Bagnall–Price valve gear is a type of steam engine

valve gear The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle. It can also serve as a reversing ...

developed at locomotive manufacturer W.G. Bagnall as an alternative to the more common

Walschaerts valve gear The Walschaerts valve gear is a type of valve gear used to regulate the flow of steam to the pistons in steam locomotives, invented by Belgian railway engineer Egide Walschaerts in 1844. The gear is sometimes named without the final "s", since it ...

and also to supersede the

Baguley valve gear The Baguley valve gear is a type of steam engine valve gear invented by Ernest E. Baguley, the Chief Draughtsman of the W.G. Bagnall company of locomotive manufacturers and patented in 1893. It was used by Bagnall during Baguley's time there, t ...

their designs had previously utilised. The gear was patented in 1903 by W.G. Bagnall and T. S. Price, the manager of the works.

Layout

The valves are driven from an eccentric

cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...

mounted on one of the driving axles and linkage from the crosshead. The driving axle cam drives a ''rocking shaft'' that is mounted inside a cylindrical sleeve (known as the ''rocking shaft bush'') above the cylinder. A drop lever and connecting link from the crosshead oscillates the sleeve to control the lap and lead of the cylinder.

Comparisons

;Walschaerts W.G. Bagnall claimed that Bagnall–Price valve gear eliminated some of the complexity of the Walschaerts gear, specifically the combination lever and return gear; this in turn meant the externally mounted gear had greater ground clearance which was an advantage in industrial locations where lineside obstructions could damage the gear of passing locomotives. ;Baguley valve gear According to Baker the Bagnall–Price valve gear had only one common feature with the preceding

, namely that "the application of the lap and lead motion by oscillating the expansion link (or sector) bodily, and thus superimposing this motion on the. normal die block travel, the lead remaining constant in all positions of the gear."

References

{{DEFAULTSORT:Bagnall-Price valve gear Locomotive valve gear Bagnall locomotives