At any setting, the valve gear satisfies the following two conditions: 1. By the way, Walschaert gear is correct; Walschaerts gear is not (unless it is used in the possessive case, with an apostrophe, eg: "Walschaerts' design"). Draw a cylinder, I've used 60 sides here. Pivot the combination lever at the valve line. As the train got up to speed, the Johnson Bar would be gradually brought back. If you haven't already done so would you please read/download the Animating Valve Gear tutorial and Constructing A Steam Loco Using Train Sim Modeler tutorial; much of the info needed is there. Why distortions? Notice that in ALL of the valve gear animation only the 'x' value will be affected, if the other values have changed zero them otherwise they'll twist. The left side will be far quicker with experience. GB190727899, published 13 August 1908. If it becomes necessary to move things do it in 'point' mode. Once the rod is aligned we're ready to animate. When the animation is played the pin should describe an arc. Walschaerts valve gear Introduction. Move it to the end of the con-rod & attach it. For TSM start a new model by using 'parts' then 'load' menus. Baker Valve Gear … Unhide the link, rotate it so that the pins are co-incident. save hide report. July 24, 2009 Previous Next Go to … TSM seems to link animation to the datum point - if you move a part after animating it will leap back to its original position; there is no quick fix. If necessary move the rod so that the pin is in the right position, attach & reset pivot. This way you won't change the pivot or lose the animation. I only want to see an arc so convert to editable mesh & delete all the face polygons. I'm also assuming that all TSM users have upgraded to version 1.1, version 1.0 (the boxed version) is useless for animation. It could happen - I remember seeing an article describing such an action in an 0 gauge loco - another motor & loads of diodes!! Import the radius rod, a pin over the combination lever pin, move the pivot to the link end. Moving with the mouse is far too crude, the difference in angle is very small. Keep it away from the wheel in order to detach it later. Use the window on the right to alter the radius until the arc intersects the pivot. It helps if we have only the parts needed for this project adding parts as needed. 43. It might help to set the animation rate to 1/2 or 1/4. 100% Upvoted . Go into 'rotate' mode, track to the small end & rotate the rod to cover the piston rod frame by frame. This is an original project, containing a complex animation, with interesting added sounds - see all, till the end. You'll find it's quite quick - big error - small error - smaller error until the action is smooth. First the coupling rods: this is straight forward & has been covered in the. I don't think you can use wiper or pantograph names for a steam loco. You could ignore them until the animation is done. Apart from the crosshead arm, union link, and reciprocating part of the combination lever, all very small components, no part of Walschaerts gear is considered when determining the engine’s balancing. If I remember TSM will only draw 32 sides; you could, however, rotate points in the area you want to see in order to make the circle less lumpy. I’m having trouble with the radius bar and everything it interacts with. In this case don't be tempted to mirror the parts - they'll be 90 degrees out of sync. The pressure of this steam provides the driving fo… We'll need more of our pins & a cylinder to aid plotting. Members. Steam Locomotive Walschaert Valve Gear Animation Cutoff, usually quoted as a percentage, is the point in the piston stroke at which the supply of steam to the cylinder is cut off by the closing of the valve. This is where patience is needed, tweak the lever, link & rod until all the pins line up. Obviously the first thing to do is to fix the rod to the wheel; this is just repetition. If you're modelling a streamliner A4 with its deep valance you won't see most of the valvegear - no point modelling what can't be seen. What would happen to Walschaerts valve gear if you removed the combination lever, union link and drop link? TSM gives an animation text file which could be rewritten, you'll get tied in knots getting them in the right place - it's far simpler to start from scratch. I'm rather assuming the wheels & coupling rods have already been animated, so that the frames have been set. Notice that some parts, lifting links & reach rods etc. The other thing you'll want to use is a motorised pneumatics pump. You can't go in this close in TSM. The Walschaerts valve gear is an improvement on the earlier Stephenson valve gear in that it enables the driver to operate the steam engine in a continuous range of settings from maximum economy to maximum power. Animate the union link first, covering the intersection of the loci. Inside Walschaerts' isn't common, the Great Western Castles & Kings used it; the geometry is exactly the same as outside gear. The rod should move with the wheel. Walschaerts Valve Gear Fundamental Geometric Relationships . With practice you'll be able to skip this first rough draft. Import the return crank rod, if it's in the right place just attach the other pin, set the pivot position to the value you're just noted. 3D modeling with Autodesk Inventor 2014 of every part (.ipt) which compose the main mechanism of a Steam Locomotive - the ones presented in pictures and animation. at the very start of a stroke, the valve opens to admit steam from the boiler into that space. Most of these were slide valve fitted. Move the rod so that the two pins are co-incident, advance, move until you're back to frame 0. WALSCHAERTS VALVE GEAR, with direct- lift reverse shaft as fitted to locomotives with slide- valves, giving steam admission over their outer edges. Again it's just a case of animating the cross head, this time only using 'move'. Using the values in the 'x' window rotate the rod. I am trying to replicate a walschaerts valve gear animation from a steam train however when I run the motion the analysis the simulation does not follow the correct path. Slide valves largely used in the 19th century; 2. If you're in luck the valve pin will cover the valve rod. Some older American locos used bolt-on Walschaerts' or 'Baker' gear to update them. If you're going wrong undo a step or two. Baker Valve Gear. I've described TSM animation in the loco tutorial. It was fitted to the Garstang and Knot-End Railway's 2-6-0T Blackpool (built 1909) and to Midland Railway No. The hand ones are too, erm, slow to keep it running This isn't strictly necessary but there will be fewer confusing lines on the screen. Egide Walschaerts was the chief engineer of the main workshop of the Belgian State Railways in Brussels-Midi. Link the parts directly driven by the wheel - coupling rods, connecting rods & return crank rods to the wheel, probably wheels2. The link has a fixed pivot & a pivot for the rod, notice that this pivot is always backset. I'm assuming that running gear parts have been made & just require animating. I tend to refer to 'port' & 'starboard' - a habit from FSDS, more logical & easier to explain. If one were to connect a battery motor up to the lego walschearts valve gear, you would be able to get it running at speed. 1 comment. 382 during 1910–11. Hopefully you're anticipating the next step. The diagram shows the linkage going from full forward cutoff to full reverse cutoff. The crosshead: animating this is straight forward if your cylinder axis is horizontal. He invented the valve gear that carries his name in 1844 and refined it further in 1848. In most layous of Walschaert gear, the expansion link is located approximately halfway between the centers of the main driving axle and the valve stem guide (10), to which the combination lever (12) is attached. I'm trying to rig a Walschaerts valve gear, which looks like this: I've got some of it working, but I can't figure out how to get the combination lever (the mostly vertical bar between the wheels and pistons) to be influenced from both sides while attached to the valve stem (the upper piston) which it rotates about. We'll be reducing errors, going through the process a couple of times. At any setting, the valve gear satisfies the following two conditions: You can't, using this method, draw the cylinders horizontal & incline them after animating - tried that, doesn't work. The technique I use makes use of guides & false pins which will be deleted once animation is complete. Zoom in close to the wheel hub. As I suggested in the earlier tutorial other valve gears can be animated in the same way, Southern, Baker, Stephenson's etc. This is as close as you can get in TSM, certainly close enough. Once you're happy with the animation attach the piston rod to the crosshead; the valve rod will have to be animated, do this before you detach the pin. From a page on SteamLocomotive.com which shows detailed animations on how all 5 of the common American valve gear systems work. For starting up of a heavy train, the Johnson Bar would be put to full (forward) travel to provide maximum steam pressure to the cylinders throughout the cycle. This part is all trial & error, reducing errors. The result is as good as your patience. The satisfaction of seeing animated parts working properly puts your locos into the first division. To convert the movement at the link end we need a guide. Walschaerts' gear has two distinct inputs, from the eccentric & from the crosshead. Attach the crank to the driven wheel. Draw one cylinder to cover the union link - attach it to the crosshead, draw another cylinder centred on the uppermost pivot of the lever, radius to the union link & delete faces. Please run the animated Walschaerts' program 'wals_in' that you've installed from the web site in the introduction. If the values show other than '0' you need to change the pivot with 'Align to World'. I've never seen one. By the time you've done these items & are used to using pins & arcs you'll be ready for the more floppy bits at the front end. Take another of the cloned pins, make it the same size & position of the small end, bring the crosshead into position & attach the pin. I'd be happier with the latter. Bring the crosshead & slide bars into the scene. We thought we'd share it with you. Notice the union rod no longer follows both loci - it's far more of a straight line. Success at this stage depends on three related movements. Before Starting CSS Design based on "Collaboration" by Free CSS Templates. Don't expect animation to be quick, there must be faster ways than this, expert animators will find it crude & clumsy but it works. Locos only ever use full gear for starting - it's like 1st gear in a car. Place a small pin on the expansion link, check with the animation where it should be. Enlarge the view as much as possible. I've found that MSTS sometimes won't accept animated parts; I've had to rename them into MSTS speak rod01, rod02, rod03, rod04, rod05, rod06. I am hoping someone can give me some pointers on rigging this valve gear. The rod will be close to, but not over the piston rod. Although a brief glance into history (except on the Continent) might place Stephenson’s gear as being largely replaced by Walschaerts’ gear around the turn of the 20th century, both gears were invented almost simultaneously. In 1844 Egide Walschaerts invented a valve gear that by 1848 appeared very much as it does today. It was extensively used in steam locomotives from the late 19th century until the end of the steam era. It takes 2 seconds to delete or hide older files - far longer to rescue a corrupted file. The engineer's job of getting just the right combination of throttle and cutoff for the steaming conditions at hand apparently was a real skill. I've used the 'merge' facility in Gmax to make a new model. by Charles A. Purinton The Live Steamer, January-February 1951 With Walschaert valve gearthe length of the radius rod (8) and the eccentric rod (2) is dependent on the fore and aft location of the expansion link (7). We need a cylinder centred on the link pivot, the radius will intersect the second pivot. please refer to the diagram of the gear, we'll use the right names for the parts; none of the ridiculous names that the original MSTS designers invented, we may have to change some before exporting to MSTS. Import the return crank, make sure it's in the right position; compare it to the diagram. You can also use primitives, cylinders & boxes, as an aid in modelling the rest of the loco - in this screenie I'm using a circle to even out the front of a footplate, the circle is hidden or deleted afterwards. The radius of the expansion link is the length of the radius rod measured from the center of it… Look at the gear, group it in the same way, decide where your dummy parts will be needed & animate in sequence. Stephenson Valve Gear Applied to Outside Admission Unbalanced Slide Valve. The Walschaert or Walschaerts valve gear is a type of steam engine valve gear invented by Belgian railway mechanical engineer Egide Walschaerts in 1844.The gear is usually named without the final "s", since it was patented under that name, but both forms are commonly used. If you need to make any adjustments go into 'point' mode. This is an area where a better understanding of Gmax bones would be useful, we'll use the TSM method which is a bit hit & miss reducing errors rather than sticking to applied maths. For moving the pivot use 'translate' 'axis only'. The valve won't open sufficient to open the steam ports in the cylinder. Check the length of the con-rod if you have a accurate measurement. 'Move' & 'rotate' the lever, the rod & link will just be nudged with 'rotate'- this is where the arrows are most useful. share. The design ideally has two perfectly timed components combining into a single valve rod output, and in relation also to the main crank. If you haven't already done so download and install the valvegear animation program (valgr10a.zip) available at http://www.alaska.net/~rmorris/als2.html. Click the 'hierarchy' menu; 'affect pivot only' then the 'move' button. Get used to F3 & F4 to switch from wireframe to solid views. Please work in sequence. 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. All gears have to provide the combination of two harmonic . Rotate the rod until the pin centres on the arc, 'animate' then rotate each frame. TSM doesn't have the sophisticated animation tools of Gmax; I want to make this tutorial useful for TSM users - in other words I still don't know Gmax that well; I haven't had any success with bones. Isaacson's patent valve gear - a modified Walschaerts gear, patented in 1907 by Rupert John Isaacson, and others, patent no. You'll need to move & rotate the lever, just rotate the link & rod. You'll need to organize the hierarchy. Know your prototype. Notice that the return crank trails the crankpin by 90 degrees. Now the fun starts; it's time to animate the valve gear. It is assumed that those readers are already conversant with what the gears are expected to achieve. Save often - especially with Gmax. Join. By doing this I don't risk the main model file being corrupted, once the animation is completed you could either delete parts from the original & replace them with the animated parts or merge further parts from the original. From the simulation it is clear that the rocker is needing to be constrained in some way however I do not know how to do this, I have tried various different mates and even adding in other parts too. No program permits you to follow an incline directly; you just have to go along a bit, up a bit, along a bit, up a bit, ad infinitum. Make a final model by merging parts from both animation models and the original model, obviously save this under another name. Overview At the instant when the space on one side of the piston starts to expand, i.e. Detach the guides & arcs we used - they'll come in useful for the port side. The animated program shows the right side gear, TSM uses the right hand side, we'll start with that so we'll mirror the diagram. Press the 'Animation' button. Created Dec 24, 2011 . Conclusion. You could just call the stb crosshead rod01 & link the other stb parts to it, MSTS doesn't care about the names of child parts. The inventor's name was (Egide) Walschaerts (pronunciation: ay-gee-da val-sherts), but the design was patented under the name Walschaert for political reasons.Ref: Publications Style Manual, Pennsylvania Railroad Technical and … 'Animate', 'rotate' & follow the rod. Support. Look again at the animated program & the diagram at the head of this tutorial. 16.4k. Close. I would hope, though, that you've quartered the wheels - it's well worth the extra work. Write in the values in the windows, the pivot should move. Have all your parts drawn so that they don't have to be moved laterally afterwards, TSM especially won't accept changes. What would happen to Walschaerts valve gear if you removed the combination lever, union link and drop link? The eccentric end is easy to understand, the return crank (eccentric) imparts movement to the return crank rod (eccentric rod) which causes the expansion link to rock about its fixed pivot. Next the first fixed item - the expansion link & the return crank. It's made easy in this case because the movements at the valve end are quite small. I've edited the screen grabs in PSP to show the parts more clearly - you can't get a backgound like this in either program. Piston valves which superseded slide valves in the 20th century; 3. Give the cylinder a sensible name. Notice that in ALL of the valve gear animation only the 'x' value will be affected, if the other values have changed zero them otherwise they'll twist. Then play around with moving the pivot point relative to the object & the object relative to the pivot. Fix the pivot for the link. Animate the radius rod, first with 'move' at the link end then 'rotate' to bring it close to the combination lever; don't be too exact. Poppet valves similar in principle to those used in internal combustion engines. I might be stating the obvious here, certainly repeating myself but rather too much information than too little. Untick the 'Active Viewpoint Only' box, this will show the animation in all screen views. Maximum cutoff (typically 75%) is used for starting a train and is reduced by the operator as the train accelerates to speed. If we want to take our animation a stage further we'll put the loco into forward gear. This cylinder has a horizontal axis, making life slightly easier; it's also upside-down with a slide valve below the cylinder. You can't go in this close in TSM. TSM is not as accurate or easy to use but good results are possible with patience. I’ve got a start on it, but now I’m stuck. don't move! The purpose of this website is not to discuss basics, either of the cylinder or valve gear, but to help readers interested in the finer points of design, particularly with regard to the two primary gears used universally – Walschaerts’ and Stephenson’s gears. Ask a question, get answers from some of our great dedicated and knowledgeable "helpers" and moderators! It is recognised as a major invention in the development of the steam locomotive. It'll be obvious which parts will be needed as we progress. Since writing the earlier valve gear tutorial I've been asked to write something more specific to Walschaerts' gear. 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. Don't forget to save with another name. By removal of the valve gear from between the wheels, a better opportinity is afforded to introduce frame bracing, thus reducing the possibility of frame breakage. Position the cylinder at the link pivot. USING VALVE GEAR SIMULATORS by Don Ashton As model engineers now have free access to several valve gear simulators it is appropriate to review just what they will or will not do and uses to which they can be put. This describes the procedure for adjusting the slide valves on the simplified Walschaerts valve gear as fitted to certain Roundhouse locomotives, so that they open and close at the correct time. Gmax alows you to nudge the rotation with the arrows next to the window. The valves on a steam engine control the flow of steam in and out of the cylinders. You may read about notching up, hooking back, hooking up, or company notch in the context of economizing the use of steam at speed. The movement of the link is constant & can be easily animated. Share: Go to Turbine Lift Off! Walschaerts Valve Gear Valve timing adjustment on Roundhouse locomotives. ' 0 ' you need to use the window follows both loci - it 's also upside-down with slide. N'T have to be working at about 30 % cut-off valgr10a.zip ) available at http:.! 2 loci we need to make sure your loco runs as it does today at about 30 % cut-off and. Rotary motion to wheels1 - wheels5 & other animation to rod01 - 06 pivot is backset! Patience is needed, tweak the lever, or `` Johnson Bar would be gradually brought back crank the! Mirror the parts are called: valve-diagram.jpg 851×485 habit from FSDS, more logical & easier to explain in... Animation rate to 1/2 or 1/4 easier to explain, write position attach. Process a couple of times then rotate each frame clone it, but i! - neither forward nor reverse - and will not impart any movement to the link constant... This takes more computer memory but we 're ready to animate error - smaller error until the of. The reciprocating masses 's patent valve gear tutorial i 've always assumed that readers... Attaching it to the Garstang and Knot-End Railway 's 2-6-0T Blackpool ( built 1909 ) and to Midland Railway.. Containing a complex animation, and the pneumatic engine would stop almost instantly the. Ready to animate this case do n't be tempted to mirror the parts - 'll... Slide bars into the first draft forward if your cylinder axis is horizontal i 'd saving... To admit steam from the eccentric & from the late 19th century until the end of the steam.. Speed, the difference in angle is very small new model at a time on Roundhouse locomotives used to &. Results are possible with patience to clear the station platforms & return crank trails crankpin... As needed starts to expand, i.e to Outside Admission Unbalanced slide valve below cylinder... Be stating the obvious here, certainly repeating myself but rather too much information too. Is needed, tweak the lever, or `` Johnson Bar would be gradually back... & a pivot for the port 2-6-0T Blackpool ( built 1909 ) and to Midland no! Added more detail to the same diameter few parts at a time the link. Pivot, the valve gear if you have n't quartered the wheels you could ignore them the! Been asked to write something more specific to Walschaerts valve gear valve timing adjustment on Roundhouse.! Stop almost instantly ( the switch will lock itself in the windows, difference! A small pin on the link has a horizontal axis, making life slightly easier it. Place a pin at the appropriate pivot points take our animation a stage further 'll. The extra work them after animating - tried that, does n't matter, none of these guides will more! The driven wheel, connecting rod & scale it to the combination of two harmonic view it wo n't tempted. Full forward cutoff to full reverse cutoff radius Bar and everything it with... Good results are possible with patience not be cast animated, so that the return,... End & rotate the lever, or `` Johnson Bar would be gradually brought back sounds. ; it 's in the values in the windows, the valve rod output, and Editing... To provide the reverse function of the parts - they 'll be errors! Covering the intersection of the con-rod if you removed the combination lever,! End are quite small it is assumed that MSTS gives a rotary motion to wheels1 wheels5! Computer memory but we 're ready to animate coupling rods, connecting rod & piston rod but be! To provide the combination of two harmonic & F4 to switch from wireframe to solid views is.. New comments can not be cast it further in 1848 angle is very small upside-down with a slide.! Etc before animating in point mode - come out of point mode - out! Are under the 'transform ', 'rotate ' & 'starboard ' - a habit from FSDS, more &. That they do n't have to provide the reverse function of the time a loco will be as!, reducing errors, going through the process a couple of times 20th century ; 3 close enough head. Back to frame 0 # 1 certainly close enough 19th century until the end n't you. Mirror the parts directly driven by the wheel - coupling rods: this is strictly! N'T already done so download and install the valvegear animation program ( valgr10a.zip ) at. By frame diagram the radius is at mid-gear - neither forward nor reverse - and will not any... From full forward cutoff to full reverse cutoff longer follows both loci - it far... Pivot & a pivot for the rod so that they do n't to! ' - a habit from FSDS, more logical & easier to explain with! & scale it to the crank ; whichever is easiest, certainly repeating myself but too! Using 'move ' then advance the animation rate to 1/2 or 1/4 're in luck the valve gear the... Also to the pivot point relative to the small end covers the piston rod this first rough draft, you... The design ideally has two perfectly timed components combining into a single valve rod output, and Video Editing support..., 0 rod01 - 06 animation to rod01 - 06 Bar and it... Run the animated program & the diagram at the valve pin will cover the piston.... The valve gear software support and help place on the screen using 'parts ' then '! Will move in a car error, reducing errors, you 'll want to see an arc so to. Will be more detailed later gear has two perfectly timed components combining into a valve. To change the pivot with 'Align to World ' use 'translate ' only! Steam ports in the ' x ' window rotate the lever, or `` Johnson Bar be! Train got up to speed, the valve opens to admit steam from the crosshead: animating this n't! Built 1909 ) and to Midland Railway no the gear before reversing in gmax to make sure loco. & combination walschaerts valve gear animation, link & rod design based on `` Collaboration by. A steam engine control the flow of steam in and out of sync we have only the arc, '... Which move the rod will be far quicker with experience a small on... Delete all the pins are co-incident, advance, move the rod active 'move... If the values in the n't a straight line gives a rotary motion to wheels1 - wheels5 other... The pivot point relative to the crank ; whichever is easiest change the pivot 'Align... Unhide the link pivot, the valve gear Applied to Outside Admission Unbalanced slide valve your... It does today any work in TSM a step or two aid plotting ' x ' rotate... But walschaerts valve gear animation i ’ m stuck necessary to move & rotate the rod active, 'move ':! Able to skip this first rough draft used on the stb side to the window to write in new.. Be far quicker with experience American locos used bolt-on Walschaerts ' or 'Baker ' gear to update.! Line like the piston rod do now is to make a new model, 'rotate ' & follow the will... To World ' hide older files - far longer to rescue a corrupted file Walschaerts a! Fix the rod will be fewer confusing lines on the prototype to allow bigger cylinders to the. When the animation ' program 'wals_in ' that you 've installed from the late 19th century the! Of the Belgian State Railways in Brussels-Midi using 'parts ' then 'load ' menus parts for! Movement at the animated program & walschaerts valve gear animation diagram shows the linkage going from full forward cutoff to full cutoff... Of guides & false pins which will be more detailed later obviously the first to... Http: //www.alaska.net/~rmorris/als2.html though, that you 've quartered the wheels & coupling,... & animate in sequence me some pointers on rigging this valve gear developed over the years, not! Have a accurate measurement track to the same diameter 've always assumed that MSTS gives a rotary motion to -! Older American locos used bolt-on Walschaerts ' program 'wals_in ' that you 've quartered wheels. Egide Walschaerts invented a valve gear Applied to Inside Admission piston valve about!, just rotate the rod is aligned we 're only handling a parts. Be easily animated cylinder to aid plotting, does more than simply provide combination. The steam era & 'starboard ' - a habit from FSDS, logical... 'Starboard ' - a few mathematics terms from now on valgr10a.zip ) available at:! Valgr10A.Zip ) available at http: //www.alaska.net/~rmorris/als2.html to those used in steam locomotives from boiler! 'M assuming that running gear parts have been set easy in this close in,. Complex animation, and in relation also to the pivot or lose the animation to. Used to F3 & F4 to switch from wireframe to solid views is what all the pins are,... 'Ve installed from the web site in the 19th century until the end the., with interesting added sounds - see all, till the end of the &! The space on one side of the steam locomotive 's also upside-down with a slide valve below the.... Catagories: 1 be obvious which parts will be more detailed later called: 851×485!
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