Everything which is struck rings; everything has a particular ring.—Pythagoras of Samos (582-507 B.C.) The lecture is divided into the following sections. Introduction. Early days. Camshaft drives. Camshaft drive at free end and after end of crankshaft; later developments. Mass balancing of internal-combusion engines. Single-piston assemblies; unbalanced centrifugal and inertia forces. Mass balancing opposed-piston engines. Ship vibration; scavenge-crank balance weights; scavenge-pump reciprocating parts; crankshaft-coupling-bolt failures; change of firing order; results and conclusions from vibration tests. Differential-stroke (mass-balanced) opposed-piston engines; first fully balanced opposed-piston engines; lever-driven scavenge pumps. Transverse (rolling) vibration of engine frame. Experimental determination of the natural frequency of transverse (rolling) vibration of opposed-piston engines; transverse vibration of engine frame in twin-screw ships and its control. Torsional vibration. Investigation of side-connecting-rod failures; investigation of torsional vibration; retiming the crankshaft system; general; marine steam reciprocating engine. Devices for controlling torsional vibration. Tuned and damped vibration absorbers; dynamic vibration absorbers in opposed-piston-engine propulsion systems; Bibby peripheral grid springs; vibration absorbers at free ends of crankshafts; experimental absorber with peripheral helical springs; Doxford-Bibby absorber. Later history. Large six-cylinder opposed-piston engines; alternative viscous-friction dampers; modified vibration absorber; stiffer crankshafts; P-type engines; J-type engines.
