Connecting Rod of a Gamma-configuration Sterling Engine

[JunJae_imd]

Why is that the wire connecting crankshaft and displacer must be soft (nylon), but wire connecting crankshaft and power piston be hard(steel)?

[Ian S C]

Don't know, I would have to see the motor, but a guess would be that it is a tin can motor, and the displacer is vertical, gravity takes the displacer down and the crank lifts it up, so it only has to be able to take tension. The power piston has to push against the crank, so it must be ridged.
Ian S C