Parker Chelsea’s Power Take-Off (PTO) is designed and built to meet the demands of the mobile equipment industry. The Chelsea PTO is intended to provide a long service life, both on-highway and off-highway. In order to maximize the life of Chelsea’s PTOs, it is important to have the PTO in proper use and constantly maintain the PTO as well.
The Chelsea PTO application worksheet and owner’s manual will help you properly specify your PTO and install it. However, the understanding of how a power shift PTO operates will help the troubleshooting process run more smoothly and effectively. For power shift operation, when a power shift PTO is engaged, a solenoid is energized. Air or hydraulic fluid then compresses a clutch pack in the PTO. This locks the PTO output gear to the output shaft and allows work to be done. When the power shift PTO is disengaged, the solenoid de-energizes. Air or hydraulic fluid deadheads against the valve. From there, air is released to atmosphere through a valve, and hydraulic fluid exhausts into the PTO.
Here are some breakdowns of the potential causes and solutions for troubleshooting the PTO. It is first important to understand that many problems from a Power Shift PTO are the result of incorrect plumbing. A good first procedural step can be found in the Owner’s Manual, which is to compare what pressure is coming from the air or hydraulic source against what pressure is entering the PTO.
PTO unit not engaging
Dealing with the PTO unit not engaging, these are some of the potential causes with solutions for shifting problems from Power Shift PTOs. (Probable causes are listed in a logical test sequence. Don’t assume any one thing is wrong.)
There are situations where the PTO will engage but may not operate under system load. Here are some potential causes and solutions for Power Shift PTOs.
PTO engages without switching the solenoid valve
An issue run into can be the relation between Power Shift PTOs and the solenoid valve. Here are some potential causes and solutions for Power Shift PTOs engaging without switching on the solenoid valve. 
Potential shifting problems with Power Shift PTOs may lead to the PTO not disengaging. Here are some potential causes and solutions for Power Shift PTOs.
In addition to troubleshooting PTO issues, there are safeguards that keep drivers safe and prolong equipment life such as overspeed controls. Chelsea has developed the next generation of Overspeed Controls for Power Shift PTOs. With Electronic Overspeed Controls (EOC ), it is important to keep in mind that the EOC needs to be properly adjusted before conducting troubleshooting steps. This system helps prevent the driver from going down the road with the PTO engaged and prevents the power take-off and driven equipment from being operated at excessive speeds. When the Electronic Overspeed Control Operation (EOC control) is changed to the “on” position, it energizes a solenoid valve that pressurizes the clutch pack. This then engages the PTO. A main feature of the EOC is the measuring of speed of the PTO electronically and uses that measurement in comparison to the selected overspeed RPM setting. If/when the PTO exceeds the preselected RPM setting, the EOC will de-energize the solenoid valve, disengaging the PTO. The PTO will remain disengaged until the speed has been reduced to the preselected reset speed. At that time, the PTO will re-engage. It is a very simple set up with easy set-up buttons. LED lighting is outputted in three settings for great visibility in the EOC. When the PTO is in overspeed protection mode, audio and visual blinking overspeed warning alerts the operator. This system can be used in applications including LP Gas Trucks, Water Trucks, Fire and Rescue, Aerial Devices, Dump Truck & Trailers, Snow and Ice Removal. Learn more on our Electronic Overspeed Control product page.
This article was contributed by Michael Mabrouk, marketing leadership associate, Chelsea Products Division, Parker Hannifin Corporation.
Related articles:
Ten Frequently Asked Questions You Should Know About PTOs
Understanding Why There are So Many Options for Mounting a PTO
What’s All the Noise About with My Power Take-Off (PTO)?