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.
Piston rod
Almost all steam locomotives have used a similar design of cylinder, with a crosshead slide mounted adjacent to the cylinder and a short piston rod between them.
In some cases, tail rods were also used. These were rare in the United Kingdom, but relatively common in Europe, at least for large locomotives.