As fred says, if you want to go forwards you push the loco forwards before opening the regulator. Gear design dontyne systems gear design software, gear. With no wear on the gears pins the setting will allow forward and reverse movements in proper time. You can model most gear design arrangements and gear trains. Eccentric gear equivalent to a crank and connecting rod. For example, the hit and miss methods described to set up the return cranks and determine the eccentric rod length on walschaerts gear are not necessary. 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. Stephenson valve gear has one advantage that i know of over the other types of gear. These are the connecting rods from the eccentric strap the ring around the eccentric to the valve rocker there is another name but is escapes me at the moment.
Most small engines like this have either an unrealistically small diameter flywheel or they need mounting on a base with the flywheel overhanging it. That is, at the neutral position, the valve ports should not open at all. This animation shows how a steam engine with a d or slide valve works. An approximate, but logical, method of designing walschaerts. 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. Charlies valve gear program has a simulation for slip eccentric. Slipeccentric valve gear page 1 australian miniature. Steam locomotive valve gear gold coast model railway. Originally, the eccentric plug valve was developed by matt dezurik in 1928.
Twenty were made by swanage models, all with slip eccentric valve gear. The valve gear is there to move the valve over the cylinder ports allowing steam to enter the cylinder at the correct time and then allow it to escape once its job is done. Disassembly of 3 through 8 eccentric plug 14 turn refer to 3 through 12 parts list note. The lnwr teutonic class was a class of 10 passenger threecylinder compound 2220 locomotives designed by f. Move the blade to set the exact timing and resecure with bolts. Unfortunately tests on steam showed little improvement. The number on the tender, 6285, was the phone number of bassettlowkes shop in high holborn, london. On baker and walshaerts valve setting is done by moving the eccentric crank position. Ill hope to revise the model and make a new video, soon.
Gear design software to model most gear arrangements. Instructions for download and installation the bcwrr is delighted to host charlies valve gear program on its web site. Does anyone have any drawings of slip eccentric valve gear. Since then, dezurik has advanced valve reliability and application technology with the design enhancements delivered in the. Since then i have made continuous additions and improvements to add other types of valve gear and improve functionality and ease of use. Explain how the fundamental law of cam design applies to selecting an appropriate cam profile design double dwell cam profiles using a variety of motion types cam motion design. The enginedriver can then cause the engine to run in the reverse direction by giving a.
Any valve gear and valve designed with lead will try to kick back in reverse direction till the eccentric and rod journal move off tdc to the angle of lead, but then stops because the valve opens in the opposite direction again. The 3z twin slip double block and bleed valve can completely isolate a line without leakage. If you take the fixed pivot as 0,0 then the position of the end of the control arm is the cosine and sine of the control arm angle multiplied by the length of the arm. 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. The woolf valve and all valves of its class provide for a constant lead for all positions of cutoff, on either the forward or backward movement, and provides for a much quicker opening of the port than a valve moved simply by means of an eccentric, such as, for example, a plain slide valve or a link reverse engine. Both components of the motion come from a single crank or eccentric.
I have read lbscs comments on the subject, at least from the books that i have, and have also looked at the notes published in a few other books. Internal gas firing using the roundhouse fg gas system. You can edit and analyze all of its kinematic properties. Full text of valves and valve gear mechanisms internet archive. I have made the software available by placing it in the public domain as freeware. Slip eccentric valve gear its a heavy engine and will go at a fair pace, and is perfectly capable of charging up a steep gradient, stopping, and then rolling back into reverse. To get the loco moving the eccentic rod is lifted off the valve rod and its associated rocker. Fairly obviously from the diagram, the valve phase angle.
Analysis of beyerpeacock valve gears reveals design in matching the events of forward and reverse gears. This page was last edited on 28 february 2014, at 15. It is named after robert stephenson but was invented by his employees. The seat of the triple offset valve is designed to minimize wear, provide lower maintenance cost and extend service life.
Valve timing adjustment on early roundhouse locomotives. Copies of fullsize valve gear in these sizes comprise tiny components which can be fiddly to make and to operate. Design and layout of a valve gear from time to time there has appeared references to valve gears or parts, but no complete or logical method of deriving proper proportions. Since there is only one eccentric there is only one direction the engine can run in unless it is a slip eccentric and it does not look to be. The myfordboy steam engine myfordboy blog and online. A very late british design, the sr leader class, used sleeve valves. In this respect it is more sensitive than the link or a slotted eccentric valve gear. Eccentric plug valves are currently present in most u. Completely close the valve against the closed stop. Eccentric gear article about eccentric gear by the free. Next simplest would probably be hackworth, followed by any number of linkage gears.
Isaacsons patent valve gear a modified walschaerts gear, patented in 1907 by rupert john isaacson, and others, patent no. The model has been first designed with the valve gear program of. Arnold, the reason i was excited to find slip eccentric in dockstaders valve gear programs was it is really a single eccentric solution. This fifth edition presents vital information on control valve performance and.
Charlie has put this program in the public domain but is. Beyer garratt locomotives must have the same chassis performance in forward gear matching that of the trailing unit in reverse gear. The drawing i posted is for outside admission, the eccentric. Many designs tend to favour forward gear where more astute design work could have produced a better compromise. Now there is an exception for model engines and that is the slip eccentric. The valve gear also controls the distance that the valve travels across the ports and the time that the ports open and close relative to the stroke of the piston. The green crankshaft and green eccentric are mounted on the same shaft red circles and rotate together as one unit. I looked at the lamken valve gear again and realized that the motions arent terribly complicated from a mathematical point of view. Steam locomotive valve gear gold coast model railway club. This makes control of the valve gear easier for the driver. Since there is only one eccentric there is only one direction the engine can run in unless it is a slip eccentric. Locomotive valve gears 1 railway wonders of the world. Encyclopedia article about eccentric gear by the free dictionary.
Obviously, the manufacturing of helical gears is easier with the normal system than with the transverse system in theplane perpendicular to the axis. Lamken valve gear steam automobile club of america. Valve gear design simulator software southwest cyberport. I know barry potters 5 gauge blowfly design has slip eccentrics. Garden rail 1994 ross harrisons 16mm hunslet lilla. Similarly, you can choose authentic coal firing but gas is the practical option. Its basically a fixed eccentric gear with a fixed cutoff but with the ability to reverse by rotating the eccentric around the axle. Because its similar to the walschaerts, i was able to design the baker in. Loose eccentric reversing gear rankin kennedy, modern engines, vol iv. Where the slip eccentric pin moves is in the nogo arc for stephensons valve gear. Our awardwinning staff of trained professionals have extensive water treatment and wastewater treatment experience and can provided a wide array of information specific to each valve applications to assist you in choosing the best valve for your application.
Mechdesigner software makes it easy to add gear pairs that will transmit motion and force naturally through the mechanisms linkages. I own one and it took some considerable time to get running to what i would call an acceptable standard. At one end of the slot, say the top in the diagram, the eccentric pin drives the valve gear for forward motion. The threshers steam traction engine guide, volume 1. Another design that was quite popular was the author lbscs. In 1986 i wrote the first of the msdos versions of the software to simulate baker valve gear. Baker valve gear fairly common in the united states, it had no sliding parts radial gears. In designing the initial parameters it is perhaps wise to realise that at the time of its. Complete working 040 chassis with twin 916 slide valve cylinders and slip eccentric valve gear, as used on bertie. It is used most often in steam engines, and used to convert rotary into linear reciprocating motion to drive a sliding valve or pump ram. I do not claim to be an expert on loco valve gears, more an enthusiastic amateur but i have spent a lot of time reading up on the subject and i think im getting a reasonable grasp of the subject. Isaacsons patent valve gear a modified walschaerts gear, patented in 1907 by rupert john isaacson, and others, patent. Kodi archive and support file community software vintage software apk msdos cdrom software cdrom software library console living room software sites tucows software library shareware cdroms software capsules compilation cdrom images zx spectrum doom level cd. Everyday low prices and free delivery on eligible orders.
Our gear designers have many years experience in the industry and will be happy to discuss your requirements with you. The valve design is such that the seals do not come into contact with the valve body at any time while opening or closing of the valve. I then decided to change the design of the valves to ones that were similar to roundhouse. The walschaerts valve gear on a steam locomotive a prr e6s. That includes a slip eccentric valve gear version which would be the choice of many. Slipeccentric valve gear animation the home machinist. Triple offset valves outperform traditional valves with increased durability, reliability and lower ownership cost.
While begging his pardon, should i be mistaken, but it looks to me that in paragraph of his article on design and layout of a valve gear, that our good friend has made a slip. Stephenson valve gear, the joint invention of williams and howe in 1842, was. Nothing wrong with the valve gear, but poor chassis design and construction did their best to stop it working as it should. Growth has been constant with the addition of a awwa butterfly valve, general service butterfly valve, swing check valve, rubber flapper check valve, double disc check valve, wafer outside spring check valve, globe style check valve and compact wafer check valve. What we know about this valve gear is first its an eccentric operated valve, the aliment of an eccentric has to be offset from the crank shaft in the direction of rotation no mater how its attached. Due to the progressive lobe on the eccentric shaft, this rotation positions the intermediate lever 2 closer or further to the camshaft lobe. Steam engine valve gear on the computer windows version by charles dockstader hcr 69 box 3111 california valley ca 93453 805 475 2519. Id say it was about the same difficulty as stephensons from that point of view.
The zero leakage sealing capabilities of triple offset valves provides the performance to keep your. Files are available under licenses specified on their description page. At the other end the pin drives the valve gear for reverse motion. The control of the foreandaft movement of the valve spindle depends on the combination lever and the expansion link combined movements. To determine just what is the matter, first put the engine on dead center, according. Service sheet 04 slip eccentric valve gear valve timing adjustment on early roundhouse locomotives. In early 1999 i started converting one of the valve gears to the windows format.
Longer valve travels inevitably make this area more difficult to appease. Cph cph quite simple, but explaining it requires you to use a little imagination, so bear with me. The bilgram diagram design of the gear to fulsi given conditions. Successful operation of the slip eccentric depends on a little friction in the valve train to make it operate, and as little friction as possible in the eccentric itself. The oval diagram shown in the curve section is the best you can do for a given port design and stroke and con rod length. The geometry of slip eccentric valve gear john caldwell. Page 30 valve lift the valvetronic motor worm gear rotates the eccen tric shaft clockwise or counterclockwise at a very quick rate 1.
I have made the software available by placing it in the public domain as. A new graphical method for analyzing the action of slide valves, moved by eccentrics, linkmotions and cutoff gears, offering easy means for properly designing valves and valve gears, and for establishing the comparative merits of their various constructions. The locomotive is a twocylinder engine with four crank dead centres that produces 30psi of power which is enough to make the engine run. Dec 08, 2010 valve gear design simulator software charles dockstader has written a program for ms windows which will take the geometry of your valve gear design pretty much every gear type imaginable and show the physical arrangement of the motion, animate the events, draw an indicator card, etc. Matching valve events is necessary in a 4cylinder arrangement.
Loose eccentric is the same as slip eccentric and works the same way. Slipeccentric this gear is now confined to model steam engines, and low power. The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves. Media in category slipeccentric valvegear the following 4 files are in this category, out of 4 total.
In mechanical engineering, an eccentric is a circular disk eccentric sheave solidly fixed to a rotating axle with its centre offset from that of the axle hence the word eccentric, out of the centre. The control valve handbook has been a primary reference since its first printing in 1965. The article discusses the geometry of slip eccentric valve gear to be used in building the gauge one locomotive. All structured data from the file and property namespaces is available under the creative commons cc0 license. Joy gear has the problem of creating the slideshaft. The model is designed for a long life and built using copper, brass and stainless steel to ensure this.
The engine is nicely proportioned and might be considered semiscale, despite its tinplatelike wheel flanges. The locomotive valve gear enables the driver to choose the cutoff of the steam admission and to reverse the locomotives. Slipeccentric valve gear is very simple as shown in the diagram below. Line pressure must be 0 psi and the line drained if possible. Whether or not you have purchased dontyne systems software, there may be times when the simplest, quickest or most cost efficient way for your company to complete a project is to outsource the gear design. I decided that the fault probably lay with the valve gear so i decided to make the loco slip eccentric. If you make a slip eccentric, and you cant get the engine to run, turn the fixed part of the assembly through 180 o on the shaft. Buy model locomotive valve gears new edition by evans, martin isbn. The threshers steam traction engine guide, volume 1, chapter 7 print. The model is spirit fired with slip eccentric valve gear, working cylinder drain cocks, sprung buffers, tender hand pump, axle pump, lubricator, pressure gauge and water gauge. Slipeccentric with and without rocker, outside admission.
Charlie has put this program in the public domain but is not to be sold. Since the inventor was unable to modify the design, the valve gear was replaced by standard walschaerts gear between 24 march and 11 april 1934. Mechanically, it is unsophisticated, with a pot boiler and slip eccentric valve gear driving piston valve cylinders. For my design, the eccentric angle ea was given as 120 degrees.
The engine features slip eccentric valve gear so the engine will run in either direction. Hello group, so im just going around and around in my my head about the use of slip eccentric gear for one of my up coming projects. Gear design national broach and machine division,of lear siegler, inc. Valve gear on the computer has been placed in the public domain by the author and it is not to be sold.
Norton, design of machinery introduction to cam design. Have been making sketches of the walschearts valve gear for my 434 inch gauge loco, and found the article of h. The eccentric rod has a hook, called a gab, which is dropped down onto the valve actuating rod or rocker. In the equivalent for stephensons valve gear, full forward gear is at the top of the slot, neutral gear is to the right and full reverse gear is at the bottom of the slot. Joy valve gear design model engineering clearing house. A gear can be defined as a toothed wheel which, when meshed with another toothed wheel with similar configura. Mar 05, 2017 link gear mechanism with an eccentric. Back off operating nut 1 turn to relieve closing torque on internal of gear. It is purely an exercise in using modern computer software to give a more accurate picture of the valve events given by a specific design. In 1844 egide walschaerts invented a valve gear that by 1848 appeared very.