Types of Power Take-Off (PTO)

In addition to the various sizes, there is a variety of power take-off (PTO) types on the market and we are here to help. Whether you are upgrading a PTO, or need a replacement unit or part, our experts will assist you in finding the perfect solution. While we are happy to help in finding the correct power take-off, it can be helpful to know and recognize the different types of power take-offs to ensure you are getting the correct type for your application.

Here are the standard types of PTOs:

Mechanical Engaged Power Take-Offs

The most common type of PTO's utilize a hand lever engagement mechanism. There are a few different types within this category:

Standard Friction Power Take-Offs

Standard friction PTOs are easy-to-mount units consisting of a clutch assembly with a shaft and bearings housed in a durable cast iron casing. These are often referred to as an over-center clutch. They are designed for manual operation and fit all internal combustion engines with standard SAE flywheel housings, from No. 6 to No. 00. These PTOs are available in single-, double-, and triple-plate configurations, with sizes ranging from 6.5" to 21". They support capacities up to 1,670 horsepower and 8,400 lb-ft of torque.

Pilot Bearingless Power Take-Offs

Pilot bearingless PTOs function like standard friction PTOs but eliminate the need for a pilot bearing. This design is especially useful for industrial diesel engines that do not include a pilot bearing bore in the flywheel. Removing the pilot bearing also simplifies PTO installation, making the process quicker and more convenient.

Straddle Bearing Power Take-Offs

A straddle bearing PTO is a heavy-duty power take-off designed for applications with high side loads, such as those involving belts, pulleys, or other driven equipment. It features a sheave housing and an additional bearing located outside the clutch assembly, which helps absorb and manage both radial and axial forces, significantly reducing stress on the PTO. This configuration places large roller bearings on both sides of the support housing, minimizing shaft deflection and increasing torque capacity by approximately 25% compared to standard PTOs. Additionally, the need for an engine-mounted pilot bearing is eliminated, simplifying installation and reducing maintenance requirements. This makes straddle bearing PTOs ideal for demanding, high-load environments where durability, performance, and reliability are critical.

Remotely Engaged Power Take-Offs

These are often referred to as "push button" PTOs as they allow the PTO to be remotely engaged from a distance or from within an operator cab. It eliminates the need of an operator in immediate proximity of the PTO.

Hydraulically Engaged Dry Clutch PTO

A hydraulically engaged dry clutch PTO uses hydraulic force to actuate a mechanical clutch that operates without oil immersion. The system relies on direct contact between dry friction plates, which provides high static friction and strong holding torque once engaged. Unlike wet clutches, heat is not dissipated by oil but instead through conduction and radiation to surrounding components. Because the friction material wears over time, dry clutch PTOs require regular manual adjustment to maintain proper engagement force and performance. This type of PTO is commonly used in applications where simplicity, reliability, and strong torque transfer are prioritized.

Hydraulically Engaged Wet Clutch PTO

A hydraulically engaged wet clutch PTO operates within an oil bath, using multiple alternating friction discs and steel plates housed in an oil-filled chamber. When hydraulic pressure is applied, these plates are compressed together, allowing power transfer through friction—even in the presence of oil. The oil serves dual purposes: it continuously cools the clutch during slip and frequent engagements, and it lubricates the moving parts to minimize wear. Many systems also feature self-adjusting mechanisms to maintain consistent pressure as the friction plates wear, ensuring reliable performance over time.

The Bottom Line

Selecting the appropriate Power Take-Off (PTO) is crucial for optimizing performance, reliability, and efficiency in your equipment. Understanding the various types—ranging from mechanical options like standard friction, pilot bearingless, and straddle bearing PTOs to remotely engaged hydraulic dry and wet clutch systems—empowers you to make informed decisions tailored to your specific application needs. For expert assistance in choosing the right PTO or addressing any related inquiries, reach out to Palmer Johnson Power Systems. Our experienced team is ready to provide guidance and support to ensure your equipment operates at its best.