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London & North Western Railway Society
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Glossary Results for Word "Walschaerts valve-gear"

Walschaerts valve-gear A steam-engine valve-gear used extensively on outside-cylindered locomotives. One component of motion is taken from an eccentric or return crank secured to one of the driving axles at approximately 90 degrees to the main crank. From this a rod (eccentric rodExplain 'Eccentric Rod') transfers movement to one end of a centre-pivoted link (radius linkExplain 'Radius Link') which is thus oscillated. Movement is then taken from a die block which is free to slide within the radius link via a rod (radius rodExplain 'Radius Rod') to one end of a lever (combination leverExplain 'Combination lever'). The combination lever combines the movement of the radius rod with that of the cross head via a union link connected to the other end of the combination lever. The combined movement is transferred to the valve spindle via a third connection on the combination lever near the end connected to the radius rod. Reversal is carried out by moving the radius rod so the die block takes up a new position at the other end of the slide.