Spur gear design

7 comments

Bridgeward Participant Join Date: Sep 2009 Posts: 3	Spur gear design 09/06/2009 4:52 AM
	Is it possible to design a spur gear that has an external spur for part of its circumference and an internal spur for part of its circumference. It is envisaged that the connecting gear would turn in one direction (external spur) for part of its rotation and reverse direction when engaging the internal spur and so on. The external spur radius would be smaller than the internal spur by the diameter of the connecting gear.
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	Pathfinder Tags: external spur gear internal

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sb Guru Join Date: Mar 2007 Posts: 2547 Good Answers: 103	#1 Re: Spur gear design 09/06/2009 5:06 AM
	The manufacturing will be complicated, but most likely it can be broached. The cost will shoot up. Think about some other way of transmission. Why not have two gears longitudenally with the portions of the threads washed off so that they do not engage? __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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Bridgeward Participant Join Date: Sep 2009 Posts: 3	#2 In reply to #1 Re: Spur gear design 09/06/2009 6:02 AM
	sb, the spur gear would be 30cm in dia and fixed, with the connecting gear, the winch, being rotated around the fixed gear which would drive the winch, this has to wind rope on and off itself, the rope is attached to each end of a long weight, the action of the apparatus rotating moves the weight approximately 1m backwards and forwards, is it possible your suggestion would achieve this and if so how.
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tcmtech Guru Join Date: Jun 2009 Location: South of Minot North Dakota Posts: 8378 Good Answers: 774	#3 Re: Spur gear design 09/06/2009 1:58 PM
	If your just intending to move a cable back and forth a simple cam or crankshaft system will be far more cost effective and simpler to make and far more reliable.
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Bridgeward Participant Join Date: Sep 2009 Posts: 3	#4 In reply to #3 Re: Spur gear design 09/06/2009 3:21 PM
	I think moving the cable back and forth is easy but becomes alot harder if the apparatus is rotating thru 360deg. The apparatus is 2m long x 150mm Dia and rotates continously at 15rpm the cable is attached to the tube and moves the weight backwards and forward inside the tube without any input of energy creating rotation of its own accord using gravity.Could a simple cam or crankshaft attached to the tube achieve the outcome desired, if so how?.
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bwire Guru Join Date: Dec 2007 Location: Upper Mid-west USA Posts: 7498 Good Answers: 96	#5 Re: Spur gear design 09/07/2009 12:52 AM
	Yes. I think a spline or shaft coupling would suffice for the ID and a spur gear can be fit to it. __________________ If death came with a warning there would be a whole lot less of it.
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Anonymous Poster	#6 Re: Spur gear design 09/07/2009 9:49 AM
	Can you build a flat washer with the OD smaller than the ID?
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bwire Guru Join Date: Dec 2007 Location: Upper Mid-west USA Posts: 7498 Good Answers: 96	#7 In reply to #6 Re: Spur gear design 09/07/2009 1:02 PM
	An AB-1.2 compression type... __________________ If death came with a warning there would be a whole lot less of it.
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Anonymous Poster (1); Bridgeward (2); bwire (2); sb (1); tcmtech (1)