Geared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.
Holcroft valve gear
When working for the GWR at Swindon, Holcroft schemed out and patented (in 1909) a conjugated valve gear for three-cylinder steam locomotives, which allowed for the elimination of the valve gear for the inside cylinder by deriving the motion for the inside valve from that of the outside valves. This would be done by an assembly of levers behind the cylinder block.