Dead center - Revision history

Dnevil: /* Videos */

2024-04-04T22:41:58Z

Videos

← Older revision		Revision as of 17:41, 4 April 2024
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	== Videos ==		== Videos ==

	<~~videoflash~~>E2XdFUt8sqI</~~videoflash~~>		<youtube>E2XdFUt8sqI</youtube>

	== See Also ==		== See Also ==

Dnevil: /* External Links */

2019-02-08T18:11:11Z

External Links

← Older revision		Revision as of 13:11, 8 February 2019
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	* [http://www.discoverlivesteam.com/magazine/07/07.html "Finding Locomotive "Dead Centers", <i>DiscoverLiveSteam.com</i>]		* [http://www.discoverlivesteam.com/magazine/07/07.html "Finding Locomotive "Dead Centers", <i>DiscoverLiveSteam.com</i>]
	* [~~http~~://www.jghtech.com/~~html~~/~~dead~~-~~center~~-1.~~html~~ "Finding Locomotive Dead Centers", Jeffrey G. Hook]		* [https://www.jghtech.com/assets/applets/LFLSRM-Finding-Dead-Centers-current.pdf "Finding Locomotive Dead Centers", Jeffrey G. Hook]

Dnevil: /* Videos */

2018-01-01T00:27:45Z

Videos

← Older revision		Revision as of 19:27, 31 December 2017
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	<videoflash>E2XdFUt8sqI</videoflash>		<videoflash>E2XdFUt8sqI</videoflash>

			== See Also ==

			* [[Getting Stuck on Dead Center]]

	== External Links ==		== External Links ==

Dnevil: /* Finding Dead Centers */

2016-06-07T20:07:43Z

Finding Dead Centers

← Older revision		Revision as of 15:07, 7 June 2016
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	I recommended that valves be set to give equal Lead at each end of the cylinder, when the piston is on its "dead centers" and the reverse lever in mid-gear. This allows the engine to be "hooked up" after it gets the load rolling, without having it go out of square. To do this you have to know exactly where the "dead centers" are.		I recommended that valves be set to give equal Lead at each end of the cylinder, when the piston is on its "dead centers" and the reverse lever in mid-gear. This allows the engine to be "hooked up" after it gets the load rolling, without having it go out of square. To do this you have to know exactly where the "dead centers" are.

			== Videos ==

			<videoflash>E2XdFUt8sqI</videoflash>

	== External Links ==		== External Links ==

Dnevil: /* Finding Dead Centers */

2016-04-07T18:43:30Z

Finding Dead Centers

← Older revision		Revision as of 13:43, 7 April 2016
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	Then re-tram from the point '''P''' to the tire using the same tram as in Figure #1, and with the wheel tram set at the point '''P''', scribe another arc '''Y''' on the face of the tire as shown in Figure #2.		Then re-tram from the point '''P''' to the tire using the same tram as in Figure #1, and with the wheel tram set at the point '''P''', scribe another arc '''Y''' on the face of the tire as shown in Figure #2.

	Now with a pair of [~~http://en.wikipedia.org/wiki/Calipers#Oddleg_caliper hermaphrodite~~ calipers] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.		Now with a pair of [[Hermaphrodite calipers]] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.

	Both front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.		Both front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.

Dnevil: /* Finding Dead Centers */

2014-11-17T19:38:11Z

Finding Dead Centers

← Older revision		Revision as of 14:38, 17 November 2014
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	Now with a pair of [http://en.wikipedia.org/wiki/Calipers#Oddleg_caliper hermaphrodite calipers] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.		Now with a pair of [http://en.wikipedia.org/wiki/Calipers#Oddleg_caliper hermaphrodite calipers] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.

	~~both~~ front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.		Both front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.

	The four important points on the stroke are now definitely located on the wheel, and are ready to be used for valve setting. In order to be able to test the correctness of the outside radial valve-gears and to set the valves properly, it is necessary to know exactly where all four "dead centers" are located.		The four important points on the stroke are now definitely located on the wheel, and are ready to be used for valve setting. In order to be able to test the correctness of the outside radial valve-gears and to set the valves properly, it is necessary to know exactly where all four "dead centers" are located.

Dnevil: /* Finding Dead Centers */

2014-11-17T19:37:37Z

Finding Dead Centers

← Older revision		Revision as of 14:37, 17 November 2014
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	Then re-tram from the point '''P''' to the tire using the same tram as in Figure #1, and with the wheel tram set at the point '''P''', scribe another arc '''Y''' on the face of the tire as shown in Figure #2.		Then re-tram from the point '''P''' to the tire using the same tram as in Figure #1, and with the wheel tram set at the point '''P''', scribe another arc '''Y''' on the face of the tire as shown in Figure #2.

	Now with a pair of [http://en.wikipedia.org/wiki/Calipers#Oddleg_caliper hermaphrodite calipers] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved ~~until the wheel tram reaches~~ until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.		Now with a pair of [http://en.wikipedia.org/wiki/Calipers#Oddleg_caliper hermaphrodite calipers] set about one half the thickness of the tire, draw a line '''RS''' parallel to the wearing face of the tire so as to cross both of the arcs made by the wheel tram at the points '''X''' and '''Y'''. With a pair of dividers carefully bisect the line '''RS''' between the points '''X''' and '''Y''' and scribe the center punch the exact center between '''X''' and '''Y''' as shown at '''Z'''. This point is the dead center mark, and the engine crank is at right front "dead center" when the wheel is revolved until the wheel tram reaches exactly from the point '''Z''' to point '''P'''.

	both front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.		both front and back "dead center" positions must be determined in the same way, except that when locating the back centers, the crosshead tram is used from the back guide block, or rear end of the guide. The effect of measuring on the crosshead is to find a point where the crosshead travel (from the end of the stroke) is the same, both when approaching, and when leaving the end of the stroke. By transferring these points to the driving wheel and dividing them to find the central point, the actual end of the stroke, or "dead center" is determined absolutely.

Dnevil: /* External Links */

2014-11-17T19:35:39Z

External Links

← Older revision		Revision as of 14:35, 17 November 2014
Line 35:		Line 35:

	* [http://www.discoverlivesteam.com/magazine/07/07.html "Finding Locomotive "Dead Centers", <i>DiscoverLiveSteam.com</i>]		* [http://www.discoverlivesteam.com/magazine/07/07.html "Finding Locomotive "Dead Centers", <i>DiscoverLiveSteam.com</i>]
			* [http://www.jghtech.com/html/dead-center-1.html "Finding Locomotive Dead Centers", Jeffrey G. Hook]

Dnevil: /* Finding Dead Centers */

2014-08-12T03:17:27Z

Finding Dead Centers

← Older revision		Revision as of 22:17, 11 August 2014
Line 31:		Line 31:

	I recommended that valves be set to give equal Lead at each end of the cylinder, when the piston is on its "dead centers" and the reverse lever in mid-gear. This allows the engine to be "hooked up" after it gets the load rolling, without having it go out of square. To do this you have to know exactly where the "dead centers" are.		I recommended that valves be set to give equal Lead at each end of the cylinder, when the piston is on its "dead centers" and the reverse lever in mid-gear. This allows the engine to be "hooked up" after it gets the load rolling, without having it go out of square. To do this you have to know exactly where the "dead centers" are.

			== External Links ==

			* [http://www.discoverlivesteam.com/magazine/07/07.html "Finding Locomotive "Dead Centers", <i>DiscoverLiveSteam.com</i>]

Dnevil: /* Finding Dead Centers */

2014-07-01T03:12:08Z

Finding Dead Centers

← Older revision		Revision as of 22:12, 30 June 2014
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	For some reason, there always seems to be, among many of the builders of our small locomotives, a certain amount of mystery about what is meant by the term "Dead Centers" and why they are important in correct valve setting and in the testing of the radial valve-gears. The three commonly used radial gears in this country are the [[Baker valve gear\|Baker]], [[Walschaert valve gear\|Walschaert]] and [[Southern valve gear\|Southern]].		For some reason, there always seems to be, among many of the builders of our small locomotives, a certain amount of mystery about what is meant by the term "Dead Centers" and why they are important in correct valve setting and in the testing of the radial valve-gears. The three commonly used radial gears in this country are the [[Baker valve gear\|Baker]], [[Walschaert valve gear\|Walschaert]] and [[Southern valve gear\|Southern]].

	It is absolutely essential that we know where the "Dead Centers" are located, in order to set the valves so that they will give equal Lead on both front and back dead center. The manner in which this is done is taken from [[The Locomotive Up To Date]] by McShane.		It is absolutely essential that we know where the "Dead Centers" are located, in order to set the valves so that they will give equal Lead on both front and back dead center. The manner in which this is done is taken from [[The Locomotive Up to Date]] by McShane.

	[[File:CharlesAPurinton DeadCenters Diagrams.jpg\|thumb\|right\|500px]]		[[File:CharlesAPurinton DeadCenters Diagrams.jpg\|thumb\|right\|500px]]