lever assembly

By using the combination lever assembly to drive the "middle" cylinder, Holcroft managed to circumvent these problems.

The middle cylinder was driven from the combination lever assembly that controlled the fore and aft movement of the valve spindle on the right-hand "outside" cylinder.

It varied from the Gresley method of operation by using the combination lever assembly instead of the valve spindles to drive the middle cylinder of a three-cylinder design.

Two varieties of hoods were supplied: half-hoods covering only the top of the lever assembly, or full-hoods covering the entire body of the lever assembly.

This was achieved by using the combination lever assembly that controlled the fore and aft movement of the valve spindle, which admitted "live" steam into the cylinder and ejected "spent" steam through the ports.

Harold Holcroft devised a different method for conjugating valve gear by linking the middle cylinder to the combination lever assembly of an outside cylinder, creating the Holcroft valve gear derivative.