This is usually of mechanical or hydraulic type, fitted to the top part of the engine to provide stiffening and support against twisting forces from the crosshead guide. Normally, these braces are fitted to only one side of the engine e.g. the exhaust side.
FIG.: Mechanical top bracing
A mechanical top bracing consists of shims between two plates hydraulically fastened by a bolt. The bracing stiffening plates are thereby attached to a strong support.