PTO shafts are an efficient way to transfer mechanical power from a tractor or truck to implements with mating attachments. They can be found on farm tractors, hay balers, skid steers, and many other types of agricultural machinery.
The splined drive shaft of a PTO allows the attached implement to be powered directly from the engine of the tractor, which in turn reduces the amount of engine power needed to run the machine. This system is also a more durable and convenient way to transfer power than flat belts, which were used in many applications before the development of power take offs.
Depending on the manufacturer, the shaft can be made in different shapes. Some are splined, while others have a round or square end and can be made in a variety of sizes. In addition, metric shafts are available in bell or star shapes, while domestic-shaped shafts are available in round, rectangle, square, or splined forms.
A splined shaft is usually more durable than a flat-belt style, which may tear or crack over time, and can be more difficult to replace than an internal belt. They also have a higher wear rate, so it is important to select the correct size and shape of splined shaft for your application.
Shaft Types
The most common splined PTO shafts are rated for rotation at either 540 rpm or 1,000 rpm. This can be easily determined by examining the diameter and number of splines on the shaft. A 540 rpm shaft will measure about 1 38 inches and have 6 splines, while a 1000 rpm shaft will measure about 138 inches and have 21 splines.
Safety Shafts and Yokes
The two yokes on the end of the PTO shaft are welded to both the tractor and the implement. The yokes are designed to be both in phase (meaning the shafts do not have unequal joints) and to provide enough directional clearance between the PTO shaft and the equipment, avoiding contact with the rotating machinery. They are especially useful for heavy-duty machinery, as they can be used to protect the equipment against sudden halts and other unexpected forces.
Universal Joints and Shields
The universal joints are welded on both the yokes to connect them to each other, and they are used to prevent the tractor and implement from pulling apart while in use. They are also a great way to keep the PTO shaft secure, reducing the chances of it being pulled off during operation.
Shields are cone-shaped pieces of metal that are welded on the end of the shaft to protect against the rotation of the PTO shaft. They are primarily used on rotary mowers and hay balers, as they protect against the possibility of objects being stepped on by the machine or contacting the operator.
Safe Use
A splined PTO shaft should always be used with proper protective gear when in operation, including gloves and goggles. Never reach over the shaft for any reason and never wear loose clothing that can become entangled in the shaft.