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Model Engineering Glossary: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Transfers forces and reciprocating motion between piston and crankshaft. Small end is connected to the piston with the Gudgeon Pin. Large end is connected to the crankshaft.

The steam engine conrod is quite different to the internal combustion engine conrod in a number of ways, therefore, we will treat them in separate sections.

Internal Combustion Engine Conrods


  • Aluminium with phosphor bronze bearing inserts. Aluminium is very light and so reduces the reciprocating mass.
  • Steel -

Steam Engine Conrods

Most steam engine conrods are in two parts with the piston solidly mounted on the conrod which is then supported in a linear bearing at one end of the cylinder. This then has a coupling to a second conrod that then connects to the crank. The part connected to the piston is normally steel running through a cast iron cylinder end cover and phosphor bronze gland. The second part of the conrod is then phosphor bronze or again steel.


  • Steel - first part of the connecting rod fixed to the piston and the second part on connecting rods on steam trains.
  • Phosphor Bronze - most stationary steam engines (eg Stuart Models) are cast in PB.

See also: Engine, Gudgeon Pin, Pistons..

Model Engineering Glossary: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z