setting stephenson's valve gear
In the past I know that if the links of this type of gear are not positioned right it will not time correctly. Everything to me looked good. If your cams are properly spaced 90 degrees apart and you have done everything else right while building it, you should hav enot difficulty in timing it. ! 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. This fine model in the Science Museum, South Kensington, can be operated by the public and clearly shows the application and working principles of the Gooch gear. 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. This is easily ascertained by measuring from the rail to the footplate on all four corners. Again the pencil marks come in handy. Or, if you have not yet put the boiler on you can time it and see the valve from above. Your illustration notes For reasons of practicality two significant deviations from the prototype have been made. Just blank with a red X in the left corner. to avoid excessive lead when notched up, the gear must be set for negative lead in fullgear. Then put rods in the 9 o'clock position, lock down the drivers, reverse lever in full reverse and move the reverse cam until the head covers the back opening in the head. With the crankpin at apporximately 150 – 160 degrees of rotation, the slide valve should close the rear steam port. (Railway Heritage) Take the heads off both 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. It is named after Robert Stephenson but was invented by his employees. Take a soft lead pencil and mark the exact edge of the opening on both the front and back of the valve head. The valve must be equally located between the front and rear openings in the head. 3.) My loco has 2 reverse cams inside Please advise on how to get the pictures herein. What I did not realize was the die block was not up the full height in line with the eccentric rod, hence my problem. 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. Can you email them to me? 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. 1. Preparation. I really need the pictures for setting up the stephenson gear. photos are not showing up on the valve gear page. IN FORWARD GEAR. Put your revers lever in full forward. Thank you kindly. The front valve covers are Before setting my height of the underside of my boiler, I moved the linkage into what I thought was the upper position. I owned at one time a 3/4" 4-4-0 that had inside Walschaert valve gear. Slide valves largely used in the 19th century; 2. ... Lead is governed by the valve gear and its setting. 1 Historical background; 2 Applications; 3 Derivatives. When the link is fully raised as depicted in the drawing to the left, the eccentric that sets the valve motion for forward engine operation is directly in line with the valve rod (shown in the drawing as the line off to the left). Download Windows Valve Gear Programs File 10A, 1.57 MB, Version 2.7.3 Download Windows Valve Gear Programs File 10B, 1.26 MB, Version 2.7.3 Download Windows Valve Gear Programs File 10C, 1.25 MB, Version 2.7.3 Download Windows Valve Gear Programs File 10D, 1.28 MB, Version 2.7.3 Then lock it down. Preparation. Take a soft lead pencil and mark the exact edge of the opening on both the front and back of the valve head. 4.) If not use the adjustment screw on the valve rod to center it. Better to set the eccentrics at full gear so that the valve only just cracks the ports at TDC/BDC and adjust the spindle length or slide position so it is sy… William T. James valve gear 1832, used first by Baltimore and Ohio Railroad, United States. They can tell you when to stop or to go the other way etc. Understand that moving the reverse cams will slightly affect the forward valve position and vice versa and that you will have to repeat the above steps a couple of more times to get the engine to time as close as possible. Place the rods on the engineer side of the engine at 3 o'clock taking care to position them properly as close to 3 as possible and lock the drivers down. Setting valve line-and-line again, ... FITTED WITH STEPHENSON’S GEAR. David Bothwell 1: 17/01/2020 17:05:39: 155 forum posts: Thanks for that Baz, a big help, I,ll get to the bottom of the valve setting somehow/some way! At the instant when the space on one side of the piston starts to expand, i.e. Not the simplest solution, but the gear had the distinctive feature of the drive rod having a large mass at the valve gear end, and thus a taper in the reverse direction. At any setting, the valve gear satisfies the following two conditions: 1. Poppet valves similar in principle to those used in internal combustion engines. Valve setting with Stephenson link valve timing on our 7 1/4" Forney locomotive. The difference is that stevension valve gear used 4 eccentrics. 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Information is the same for all Stephenson link valve gear on Allen Models,... Backstrip w/gilt spine lettering, marbled end papers, illustrated, three.! Gear in full forward set the eccentric so that the engine one correct position for them a...
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