In May 1920, a long century ago in the shadows of Cleveland’s steel mills, two brilliant and visionary engineers founded The Ohio Crankshaft Company. The young engineers were William C. Dunn and Francis S. Denneen. An inventor, Dunn had a special interest in race cars and would often race at the Indianapolis Speedway. He served as Ohio Crankshaft’s first president. Just prior to his Ohio Crankshaft career, Denneen owned Denneen Motors and invented a truck that boasted electric lights and an electric starter. He later sold the business to Grant Motors, which was later purchased by General Motors. Denneen was the company’s first vice president and secretary treasurer.

The mission of Ohio Crankshaft was to supply crankshafts and camshafts to the automotive and trucking sectors, and the next decade brought enormous success to Dunn and Denneen. They moved their start-up from a small garage into a larger building in Cleveland (only a few miles away from the current 250,000-square-foot facility). By the early 1930s, they were producing 300 camshafts per day. In 1933, the founders invested $8,000 ($114,000 in today’s currency) for a Landis automatic camshaft grinder.


The TOCCO Process is Created

As their business matured, Dunn and Denneen became intent on finding a way to improve the wear life of crankshafts and camshafts, which would often show wear after only 30,000-50,000 miles in truck engines. They set out to make more durable products to take to the market. The process that they would soon perfect would increase the life span of a crankshaft to over 500,000 miles.

What was needed was a good method to harden Ohio Crankshaft’s products. Common methods of the era – including chromium plating, nitriding or cyaniding – could take hours, or even days, to process. Some of these methods generally required the addition of other elements to the surface to be hardened. In some cases, lengthy thermal cycles were required that could cause excessive distortion and lead to part straightening before machining. This, in turn, could lead to cracked parts. Another problem caused by distortion was the need to add more stock if the part was to be ground, further adding to the cost and time to machine. In theory, one would have to “heat 1,000 pounds to harden 10 pounds.”

After experimenting with several methods, including gas, electrical and flame hardening, Dunn and Denneen felt that surface hardening by high-frequency electrical induction would be the most satisfactory and cost-effective process to produce an exact result time after time. In April 1934, they entered into an agreement with Ajax Electrothermic Corporation and Westinghouse Electric for a license to use patents owned by Ajax for the purpose of developing a process to harden camshafts and crankshafts.

Ajax Electrothermic was founded by Francis Clamer in 1880 as the Ajax Metal Company to develop a new bronze alloy. Clamer worked with other prominent entrepreneurs of the era, such as Dr. Carl Hering, an electrical engineer and a developer of high-electrical-frequency melting furnaces. He also worked with Edwin Northrup and Morris Leeds to produce billet heaters for extrusion presses.

The initial cost of the start-up induction equipment to harden crankshafts was $30,000. Ohio Crankshaft soon realized that they could design and build systems to induction harden parts – large and small, and both simple and intricate – for many industries. They sought and were given permission to issue sub-licenses and collect royalties for the manufacture and sale of induction-hardening systems for a variety of industries.

The TOCCO process, an acronym for The Ohio Crankshaft Company, was born. It enabled the localized hardening of steel parts in mere seconds to a consistent hardness depth with excellent metallurgical properties. Additionally, the surface-hardened zone blends seamlessly with untreated areas, so there is no flaking or spalling, no scale formation and minimal part distortion.


On a Growth Track

In 1936, the American Metallurgical Society (AMS) held a trade show at the Cleveland Public Hall. As it turned out, the TOCCO process was the “star of the show,” as the exhibited process demonstrated its localized hardening capabilities and speed.

TOCCO demonstrated their equipment that heated metals for hardening, brazing, forming, soldering, annealing and welding. Their process equipment allowed the user to surface-harden only the needed portion of almost any steel object. The TOCCO process eliminated the need for typical expensive pretreatment, such as copper plating and carburizing, and costly subsequent straightening and cleaning operations.

Automatic control and accuracy were TOCCO keynotes. International Harvester was so impressed with what they witnessed at the show that they ordered and installed a TOCCO line in one of their factories at a cost of approximately $100,000. The Packard automobile was the first car to ever use an induction-hardened crankshaft. Allis Chalmers, Caterpillar Tractor, Cummins Engine, Fafnir Bearing, General Electric, General Motors, Cleveland Diesel, Detroit Diesel, Kearney Trecker, Robbins and Meyers and many more companies would soon follow suit with the purchase of TOCCO systems.

As the process gained momentum, Dunn traveled to Europe in 1938 to promote it and TOCCO machinery systems. He visited Fiat, AEG, Rolls-Royce, Mercedes Benz, Alfa Romeo, Gardner Company and Bristol Aeroplane. Dunn would name Electric Furnace Company of Covington, England, as an authorized Ohio Crankshaft agent.


The Effects of WWII

The onset of World War II dramatically altered Ohio Crankshaft’s course. The U.S. government would turn to the country’s manufacturing sector to produce parts needed for the war effort.

As a supplier for wartime manufacturers such as Alcoa, Wright Aeronautical and Detroit Diesel, Ohio Crankshaft churned out many thousands of crankshafts and other critical components. These powered planes, ships, tanks and other military vehicles, and they all contained components that were induction hardened with the TOCCO process.

Company employment swelled to over 4,000 during the war. In March 1945, Ohio Crankshaft was awarded the prestigious “E” award (also known as the Army-Navy Production award) by the U.S. Navy and Army for Excellence of Production in Support of the War Effort. Only 5% of more than 85,000 companies involved in producing material for the U.S. war effort received the award.

During the post-war years, the TOCCO induction machine systems’ business continued to increase. Having outgrown the space provided in Ohio Crankshaft’s factory, a new plant was erected nearby on 33 acres of property in 1951. Within a few years, another plant would be built in Madison Heights, Mich., and subsequently yet another in Boaz, Ala.


The Park Drop Forge Story

A partner to Ohio Crankshaft since its inception was another Cleveland powerhouse, Park Drop Forge. Founded in 1907, Park Drop originally forged sewing-machine parts and horseshoe cleats that could be replaced without re-shoeing the horse. They forged parts that were used on the Spirit of St. Louis, Charles Lindbergh’s history-making aircraft.

They became forging-industry pioneers in the developing auto industry and would later produce crankshafts and camshaft forgings for Ohio Crankshaft. These were used for locomotive and truck engines. They also forged landing gears for the commercial aerospace industry. Park Drop held key seats on Ohio Crankshaft’s board of directors for nearly 40 years and aided greatly in their success. This partnership would last for five decades before the two companies would mark another milestone.

Ohio Crankshaft and Park Drop Forge merged their operations in 1967 to form Park Ohio Industries. Today, Park Ohio is a diversified international company providing global customers with a supply-chain management outsourcing service, capital equipment used in their production lines and manufactured components used to assemble their products. Headquartered in Cleveland, Park Ohio operates more than 125 manufacturing sites and supply-chain logistics facilities worldwide, employing over 6,000.

Throughout the next five decades, the company’s crankshafts could be found in tugboats, locomotives, heavy-construction equipment, trucks and high-pressure water-jet cutting equipment. Along the way, Ohio Crankshaft earned their first Association of American Railroads (AAR) M-1003 Quality Certificate in 2004 as well as numerous customer awards and recognitions.


Recent History

In 2001, ASM International recognized Ohio Crankshaft as the site of the first production application for selective induction hardening of steel parts. The success of the TOCCO process helped spur the growth of induction-hardening technology.

In 2002, Park Ohio purchased Ajax Magnethermic, renaming the company Ajax TOCCO Magnethermic. Today, Ajax TOCCO Magnethermic is a global company manufacturing and servicing modern induction heating systems, high-frequency welding systems, melting systems and Windows-driven power supplies many times more powerful and reliable than those of the past.

Their modern systems have barcode capability that allows for the recipe of a perfect part to be duplicated repeatedly while building and logging the history of each part. The systems are designed to take all the risks out of part processing, with automatic shutdown of units should an operating parameter be out of specification (quench temperature, part misalignment, below operating temperature, etc.).



Today, Park Ohio is proud of its roots and celebrates its industrial heritage. As subsidiary Ohio Crankshaft’s name implies, the company has a long history and specific expertise in the manufacture of heavy-duty crankshafts for internal combustion engines and reciprocating pumps.

Crankshafts up to a 27.5-inch diametric envelope, 165 inches long and weighing up to 10,000 pounds can be manufactured. Ohio Crankshaft manufactures and repairs a broad range of shafts for reciprocating and rotary-motion machinery, including: heavy mechanical reciprocating presses; heavy-duty, high-pressure water pumps; heavy-duty reciprocating compressors; and on- and off-highway equipment up to 700 HP.

It should be noted that, along with these considerable manufacturing capabilities, one of Ohio Crankshaft’s current core services is reconditioning the locomotive crankshafts it originally produced in the 1960s-1980s. This speaks highly about the strength, durability and quality of the products produced by this 100-year-old Park Ohio subsidiary and the proud story that it continues to write.