Mechanical Gears Project
Simple Gear Train
1/11/17
This was the first build of the Mechanical Gears Project, and my project partner was Erika. For this build, we had to take turns to both individually build trains A and B. In addition to the build, we each had to answer a set of questions to understand the purpose of the build and how it works. Here are some examples of what I learned when I finished this build:
1) I learned that the input shaft and the output shaft both work together in order to make the gears move. In a way, the input shaft is the one who starts the movement of the gears. The output shaft is the shaft being affected, which is mainly the last shaft. The clear difference is that the input shaft could work independently while the output shaft is dependent on the gears before it.
2) I learned that the driving gears are the input shafts, the gears who start the movement. The driven gears are the output shafts or idlers, whichever gears that are being driven by the gears before them. Idler gears are gears that do both jobs, driving and being driven because they are in between two gears.
3) I learned that you can find the gear ratio of the gear system by counting how many pegs or teeth the gears have. Another way to find the gear ratio is by counting how many times it takes for the gears to pass each other. For instance, if I have a bigger gear and a smaller gear, the ratio would be 3:5. Every time the bigger gear spins 3 times, the smaller gear spins 5 times, so the smaller gear spins more than the bigger gear.
Gear Train A
Gear Train B
Simple Gear Train with Idler
1/12/17
This is the second build of this project, and this time, we are building a simple gear system with an idler, a gear between two gears. There were several things I learned in this build that I would like to share, including the rule for speed and torque and what exactly torque is.
1) I learned that torque is the spinning force in an object. It is also the opposite of speed. If the speed increases, then the torque decreases, but if the speed decreases the torque increases. Therefore, if the speed is constant, then the torque is also constant.
2) I learned that the rule of speed is if the input shaft is bigger than the output shaft, regardless of the idler, then the speed will increase. If the input shaft is smaller than the output shaft, it would be the opposite and the speed would decrease. Lastly, if the input shaft and output shafts are the same, the speed is constant.
Bevel Gear
1/13/17
This is the third build of the Mechanical Gear system, and this time, I built a gear system that is aligned 90 degrees above it instead of being horizontally aligned. In this gear system, I learned about the gear ratios, how the flow of power is reversible, and where this system could be used.
1) I learned that the gear ratio is 1:1 because they are both the same size gear. Every time the input gear spins 360 degrees, the output gear does the same, and they end up on the same spot on the same number of spins. I could test that out with the blue tape, and every time I spun it, they would face the same direction.
2) I also learned that the flow of power is reversible because as long as the gears are connected, they would be able to spin either direction. If I reverse the input shaft with the output shaft, it would still work either way, horizontally or vertically.
3) An example where this gear system would be needed would be in car differentials. The bevel gears allow the motor gears to be lower than the other gears, making the whole system more flexible.
Worm and Wheel
1/17/17
This is the fourth build of this project, and this time, we are using a new gear, called the worm. It's the twisted gear that is on the bottom with 5 pegs/teeth. In this gear system, I learned about how it affected the speed, how the flow of power was irreversible, and how it might be used in a real world example.
1)I learned that the speed decreased because the input shaft is smaller than the output shaft. The worm didn't have pegs like the gear, so the whole system moved really slow. The worm has to spin around 5 times in order to make the gear spin once.
2) I learned that the flow of power is not reversible because if you switch the output shaft and input shaft, the gear won't be able to move the worm. It won't work this way around since the gear would be spinning one direction while the worm spins a whole different direction.
3) Lastly, I learned that a real life example this mechanism might be used in are conveyor belts. In conveyor belts, the gears would be the engine to move the system while the worm gears move the surface of the conveyor belt. They also use the fact that the gear can't move the worm as a locking feature when the engine is not moving, so it can't go the other way around.
Leadscrew
1/23/17
This is the fifth build of the Mechanical Gears Project, and this time, we are building something quite different. Instead of using gears as the input shafts, we are now using worm gears. We spin the crank around 5 times in order to move the screw block (the green block on the bottom of the horizontal H) forward or backward. It's quite different from the usual builds we do, so it took us several days compared to half the day. We made a lot of mistakes with how and where to position the screw block.
1) One thing we learned from this build was that the flow of power was not reversible. In other words, I couldn't make the lead screw spin if I'm pushing the screw block. The lead screw spins a different direction and angle, so pushing it won't make the lead screw spin. Another worm would probably move the lead screw, but not something that moves the shaft by pushing.
2) Another thing I learned from this build was that a metro train uses this mechanism because these trains slide along the rails to move. Using the same rule for the direction of travel, they can go both ways. The metro trains also have two heads to move in two directions.
Rack and Pinion
1/24/17
This is the sixth build of the Mechanical Gears project, and this time, we are utilizing a new gear, called the rack. The rack is the output shaft and the pinion gear is the input shaft. The pinion is the one moving the rack gear, so the pinion is basically the wheel gear. In other words, the green gear row on the bottom is called the rack. By turning the crank forward or backward, the rack would move horizontally, with a linear movement. Since the rack is attached to the C-channel, the C-channel also moves along with the rack. There are also a few other things I learned from this build, such as how the diameter of the pinion affects the rack and what real life example could this mechanism be used in.
1) If the diameter of the pinion gear has increased, the rack would move a greater distance with one revolution of the axle. That's because the pinion gear would have more teeth, therefore moving the rack a longer distance.
2) An example where this mechanism might be used is a train using the rail to move. For instance, the wheel gear, which is the pinion, will spin forward on the rail, which is the rack. The purpose of this mechanism is to convert rotary movement to linear, so trains are a perfect example for this.
Universal Joint
1/25/17
This is the seventh build of the Mechanical Gears Project, and this time, we are utilizing a new mechanical part, called the Universal Joint. (UJ) In this build, it was nothing too complex, since it was just to test out new tools and materials. The function of the universal joint was that it was able to connect 2 shafts and transfer the speed and torque from one shaft to another. For example, let's take one shaft positioned at 90 degrees and another shaft, positioned at 45 degrees higher. In order to connect those two shafts and transfer the power from the first shaft, I need a universal joint to connect them. As you can see below, the shafts are now connected, and all the speed and torque from the first shaft is being conveyed to the second.
1) The one thing I did learn from this project was how this mechanism could be used in rear-wheel-drive cars. In these cars, the universal joint allows the rear axle to move up and down without snapping or bending the shaft. It adds more flexibility to the motion of the shaft, so the cars don't have to constantly check their shafts for damage. However, the universal joints in modern cars are permanently fixed on, so if they are damaged, you can't remove them to fix them.
Chain Drive
1/26/17
This is the eighth build of the Mechanical Gears project, and this time, we are using chains to generate and circulate the motion. For instance, the input gear would start spinning to start the system, but instead of having the output gear directly connected to it, the chain allows them to be connected indirectly. The difference with the Chain Drive compared to normal spur gears is that it makes the gears spin in the same direction. For example, if the input gear moves forward, the chain would carry that to the output gear, therefore pushing it to go the same motion. A real life example where this mechanism might be used are in bicycles. The chain drive functions by pedaling, which turns the spur gears, therefore moving the chain. The teeth of the gears mesh together with the chain to create a moving motion towards the next gear and the process repeats.
Belt Drive
1/27/17
This is the ninth build of the Mechanical Gears Project, and honestly, this build isn't so unique. The belt drive has the same concept as the chain drive, with the chain or rubber band pulling the gears to make them turn in the same direction. However, what sets them different from one another is how the belt drive is much more silent than the chain drive, so it's preferably used more often in real life. In this build, the belt drive's speed is constant because the 2 pulleys are the same size, therefore generating the same amount of speed and torque. In addition to the speed, another major fact that sets these 2 builds apart are the crossed rubber bands. If you were to test out the system with a straight rubber band, the gears would both go the same way. However, if the rubber band was crossed, they would go against each other, like spur gears. The reason why is because the crossed bands reflect the same turning motion against each other, so the direction of power is getting reflected back to the pulleys, creating the opposite direction.
1) One thing I learned from this build was that this mechanism can be used in garage doors. When the doors open or close, the belt drive would silently move to open them. Using the same process as the chain drive, they use the belt to lower the garage doors.
Crank and Slider
1/30/17
This is the tenth build of the Mechanical Gears Project, and this time, the gears have a different type of motion. For the input shaft, the crank gear has a rotary movement while the output shaft has a linear movement. That means it moves forward and backward in a straight line. This mechanism works by turning the smaller crank to move the bigger crank, which creates a linear movement that pulls the slider back and forth in a linear movement. There were also several things I learned from this project, such as;
1)With each revolution of the crank, the slider moves forward approximately 4 inches and then goes backward 4 inches. The slider can't completely go to the edges of the C-channel, because the frame is too long. There's only so much distance the slider can slide, depending on the radius of the crank and frame.
2 )The flow of power is not reversible because the slider is only able to move the crank gear by moving forward or backward. Since the slider has a linear movement, it can raise the frame up and down to rotate the crank gear, but only up to 4 inches. It can't move it fully 360 degrees. After testing it out, the slider can only move the crank 180 degrees.
Cam and Follower
1/31/17
This is the final build of the Mechanical Gears Project, and we are utilizing a cam and follower for this mechanism. What's unique about this build compared to others is the output movement. Usually, in the last few builds, the output movements were either linear or rotary. There was no reciprocating movement, which goes vertically up and down, back and forth. You can think of how it's similar to the crank and slider with its back and forth movement, but this one goes up and down more often. This is how the process works. Every time the cam rotates, the follower follows the flow of direction. Since the follower has a small wheel on the bottom, it would follow the cam's trail to create an up and down movement. It may seem like it's just going forward in one place like a treadmill, but the output movement it generates is reciprocating. There are also a few other concepts I'd like to point about this build;
1) The direction of travel is not reversible because turning the cam the opposite direction won't make the follower move. They are unable to go both directions, only one. One part of the cam is raised higher, so the follower can't go up at that spot. It can only go down when it's turned counterclockwise.
2) The flow of power is not reversible because the follower has a wheel, so pushing down won't make the cam move. The only reason why the follower is able to move is because the wheel is getting moved by the cam's rotary movement, but the wheel won't move if the follower is pushing down vertically. It's a one-way process.
