USRA Designs

USRA Mikado Steam Engine






Walschaet Valve


Walschaet Valve

(Source: Robert Booty )


The Walschaert valve gear is a type of steam engine valve gear invented by Belgian railway mechanical engineer Egide Walschaerts in 1844. The gear is sometimes named without the final "s", since it was incorrectly patented under that name. It was extensively used in steam locomotives from the late 19th century until the end of the steam era.


The Walschaert valve gear was slow to gain popularity. The Stephenson valve gear remained the most popularly used valve gear on 19th-century locomotives. The Walschaert gear had the advantage that it could be mounted entirely on the outside of the locomotives, leaving the space between the frames clear; this caused adoption first among some articulated locomotives. The Mason Bogie locomotive type was the first to use the Walschaerts gear in North America.


In the 20th century, the Walschaert valve gear was the most commonly used type, especially on larger locomotives. In Europe, its use was almost universal, whilst in North America, the Walschaert gear outnumbered its closest competitor, the Baker valve gear, by a wide margin.


Components of the Walschaert Valve


Walschaet Valuve Components

1. Eccentric Crank (Return Crank)

2. Eccentric Rod

3. Reach Rod

4. Lifting Link

5. Lifting Arm

6. Reverse Arm & Shaft

7. Link (Expansion Link)

  8. Radius Bar/Rod

  9. Crosshead Arm (Drop Link)

10. Valve Stem Guide

11. Union Link (Anchor Link)

12. Combination Lever

13. Valve Stem

14. Valve Spindle

(Source: Wikipedia)