Tractor PTO Shaft | PTO Shaft | Power Take Off PTO

What is a PTO shaft?

The Power Take-Off (PTO) shaft is a mechanical means of transferring rotational power and torque from the engine (usually via the transmission) between your tractor and implement or attachment. Early PTOs were driven mostly from the transmission, based at the back of the tractor -  this allowed easy access to an output shaft.  

There are two major types of independent PTO; mechanical and hydraulic.

Parts of the PTO Shaft:

Internal Yoke

Universal Joint

External Yoke

Safety Chain

Safety Shield

How does a PTO work?

The PTO transfers an engine's power to another piece of equipment or machine that does not have its own engine or motor.  The power is transferred through a driveshaft.

The tractor's PTO shaft transfers power from the tractor to the PTO-driven machine or implement. A drive shaft is connected from the machinery to the tractor's PTO shaft. The PTO and drive shaft rotate at 540 rpm (9 times per second) or 1,000 rpm (16.6 times per second), significantly faster than our reaction times. 

PTO RPM

540 rpm—6 spline—1 3⁄8-in. shaft
1000 rpm—21 spline—1 3⁄8-in. shaft
1000 rpm—20 spline—1 3⁄4-in. shaft

Transmission PTO’s

PTO’s coupled directly to transmission only engage when the transmission clutch is engaged. When the clutch is depressed, the PTO isn’t driven. The clutch PTO prevents torque from being applied in the opposite direction.

Live PTO

A live PTO uses a transmission clutch with two stages. The first stage of the clutch operates the driven portion of the transmission, and the second stage of the clutch controls the engagement of the PTO. This method allows independent control of the transmission, so that the PTO maintains operation regardless of transmission clutch activity, including stopping of the tractor itself. 

Independent PTO

The independent PTO can be activated while the tractor is stopped or moving and works exclusive of the transmission clutch. A button or lever is pushed to engage the PTO.

PTO Safety

• PTO guards should always be in place.  Most accidents occur when clothing, shoes laces or even limbs are caught by a spinning and unguarded PTO shaft. The PTO should always be disengaged when not in operation. Many older tractors, may no longer have PTO shields. Over time they may have become damaged and removed. It is advisable to replace or repair PTO guards to reduce the risk of injury.
• Keep all components of PTO systems shielded and guarded
• Regularly test driveline guards by spinning or rotating them to ensure that they have not become stuck to the shaft.
• Disengage the PTO and shut off the tractor before dismounting to clean, repair, service, or adjust machinery.
• Always walk around tractors and machinery instead of stepping over a rotating shaft.
• Always use the driveline recommended for your machine. Never switch drivelines among different machines.
• Position the tractor's drawbar properly for each machine used to help prevent driveline stress and separation on uneven terrain and during tight turns.
• Reduce PTO shaft abuse by observing the following: avoid tight turns that pinch rotating shafts between the tractor and machine; keep excessive telescoping to a minimum; engage power to the shaft gradually; and avoid over tightening of slip clutches on PTO-driven machines.
• Be sure PTO driveline is securely locked onto the tractor PTO stub shaft.
• Keep universal joints in phase. (If unfamiliar with this term, check the operator manual or talk with a farm implement dealer.)
• Stop the tractor engine and disengage the PTO to work on the machine or unclog it.
• Keep guards in place.
• Wear close fitting clothing to prevent entanglement of loose clothing parts.
• Secure long hair under a hat when working around the PTO.
• Instruct all operators about the hazards of the PTO.
• Keep children away from all turning parts of the machine not just the PTO.

At Anglo Agriparts we supply PTO guards parts, PTO shaft with shear pin, over run PTO shaft, quick release PTO shaft and more.

Sources: Pennsylvania State University