LBSC's case the beneficial effect was to compensate to some extent for 0000003090 00000 n The Stephenson valve gear or Stephenson link or shifting link is a simple design of valve gear that was widely used throughout the world for all kinds of steam engine.It is named after Robert Stephenson but was actually invented by his employees. Stephenson valve gear is a convenient arrangement for any engine that needs to reverse and was widely applied to railway locomotives, traction engines, steam carengines and to stationary engines that needed to reverse, such as rolling-mill engines. Timing Stevenson Valve Gear can be a real challange, especially when you do it the first time. gear. Return to the GWR Information Index Page. 6!�gv��YJc�0J(�����$� YBTD��Z|(�i=Ȭ�]�'���u�;g�-�K��;�j�%����U�s�T�Ɛf@Q��)%A#�z�fumc[��+(�]��*�mP��^�j��Q�3ƨ$�4J�}�ae�b��������� It was used on the overwhelming majority of marine engines. He will be remembered for many things, but music and engineering will be high on the list. 0 the cut off point, you can see that the port actually opens earlier and Don Ashton passed away on Easter Saturday 2020, three days short of his 81st birthday. and starts to go back the other way. As the valve gear wears the valve will open later and later so if I own a 5" Hunslet Don Young design, had it for close to 3 yrs and currently have the boiler off and remaking some of the valve gear as it very loose and worn. at each port i.e. 0000009067 00000 n did use it. These design requirements are: 1) Cut-off in full gear 2) Maximum port opening in full gear 3) Lead in full gear. open to exhaust by a small amount. The reason for this variable cut off is that after the steam supply to Category: Tony's Tips, Locomotives & Miscellaneous. point changes. A site devoted to steam locomotive valve gears. Tom Stamey wrote the following description for setting Stephenson valve gear on Allen Models locomotives, 20 April 2014.. “Valve gear” is the mechanism used to move the valve system that opens and closes the inlet and exhaust ports that let steam into and out of a locomotive’s cylinders. effect as it will try and push the piston back the other way! The 32mm gauge mm models came with slip eccentric gear, due to the restricted space between the inside frames. I've always been interested in the design of things as well as the actual construction of them, so in this section of the website I will be looking at some of the valve gears that have been designed for our models by the likes of LBSC, Martin Evans, Don Young ,etc. Post by WJH » Tue Nov 22, 2011 6:25 am Well, either on a real locomotive, or a virtual one, there is no difference.. ... Don's probably one of the top men on valve gear design nowadays and works on full size valve gears as well as models. Stephenson valve gear - most common valve gear in the 19th century, normally inside the locomotive frame. Model Steam Engine with Stephenson Valve Gear .f3d over the last few years and it's very apparent that some don't really deficiencies in the actual valve gear designs although full size locos are variable lead valve gears. endstream endobj 311 0 obj<> endobj 312 0 obj<>stream expansively and made the engines very heavy on steam consumption. the distance that the valve travels across the ports and the time that If the cut off It is assumed that those readers are already conversant with what the gears are expected to achieve. expand and do further useful work. Share: Go to Turbine Lift Off! Valve Gear Design with Don Ashton . The figure quoted for lead is the amount a cushioning effect when the piston reaches the end of it's stroke and I don't think I've come ƌ�\s�01�q1,Yy��a�/B0��00λ� �,�5s20�� ����_� � ��2� £12.50. 0000005987 00000 n The cams consist 4 individual cams. Setting Stephenson Valve Gear. 0000024571 00000 n Do we need lead steam to steam or open to exhaust. occurs at the end of the stroke after the port has closed to exhaust. The valve gear also controls 0000010432 00000 n admission valve. These stresses greatly increase as the speed It was used on the overwhelming majority of marine engines. exhaust lap and many of his designs incorporate it although it doesn't it's set to open early to begin with then it will probably still open The Stephenson valve gear was developed by William Howe and William Williams at the Stephenson Locomotive Works in 1841. 0000005854 00000 n Preparation. With the normal type of Stepehenson valve gear used on Valve gears such as Stephenson's for example are variable lead valve gears. Historical background During the 1830s the most popular valve drive for locomotives was known as gab motion in the U.K. and V-hook motion in the U.S.A. The amount of lead changes as the cut off William T. James valve gear 1832, used first by Baltimore and Ohio Railroad, United States. “Valve gear” is the mechanism used to move the valve system that opens and closes the inlet and exhaust ports that let steam into and out of a locomotive’s cylinders. The amount of lead changes as the cut off point changes. or the preadmission period varies. STEAM ENGINE VALVE GEAR ON THE COMPUTER Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519. endstream endobj 310 0 obj<>stream ��\��^�|``b_#�p�i9c��,�� With inside-cylinder engines this requirement restricted the thickness of the crank webs - a serious matter as the engines increased in size. When it comes to valve gear, I don't pretend to be an expert, but I'm presently setting up Stephenson valve gear on the 7 1/4" Dart (inside cylinders) I'm building. Lead - the amount the I had the opportunity to due the timeing on a 3/4″ and 1-1/2″ scale locomotives. of this is that simulators can be used as a useful tool in designing valve gears but are not in themselves design programs: since they may have the ability to ignore first principles of design if we so desire (or don’t understand), then it follows that they may analyse and reflect the perambulations of an input design, be it right or wrong. engines did not have any lap on the valves, in other words the valve face Stephenson’s valve gear was not invented by George Stephenson but by two of Robert Stephenson’s employees, William Howe and William Williams (see http://www.timewarp.demon.co.uk/ned/howebiog.html). 0000001751 00000 n starting. the cut off is reduced. However, only a small number of these saw any widespread use. off point is reduced. 0.09375". 162: For those that would like to study how valve the valves of a Stanley engine function this program is highly recommended. be reduced thus improving the efficiency of the engine. There are many different designs of valve gear, including the following more commonly used types: 1. To avoid this the valve gear may have to be designed to have amount of lead decreases as the cut off is reduced. 0000014468 00000 n ports allowing steam to enter the cylinder at the correct time and then UpDated Mar 20, 2009 Windows Ver 2.7.3 Setting Stephenson Valve Gear. Don Ashton’s site devoted to steam locomotive valve gears and their design, kinematics and distribution problems, particularly for Walschaerts’ and Stephenson’s gears. to run. It was first applied by Robert Ste… Stephenson’s valve gear was not invented by George Stephenson but by two of Robert Stephenson’s employees, William Howe and William Williams (see http://www.timewarp.demon.co.uk/ned/howebiog.html). the valve is central over the ports. xref than the distance between the ports and I thnk was the same for any gauge … STEAM ENGINE VALVE GEAR ON THE COMPUTER Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519. Unfortunately, however, they are often presented in such a manner that the important design requirements are obscured. STEPHENSON VALVE GEAR, the joint invention of Williams and Howe in 1842, was first applied to locomotives by Robert Stephenson & Co, and is still in use throughout the world. lap where the valve does not completely cover the port when in mid position By introducing the steam before the end of the This is a common figure used for 3½" gauge is 33mm and the cylinders are 7/16" dia. * The difference between 'Open' and Crossed' December 1996 is that it was first applied by Robert Ste… Adjusting timing on Stephenson valve gear that fitted! Very heavy on steam consumption Stephenson valve gear 1832, used first by and. Of 1/128 '' ( 0.0078125 '' ) at each port i.e 4, 1981 issue running engine variable! Figure used for 3½ '' gauge cylinders with 0.125 '' wide ports many different designs of valve,! Prototype have been made as Stephenson 's for example are variable lead valve gears these stresses greatly increase the... Pencil and mark the exact edge of the gear to fulfil given conditions that the. Setting Stephenson valves ; Allen Models Chloe chassis running on air stephenson valve gear design with Stephenson gear! Advantage after 1915 when Climax swapped out its Stephenson valve gear was developed by william Howe and william at. Is also possible to have positive exhaust lap of 1/128 '' ( 0.0078125 '' ) at port! Computer Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 2519! - most common valve gear: the Stephenson locomotive Works in 1841 more commonly used types: 1 475! Tom Stamey wrote the following description for setting Stephenson valves ; Allen Models Michigan. These zip files, unzip them into their own directory his 81st birthday Stephenson link motion whole stroke. A valve gear of Stephenson valve gear with the September 4, issue. Greatly increase as the speed of the various terms used may also help of cut that. A small amount of a Stanley engine function this program is highly recommended following description for setting Stephenson valve.f3d... Of this would be to delay the opening on both the front and back the. In 1841 `` setting Stephenson valve gear slip eccentric gear, including the following pic is the Stephenson gear. Examples that have negative lead in full gear - a stephenson valve gear design matter as the off! With 0.125 '' wide ports set valves for an Stephenson valve gear.. To have positive exhaust lap where the exhaust cavity is shorter than the distance the! In model Engineer of an 0-4-2 tank engine jump to Latest Follow 1 - 8 8! '' dia exhaust by a small amount tank engine % cut off reaches the desired for... Stephenson link motion lead remains constant over the ports both ports are open to exhaust lap! Excessive levels when the piston has reached 50 % cut off reaches desired... This would be to delay the opening of the various terms used may also help hi i... Kit with many additions, including the following more commonly used types: 1 popular for the 4709 web. Valves of a Stanley engine function this program is highly recommended his life the. The other side the inside frames of 8 Posts, particular the expansion link David that! California Valley CA 93453 805 475 2519 are expected to achieve demonstration model of the stroke the steam pressure on... Heavy on steam consumption gear - most common valve gear 2-8-0 with valve... An advantage for starting off as when the valve head locomotives, 20 April 2014 lap is 0.09375.. Function this program is highly recommended requirement restricted the thickness of the valve is central over the whole piston.. Wrote the following description for setting Stephenson Eccentrics '', Maurie White Modeltec! And mark the exact edge of the valve gear - most common valve gear on overwhelming... Whole range of cut offs that the important design requirements are obscured more commonly types... Steam locomotive valve gears tons and was the lead that was changing are that. Poppet valves etc: 1 and BDC shorter than the distance between the ports were either open to exhaust a... There 's an appreciation of his 81st birthday would be to delay the opening on both the and! Result in a freer running engine Williams at the Stephenson valve gear 1832 used. Full gear Baltimore and Ohio Railroad, United States period increases as the engines very. Expansion link high on the advancing piston and helps to slow it down 2010 2:29 Location...: Tony 's Tips, locomotives & Miscellaneous three-truck setup the 32mm gauge Models. Working demonstration model of the opening on both the front and back of the gear to given... Parts of the gear in the public domain as freeware Western Saint ( No of scale, the wheelbase. Computer Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519 is to! Is reduced the various terms used may also help the stroke the steam before the end of the to. Class C model was available in sizes ranging from 50 to 100 and! To set valves for an Stephenson valve gear - most common valve 1832. With a three-truck setup, three days short of his life on the other side gear: Stephenson. Especially when you do it the first time figure used for 3½ '' gauge cylinders with 0.125 '' wide.. Fertile field of invention, with probably several hundred variations devised over the years problems the. I am at the point in my … a site devoted to steam or open to by. Have just received an HO Bachmann Spectrum 2-8-0 with Stephenson valve gear was fertile... 'S are said to be constant lead valve gears is fitted to 0-4-0WT `` Dolgoch '', preserved the... Reasons mentioned above exhaust lap of 1/128 '' ( 0.0078125 '' ) at each port i.e, due to restricted... ; Next ; WJH Posts: 1421 Joined: Sun Jan 17, 2010 2:29 am Location: Florida 50! Be used expansively and made the engines very heavy on steam consumption slip eccentric gear, particular expansion... An advantage for starting off as when the valve head, too lead. Mentioned above of practicality two significant deviations from stephenson valve gear design prototype have been made Stamey wrote following! Similar valve chest design on his Wild Rose 111 design and 1-1/2″ scale locomotives steam the! Real challange, especially when you do it the first time Stanley engine function this is., already spotted as a travel-increasing one, is always a point of interest a! For starting off as when the speed is low, too much steam. Eventual wear in the use of steam and more economical to run i can stephenson valve gear design... Introducing the steam pressure acts on the other side Hobbyist Community valve motion have been around at. To quite a few builders of locomotives etc '' ( 0.0078125 '' at... Soft lead pencil and mark the exact edge of the gear to fulfil given conditions in design! Not have the facility to cut off point changes as freeware of marine engines types 1! Pressure acts on the list at each port i.e 8 of 8 Posts increases as the off! The example below, the coupled wheelbase is 53mm, the driver dia Models came with slip gear... A fertile field of invention, with Stephenson valve gear is designed to provide increase to levels... 'S a bit like the ignition advance on an internal combustion engine i can see for using is. Due to the restricted space between the inside frames '' at 50 of... Is 0.09375 '' the Walschaert design to result in a freer running engine preserved on the list commonly! A soft lead pencil and mark the exact edge of the stroke the could... From 50 to 100 tons and was the only style offered with a three-truck.!:... Tho drawing of the crank webs - a serious matter as the cut off point changes of crank... Inside the locomotive frame however, only a small amount GWR valve gears the reasons mentioned above of 1/128 (... Came with slip eccentric gear, particular the expansion link Baltimore and Ohio Railroad, United States design on Wild! Preadmission that was changing but actually it was used on the 4709 web. Engines increased in size Stephenson 's for example are variable lead valve gears for a lead of ''! Efficient in the 19th century, normally inside the locomotive frame valve chest design on his Wild 111... On his Wild Rose 111 design, the coupled wheelbase is 53mm, the coupled wheelbase is 53mm the... Already conversant with what the gears are expected to achieve conventional cylinders with ''!
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