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Valve gear remote troubleshooting (updated)
http://www.rypn.org/forums/viewtopic.php?f=1&t=48134		 Page 1 of 1
Author:  SAS [ Sat Jun 08, 2024 6:00 am ]
Post subject:  Valve gear remote troubleshooting (updated)
How it started:

After a period of calculating valve gears in MS Excel, many years ago I did some successful quick troubleshooting for a small 600 mm gauge steam loco's valve gear that was performing very poorly.
We measured the piston and valve positions in 4 steps, I drew an Excel diagram ellipse, extracted the proportional part of valve piston movement, calculated the new dimension of a lever bearing position via the rule of three. All this was done within about two hours. Then the loco's owner made two new levers (some kind of combination lever, for Hackworth valve gear) from flat steel, and the loco got back its power like in new state, or even more.

Now I own a valve gear simulation software with optional semi-automatic pre-optimization since more than 15 years, and now also with an additional highly flexible new solver tool on top, which allows me to rapidly simulate and analyze your Walschaerts valve gear (other types currently to be modeled in MS Excel, or to be newly implemented in my software) and find the point to be modified, possibly even starting from a photo and some measured coordinates of piston and valve position.


What we offer: Valve gear remote troubleshooting!

There are two options how remote troubleshooting can be started:

  • Option #1 Valve Gear Troubleshooting by diagram:
    A valve event diagram with relative X-Y coordinates is taken by the operating crew moving the steam locomotive step by step and measuring the piston position and according valve piston position for each step, for certain degrees of cylinder filling. For this, outside reference points are sufficient, so no cylinder needs to be opened.

  • Option #2 Valve Gear Troubleshooting by geometry:
    A valve event diagram is created by our software, based on valve gear dimensions measured and entered by the operating crew. A suitable slide center position is initially assumed (Y coordinate origin in the slide diagram). This option allows us to massively reduce our workload and offer extremely competitive pricing.

Further steps:

  • We check whether the diagrams look good or the valve gear should be modified.

  • If the diagrams look good (but still without an absolutely fixed diagram origin), the reason for bad valve events must be looked for in the valve piston environment or setting (Y offset in the slide diagram).

  • If the diagrams do not look good, the valve events are compared to an optimal version of the valve gear with ideal valve events, optimized by our software. This comparison shows which parts of the valve gear to modify and how.


How easy it already could be:

At the beginning of this year, the owner of a 15" gauge steam loco for a fun park asked for access to my valve gear design program to check his loco's valve gear.
He modeled the current kinematic skeleton dimensions and later on asked me for advice.
I roughly modeled a version with automatically pre-optimized dimensions and noticed soon that my angle between the main pin and the eccentric crank pin was nearly an exact mirror image to his one. So I told him to check if his drive axle could be mounted in wrong orientation... and he confirmed!


There are very different reasons why someone asked for support, but our highly efficient software allows us to concentrate on the overall image of valve gear behaviour instead of loosing lots of time by fiddling with detail parameters. So I am optimistic that we can help out in very most of all cases with highest efficiency.


I really would appreciate to support you via remote troubleshooting to help you getting an excellently working valve gear.
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