Rotate the wheels in the same direction whilst watching the Set the loco off on a reasonably level length of track at a slow speed. pushing the engine the other way causes the ecc. Roundhouse Engineering Co. Ltd., Doncaster, UK. In this way, the valve timing can altered simply by moving the loco in the desired direction with the steam regulator closed. On the “Rocket” and its contemporaries, this was accomplished by leaving the eccentric loose on the axle, and driving it … Timing the valves simply means ensuring that the correct port opens at the correct time, so Secretary of The National 2½" Gauge Association. There is one variation. 3 - Eccentric. i don't have a vid. Most small engines like this have either an unrealistically small diameter flywheel or they need mounting on a base with the flywheel overhanging it. Disconnect the rocker arm on that side and rotate the valve spindle half a turn to move the slide valve forward a fraction as detailed in valve timing earlier. 2 - Eccentric rod. Here we have a really cool little thing! This should again be a little after dead centre. Refering to the diagram above, rotate the driving wheels in the forward direction until the crank pin on the drive axle outside crank on one side is a little after front dead centre. For instance, if the front inlet port was opening more than the rear one, then the To get the loco moving the eccentic rod is lifted off the valve rod and its associated rocker. Charlie's valve gear program has a simulation for slip eccentric. When, therefore, the gear connecting-rod is swung back and froth by the action of the return crank and eccentric rod, both gear connecting-rod and radius bars swing in unison, and no movement of the bell-crank takes place; the valve rod, or course, also remains stationary. Left hand drive axle outside crank. idea is to get both ports opening when the outside cranks are at the same position after If it is not, the valve spindle will lock up and may be damaged when the valve chest cover screws are tightened. 84: ... Slip and slip curves Variation of k . Eccentric gear equivalent to a crank and connecting rod . 5 - Rocker arm. Publication date 1906 Topics Steam-engines Publisher London, E. Arnold Collection americana Digitizing sponsor Google Book from the collections of University of California Language English. The “Rocket’s” gear worked on this principle. This describes the procedure for adjusting the slide valves on the internal slip-eccentric valve gear as fitted to early Roundhouse Lady Anne and Dylan locomotives and also, in a slightly shorter form, to the L & B locomotive. When all is correct, lock up the stop collar grub screw and replace the valve chest cover etc. spindle should be rotated anticlockwise to move the valve forward along its length. Stephenson gear. When lap equals port width, the full-gear cutoff will be 75%, a little short for starting but economical for running. With the steam animation turned on this is roughly equal to 75% travel of the piston, all other settings are the default at start up. If it stalls, note the position of the drive crank pins and if either is at front or rear dead center. Make sure that the eccentric is always free to "slip" on the axle so that forward and reverse gear are being fully set. Bid now on Invaluable: DOLL ET CIE TOY STEAM PLANT & WORKSHOP 1920s Copper boiler mounted on tinplate brick effect oven with chimney, boiler with pressure gauge, water level glass, safety valves and whistle, piping to horizontal twin cylinder engine with slip eccentric ... from Bonhams on November 4, 0120 10:00 AM PST. 2018. The flanged valves feature streamlined flow passages and rugged, metal trim components for dependable service in slurry applications. ... with a nice animation. by Benjamin Maggi » Tue Feb 16, 2010 7:18 am, Post by baggo » Sun Feb 14, 2010 7:22 pm, Post Does not cover 'Basic Series' locomotives. spindle. By setting up a second eccentric at an appropriate angle to the first, by re-attaching the valve rod to the second eccentric, the engine can be made to run in the opposite direction. The locomotive is a two-cylinder engine with four crank dead centres that produces 30psi of power which is enough to make the engine run. It has a double acting cylinder and piston valve. There’s a twin cylinder Stuart 10 hidden up front just as in the 5″ gauge published design for a Sentinel 100hp loco ‘Serena’, and the boiler is also far more like the 5″ loco size. You probably have the formula for that, if not I can email it direct. by 10 Wheeler Rob » Tue Feb 16, 2010 10:50 am, Post Service Sheet 04 Slip-eccentric Valve Gear Valve timing adjustment on early Roundhouse locomotives. Each reverse lever position video sequence continues for six revolutions of the driving wheel. There are three steam ports under the valve though you will only ever see two of them, the It's basically a fixed eccentric gear with a fixed cut-off but with the ability to reverse by rotating the eccentric around the axle. A site dedicated to enthusiasts of all skill levels and disciplines of the metalworking hobby. API 609 Centric butterfly valves (soft seated) are preferred to gate and ball valves for low-pressure and non-critical applications as they are cheaper, lighter and easier to install. The valves on a steam engine control the flow of steam in and out of the cylinders. THE BAKER VALVE GEAR shown with the rods separated to illustrate the action. A cardboard model, eh? She doesn't already, with your hobby? ... Now there is an exception for model engines and that is the slip eccentric. As you rotate the wheels, the valve moves backwards and forwards over the steam ports. The small drive pin in the eccentric should travel freely from one end of the stop collar slot to the other. Squirt a little steam oil into the valve chest as you replace the top cover and gasket, to help lubricate and seal the valve. This is like a gab hook or slip-eccentric engine, fundamentally. and by the same amount. As the valve moves backwards and forwards, it should uncover both the inlet ports in turn When the locomotive is capable of running on the track under its own steam, the timing can be fine-tuned for best performance. PLEASE NOTE - this model and explanation contain a glaring error. Repeat this several times and it will soon show up if there is a 'dead spot' at any particular point of the valve cycle. Keep turning the stop collar until the front edge of the front The valve timing is controlled by the stop collar on the drive axle. Always check for excess wear in the valve gear first as it will not be possible to achieve correct timing if there is too much lost motion. Several types of valves were developed over the years, but most fall within three main catagories: 1. As shown in the figure, because the bottom of the eccentric gear deviates from the center of the circle, when the eccentric gear is rotated, the connecting rod stuck in the arc will slowly approach the center of the bottom of the eccentric gear along the arc, thereby tightening the distance between the two plates and make it tightly connected. Remove the valve chest cover from the cylinder and replace a couple of screws to hold the Does not cover 'Basic Series' locomotives. plays no part in the setting. A positive displacement pump has a phenomenon known as “slip”, which is the recirculation of the pumped fluid from the discharge side of the pump back to the suction side of the pump. Animated Steam Valve Gears By fisker76 From a page on SteamLocomotive.com which shows detailed animations on how all 5 of the common American valve gear systems work. With slip eccentric you are stuck with whatever full-gear cutoff you decide on. pump slip You will notice that this curve has two speed vs. flow lines at different discharge pressures. That is, at the neutral position, the valve ports should not open at all. A problem with this arrangement (when applied to locomotives) is that one of the components of the motion is affected by the rise and fall of the locomotive on its springs. It's basically a fixed eccentric gear with a fixed cut-off but with the ability to reverse by rotating the eccentric around the axle. by Fred_V » Sun Feb 14, 2010 6:19 pm, Post A short time spent running the engine and making adjustments of just half a turn of the valve spindle at a time should soon show its optimum positions. UpDated Mar 20, 2009 Windows Ver 2.7.3 Central Pacific RR 229 4-8-0 1882 Feb 2, 2007 at Bitter Creek Western RR In 1986 I wrote the first of the MS-Dos versions of the software to simulate Baker valve gear. A strange Hybrid Valve Gear applied to an 0-6-0 Shunting Tank Locomotive by John Aspinall of The Lancashire and Yorkshire Railway in 1897. by Benjamin Maggi » Wed Feb 17, 2010 8:40 am, Post The engine features slip eccentric valve gear so the engine will run in either direction. This describes the procedure for adjusting the slide valves on the internal slip-eccentric valve gear as fitted to early Roundhouse Lady Anne and Dylan locomotives and also, in a slightly shorter form, to the L & B locomotive. Understanding 9/11. Think I'll stick to slip eccentric for the next loco ;D John. The rear inlet port should just start opening as the crank pin on the same outside crank is a little after However, in this case it is less easy to relate the valvegear mechanism to the equivalent eccentric. Any locomotive valve gear has to consist of two components which are combined so that the valve can operate the two ports of a double-acting cylinder. The double eccentric butterfly valve is resilient enough to seal, and the disc only wipes the seat for a few degrees at seating. ; Radial gears. Holding the wheels in this position, slacken off the grub screw holding the stop collar on Check the position of the slide-valve on the spindle by rotating the wheels and watching dead centre in both forward and reverse rotation. happens. pivot screw, lift the rocker arm out of the valve spindle end socket, then screw the valve Repeat for the other side. cylinders. "One cannot learn to swim without getting his feet wet." The design ideally has two perfectly timed components combining into a single valve rod output, and in relation also to the main crank. The spacious arrangement of the reversing gear gives full gear at the shallow lifting arm angle of only 24.5 o to give very comfortable mechanics for the 6 21/32″ valve travel, albeit with an expansion link total swing fractionally under the advisable maximum of 50 o. Eccentric and sheave (Heat Engines, 1913).png 410 × 581; 15 KB Eccentric animation.gif 400 × 300; 103 KB Eccentric bottom bracket shell.jpg 2,592 × 1,944; 2.21 MB The stop collar has a slot machined (either radially as show or accross one face on original version) which allows the eccentric to 'slip' freely on the axle for about half a turn of the wheels. Replace the rocker arm and check the valve movement again. STEAM ENGINE VALVE GEAR ON THE COMPUTER Windows Version by Charles Dockstader HCR 69 Box 3111 California Valley CA 93453 805 475 2519. If it does not, adjust its position by unscrewing the rocker arm when the ports are just cracking open. Repeat the operation until - Benjamin Maggi. The stop collars rotate with the axle and the eccentrics 'slip' untill the drive pins reach the ends of the slots, at which point they start to drive the valves. It mirrors a true stevenson gear by reversing the orientation of the eccentric to the crank. When looking at right hand side of locomotive, forward rotation of wheels is clockwise. Slip-eccentric valve gear is very simple as shown in the diagram below. A butterfly valve is used to shut off or modulate the flow of a fluid (isolation and regulation). 6 - Rocker arm pivot screw. Compared to the existing Stephenson valve gear, Walschaert's gear had the advantage that it only required one eccentric per val… In 1848, Heusinger independently invented a very similar valve gear in Prussia, and Walschaert gear is occasionally known as Heusinger gear.Walschaert's gear proved to be reliable and light weight with only moderate space requirements. 4 - Spacer. Regards, John. This results in a lot less friction, meaning the seats can last longer. All adjustment to achieve this is done by moving the stop collar a little at a time and re-checking. A 3 1/2″ gauge vertical boilered 0-4-0 ‘Sentinel-esque’ twin cylinder steam loco. valve. Slide valves largely used in the 19th century; 2. Some examples are prepared for reference should the otherwise blank window baffle the new user and input designs can be saved to the list. The amount will vary depending on wear in the valve gear but if you are getting less than half a port width open, it may not be possible to achieve smooth running and replacement parts will be needed. Post The article discusses the geometry of slip eccentric valve gear to be used in building the Gauge One locomotive. You can now look down into the valve chest and see exactly what The earlier version for fixed gauge models is similar but the stop collars are on the inside (back to back) and the eccentrics are to the outside, just behind the wheels. The stop collars are fixed to the drive axle by grub screws and these drive the eccentrics by means of a small drive pin which is pressed into the eccentric. Once you are happy with the visual settings, the valve chests can be closed ready for a steam test. link but it works by having a pin in a circular groove that goes half way around the eccentric. Walschaert developed his valve gear in 1844-8 through a number of trials and patents whilst working as a foreman for the Belgian State Railways. Make a card baord model and it will be come aparent real quick how it works. Although the original version of this valve gear, as fitted to the non gauge-adjustable Dylan and Lady Anne models, had a different layout of eccentric and stop collar, the setting proceedure is the same for both. 166: This has the effect of moving the valve along the Loose eccentric is the same as slip eccentric and works the same way. Stephenson valve gear has one advantage that I know of over the other types of gear. Poppet valves similar in principle to those used in internal combustion engines. As Fred says, if you want to go forwards you push the loco forwards before opening the regulator. baggo Guest. equal opening is achieved Note that when they are opening equally, the ports are not Notes to Valve Gear Animation Videos. It can also serve as a reversing gear.It is sometimes referred to as the "motion". You will find it easier if you concentrate on setting one side at a time. Reconnect the rocker arm and try the loco again in both directions to check that your adjustment has not simply removed that dead spot only to replace it one in a different position. to slip and let the pin hit the other end of the slot and the engine goes the other direction. axle in the same direction. the same side and, whilst looking down into the valve chest, rotate the stop collar on the by Benjamin Maggi » Sun Feb 14, 2010 5:36 pm, Post Shown above is the later version of the slip-eccentric valve gear as used on adjustable gauge models. port is just visible (cracking open as it is known) as the slide valve is moving backwards. Both components of the motion come from a single crank or eccentric. The Gently tighten the grub screw. ... Youtube videos show the setting of Stephenson's valve gear as establishing FDC and BDC and checking at FDC that the valve is at line for line, ... and Back gear eccentric at the bottom. that steam is admitted to push the piston along the cylinder just when its needed and This forum is dedicated to the Live Steam Hobbyist Community. Spirituality & Religion Sports Videos Television Videogame Videos Vlogs Youth Media. Eccentric plug rotary control valves control erosive, coking, and other hard-to-handle fluids, providing either throttling or on/off operation. by JJG Koopmans » Mon Feb 15, 2010 7:43 am, Post The initial stage of the analysis which determines the details of the 'equivalent eccentric' is the same as for Walschaerts gear. Piston valves which superseded slide valves in the 20th century; 3. Detailed relationships of piston to valve over a 360o cycle can be printed out to aid valve setting on completing the running chassis. 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Scratchbuilt Live steam Gauge-1 engine will run in either direction forwards you push the loco forwards before the! The regulator animation & Cartoons Arts & Music Computers & Technology Cultural & Academic Films Ephemeral Films Movies News Public. Hard-To-Handle fluids, providing either throttling or on/off operation Railway in 1897 an for. From this window and all windows are printable 75 %, a little after dead center ) vary. Backwards before opening the regulator to travel too and from the cylinder and valve! The desired direction with the ability to reverse by rotating the eccentric crank position were developed over the other will... Skill levels and disciplines of the 'equivalent eccentric ' is the same as Walschaerts! Gear valve timing can altered simply by moving the eccentic rod is lifted off the valve and plays no in! Gear to be used in building the gauge one locomotive in relation also the... 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Onto the valve moves backwards and forwards over the other end of the cylinders Cultural & Academic Ephemeral. Dropped down onto the valve chest cover from the cylinder and piston valve position... Travel freely from one end of the stop collar grub screw and replace a of... Eccentric you are happy with the visual settings, the valve though you only. Which superseded slide valves largely used in building the gauge one locomotive flow passages and rugged, trim... By having a pin in the valve chest cover etc wipes the seat for a steam control! You switch the parts with pins & slots then the locatoing the slot and engine... Fine-Tuned for best performance but economical for running once you are stuck whatever. Eccentric gear equivalent to a crank and connecting rod Public Affairs the orientation of slip-eccentric! Lancashire and Yorkshire Railway slip eccentric valve gear animation 1897 arm and check the valve chests can be saved to the eccentric! Slip-Eccentric engine, fundamentally forwards over the other way causes the ecc fixed gear... If not I can email it direct should again be a little after rear dead center think I 'll to... The metalworking hobby and connecting rod the gauge one locomotive produces 30psi of power which is enough seal!
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