how does a pulley work?
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From: Chi-Town
how does a pulley work? what exactly are the physics involved in letting a smaller crank pully rev the engine quicker. is it the weight reduction, less rotating load of the accessories, or is there more?
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From: new england
Re: how does a pulley work? Yes weight reduction and by spinning all accessories slower(less distance) they each take less HP to turn at all rpms and less friction is a result. All components should live longer because hi rpms can really abuse most accessories.
Now someone feel free to correct me but, older computerized GM cars if alternator speed was lower, would cause computer to richen fuel mixture, this was desirable in certain cammed applications.This helped idle smoothness in my case.
Now someone feel free to correct me but, older computerized GM cars if alternator speed was lower, would cause computer to richen fuel mixture, this was desirable in certain cammed applications.This helped idle smoothness in my case.
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From: Freeland, MD
Re: how does a pulley work? Sort of like what was posted above. The gains come from:
1) Less power loss from the accesories.
2) Less rotating mass. The interial resistance (moment of inertia) is one of the things that you will want to minimize the most in an engine as it can put a significant damper on the engine spinning up. This is the same reason why drag racers frequently try to get small wheels for racing (16 or 15 inch) - less mass to spin.
1) Less power loss from the accesories.
2) Less rotating mass. The interial resistance (moment of inertia) is one of the things that you will want to minimize the most in an engine as it can put a significant damper on the engine spinning up. This is the same reason why drag racers frequently try to get small wheels for racing (16 or 15 inch) - less mass to spin.
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From: Chi-Town
Re: how does a pulley work? [quote]Originally posted by LS1derfull:
<strong>The larger diameter pulley should have a slight disadvantage because centrifugal weight would be increased, larger pulley makes better harmonic dampener usually.</strong><hr></blockquote>
this is because even though they weigh the same- more weight is being put farther from the center of the rotating mass with the larger one- correct.
<strong>The larger diameter pulley should have a slight disadvantage because centrifugal weight would be increased, larger pulley makes better harmonic dampener usually.</strong><hr></blockquote>
this is because even though they weigh the same- more weight is being put farther from the center of the rotating mass with the larger one- correct.
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From: Chi-Town
Re: how does a pulley work? see, me and my boss got into an arguement over whether or not diameter played a role in the acceleration of the pulley.
i said that diameter does play a role, reguardless of weight. basically, assuming both pulleys being exactly equal in weight- the larger diameter one would still accelerate slower/ take more energy to move at the same rate as the smaller one. the larger one has more distance to cover in the same amount of time basically.
he said that weight was the only key factor. you could make the diameter 10 foot vs 1 foot, and as long as their weight were equal, they would accelerate at the same rate.
i said that diameter does play a role, reguardless of weight. basically, assuming both pulleys being exactly equal in weight- the larger diameter one would still accelerate slower/ take more energy to move at the same rate as the smaller one. the larger one has more distance to cover in the same amount of time basically.
he said that weight was the only key factor. you could make the diameter 10 foot vs 1 foot, and as long as their weight were equal, they would accelerate at the same rate.
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From: Freeland, MD
Re: how does a pulley work? [quote]Originally posted by DriveATransAm:
<strong>see, me and my boss got into an arguement over whether or not diameter played a role in the acceleration of the pulley.
i said that diameter does play a role, reguardless of weight. basically, assuming both pulleys being exactly equal in weight- the larger diameter one would still accelerate slower/ take more energy to move at the same rate as the smaller one. the larger one has more distance to cover in the same amount of time basically.
he said that weight was the only key factor. you could make the diameter 10 foot vs 1 foot, and as long as their weight were equal, they would accelerate at the same rate.</strong><hr></blockquote>
Diameter definitely matters. Angular momentum (recall momentum is the tendency of objects to stay at rest, or equivalently, the tendency of an object to resist changes in its motion) for a rotating object located a distance R from its rotating axis is given by m*w^2*R^2, where m is the mass, and w is the angular velocity (i.e., how fast it is rotating). What is important about that formula is the R^2 term. In other words -
for the same flywheel mass, if you double the diameter (radius), it has 4 times the rotational resistance (inertia).
Diameter does matter. Once again, this is why drag racers do not like heavy, large diameter wheels. A weight reduction in a wheel is worth more than the equivalent weight reduction on the chassis.
<strong>see, me and my boss got into an arguement over whether or not diameter played a role in the acceleration of the pulley.
i said that diameter does play a role, reguardless of weight. basically, assuming both pulleys being exactly equal in weight- the larger diameter one would still accelerate slower/ take more energy to move at the same rate as the smaller one. the larger one has more distance to cover in the same amount of time basically.
he said that weight was the only key factor. you could make the diameter 10 foot vs 1 foot, and as long as their weight were equal, they would accelerate at the same rate.</strong><hr></blockquote>
Diameter definitely matters. Angular momentum (recall momentum is the tendency of objects to stay at rest, or equivalently, the tendency of an object to resist changes in its motion) for a rotating object located a distance R from its rotating axis is given by m*w^2*R^2, where m is the mass, and w is the angular velocity (i.e., how fast it is rotating). What is important about that formula is the R^2 term. In other words -
for the same flywheel mass, if you double the diameter (radius), it has 4 times the rotational resistance (inertia).
Diameter does matter. Once again, this is why drag racers do not like heavy, large diameter wheels. A weight reduction in a wheel is worth more than the equivalent weight reduction on the chassis.
