Valve Gear Simulators

Charles Dockstader created a brilliant collection of fully graphically animated valve gear simulations (for Windows OS), starting in 1986 and continuing until approx 2007. He made the software freely available by placing it in the public domain as freeware. The programs cover just about all the valve gears in common use, and can be used for the design or analysis of steam engine valve gear.

These programs were never sold, and are not to be sold. Support for these programs ceased in 2007, and when Charlie died in 2011 his web site and his expertise disappeared forever. The programs are available here from archived copies previously downloaded.

Typical screenshots

P/N 450020 P/N 450020 P/N 450020

Charlie Dockstader's Valve Gear Simulators (for Windows). WinXP version, but does run in Win7.
All programs in a single .ZIP file

Price: Free download
Part No.: 450020 Immediate download [23,394 kB]

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  1. Download the whole package of zipped programs.
  2. Unzip all the files into their own directory or folder.
  3. Start the program 'VGStart.exe' to open the main screen.
    This is the only action required to begin.
  4. Select the type of valve gear desired.
  5. Design/analyse your valve gear.


  • See the Help menu for the Instructions and special instructions.
  • Clicking on the icon in the menu bar will activate the steam animation and exhaust sound for the simulation.
  • The software is portable and will run from a USB Flash drive.

Disclaimer: Note the accuracy of these calculations is not necessarily exact, and figures calculated here may vary from actual results. Results to be used at your own risk. No responsibility accepted for any claim arising from the use of this software. Note that this software is not supported.


Other Valve Gear Simulators

There are other valve gear analysis tools available.

Don Ashton’s steam locomotive valve gear treatise on full and scale valve gears, including simulation and setting of model valve gears, is quite useful.

Allan Wallace also has a steam locomotive valve gear simulator and notes on full and scale valve gears.