is that lots of force would be needed to get the car moving from a standstill. Similarly, an engine will be unable to generate enough force to bring itself to stop speed.
If you rotate a mutilated gear with half its teeth missing, whose teeth mesh with a full spur gear at one rotation every 30 seconds, the spur gear will turn for 15 seconds, and then stay put for 15 seconds. In this way you can turn continuous rotational motion into discrete rotational motion, meaning that the input shaft turns continuously and the output shaft turns a little, and then stops, then turns again, then stops again, repeatedly.
Although rare in industry, non-circular gears are pretty interesting mechanisms. The diameter of the gears where they are contacting each other change as the gears rotate, so the output speed of the system oscillates as the gears rotate. Non-circular gears can take almost any shape. If the two axes constraining the gears are fixed, then the sum of the radii of the gears at the point where they mesh should always be equal to the distance between the two axes.
A ratchet is a fairly simple mechanism that only allows a gear to turn in one direction. A ratchet system consists of a gear sometimes the teeth are different than the standard profile with a small lever or latch that rotates about a pivot point and catches in the teeth of the gear. The latch is designed and oriented such that if the gear were to turn in one direction, the gear could spin freely and the latch would be pushed up by the teeth, but if the gear were to spin in the other direction, the latch would catch in the teeth of the gear and prevent it from moving.
Ratchets are useful in a variety of applications, because they allow force to be applied in one direction but not the other. These systems are common on bikes how you can pedal forward to turn the wheels, but if you pedal backward the wheel will spin freely , some wrenches, and large winches that reel in loads. Clutches are mechanisms found primarily in cars and other road vehicles, and they are used to change the speed of the output shaft, as well as disengage or engage the turning of the output shaft.
A clutch mechanism involves at least two shafts, the input shaft, driven by a power source, and the output shaft, which drives the final mechanism.
As an example, I'll explain a simple 2 gear clutch mechanism, referencing the image above. The input shaft would have two gears on it of different sizes the two blue gears on the top shaft , and the output shaft contains two gears that mesh with the gears on the input shaft the red and green gears , but can rotate freely around the output shaft, so they do not drive it.
A clutch disc the blue grooved piece in the middle sits between the two gears, rotates with the output shaft, and can slide along it. If the clutch disc is pressed against the red gear, the output shaft would engage and turn at the speed defined by the gear ratio of that set of gears If the clutch disc presses against the green gear, the output shaft drives at a different gear ratio, defined by that gear set If the clutch disc sits between the two gears, then the output shaft is in neutral and is not being driven.
The clutch disc can engage with the gears in a few different ways. Some clutch discs engage via friction, and have friction pads mounted to their sides as well as the sides of the gears. Other clutch discs, like the one in the image above, are toothed, and they mesh with specific teeth on the faces of the gears.
A gear differential is a pretty interesting mechanism involving a ring bevel gear and four smaller bevel gears two sun gears and two planet gears that orbit around them , acting sort of like a planetary gearbox.
It is used mostly on cars and other vehicles, because it has one input shaft that drives two output shafts which would connect to the wheels , and allows for the two output shafts to spin at different velocity if they need to. It ends up that the average of the rotational velocities of each output shaft always has to equal the rotational velocity of the ring gear. I'll explain how a differential works using the images above. The input shaft spins the yellow bevel gear, which spins the green bevel ring gear.
A carriage is fixed to the ring gear that spins with it. Both the carriage and the ring gear rotate around but do not directly turn the axis of the red output shafts. The two blue bevel gears turn in big circles around the central axis, the axis the output shafts go through.
Lets imagine this differential sits with the output shafts connected to the back two wheels of a car. If the car is going straight, the two blue bevel gears will spin around the output shafts, because of the rotation of the carriage, without rotating about their own axis. Their teeth will push the two red gears at the same speed, each connected to their respective output shafts. Thus, the wheels spin at the same speed and the car goes straight. You'll notice the blue gears have the ability to spin about their axis though, which is important to the mechanism.
Keep reading! Should the car turn, then the two wheels will want to spin at different speeds. The inner wheel will want spin at a velocity slower than the outer one because it is closer to the center point of the car's turn. If the two wheels were connected on the same shaft, then the car would have a difficult time turning: one wheel would want to spin slower than the other, so it would drag.
With the differential gear mechanism, the two shafts not only allow the wheels to spin at their own speeds, but also are still powered by the input shaft. If one wheel is spinning faster than the other, the blue planetary bevel gears just rotate about their axes instead of staying fixed.
Now, the planetary gears are both rotating about their axes and about the output shafts because of the carriage , thus powering both wheels, but allowing one to spin faster than the other. This is a pretty tricky mechanism to explain. If you're still confused, I encourage you to check out this video , also shown above, which shows the process visually very well.
While you can purchase gears of specific sizes from vendors, there are also situations in which you may want to design your own gears for a specific purpose or so that you can modify them to create non-standard gear parts. Here's some software to help you get started.
If you know of any more, let me know and I'll add them! Autodesk Inventor Free for Students : Has a gear design feature for spur and helical gears, worm gears, and bevel gears. RushGears: Contains a customizeable online gear template that allows you to download 3D CAD files of your designed gears. Gearotic: Online gear mechanism design software. DelGear: Gear design software package.
WoodGears: Gear design software for designing laser cut and wood gear profiles. Now its your turn to make something cool with gears! I made this simple GearBot to go along with this Instructable, but there are many other directions to go in from here. Use what you've learned and don't forget to share it! If you have some more gear advice or ideas to share, or have any questions about mechanisms, please do so in the comments. Question 7 weeks ago on Step I want to try and make a waistcoat with a sort of steam punk panel of moving cogs and gears.
I was just wondering what it is that you attatch the gears onto rotor or axle or something? Also, if possible, where I might be able to get some small spur cogs for it. Thank you! Question 7 months ago. Question 8 months ago on Step 4. Question 9 months ago on Step 1. Question 9 months ago on Introduction. This is very informative and nicely illustrated but I did not see how the bearings interface with the gears and shafts. Let's say you are using only one compound gear on each shaft.
Does it require one bearing on each side of the shafts resulting in 2 bearings per gear? Or would one bearing in the center of each gear on a stationary shaft work also so only half the number of bearings are needed? Question 1 year ago. This is a nice write-up but I am looking for something similar. Maybe you guys have some ideas. What I am looking to do is drive a parallel set of shafts in the same direction at the same speed How do you drive these shaft commonly Positioning is quite important here as well, it seems as if.
I've been trying to figure out gears for a while now, and your 'ible is amazingly easy to understand. The link to the differential gear box is a real gem, too. Would love to see how to make non-round gears, as well as show how to figure an assembly of them. Like, how the thought process would be for making something - which goes first, what the ratios are, etc.
Reply 3 years ago. Non round gears is a multi step process. First, you want to find the shape that you want, it can be almost anything but don't have your lines come back on themselves, ie, always go forward with your pencil, no back wards drawing.
Next 3 I print out the rack portion so I basically have a straight edge of gear teeth.
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