Why Pick an Extended Shaft PTO (Medium or Heavy Duty)?

Why Pick an Extended Shaft PTO (Medium or Heavy Duty)?  Truck Chelsea Products DivisionTransmissions within work truck applications are highly customizable leading to multiple Power Take-Off (PTO) designs aligning with the transmission, chassis and space claim requirements. When it comes to PTO manufacturers, different product series are created to align with the different transmission manufacturers in the market. When installing a PTO on a transmission, a common issue with the installation process is the clearance in the truck chassis with how much room is available for installation. This is where the design and unique configurations of the PTOs are maximized to best match with the transmission applications.  


When an extended shaft makes sense

Installation clearance around the transmission can become problematic for many installers. Not only with the installation of the PTO itself, but attaching pumps may lead to situations of clearance issues that can, therefore, limit the type of pump sizes used. Allison is an example of a manufacturer that makes transmissions with customizable options. Popular transmissions from Allison are the 3000 and 4000 Series with the 3000 Series applying to medium duty applications and the 4000 series applying to heavy-duty applications. For Allison, PTO manufacturers have been creating product series that are designed for their transmission customization options. This is where extended shaft PTOs come into the discussion for the right application.

Extended shafts were designed to accommodate the Allison 3000 and Allison 4000 transmissions which feature a retarder or transmission mounted cooler. Transmission coolers help prevent transmissions from overheating from heavy hauling and towing. Transmission retarders help slow down vehicles when driving situations make it difficult to control the speed such as going downhill. These transmissions may have a transmission mounted cooler attached, a retarder attached or neither. Extended shaft PTOs provide a product series alternative to align with the transmission being used with a transmission mounted cooler and retarder since both impact clearance around the transmission. The design of the extended shaft product series help with these clearance issues.  

Parker Chelsea offerings

Parker Chelsea’s extended shaft product series offerings include the 890 series and the 870-XL Series PTO. The 890 was the first extended shaft PTO. The design keeps the PTO close to the transmission and allows for a large pump to be mounted behind the transmission. The 890 output is just behind the transmission and does not extend beyond the transmission mounted cooler or retarder. The 890 also sometimes allows for a drive shaft to be mounted at a better angle or in the relatively clear area behind the transmission.

When comparing the 870-XL Series and the 890 Series to each other, they both have a torque capacity for each is up to 670 lbs.-ft / 908 Nm. The difference in the design of the two is the 890 Series extends 23 inches from the center of the aperture while the 870-XL Series extends 29 inches. There is approximately 6 to 7 inches of extra clearance with the 870-XL Series. If the 890 has an issue, the 870-XL extends beyond the transmission mounted cooler or retarder to help solve the clearance issue. Another feature with the 870-XL series is the pump flange is rotatable every 7.5 degrees. The pump should be able to be locked to whatever angle it fits best. The 870-XL also allows for larger pump fitment options.

The design of the 870-XL Series has the same main PTO body and internals common to the standard 870 Series. The 870-XL Series is a PowerShift PTO specifically designed for the Allison 3000/4000 Transmissions. The Allison 3000 Transmission is designed for medium-duty vehicles while the Allison 4000 Transmission applies to heavy-duty vehicles. The 870 series already provides a compact housing design that helps eliminate certain clearance issues.



It is important to note what transmission manufacturer is used in your truck application. With a transmission manufacturer like Allison, customization varies greatly with the design of a cooler and retarder. This has led to PTO manufacturers creating product series lines that best match with the unique customization of the Allison transmission and to help improve the end user customizable offering experience as well as the installation process. Other transmission manufacturers may have transmission offerings that have led to PTO manufacturers adapting and design product series to best serve the end-user with a proper PTO for best performance and offerings of customization.

To take a more in-depth look at the 890 and 870-XL PTO series offered by Parker Chelsea, check out our products page which newly features a selection filter of type of transmission manufacturer that will allow for you to easily categorize your search result based on the transmission manufacturer that you are inquiring about.


Why Pick an Extended Shaft PTO (Medium or Heavy Duty)? Michael Mabrouk Chelsea Products DivisionThis article was contributed by Michael Mabrouk, marketing leadership associate, Chelsea Products Division, Parker Hannifin Corporation.  





Other related articles:

Understanding Why There are So Many Options for Mounting a PTO

How to Specify a Power Take-Off (PTO)

Ten Frequently Asked Questions You Should Know About PTOs


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