Need help understanding
Posted: Fri Dec 04, 2009 1:48 pm
I researched "mechanics of gears" and got this: A wheel and axle assembly becomes especially useful when gears and belts are brought into the picture. Gears can be used to change the direction or speed of movement, but changing the speed of rotation inversely affects the force transmitted. A small gear meshed with a larger gear will turn faster, but with less force. There are four basic types of gears: spur gears, rack and pinion gears, bevel gears, and worm gears. Spur gears are probably the type of gear that most people picture when they hear the word. The two wheels are in the same plane (the axles are parallel). With rack and pinion gears there is one wheel and one rack, a flat toothed bar that converts the rotary motion into linear motion. Bevel gears are also known as pinion and crown or pinion and ring gears. In bevel gears, two wheels intermesh at an angle changing the direction of rotation (the axles are not parallel); the speed and force may also be modified, if desired. Worm gears involve one wheel gear (a pinion) and one shaft with a screw thread wrapped around it. Worm gears change the direction of motion as well as the speed and force. Belts work in the same manner as spur gears except that they do not change the direction of motion.
In both gears and belts, the way to alter speed and force is through the size of the two interacting wheels. In any pair, the bigger wheel always rotates more slowly, but with more force. This "tradeoff" between force and speed comes from the difference in the distance between the point of rotation and the axle between the two wheels. On both the big and the small gear, the linear velocity at the point of contact for the wheels is equal. If it was unequal and one gear were spinning faster than the other at the point of contact then it would rip the teeth right off of the other gear. As the circumference of the larger gear is greater, a point on the outside of the larger gear must cover a greater distance than a point on the smaller gear to complete a revolution. Therefore the smaller gear must complete more revolutions than the larger gear in the same time span. (It's rotating more quickly.) The force applied to the outer surface of each wheel must also be equal otherwise one of them would be accelerating more rapidly than the other and again the teeth of the other wheel would break. The forces of interest however are not the forces being applied to the outer surfaces of the wheels, but rather the forces on the axles. Returning to the concept of levers, we know that the distance at which the force is applied affects the force yielded, and a wheel and axle works like a lever. Equal forces are being applied to each wheel, but on the larger wheel that force is being applied over a greater distance. Thus for the larger wheel the force on the axle is greater than the force on the axle for the smaller wheel. also I researched physics of gears and got this:A gear is a device that transfers force to another device via rotation mechanism. It, with the aid of its teeth is joined with another and applies full force. According to its mechanism it has the capacity to enhance force at various torques towards diverse directions originating from the root source whence it attains power.
It is an acceptable fact; a gear is fitted well with another that has teeth. But the matter to be considered is that it fits well with any device, not specifically with another of its kind, that owns its teeth to be fitted quite coherently.
They come in different sizes, may be easily combined with another of a different size. The factor that dominates to a great extent is that though the second device with which the first is fitted with creates no problem to generate force and the rotational source of force is kept intact.
We can define a gear according to the teeth it has. Teeth and the diameter play the crucial part in the mechanism of a gear. Hence it can be easily told that the performance solely depends on the characteristic qualities that it originally possesses. The actual role that it plays is that it generates force to one shaft to another one irrespective of teeth and diameter.
The mechanism follows the rule of linear physics that determines its rotation per second or minute. The speed is generated vide an equation of the gear's circumference dived by the radius of it. Actually it must be taken care that the second gear is also given the tremendous importance too.
The teeth play the most crucial role in generating force. Again the radius of it also is of no less importance. Probably depending on the diameter the force is generated. The larger is the radius the slower is the speed.
It is to be noted that the teeth adjoining gears are corresponded to one another to rotate. Thus when teeth related to the smaller one, and press the other one, the large one makes one rotation. As a matter of fact when the small one moves in a fast pace and the large one moves faster generating more power. The points of contact must have to pass a particular point to rotate following a comprehensive mechanism to generate actual force.
When we find an ordinary gear we notice that it has axes that are absolutely static when there is rotation. The axes can be much in number as in the case of an epicyclic one. Again the one referred to as the sun - planet gear has a wonderful mechanism. In this a gear called planet rotates round the sun.
If we think about the mechanism of, we have to keep in mind the fact that it is based on particularly four items as the axis, the pitch point, pitch circle and the pitch diameter. Can you help me understand it?
In both gears and belts, the way to alter speed and force is through the size of the two interacting wheels. In any pair, the bigger wheel always rotates more slowly, but with more force. This "tradeoff" between force and speed comes from the difference in the distance between the point of rotation and the axle between the two wheels. On both the big and the small gear, the linear velocity at the point of contact for the wheels is equal. If it was unequal and one gear were spinning faster than the other at the point of contact then it would rip the teeth right off of the other gear. As the circumference of the larger gear is greater, a point on the outside of the larger gear must cover a greater distance than a point on the smaller gear to complete a revolution. Therefore the smaller gear must complete more revolutions than the larger gear in the same time span. (It's rotating more quickly.) The force applied to the outer surface of each wheel must also be equal otherwise one of them would be accelerating more rapidly than the other and again the teeth of the other wheel would break. The forces of interest however are not the forces being applied to the outer surfaces of the wheels, but rather the forces on the axles. Returning to the concept of levers, we know that the distance at which the force is applied affects the force yielded, and a wheel and axle works like a lever. Equal forces are being applied to each wheel, but on the larger wheel that force is being applied over a greater distance. Thus for the larger wheel the force on the axle is greater than the force on the axle for the smaller wheel. also I researched physics of gears and got this:A gear is a device that transfers force to another device via rotation mechanism. It, with the aid of its teeth is joined with another and applies full force. According to its mechanism it has the capacity to enhance force at various torques towards diverse directions originating from the root source whence it attains power.
It is an acceptable fact; a gear is fitted well with another that has teeth. But the matter to be considered is that it fits well with any device, not specifically with another of its kind, that owns its teeth to be fitted quite coherently.
They come in different sizes, may be easily combined with another of a different size. The factor that dominates to a great extent is that though the second device with which the first is fitted with creates no problem to generate force and the rotational source of force is kept intact.
We can define a gear according to the teeth it has. Teeth and the diameter play the crucial part in the mechanism of a gear. Hence it can be easily told that the performance solely depends on the characteristic qualities that it originally possesses. The actual role that it plays is that it generates force to one shaft to another one irrespective of teeth and diameter.
The mechanism follows the rule of linear physics that determines its rotation per second or minute. The speed is generated vide an equation of the gear's circumference dived by the radius of it. Actually it must be taken care that the second gear is also given the tremendous importance too.
The teeth play the most crucial role in generating force. Again the radius of it also is of no less importance. Probably depending on the diameter the force is generated. The larger is the radius the slower is the speed.
It is to be noted that the teeth adjoining gears are corresponded to one another to rotate. Thus when teeth related to the smaller one, and press the other one, the large one makes one rotation. As a matter of fact when the small one moves in a fast pace and the large one moves faster generating more power. The points of contact must have to pass a particular point to rotate following a comprehensive mechanism to generate actual force.
When we find an ordinary gear we notice that it has axes that are absolutely static when there is rotation. The axes can be much in number as in the case of an epicyclic one. Again the one referred to as the sun - planet gear has a wonderful mechanism. In this a gear called planet rotates round the sun.
If we think about the mechanism of, we have to keep in mind the fact that it is based on particularly four items as the axis, the pitch point, pitch circle and the pitch diameter. Can you help me understand it?