Akademik

1. : a steam engine having a piston rod that is a pipe of sufficient diameter to enable one end of the connecting rod to be attached to the crank and the other end to pass within the pipe and be pivoted to the piston

2. : an engine (as most internal-combustion engines) having a trunk piston

1. an engine having a trunk piston or pistons.

2. a double-acting steam engine having a connecting rod passing through a trunk to the piston.

[1860-65]

trunk engine,

any one of various reciprocating internal-combustion or steam engines having a piston rod or piston open at one end and tubular. The tubular opening is large enough to permit a connecting rod connected directly to make its lateral motion within the diameter of the opening.