The concept of extending the power of the tractor to implements is as old as the tractor itself. As early as 1885, an article in Farm Implement News magazine revealed a reaper being chain-driven by a steam traction engine.

To be factual, the belt pulley represents, albeit crudely, a power take-off application (PTO).

As the tractor grew in popularity, however, interest in extending power beyond the tractor to rear-drawn implements as they operated in the field grew. Already in 1906, French manufacturer Albert Gougis built a tractor equipped with a power shaft for operating a McCormick binder. Gougis invited International Harvester representatives to a demonstration of the PTO-driven binder.

IHC’s interest in this concept had already been percolating. IHC engineer Edward Johnston had created a self-powered mower that employed a crude PTO six years previous to the viewing of the Gougis invention.

IHC Takes the PTO Plunge

Yet, the PTO remained a prototype concept until 1918, whenIHC had 50 versions of its International model 8-16 equipped with this power-beyond innovation. IHC not only added a PTO to a tractor but also designed implements that would work off the PTO. To advance this concept, IHC would extend PTO availability to the International 15-30 in 1920. The 15-30 would become the first tractor evaluated at the Nebraska Tractor Test with a PTO.

Engineer and tractor historian R.B. Gray considered the model 8-16 as the first praticable PTO mechanism. This opinion was based on the fact that the model 8-16’s PTO was driven directly off that tractor’s transmission.

Earlier attempts at creating a PTO utilized belt-driven versions that transferred power to a shaft. Often this involved a pulley working off the front of the engine that sent power through a series of jackshafts and belts to a shaft at the back of a tractor. One particular approach had a band-type clutch running off the crankshaft that transferred power through a roller chain to a cross-shaft running under the tractor. This shaft then went through a beveled gearbox that drove a PTO shaft positioned above the operator’s platform.

The IHC design involved an internal (in the transmission case) gear added to the transmission, which would drive the PTO shaft.

Interest in PTO Gains

Interest by farmers in the PTO was taking root in the early 1920s. To capitalize on this, IHC equipped both the McCormick Deering Gear Drive 10-20 and 15-30 with a PTO operating off the transmission as standard equipment.

Soon, other manufacturers offered PTOs as an option when ordering a tractor. Then in the late 1920s, a bug would spur increasing use of the accessory.

The European corn borer was devastating the eastern Corn Belt at this time. USDA research discovered that shredding corn stalks would expose corn borer larvae to the elements, causing them to perish.

Corn Borer Tractors

The theory had merit. So much so that the USDA ordered a fleet of “corn borer” tractors to rent out to farmers at $1 an acre. These tractors were paired up with an IHC stubble beater (a cornstalk shredder) and a plow. All told, the USDA program purchased a fleet of 444 John Deere Ds, 444 IHC 15-30s, and 360 Fordsons all equipped with PTO drives.

The USDA’s endorsement of the concept inspired manufacturers to offer PTO systems as an option.

Differences in PTOs

One of the major drawbacks to PTO designs of this era was the fact that the gear powering the PTO was driven off the transmission’s main output shaft. As such, whenever a farmer depressed the transmission’s clutch, the PTO would stop turning.

What was needed was a PTO arrangement that ran independently of the transmission.

Independent PTO

In 1928, Hart-Parr innovated such a design on its models 12-24 and 18-36. These tractors were offered with an optional PTO that was driven from the right end of the crankshaft. The Hart-Parr concept had its own clutches with a control lever mounted at the top of the right fender. This was the first attempt at creating an independent PTO.

Advertising material at the time pointed out that, with this feature, if a powered implement should “become clogged or overloaded, the operator can stop the tractor and operate the implement until it is cleared.”

The concept of the independent PTO was further improved upon by Cockshutt Farm Equipment in 1945. That year, the Canadian company introduced its model 30, which featured a “live” PTO that could be engaged using a separate clutch. This allowed the PTO to be put in action without stopping the tractor.

Not long after this, manufacturers started offering PTO systems that could be engaged with a push button or a selector switch.