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530 Westgate Drive
Addison, IL 60101
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(630) 543-9570
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2823 W. Fulton Street
Chicago, IL 60612
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(773) 638-0508


We make some of the largest, most complex gearboxes ever made. These gearboxes come in standard, right angle, and parallel shaft configurations, based on customer specification. We have designed and built more than 500,000 gearboxes.

Precision Gearbox Design and Manufacturing
Our precision gearbox design and manufacturing capabilities include:
  • Made-to-order helical, bevel helical and planetary gearboxes with any shaft configuration
  • Drop-in replacement gearboxes for on-going special or production applications
  • Complete engineering services, inspection and rebuild for D.O. James gearbox rebuilds and other gearbox brands
  • Reverse engineering of gearboxes, gears and gear sets
  • Spare parts for all of our gearboxes

Gearboxes Tuned for Specialty Applications
Our gearbox team designs and builds gearbox systems supporting large projects in metal processing for smelting, metal rolling, pickling, slitting and casting, public works projects such as locks, dams and moveable bridges, propulsion drive systems in the marine industry, pulverizers in power generation and cement industries, large pumps and a variety of other applications with unique needs.

These diverse customer needs often require a broad range of control mechanisms. We routinely incorporate shifters, clutches, differentials, backlash limiters and condition monitoring as needed by our customers. We can add shaft or motor driven pressurized lubrication systems to the housing or standalone skids to increase efficiency, control temperature or lubricate isolated components.

Gearbox Repair, Rebuild and Reverse Engineering
We can fix your gearbox issues. Often, otherwise useful equipment is driven by unsupported gearboxes. OCG manufactures new rotating components for these gearboxes, extending equipment life. These rebuilds restore the gearbox to like-new performance. If needed, we can often provide a much higher performance system while still reusing many components by fine-tuning gear geometry or using different materials and processing methods.

Our rebuild and repair services also include:
  • Jobsite service calls to evaluate customer application, requirements, and repair needs
  • Breakdown service to help with emergency needs
  • Reverse engineering of a component or whole unit
  • 12-month warranty on complete rebuilt gearboxes
  • No-load testing (standard); full load testing (as required)
  • Preservation for long-term storage

OCG has the expertise and tight process control needed for cost effective gearbox rebuild and repair. We do everything from retrofitting gearboxes with new bearings and seals to completely replacing all rotating elements and providing a like-new box.

We can reverse engineer a customer gear or gear box and provide a replacement unit that outperforms the original, using our materials expertise, heat treatment and profile changes.

Gearbox Design and Build to Fit
OCG has the skills and equipment to design and build new gearboxes from your required specifications or to provide a drop-in replacement with identical equipment connections and increased performance. We can also add condition monitoring to the existing shell, warning users of the need for maintenance. Our experience allows us to repair, rebuild and design to fit for almost any enclosed drive from any manufacturer.
When repair and rebuild are not options, we can custom engineer gearboxes to meet your requirements. We offer:
  • Drop-in replacements for all brands
  • Special ratios
  • High power density application products
  • Special drop-in replacement gearboxes for on-going special or production applications

Global Gearbox Reach through Strategic Partnerships
Our long-term partners overseas who are exclusive to OCG produce many types of standard and special design gearboxes manufactured to our drawings and specifications. These partners give us a global footprint with quality gearboxes and allow us to service our customers where pricing is an issue. We have more than 30 years of experience with overseas partnerships, which offer our customers greater flexibility in production and delivery.

Case Study: Gearbox Innovation for Unique Medical Device Application
Our broad scope of design work allows us to use unique approaches when solving customer problems. A large medical device manufacturer was experiencing problems accurately positioning a 100,000 pound gantry. We added a differential drive and improved micro geometry on the final positioning gear elements. This reduced motor amps, improved positioning accuracy, and increased the expected life span of the complete design. Redesign required only adding two new mounting holes to the device.
Case Study: Travel Drive Crane Gearbox Replacement
OCG was contracted to replace almost 100 right-angle gearboxes in multiple travel drive cranes. These 60-ton cranes are essential to port operations and subject to severe weather and storm surges. On-site surveys conducted by OCG engineers to measure existing gearboxes led to successful reverse engineering and design for new layout. Following customer approval, OCG performed a finite element analysis and produced a master spline gauge. Gearboxes were manufactured overseas and packaged for import to US, where OCG performed customer-site inspection and no-load testing at the OCG Lombard facility. All gearboxes were successfully installed and continue to operate today.
Case Studies: Gearbox Rebuild and Repair

We are seeing gearboxes travel thru 5-10 states to bring units to OCG, when most rebuilds do not travel more than a 6-hour drive for rebuild. We recently received a gearbox from Kansas, several trolley drive units out of Colorado, and a 15,000 pound drive out of Mexico.

Recently OCG was asked to rebuild a gearbox in Maryland. The unit required a complete bearing and seal change out. We also replaced a helical gear as well as the high speed fan in a 3.5 week turn.