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Of the many varieties of locomotive valve gears, two principal type played important role. The Stephenson gear located between the wheels, this gear was successful up to the time when modern developments in locomotive practice crowded the space between wheels. When this condition become serious the Stephenson gear was abandoned in favor of the Walschaert type shown in this animation, which, in various modifications, has been adopted later on practically all modern locomotives.

The principal advantage of the Walschaert gear lieas in accessibility of its parts, which are placed entirely outside the driving wheels. This facilitates inspection, oiling, and cleaning.

The various parts of the Walschaert gear are pin-connected and are easily lubricated; hence troubles due to overheating are reduced to the minimum. The Walschaert gear also transmits the moving force of the valve in practically a straight line; consequently there are less springing and yielding of the parts than in the Stephenson gear. 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. The Welschaert type of valve gear also possesses advantages of steam distribution and operation.

The general adoption of the Walschaert valve gear has been accompanied by a number of variations which, do not eliminate its esential elements. The Baker, the Young, and the Southern valve gears, other well-known locomotive valve gears, are simply variations of the Walschaert gear.

29 Oct 2012

good show to you guys and i like to thank is mekanizmalar

02 Nov 2012

Thank you very much for this display; wonderful. I'm building a 4-4-0 Virginia as per LBSC's book. I am not a machinist

14 Dec 2012

I want to download this but i can me please...

06 Jan 2013

not true of British Great Western design which had external cylinders but internal valve gear on the larger locos (Castles, Hall, Kings etc)

02 Feb 2013

Nice animation. Only that the reverse motion is incorrect.

06 Feb 2013

Any chance you could add the components that cause the link block (British: die block) to slide up and down in the link (british: expansion link)? These would be 1) engineman's reverse lever, 2) reach r

06 Feb 2013

PS--I just LOVE it that your animations can be SLOWED DOWN. Far too many animations on the Web go too fast for a viewer to get a good understanding of how it works,

13 Apr 2013

you cant download it.....but u can use snagit screen recorder to record the animation and save it..

Barakat Latif
22 May 2013

حقاً إنها لعمل رئع يسهل الشرح و يوضح كافة المعلومات عن البخار، وسير الحكة به و كيفية تحويل طاقة البخار ل

Barakat Latif
22 May 2013

It is wonderful work the steam engine animated, and eases description.
How we can changing the steam to do make machines useful.
I am steam engine driver in Hedjaz railway.

15 Jun 2013

This is neat

04 Jul 2013

This is very inspired me.. I love steam engine so much. Thank you for this neat and clear animation

04 Jul 2013

Fabulous animation. I agree with Marek (2/2/13) and with Steven (2/6/13). Having the "interactive" aspect of this animation include positioning the valve gear into mid-gear and reverse g

04 Jan 2014

Congratulations on producing an animation that demonstrates with clarity the elegance of Walschaerts valve gear.

13 Nov 2014


Steven Smith
09 Jun 2015

Congratulations on creating such an animation! The slowdown feature is very good for slow-witted persons such as this w

08 Oct 2015

I want a playable steam locomotive working animation! Please make that!

14 Feb 2016

Good Evening:

I am very impressed with your excellent video

21 Apr 2019

This is a great animation, and lots of people will learn from it. May I suggest that you make a parallel animation of the Stephenson valve gear, perhaps combining them in a single video?

Also, it might be good to say a few words about the term "valve gear" as to what it means, and how the slide valve works.

13 Aug 2019

This animation is not great, this animation simply is wrong.
This valve gear version is made for inside admission, as it is shown, but with this direction of the eccentric crank, the radius rod is on lower position when riding forward an on upper position when riding backward. The animation shows the opposite, and if you look at the steering edges of the valve piston exactly when the "red steam" is coming, you see the very discrepant timing.

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