Precision gears since 1888
For more than 135 years, Overton Chicago Gear has cut, hardened, and inspected precision gearing for the industries that move the world — right here in Addison, Illinois.
A name built on teeth cut right
Overton Chicago Gear has been manufacturing precision gearing since 1888. Over that span we have become one of the most capable open-gearing and custom-gearbox shops in North America — and a founding member of the American Gear Manufacturers Association.
What sets us apart is capability under one roof. We run our own gear cutting, 5-axis milling, heat treatment — including one of the largest press-quench operations on the continent — and a complete gear metrology lab. That means tight tolerances, full accountability, and gears that last.
From a single emergency replacement to a complete custom drive, our team engineers exactly what your application demands, geared to your specifications.
More than a century of milestones
Overton Chicago Gear is founded, beginning over a century of precision gear cutting.
Becomes one of the founding members of the American Gear Manufacturers Association.
Inducted into the AGMA Hall of Fame for lasting contributions to the industry.
ISO 9001 registered, cutting gears up to 160" for heavy industry worldwide.
The standard we hold
Geared to spec
Every gear is cut, hardened, and inspected to your exact requirements — AGMA, ISO, or DIN. No compromises on the numbers that matter.
Under one roof
Cutting, 5-axis milling, heat treatment, and full metrology all happen in our Addison plant — one accountable partner from print to pallet.
AGMA founding member
We helped write the standards the industry runs on, and were inducted into the AGMA Hall of Fame in 2016.
ISO 9001 registered
A documented quality system stands behind every gear we ship — with the traceability critical drivetrains demand.
Every process under one roof
From the first drawing to final inspection, we control the entire gear-making process in Addison — so your parts stay on schedule and on spec.
Engineering & design
In-house gear engineering, reverse engineering, and full 3D modeling from print, sample, or concept.
Gear cutting & milling
More 5-axis milling capacity than any gear maker in North America — cut to AGMA 11 without grinding.
Heat treatment
In-house carburizing and one of the largest press-quench operations in North America.
Gear metrology
A modern inspection lab with CMM systems verifying every tooth to AGMA, ISO, and DIN tolerances.
Assembly & repair
Complete gearbox assembly, emergency gear repair, and rebuilds that get your equipment running.
Quality assurance
ISO 9001 registered systems with full documentation traceable through every stage of production.
The industries we help power
When failure isn't an option, the heaviest industries in the world turn to Overton Chicago Gear for gearing that keeps critical equipment running.
Oil & Gas
Pump, compressor, and mud-pump gearing engineered for continuous upstream and downstream service.
Fracturing
High-strength gearing for frac pumps and pressure-pumping fleets that endure extreme, repeated shock loads.
Mining
Bevel, spur, and girth gearing for cone crushers, mills, shovels, and earth-moving equipment.
Marine
Propulsion, winch, and deck-machinery gearing built to marine standards for reliability far from shore.
Wind Energy
Precision gearing and gearbox components for wind turbine drivetrains and yaw-and-pitch systems.
Cement Processing
Girth gears, pinions, and kiln drives for cement plants that run around the clock in abrasive conditions.
Locomotion
Traction and drive gearing for locomotives and rail equipment built for high-mileage reliability.
Metal Processing
Pinion stands, drive gears, and gearboxes for rolling mills and metal-processing lines under constant heat and tonnage.