PTO Gearbox

A power take-off or power takeoff (PTO) is any of several methods for taking power from a power source, such as a running engine, and transmitting it to an application such as an attached implement or separate machine. Most commonly, it is a splined drive shaft installed on a tractor or truck allowing implements with mating fittings to be powered directly by the engine.

Semi-permanently mounted power take-offs can also be found on industrial and marine engines. These applications typically use a drive shaft and bolted joint to transmit power to a secondary implement or accessory. In the case of a marine application, such shafts may be used to power fire pumps.

What is a PTO Gearbox

Power take-offs (PTOs) are mechanical gearboxes that attach to apertures provided on truck transmissions and are used to transfer the power of the vehicle engine to auxiliary components, most commonly a hydraulic pump. The hydraulic flow generated by the pump is then directed to cylinders and/or hydraulic motors to perform work – think dump trucks, refuse collection trucks and wreckers. In some PTO applications such as pneumatic blowers, vacuum pumps and liquid transfer pumps, the PTO provides power, in the form of a rotating shaft, directly to the driven component.

The transmissions commonly found in Class 4 and larger vehicles will have provisions for the mounting of a PTO. Generally there are two apertures, one on each side of the transmission. When discussing aperture location one refers to the passenger side of the truck as the right and the driver’s side as the left.

The power take-off may be engaged by means of a cable, air pressure or hydraulic pressure. Various output shaft configurations are available to allow for a driveshaft connection or the attachment of hydraulic pumps directly to the PTO without an intermediate shaft. The Society of Automotive Engineers (S.A.E.) has established standard mounting face dimensions for hydraulic pumps, which PTOs are made to accept. The S.A.E. type B mounting is the most common.

The transmission’s PTO aperture may be of the six-bolt, eight-bolt or ten-bolt type, referring to the number of fasteners used to attach the PTO to the transmission. Six- and eight-bolt openings are S.A.E. standard sizes as found on manual and automated manual transmissions. The ten-bolt opening is exclusive to Allison automatic transmissions.

PTO Gearbox Working

The PTO is the link between the truck’s transmission and the hydraulic pump, blower, or motor doing the work to complete the job. … The PTO converts power from the engine and transmission to an output we can manipulate to drive hydraulic components in various ways to produce a service that generates revenue.

“Most importantly, PTOs make fleets money! Typically, the PTO is the first link in the vocational truck’s application chain. The PTO is the link between the truck’s transmission and the hydraulic pump, blower, or motor doing the work to complete the job. Knowing this, the truck fleet management team needs to install, operate, and maintain it correctly, so the truck is working productively and efficiently,” said Mikel Janitz, Bezares Territory manager & applications engineer. 

History Of PTO Gearbox

Various power transmission methods were available before power take-offs became common, but there were applications which would benefit more from some of the attributes that PTOs would provide. Flat belts were generally only useful for applications where the engine was stationary, such as factory steam engines, portable stationary engines, or traction engines parked in front of the work.

For moving vehicles such as a traction engine or early tractor towing a farm implement, the implement could receive rotary power by taking it from one of its own wheels (whose turning was imparted by the towing) and distributing it via roller chains (to a sickle bar’s crank, for example), but such a transmission ceases if the vehicle stops traveling, and the workload’s resistance tends to make the wheel skid rather than turn, even if cleated. The concept of a shaft drive with easily connected and disconnected couplings, and flexibility for driving at changing angles (such as when an articulated tractor-and-trailer combination turns), was a goal to pursue.

Experimental power take-offs were tried as early as 1878, and various homemade versions were constructed over the subsequent decades.International Harvester Company (IHC) was first to market with a PTO on a production tractor, with its model 8-16, introduced in 1918. Edward A. Johnston, an IHC engineer, had been impressed by a homemade PTO that he saw in France about a decade before, improvised by a French farmer and mechanic surnamed Gougis. He and his IHC colleagues incorporated the idea into the 8-16, and designed a family of implements to take advantage of the feature.

The Power Take-Off Input Gear

Power take-off input gears mesh with the transmission’s PTO drive gear and transmit power to the PTO output shaft. Muncie Power Products works closely with truck transmission manufacturers to ensure that the PTO gear matches the mounting depth, pitch and helix angle of the transmission gear.

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