The power take-off (PTO) is a vital piece of equipment.
“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.
Bezares is a global manufacturer of PTOs, hydraulic pumps, fittings, tanks, and other mobile power hydraulic components distributed through Eaton in North America.
“The PTO may only be one component of a much larger picture when it comes to truck fleet management; however, it is paramount to the successful operation of any fleet of hydraulically operated equipment. 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. This is a simple description of the operation, and we can tie it to fleet management just as easily,” according to Noel Bartlett, field service manager Southwest for Muncie Power Products.
PTOs, like other components on a truck, require visual inspections and regular maintenance to increase longevity and maintain productivity.
“Productivity drives revenue, therefore, the health and function of the PTO is a valuable and important part of truck fleet management,” Bartlett added. “Having a general understanding of how the PTO is activated, what it does, and how it works helps to reduce downtime, shortens troubleshooting efforts, and provides shop managers and technicians with a higher level of confidence that their fleet is in good working order.”
Top Factors When Considering a PTO
One important consideration when selecting a PTO would be rugged construction and durable components.
“A PTO is a gearbox with seals, bearings, and other moving parts. Simple designs and minimal parts equal fewer problems and longer life, resulting in more jobs getting completed on time and budget. Fleet managers focus on cost: the cost of the components, the cost of the entire system, and the total cost of maintenance on a vocational truck. Select a PTO that is matched correctly to the transmission, application, and operation,” said Janitz of Bezares.
Another consideration involves the technical side of the selection process.
“Gather all the information about the application you are working with before the selection process. A standard PTO may have a 13 digit or larger part number, and each number or letter is significant. The first determining factor in selecting a PTO is the transmission on the truck,” said Bartlett of Muncie.
A transmission has a specific PTO opening and drive gear, and not just any PTO works.
“A PTO manufacturer uses the transmission model number to guide you to the correct specification page in their catalog or on their website. There you can find the base model PTO part number needed to work with that transmission. To complete the part number, you need some specific information about the application you are working on. A reliable channel partner or trusted source can help acquire the necessary information to simplify the selection of the proper PTO,” said Bartlett of Muncie.
One factor to consider in selecting a PTO might come as a surprise, according to Bartlett of Muncie, but is crucial to the process: Find a business partner (PTO supplier) that is as invested in your success as you are.
“Yes, there is a technical side to selecting a PTO but finding a trusted vendor, channel partner, tech support agent, or representative that is willing to guide you through the process can only contribute to the success of the fleet,” he said.
Top Challenges Selecting a PTO
One major challenge in selecting a PTO is that many configurations can often work in an application.
“There are potentially multiple PTOs to choose when building the system. In today’s world, fuel efficiency is a big deal, and managers want to run the truck engine slow to save fuel. This must be balanced with the application torque and horsepower requirements. It also must be balanced with ‘smarter engines’ when emissions are concerned,” said Janitz of Bezares.
These two items can be in direct conflict with each other.
“One tip for a continuous application is to select a PTO and ratio that works at a higher engine rpm— approximately 1,100 rpm — and then select the pump to match the required flow rate and pressure. This allows the engine to run effectively as it goes through the regeneration phase,” Janitz added.
Additionally, as vocational vehicles get smaller, more compact, and lighter, space between the frame rails is at a premium.
“Therefore, utilizing the 8-bolt bottom mount aperture is an ideal solution. The bottom-mount location provides ample room to directly mount the pump to the PTO and facilitates easier hydraulic hose routings,” Janitz said.
Another option is to use the rear-mount aperture location.
“The rear location provides improved ground clearance and more room to directly mount the pump to the PTO and facilitates easier hose routing,” Janitz added.
There are two scenarios in which a fleet manager would be selecting a PTO.
“The first scenario is a new-build situation where he or she is selecting everything required to drive a hydraulic system or is having a new unit built for the fleet. The second is a repair/replacement scenario where an existing
PTO may be present and part numbers may or may not be available,” said Bartlett of Muncie.
Be sure to have the transmission model number before you start the process. Bartlett added that it is important to note that a truck’s vehicle identification number (VIN) does not provide the necessary information that a PTO supplier needs to determine the base model for that truck.
“The equipment manufacturer has a list of requirements for the hydraulic system. Make sure to have that information available. This information helps to determine what features are needed to complete the selection such as output shaft size, flange size, activation options, and speed of the PTO,” Bartlett said.
Another scenario, likely for a fleet manager, is a repair or replacement scenario.
“The challenges here can also be easily overcome with a few quick tips: If the original part number is available on the PTO via a production tag, a PTO can be ordered as a direct replacement. If there is no tag or it is not legible, the manufacturer often engraves the part number under the tag. A flashlight or cell phone camera can help in reading the number,” Bartlett explained. “But, if the PTO part number is not available, the part number of the input gear (the PTO gear that goes into the transmission) will have a part number stamped on it and that can go a long way to identifying the PTO properly.”
Simple PTO Maintenance Tips
Simple PTO maintenance is necessary and at a minimum should coincide with transmission maintenance.
“Maintenance can be as simple as looking for leaks and replacing seals, to removing the pump and cleaning and applying grease to the splined pump shaft. Also, if the PTO noise becomes loud or persistent, the PTO should be removed, and inspect the gears for nicks and or metal shavings. If nicks or metal shavings are found, a repair should be completed to ensure continued operation,” said Janitz of Bezares.
Maintenance for the PTO can also vary based on daily or weekly use, duty cycle times, atmospheric conditions, application, and several other factors.
“For a fleet manager, the maintenance schedule of a truck’s vital fluids, such as engine oil, can be a great time to make a visual inspection of the PTO. Adding the PTO inspection to the regularly scheduled maintenance of the truck reduces downtime and provides the technician the opportunity to talk to the driver about other concerns such as operating noise changes, the functionality of the hydraulic system, changes in duty cycles, etc. This conversation can often help in finding an issue before a downtime failure,” said Bartlett of Muncie.
Driver input should be an essential part of PTO maintenance.
“The driver knows what the truck and PTO sound like and how they function, and can also identify if something seems to be ‘off.’ Most fleet managers I work with keep a file on each truck and driver’s notes can be maintained here as well,” Bartlett said.
As for specific information about maintenance, each application is different, but there are some common areas to consider when building a maintenance routine for the PTO.
“First, a solid visual inspection of the entire PTO is a must. This can help identify damage to the housing, surrounding plumbing and wiring, and small leaks, or seepage,” Bartlett said.
The PTO is directly mounted to the transmission and uses transmission fluid for lubrication so any leak from the PTO is likely transmission fluid.
“The next, and most likely, inspection would be the mounting of the PTO to the transmission. The bolts holding the PTO to the transmission housing have specific torque requirements to maintain proper backlash and prevent leaks. Inspection of those bolts can be done quickly and prevent future failure as well. If the PTO is ever removed from the transmission visual inspection of the gears and internal components (without disassembly) would give a good snapshot as to the health of the PTO,” Bartlett explained.
PTO Changes & Breakthroughs
Changes in transmission preferences, updates to quality, and enhancements to technology have all impacted today’s modern PTO.
“In the past several years, we have seen an increase in the use of automatic transmissions or automatic/manual transmissions. The PTO used in an automatic transmission is often a hot shift, or clutch shift unit, and it operates with an internal clutch pack. These PTOs can be activated in a variety of ways, including while the truck is in operation. This contrasts with the manual transmission PTO that can only be activated when the rotation of the transmission has been stopped,” said Bartlett of Muncie.
Leaks have been a top quality issue in the past.
“The biggest breakthrough in PTOs has been incorporating better gaskets and seals. Garlock gaskets provide improved leak protection. They perform better than paper gaskets. They are also very dense, which helps reduce creep and facilitates a consistent bolt mounting torque. Viton seal material is one of the best materials used in the industry today. It has ideal physical properties to resist higher heat and aggressive fluid degradation when compared with other common gasket materials,” said Janitz of Bezares.
Some other new and exciting features include modulated clutch engagement on systems where the start-up RPM of the PTO is very high.
“The modulated engagement is used to reduce torque spikes on the entire hydraulic system by reducing the start-up speed of the output shaft on the PTO for a moment to allow the system to ramp up to speed slowly. This feature can reduce torque spikes by as much as 70% in some cases and increase the life of the PTO as well as the hydraulic components on the truck,” Bartlett said.
Another breakthrough is the Bezares Dual Output PTO.
“The Dual Output PTO provides a unique solution, which allows for two PTOs in one eight-bolt location. This saves money, better utilizes space and simplifies installation over a two-PTO (six- and eight-bolt) configuration,” Janitz said.
Lastly, Bartlett noted the growth of plug-and-play wiring harnesses for PTO installation and activation, as well as internal drag brake elements built into the PTO.
“Also, technology has given technicians and managers a chance to save time and money because the troubleshooting manuals, installation manuals, and operation manuals specific to the PTO can all be found on manufacturers’ websites and accessible on tablets and cell phones while they are under the truck working,” he said.
The Bottom Line
Fleet managers have always “worn many hats,” and today is no different.
“PTO selection can be difficult when it’s not something that you do every day. It is important to have a basic understanding of PTO operation and function, and this can be acquired through trial and error, like so many of the things we do today, or a manager can go online and participate in training through manufactures websites to help them gain additional knowledge,” said Bartlett of Muncie.
Also, when selecting the PTO, you have to balance your needs and your wants.
“As a fleet manager, you need the truck to be productive, efficient, and reliable. You want it to last a long time, run smooth, and be low maintenance. Selecting the right PTO that gives you the best performance and cost while minimizing and balancing long-term maintenance and repair costs can make a big impact,” said Janitz of Bezares.