motor speed ratio limit

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sanjaykangralkar Commentator Join Date: Jul 2008 Location: INDIA - GOLDLAND Posts: 89 Good Answers: 1	motor speed ratio limit 10/21/2008 5:25 AM
	can anybody guide/suggest for limitation / standards , to increase /decrease the speed of motor by means of V- belt-pulley transmission. if i am using std. 4pole i.e 1440 rpm, the what will be limitations?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: motor speed ratio limit 10/21/2008 6:00 AM
	One will be the minimum pulley radius for the chosen belt. Another will be the maximum bearing speed. A third will be the maximum belt speed. How about looking at belt manufacturers' data? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Ried Guru Join Date: Dec 2005 Posts: 1602 Good Answers: 19	#2 In reply to #1 Re: motor speed ratio limit 10/21/2008 9:15 AM
	Good answer, the belt manufacturer should be able to provide speed and bend radius limits. The bearing design can also be a limiting factor. Tension force on the belt may require multiple belts of a larger belt. __________________ Eventually, one needs to realize that it is far less important to be the smartest person in the room than it is to sit next to that person and make friends.
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Fangas Participant Join Date: Sep 2008 Posts: 2	#3 Re: motor speed ratio limit 10/23/2008 11:34 AM
	You have a 4pole, 50Hz motor at ?Hp. Say 5Hp. That speed is fixed, so I assume you are wanting to modify the output of the motor either up or down in speed using a transmission. That motor developes about 18 Ft/lb of torque..T = (HP X 5252)/RPM T = TORQUE IN LB. FT. Going down in speed. Say 2:1. Motor at 1440 RPM and load at 720RPM. Your driven load will have double the torque (36 ft/Lb)available Going up, 1:2, your load will only have half the torque available There will be a lot of strange things happening with with this type of change and shouldn't just "be done on a whim". The "Breakaway" and "Pull-up" torques will change up or down among others. Fans and other variable torque loads are even stranger. Do a search for "The Cowern Papers". Ed
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