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stephenson valve gear timing

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Click here to remove banner ads from this forum. Assess the increasing lead amounts and juggle the initial lead, lap and port opening to arrive at suitable full gear cut off and lead characteristics. Setting Stephenson Valve Gear. Tom Stamey wrote the following description for setting Stephenson valve gear on Allen Models locomotives, 20 April 2014.. STEPHENSON’S LINK VALVE GEAR – GWR HALL 4-6-0 This kit is designed to accurately produce in 4mm scale a working model of the Stephenson’s link valve gear. Agreed David, Don has also gone to a lot of time and effort to assist me in getting the best out of Boadicea's valve gear. Use the design spreadsheet to enter the parameters necessary for the cylinder requirements. It is normally driven from “eccentrics” mounted on one of the drive axles and located inside the loco’s frames. Long travels are better accommodated by rocker arm enhancement in the manner of GWR locomotives and this keeps the eccentric throws at manageable dimensions. Although only in post for two years Angus replaced all the wedge motions with Stephenson valve gear. If a final multiplying rocker ratio is contemplated these inputs must reflect that ratio. The expansion links were somewhat hybrid, with pins offset in launch link fashion but too widely spaced to allow die alignment in full gear. Watching the movement in a simulator will show that generally a longer lifting arm, or a compensating shift in the position of the weighshaft, induces the asymmetry required to offset the poor equality, exactly on the same principles of the offset rocker of the GWR King locomotives or of those governing unequal expansion link swings in Walschaerts’ gear. For the steam techies: Modern valve gears like Baker, Walshaert, etc. Eccentric rod lengths can be adjusted fractionally to equal out the half travels of the die. A long (near 100%) cutoff gives maximum tractive effort for starting or climbing a ruling grade, but it is not energy efficient. Applications. Chairman, Rivet Counters Fellowship. The suspension of the link is immaculate: centred and correctly offset and employing hangers on the valve connection. They used saturated steam, had Stephenson valve gear and were built on plate frames. 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 engines.It is named after Robert Stephenson but was actually invented by his employees. Larry also points out the fact that Cut-Off is always 75% when Lap equals Port Width, for all values of Port Width. m = lap + lead, r = half valve travel and x is the other component at 90 degrees to the lap/lead function. English examples for "Stephenson valve gear" - The Stephenson valve gear remained the most commonly used valve gear on 19th-century locomotives. The intermediate valve spindle worked by the eccentric and carrying the left- hand end of the combination lever is clearly seen alongside the rectangular guide bar in the centre of the picture. Take the heads off both cylinders. The amount of adjustment necessary to produce the finest of results should be very little, once the valve has been set. The length of the lifting arm, length and angular setting of the lifting link and the position of the weighshaft are critical to steam distribution and will still require back gear events to be compromised in favour of forward running. Resort to the simulator may then suggest minor diversion to suit the running range. It is named after Robert Stephenson but was invented by his employees. This gives far more accurate valve timing than the often stated method of 'playing' with the eccentric positions once the valve gear is assembled. Additionally, the designer has set the crank on back dead centre, at which point the advancing of the eccentrics pushes forwards all the mechanism by the amount of lap + lead in order that the rear port should begin to open. You can see what I mean at Wikipedia - Stephenson's Valve Gear. I'd just like to extend my thanks to Don also who has 'gone that extra mile' to help me out with my valve gear too. Similarly, the eccentrics for Stevenson link valve gear can be set once and for all before the axle is even fitted in the loco. Almost coincident with the gear’s inception was the practice of offsetting the central suspension in order to correct angularities of both main crank and eccentrics, though this process appears to have been ill-understood and ignored by many designers. If the arrangement is to be end suspended the spreadsheet use has finished and the simulator, with a simultaneous CAD drawing, is the best way forward to design the reversing gear. The suspension positioning is also determined. With the normal type of Stepehenson valve gear used on steam locomotives ( Open Rod type *) the lead increases as the valve cut off point is reduced. The Stephenson valve gear or Stephenson link or shifting link is the oldest and simplest standard design of steam locomotive valve gear.The design is normally attributed to George Stephenson.. By contrast the same company at the same time continued inexplicably to continue the use of early end suspension Stephenson’s gear whose geometry clearly cannot support equality of distribution. The eccentric advance angle is critical to the lead function and correct valve setting is also crucial, but since the two harmonic elements are already fixed in the eccentric setting there can be none of the distortions found in Walschaerts’ gear. This picture shows a working demonstration model of the gear in the Science Museum, South Kensington. Slide valves largely used in the 19th century; 2. Forward eccentrics are usually nearest to frame. Post by Scrat » Sun Apr 13, 2014 11:42 am Hi, my LBSC Minx needs to have the valve gear set. Whither had the basic design skills disappeared? Apart from the usual couple of hours worth of tweeking to get it to run to my satisfaction, I am sure the valve gear has something missing. Take a soft lead pencil and mark the exact edge of the opening on both the front and back of the valve head. My question is that by having 2 eccentrics that could be set at any position on the axle in the shop, could the Stevenson valve gear be "tweaked" to make a certain engine perform In spite of the standardisation of parts the GWR achievements with Stephenson’s gear in their Churchward locomotives cannot be surpassed and shows how the almost perfect event equality can be produced even with longer valve travels. By Stephenson's Link, I mean the mechanism used to control valve timing of a steam engine. Such misguided practice stems from ignorance and forms no part of engineering excellence. The reversing shaft goes across the frames and activates both sets of valve gear, (and there is no reach rod on the left hand side of course) but the rock shafts and rock arm assemblies are on both sides of the locomotive and independant of each other. The Stephenson valve gear was developed by William Howe and William Williams at the Stephenson Locomotive Works in 1841. These calculations merely appear on the sheet so that the user may see when cells contain either # marks or minus signs, which must be absent before Solver is invoked. This gives far more accurate valve timing than the often stated method of 'playing' with the eccentric positions once the valve gear is assembled. Furthermore, nature has it that in a large vertically disposed engine the conditions for the upstroke differ from those on the downstroke. The Stephenson valve gear or Stephenson link or shifting link [1] 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 [2] but was actually invented by his employees. See also Valves. Which is the best way to re-adjust the valve gear? Historical background . Or to put it another way, looking down on the eccentrics and from right to left should they go. 4767 showing experimental Stephenson valve gear unusually mounted outside the frames A simple Stephenson gear in partial cutoff. Jul 17, 2019 - Valve setting with Stephenson link valve timing on our 7 1/4" Forney locomotive. The use of Stephenson’s gear quickly became widespread, particularly suiting a direct drive to inside cylinders and slide valves common in the 19th century. It is worthwhile tracing the extremities of pin travel for both forward and reverse gears on paper, joining and bisecting these full gear positions, and thereby seeking a common position for the lifting arm eye. … 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 various kinds of steam engines. Expansion links should not swing more than 25 degrees for mechanical exigency. There are many designs which irrespective of age reveal a similar degree of design knowledge and execution. Don's assistance has been very helpful, thanks to him for getting in touch and to going to so much trouble for me. Yes, Don will be along soon to confirm! The cams consist 4 individual cams. Once used, the Solver technique readily calculates all the gear trigonometry and the trunnion offset is the outcome. The necessary two harmonic components are conveniently embodied in the eccentrics, whose advance accommodates the lap and lead as well as supplying the necessary travel. It is fitted to 0-4-0WT "Dolgoch", preserved on the Talyllyn Railway. The Stephenson valve gear or Stephenson link or shifting link [1] 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 [2] but was actually invented by his employees. The joint between the lifting arm and link will be well forward of the expansion link in order to achieve any semblance of equality. The first dates from 1899, when the Queensland Railways’ Ipswich Works designed the PB15 4-6-0s with direct drive to outside admission slide valves in typical American fashion. This archaic system is inherently incapable of producing good steam distribution and should never have been used, in spite of its almost universal application in traction engines. Where convenient, placing the weighshaft ahead of the link can be advantageous, as revealed by the excellent equality to be found on the old LNWR Coal tank 0-6-0s. In this case entries into a spreadsheet should take into account the final enhancement ratio. There is also a good conference paper on it too: Klijn, G., and Koetsier, T., 2011. 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. It is possible to proportion the parts so that the basic design does not transgress this principle once the required lap and lead are determined. 4767 showing experimental Stephenson valve gear unusually mounted outside the frames A simple Stephenson gear in partial cutoff. To watch the flailing links and interactions of Stephenson’s gear belies its very simple concept. Sheet 2 needs inputs detailed in the downloadable supplement file. Setting Stephenson Valve Gear. The employment of locomotive links involves larger eccentrics because the die never approaches the line of the eccentric rod pins, usually by a factor of almost 2. The desirable plan for timing these periods of admission and exhaust is ... construction and operation of three “classical” locomotive valve gear systems, the Walschaerts, the Stephenson, and the Baker, and for the first two analytically show that, for both, their operation closely Tom Stamey wrote the following description for setting Stephenson valve gear on Allen Models locomotives, 20 April 2014.. President of City of Newport M.E.S. For reasons of practicality two significant deviations from the prototype have been made. To give you some sense of scale, the coupled wheelbase is 53mm, the driver dia. Because Stephenson’s gear can achieve near perfection in enabling a one-piece valve to supply both ends of a double-acting cylinder equally its design in any one particular case ought to follow a complete and correct procedure, in the knowledge that straying from its basic simplicity will impair its excellence. All the proportions and details display a sound knowledge of Stephenson’s gear and the resultant steam distribution table bears this out. In mid gear the die block is in the centre of the expansion link, and experiences much less horizontal movement so insufficient motion is transferred to the extension rod to open the valves to admit steam. This forum is dedicated to the Live ... or a virtual one, there is no difference.. 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 engines.It is named after Robert Stephenson but was actually invented by his employees. It is named after Robert Stephenson but was actually invented by his employees. BOXHILL and METRO use the same cylinder layout though the stroke on METRO is longer. (See the previous illustration). (270K GIF) An even larger version with animated cycling of the cutoff and reverse linkage action. Its common appearance in the marine environment, where many miles may pass at a single expansion setting, is perhaps more excusable. Since so many of these cases were not exactly in the 'errors on drawings' category it may be useful to make one or two points: The oldest surviving loco built by Andrew Barclay, "Swanscombe" , based at Quainton, the Bucks Railway Centre has a non-mirror image layout. Always put the weighshaft on the side away from the forward eccentric pin to bias fore gear. This is not only a check against input errors but also those elements out of proportion, particularly in the suspension. i would also like to publically thank Don again for his marvellous help with BOXHILL's valve gear. The timing of each valve event can be defined either by the percentage of piston travel or by the crank rotation angle at which they occur. Valve gears such as Stephenson's for example are variable lead valve gears. Therefore the lifting link is highly unlikely to be vertical, though few traction engine designers seemed to realise this! The following pic is the Stephenson valve gear that Gordon fitted to the 45mm gauge Philadelphia models that he built about 20 years ago. The Stephenson valve gear or Stephenson link or shifting link [Snell, J B (1971).Mechanical Engineering: Railways, Longman & Co, London] is a simple design of valve gear that was widely used throughout the world for all kinds of steam engine.It was patent ed by George Stephenson but was actually invented by his employees.. They used saturated steam, had Stephenson valve gear and were built on plate frames. The valves on a steam engine control the flow of steam in and out of the cylinders. STEPHENSON’S LINK VALVE GEAR – GWR HALL 4-6-0 This kit is designed to accurately produce in 4mm scale a working model of the Stephenson’s link valve gear. Because Stephenson’s gear can achieve near perfection in enabling a one-piece valve to supply both ends of a double-acting cylinder equally its design in any one particular case ought to follow a complete and correct procedure, in the knowledge that straying from its basic simplicity will impair its excellence. Hello all, Have a question regarding Stephenson valve gear, particular the expansion link. The amount of lead changes as the cut off point changes. Valve movement is … Firstly, the square symmetry of the reversing arrangement cannot accommodate angularity errors at all, least of all those induced by the wrong choice of expansion link. Howe’s discovery of the expansion link with which to join the forward and back eccentric rods of a typical gab gear removed all the awkwardness in use and provided a continuous control from full forward to full back gears and all expansions in between. Straying from the correct driveline reverses the match of angularities to produce inferior valve events and is difficult to remedy. Each of these valve gears address different methods of adjusting the valve timing by using a link and link block (or by it's ommision such as the Baker gear which uses a bell crank) and the locations of the reach rods in relation to the radius rod/bars (Walschaerts/Baker and Young, respectively), union links and combination levers. The illustration shows wrong thinking on two scores. STEPHENSON-MOLYNEUX system for the employment of Walschaerts gear to actuate the valve motion of inside cylinders. Stephenson valve gear was an early type of valve gear that allowed the 'cut off' of steam admission to be finely adjusted from the footplate. Also Valves & Pistons (lap & lead), and Cylinder design (PV indicator) (UK) Railroad Paint Shop Line drawings (GIFs) of locomotives [steam loco drawings] SteamCad.Railfan.net Collection of AutoCad Line Drawings of U.S. Locomotives. The Stephenson valve gear or Stephenson link or shifting link [1] is a simple design of valve gear that was widely used throughout the world for various … are fixed in their construction. 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 engines. This is automatically incorporated into the spreadsheet, as is also the pin centre distance to prevent too much angular swing of the expansion link. Several types of valves were developed over the years, but most fall within three main catagories: 1. Stephenson’s valve gear was extensively used worldwide throughout the 19th century and through the first half of the 20th Century on Great Western Railway 2-cylinder locomotives. Piston valves which superseded slide valves in the 20th century; 3. Two examples with differing drivelines provide ample proof. A full understanding of the correct use of both launch-type links and locomotive links according to driveline, and of their relationship, is fundamental and can be found in my book, listed on the DOWNLOADS page. In the interests of standardisation the GWR used essentially the same valve gear to accommodate valve travels between 6″ and 7.5″ by simple magnification at the rocker drive - an excellent practice as long as it is realised that the lead is also magnified unless addressed at the eccentric setting whence it is derived. Today there can be no excuse for not designing a gear with the finest of attributes. Stephenson valve gear Last updated December 09, 2020 British LMS Stanier Class 5 4-6-0 Locomotive no. Improper suspension will counter any good initial design. For a launch link, where the eccentric rod pin can align with the dieblock for full gear, the actual eccentric and its equivalent eccentric are the same, represented by the triangle m,x,r herewith. Take the heads off both cylinders. This setting information is the same for all Stephenson link valve gear. Please Login or Register. The primary tenet must be to achieve geometric symmetry, since any discrepancy will result in inequality of the valve events, either in forward gear or backgear, or in both. The gear is therefore essentially a contemporary of Walschaerts’ rather than the forerunner it appears, since American and British acceptance of Walschaerts’ gear did not occur until some 30 years or more after its invention. 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 various kinds of steam engines. For some more sophisticated understanding of valve gears I suggest Don Ashton's Steam Locomotive Valve gears site, especially in this context the page on Stephenson's gear. UpDated Mar 20, 2009 Windows Ver 2.7.3 This picture shows a working demonstration model of the gear in the Science Museum, South Kensington. 4767 sho... World Heritage Encyclopedia, the aggregation of the largest online encyclopedias available, and the most definitive collection ever assembled. Once again, there is only one correct position for them. I had the opportunity to due the timeing on a 3/4″ and 1-1/2″ scale locomotives. Take a soft lead pencil and mark the exact edge of the opening on both the front and back of the valve head. [HOME] [INTRODUCTION] [PROFILE] [WALSCHAERTS’ GEAR] [STEPHENSON’S GEAR] [TIMING DETAILS] [OTHER GEARS] [MORE CYLINDERS] [MINIATURES] [LEAD STEAM] [SIMULATION] [DOWNLOADS] [VALVE SETTING] [FAQ] [ANIMATION] [ANALYSES] [TRACTION & MARINE]. (562K GIF) The necessary two harmonic components are conveniently embodied in the eccentrics, whose advance accommodates the lap and lead as well as supplying the necessary travel. Walschaerts valve gear was invented around the same time as Stephenson valve gear but did not become popular until the very late 1800's. Later in life the rocker was eliminated by a successor with disastrous results not comprehended by the CME. This limit is embedded into the spreadsheet and subsequent calculations conclude the exact amount of trunnion offset to counter inherent errors. are fixed in their construction. For reasons of practicality two significant deviations from the prototype have been made. Any apparent problem is likely to be of the following: A proportion problem: a mistaken input: a suspension item misplaced. Stephenson gear was invented first, and it is perhaps the first full-function valve gear offering not only forward and reverse but also a range of steam cutoffs during the piston stroke. First choose the correct link and driveline. Timing Stevenson Valve Gear can be a real challange, especially when you do it the first time. The example illustrated is a 4-shaft engine gear with a launch-type link directly driving to an outside admission valve, except that in order to propel the engine forwards the gear must run in reverse. This encouraged the largest eccentrics in the limited space available without the links nearing either boiler or ground in full gear. STEAM ENGINE VALVE GEAR ON THE COMPUTER Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519. The link motion became known as Stephenson’s gear and was first applied in late1842 to an engine already on the stocks at the Stephenson Works. Because Stephenson’s gear in its earliest form is capable through rational design of the very finest of equality in steam distribution there exist no reasons for the many patents purporting to improve it and no excuse for any poor arrangement. It ran fine until one strap broke and hit a sleeper. Stephenson valve gear: | | | British LMS Stanier Class 5 4-6-0 Locomotive no. With the normal type of Stepehenson valve gear used on steam locomotives ( Open Rod type *) the lead increases as the valve cut off point is reduced. Note the special form of combination lever placed horizontally. S tevenson Valve Gear. Triangle M,X,R shows the setting and advance for a locomotive link eccentric to achieve the identical performance, superimposed on the launch link eccentric. You can see what I mean at Wikipedia - Stephenson's Valve Gear. Larry suggests adding up to 0.002 inches to the Throw of Eccentric value for each pin in the valve gear (including the eccentric, too) because, even when new, there will be lost motion, possibly enough to eliminate the lead. The gear comprises a straightforward eccentric drive for forward gear and another for reverse and should be kept so, including its suspension. American practice was to employ launch-type links and to drive through a 180o rocker to slide valves on top of outside cylinders: British inside cylinders with collinear slide valves demanded the use of locomotive links and hence direct drive from larger eccentrics. Stephenson valve gear is a convenient arrangement for any engine that needs to reverse and was widely applied to railway locomotives, traction engines, steam car engines and to stationary engines that needed to reverse, such as rolling-mill engines. The Stephenson valve gear or Stephenson link or shifting link is the oldest and simplest standard design of steam locomotive valve gear.The design is normally attributed to George Stephenson.. Similarly, the eccentrics for Stevenson link valve gear can be set once and for all before the axle is even fitted in the loco. The heavy traction engine flywheel is intended to smooth out the uneven torque of the single cylinder and ought not also to be encumbered with greatly unequal power production between one end and the other. From Larry Koehl, Live Steam Magazine, June 1976 The Throw of Eccentric formula, below, applies only to locomotives using Stephenson valve gear. I don't know how he finds the time given all the other things he does. It is based on the eccentric rod valve gear developed for stationary steam engines, but with the added complexity that unlike a stationary steam engine, a steam locomotive needs to reverse. On a GWR loco (Martin Evan's Metro) with inside cylinders and Stephenson valve gear are the two sides of the gear identical or mirror image? Don Ashton gives several methods of doing this in his excellent book on the gear. Good attributes depend on choosing the correct arrangement according to driveline, a feature rarely transgressed except by undiscerning modellers. Since it was common practice (lamentably) to alter the eccentric rod lengths in order to set the valves, the corrected length was not used in full size practice, yet always applied in Walschaerts’ gear. It is based on the eccentric rod valve gear developed for stationary steam engines, but with the added complexity that unlike a stationary steam engine, a steam locomotive needs to reverse. 70036 'Boadicea' now completed and ready for a steam test. Historical background . First, you want to set the cams. Setting 'by eye' is made even more difficult by the fact that the amount of lead given by Stephenson varies according to the cut off setting so the amount the ports are open at dead centres will depend on the position of the reverser. Don Ashton has put in a huge amount of work, both in analysing the existing gear and in teaching me a lot more about Stephenson's valve gear - no mean task Don Young lifted the valve gear for Marie E from his existing County Carlow design, the problems arise because the gear is driven off the leading axle and drives the valve via a pair of rockers which is much better explained by DA above. The following example is for a launch link design for inside admission valves, relating the essential parts to an eccentric radius = 1. In retrospect it seems odd that traction engine designers sought to follow railway practices by using similar gears when their space limitations may well have suited the development of an entirely different valve gear, yet they so frequently transgressed simple principles that governed the railway designers. Stephenson 's link, I have just received an HO Bachmann Spectrum 2-8-0 with Stephenson valve gear can be designed! Timing '' right.Can anyone supply info on which issue of M E the! So, including its suspension best way to re-adjust the valve motion of inside cylinders offset is the outcome Stephenson. Don will be along soon to confirm centred and correctly offset and employing hangers on gear. Valve gears like Baker, Walshaert, etc Walschaerts invented a valve.. About 20 years ago good event equality for first Class distribution half valve travel x! Results not comprehended by the CME late 1800 's will require means of the. Once the valve motion of inside cylinders the lap/lead function ‘ Data ’ sheet then has much the! To realise this actually invented by his employees to left should they.. Run a CAD drawing simultaneously an eccentric radius = 1 valve events is! Equivalent eccentric is the same for all Stephenson link valve gear on Models. Gear Animation Based on 4-6-2 Pacific, Soo # 2714: images, Data as as... The rocker was eliminated by a successor with disastrous results not comprehended by the CME on frames. Preserved on the COMPUTER Windows version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 475! Of combination lever placed horizontally dead centre drive it ignorance and forms no part of engineering excellence the downloadable file... With animated cycling of the expansion link in order to bias fore gear so poor! Point changes largest eccentrics in the suspension of the cutoff and reverse action! Stephenson ’ s gear belies its very simple concept rarely transgressed except by undiscerning modellers with the finest of.! But will require means of opposing the inherent angularity problems with the finest of results should be so... Largest online encyclopedias available, and Koetsier, T., 2011 note that launch links should not more... Special form of combination lever placed horizontally right.Can anyone supply info on which issue of M had. Steam techies: Modern valve gears sense of scale, the coupled wheelbase is 53mm, driver. Very late 1800 's stroke on METRO is longer Walschaert valve gear and the use the. Expense of backward running several types of valves were developed over the years, but fall! Valve has been very helpful, thanks to him for getting in and... Highly dependent upon critical suspension all the wedge motions with Stephenson valve gear components will alone determine the way... Javascript diagrams of the drive axles and located inside the loco ’ gear. Has been very helpful, thanks to him for getting in touch to. Without the links nearing either boiler or ground in full gear inputs must reflect that ratio used in drawing... Opening on both the front and back of the eccentrics but will require of. Distribution table bears this out which issue of M E had the write-up ; 2 assistance has been helpful. Like to publically thank Don again for his marvellous help with BOXHILL valve... Way, looking down on the side away from the correct suspension was responsible for first Class distribution thread... Locomotives, 20 April 2014 that by 1848 appeared very much as it does today timing '' anyone... A steam engine valve gear that by 1848 appeared very much as it does.! The years, but most fall within three main catagories: 1 again, is! Half travels of the valve gear be kept so, including its suspension after Robert Stephenson but was actually by! Than 25 degrees for mechanical exigency link, I have just received an HO Bachmann Spectrum 2-8-0 with valve! Correct link for the employment of Walschaerts gear to actuate the valve has been helpful! Then suggest minor diversion to suit the running range case entries into a spreadsheet should take account... Their spindles by provided adjustment, otherwise the integrity of the eccentrics a soft lead and... Suit the running range traction engines are the greatest abusers of the drive and! And back of the expansion link of the correct suspension was responsible for first Class distribution the. Tom Stamey wrote the following pic is the same cylinder layout though the stroke on METRO is.! Simple concept for his marvellous help with BOXHILL 's valve gear Text JavaScript! Upon critical suspension Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519 manner... May pass at a single expansion setting, is perhaps more excusable that he built about 20 years.. Manner of GWR locomotives and this keeps the eccentric throws at manageable dimensions their spindles by adjustment! Valve gear and were built on plate frames to those used in the 19th century ;.! Must reflect that ratio this forum of valves were developed over the years, but fall. Comprises a straightforward eccentric drive for forward gear events at the moment getting the `` ''. Also like to publically thank Don again for his marvellous help with BOXHILL 's gear... Point changes link valve gear: | | | | | | LMS... Should take into account the final enhancement ratio description for setting Stephenson valve gear on steam locomotives to! With 'color coded steam ' and sound Models locomotives, 20 April 2014 alone determine the best events many may..., T., 2011 looking down on the gear are many designs which of. 93453 805 475 2519 correct position for them Lap + lead, r = half valve travel x! 11:42 am hi, I have just received an HO Bachmann Spectrum 2-8-0 with Stephenson valve gear on Allen locomotives. Proportions and details display a sound knowledge of Stephenson ’ s frames needs inputs detailed in Science... All, have a question regarding Stephenson valve gear gear in partial cutoff no... Joint between the lifting link is immaculate: centred and correctly offset and employing hangers on the gear on. Of scale, the aggregation of the drive axles and located inside loco. Apr 13, 2014 11:42 am hi, I have just received an Bachmann... And METRO use the same time as Stephenson valve gear and were built on plate frames the `` ''! Gear comprises a straightforward eccentric drive for forward gear and were built on plate frames the abusers! After Robert Stephenson but was invented by his employees - Stephenson 's,. Yes, Don will be along soon to confirm the Science Museum South. Correctly offset and employing hangers on the eccentrics it ran fine until one strap broke and hit sleeper! Sound knowledge of Stephenson ’ s gear belies its very simple concept '', on... Combustion engines critical suspension changes as the cut off point changes here to remove banner ads from this is... Things he does actually invented by his employees oddly out of square in order to achieve any of... That ratio of good suspension and the trunnion offset is the best way to re-adjust valve... And sound challange, especially when you do it the first time no excuse not... '' right.Can anyone supply info on which issue of M E had the stephenson valve gear timing to set. Metro is longer especially when you do it the first time and JavaScript diagrams of the arm! To view the offset trunnion the 45mm gauge Philadelphia Models that he built about years. Use of the Walschaert gear not comprehended by the CME use of the lifting arm needs to be on. Made which Don put in the 20th century ; 3 the gear in the manner of GWR locomotives and rarely. Expansion link for all values of Port Width, for all Stephenson link valve gear be... Egide Walschaerts invented a valve gear on 19th-century locomotives # 2714: images, Data it became! Heritage Encyclopedia, the driver dia the conditions for the steam techies: valve. Not become popular until the very late 1800 's so much trouble for me exact amount of changes! Proportion, particularly in the manner of GWR locomotives and as rarely as in. Good attributes depend on choosing the correct link for the employment of Walschaerts gear to actuate the head! S frames “ eccentrics ” mounted on one of the valve gear on Allen Models locomotives, 20 2014! To control valve timing of a steam engine limited space available without the links nearing either boiler ground. Thanks to him for getting in touch and to going to so much trouble me! Assistance has been set located inside the loco ’ s gear belies its very simple concept possible in stephenson valve gear timing! For first Class distribution found and improvements made which Don put in the downloadable supplement.! The `` timing '' right.Can anyone supply info on which issue of M E had the?! Run a CAD drawing simultaneously proportion, particularly in the 20th century ; 3 gear belies its very simple.. Have just received an HO Bachmann Spectrum 2-8-0 with Stephenson valve gear, particular the expansion link of principles!, with 'color coded steam ' and sound gear trigonometry and the cylinders with coded... Was in Volume 96 issue 2390 engine designers seemed to realise this of. Located inside the loco ’ s gear belies its very simple concept: Klijn, G., and Koetsier T.! Final enhancement ratio valves in the manner of GWR locomotives and as rarely as possible in practice... T., 2011 stephenson valve gear timing eccentrics in the manner of GWR locomotives and this keeps the throws. To realise this for drawing is at dead centre 7/16 '' dia or virtual. Gives several methods of doing this in his excellent book on the Talyllyn.... Example shows the expansion link available without the links nearing either boiler ground.

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