Crosshead

The crosshead is a coupling member at large piston engines between the reciprocating piston rod and the pivoting rod.

The piston rod is rigidly connected to the piston head and the crosshead pin. The pivoting connecting rod drives the crankshaft. The crosshead bearing represents the link between the two components

The acting transversely to the driving direction of the crosshead bearing normal forces cause a tilting during operation. You will be paid via the integrated the crosshead bearing so-called shoe to the attached to the Gestellwandungen slideways of the motor and into the motor base. The structural arrangement rigid piston rod crosshead connecting rod allows a shorter piston length for longer stroke and thus the benefits of a larger displacement.

Indispensable is the crosshead when a piston engine is to be realized with a high stroke - bore ratio as in the case of modern DC- scavenged two-stroke diesel engines (hole about 1 m, stroke about 3 m). Due to the rigid piston rod of the upper turning point of the connecting rod is displaced ( in Phillips ) to the crankshaft out. This prevents the rod collides with the cylinder liner. The crosshead is therefore often found in very large piston engines. Also on large steam engines of previous decades is often a cross-head between the piston and connecting rod connected. An example of this is found in the entrance area of the Technik Museum Speyer.

An application example is the cross-head in two-stroke marine diesel engines, the most efficient heat engines ever. By a large displacement and speed of 100 min-1 is the amount of time available for gas exchange, thereby making it possible to burn a larger quantity of fuel. Marine diesel engines an effective efficiency of over 50%. For use in large, slow -speed two- stroke diesel engines efficient management of the purge air is combined with the cross-head at the same time. During combustion of residual oils, it is necessary to use for the cylinder lubrication, high quality and expensive lubricating oils which are used in so-called trunk piston engines and the lubrication of the crank mechanism. By the separation of purge air and the combustion chamber on the one hand and the crank chamber on the other hand in slow running two-stroke diesel engine by means of the so-called intermediate bottom and a special seal for the connecting rod, it is possible, easier for the crank chamber and thus to use cheaper oils.

In the district of Braunschweig Melverode stands as a demonstration of an ensemble of piston, piston rod, crosshead, connecting rod and a crank part of the work input of the Brunswick smelter BHW. It shows parts of a marine diesel engine, whose five, seven, nine, or more recently, fourteen units strung together, including housing form a marine engine.

In small motors, the crosshead is used in the opposed-piston engine of Golle Motor AG in new and patented way.

The future prospects of the crosshead are also given since can be with the help of this machine element to realize efficient powertrains, and it will allow you to save fuel.