Question

Describe rationale for the design decisions, material selections and design calculations

Component	Material	Ultimate Strength Sut (ksi)	Yield Strength Sy (ksi)
Pinion	AISI 4140 Nitrided Steel	156	60.2
Gear	AISI 4140 Nitrided Steel	156	60.2
Shaft	1040 Cold-Rolled Carbon Steel	85.0	71.1

Answer 1

Gear and pinon are subjected to cyclic impact loading and continuous wear due to contact so the surface of the gear and pinon must be hardened and also they should possess sufficient stiffness and strength so they are made of AISI4140 nitrided steel which is surface hardened using nitriding process and possess sufficient strength and stiffness.

Shaft are subjected to torque and reversible bending moments due to pulleys and gears mounted on it,so a shaft must possess sufficient stiffness and strength but surface hardening is not required so 1040 cold-rolled steel is good selection.