MARINE ENGINES.

409

This arrangement of crosshead is certainly preferable to those havingthe arms forged on at an angle from the connecting rod bearing, asit assumes a more direct form ofbeam, loaded at the end with thesteam pressure communicated fromthe piston through the piston rods,taken centrally with the connectingrod, which in its turn acts on the armsof the cranked shaft, the bearing ofwhich is subjected to torsional stress.

We have now to consider the Con-nection between the piston rod andthe connecting rod for direct-actionsingle piston-rod arrangements. Thebrasses for taking the forked end ofthe connecting rod are cast in two

Fig. 291.—Crosshead for Piston Rods.

halves, on each of which is cast a A ' Pi “ owblock ° n f oss ^ eadfittedw! ‘ llbr f se J s -

bottom guide pieCe ; they are grooved E E, Eyes for the piston rods. f. Brass

out for the reception of a wedge plate, slldu ’ s piece 'the bottom of which is parallel with the centre line of the rod, but ofa wedge shape on its upper surface, which bears on the brass pieces,and which is secured at one end, but having the means of adjusting

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Fig. 292.—Crosshead for Single Piston Rod.

a, Prass crosshead. b, Cap. c, T piece forged on the piston rod. d d, Bolts and nuts.e, Adjustable plate. f, Guide for crosshead.

the sliding brass against the bottom guide plate, as in the examplesalready described. The piston rod has a T piece for attachmentto these brasses, and at the connecting-rod end a cap is fitted; theseare all held together by two large bolts passing through the T piece,