Open a PTO catalogue and you will see gears described as forged steel or cast iron — often without explanation. The two materials behave very differently under load, and the choice shapes the strength, cost and life of the unit.
Forged steel gears
Forging compacts the steel's grain structure so the grain follows the tooth shape. The result is high tensile and fatigue strength — forged gears tolerate shock loads, overloads and continuous heavy duty far better. Most high-torque and heavy-duty PTOs use forged, heat-treated steel gears. The cost is higher and machining is more demanding.
Cast iron gears
Cast iron is economical, easy to cast into complex shapes and damps vibration well — a quiet mesh. But cast iron is brittle: it carries steady loads acceptably yet cracks under shock. Cast iron gears suit low-torque, light-duty and cost-sensitive applications.
Which one do you need?
If your application involves high torque, frequent engagement shocks or continuous duty — cranes, refuse trucks, winches — insist on forged steel gears. For light auxiliary drives with modest loads, cast iron keeps the cost down without sacrificing reliability.
The honest answer
Material grade and heat treatment matter as much as the process: a properly heat-treated alloy steel gear outperforms both generic options. PFM specifies materials per application — ask us what is inside the unit you are buying, and why.