Hackworth valve gear facts for kids

Hackworth valve gear on the steam train Lydia at the Perrygrove Railway.

Hackworth valve gear on the Apedale Valley Light Railway train Stanhope.

Hackworth valve gear on the Tal-y-Llyn Railway train Edward Thomas.

The Hackworth valve gear is a special part of a steam engine. It helps control how steam moves to push the engine's parts, called pistons. It's a type of "radial" gear. This means it uses a lever that gets its power from the engine's main spinning part, called the crank.

Sometimes it connects directly to the crank. Other times, it uses an extra "return crank" to get power, like you see in the pictures. The lever connects to a small block. This block slides back and forth in a special slotted track. When this track is straight up, the engine is in "mid-gear." To make the engine go forward, backward, or change its power (called 'cut-off'), the track is tilted. The valve rod, which controls the steam, is connected to a point on this lever.

History of the Hackworth Valve Gear

This clever design was created and patented by John Wesley Hackworth in 1859. He was the son of another famous engineer, Timothy Hackworth.

How Hackworth Gear is Different from Klug's Gear

The Hackworth valve gear was an early version of what later became Klug's valve gear. However, there's a key difference. In the Hackworth design, a part called the eccentric rod moves in a straight line. It does this by using a small block that slides inside a slotted guide.

Other Valve Gears to Explore

• Joy valve gear - This design was used a lot on trains in England, especially by the L&YR and LNWR. An example you can still see is LNWR G2a Class number 49395.
• Marshall valve gear - This is a changed version of the Hackworth gear. It was patented in 1879 by a company called Marshall, Sons & Co..
• Southern valve gear - This gear was popular in the United States around 1920. It combined ideas from both the Walschaerts and Baker designs.