Air Operated PTO Won’t Engage - Reasons and Fixes

A Power Take-Off (PTO) is a device that transmits power from an engine in a machine to a connected equipment or attachment that relies on mechanical energy for its operation. You will find PTOs on agricultural and industrial machines like tractors, mowers, harvesters, generators, etc. A PTO gets its power from the engine but will not transmit it until engaged. There are different methods for engaging the PTO. Cables, Air pressure, and hydraulic pressure are ways to engage the PTO.

Air-operated PTO uses compressed air to activate the engagement mechanism for connecting, engaging, and disengaging the PTO from a machine's power source. A failure of the air-operated PTO can be troublesome and inhibit productivity. Here, we consider some reasons why air-operated PTOs fail to engage. In doing so, this article also explores the means of fixing such problems.

Reasons For Failed Air-operated PTO Engagement and Fixes

Many PTO implementations rely on mechanical linkage or hydraulics for PTO engagement. However, the engagement mechanism we are concerned about occurs with air pressure. There are many reasons why an air-operated PTO might not engage. We explore the more likely reasons below.

1) Low Air Pressure

After an operator activates the PTO, which opens up the valve for air to enter the clutch chamber, the buildup of air pressure in the clutch chamber forces the clutch diaphragm to shift, which engages the clutch.

Following the clutch engagement, the PTO shaft connects to the driveline. It starts to rotate and supply power to linked attachments. But for this process to be successful and the air-operated PTO to work, it needs to meet a certain threshold of compressed air. If the air pressure is lower than the required amount, the clutch cannot engage the PTO.

Low air pressure could result from air pressure dissipating with frequent usage. However, low air pressure could also result from an air leak in the PTO's air supply system, leading to engagement failure.

Fix

Before attempting to remedy this or any other issues, we must be sure that it is the source of the engagement problem. To diagnose if low pressure is the reason your PTO will not engage, check its air pressure gauge. Put the engine on, activate the PTO control valve, and compare the gauge readings with the manufacturer's requirements. Supposing the air pressure is the issue, you must add more air to the system to fix the problem.

Examine air pressure connections for leaks. Should you detect leaks, you must repair faulty parts. Sometimes, you may need to replace the component responsible for the leak.

2) Bad Solenoid Valve

Solenoid valves are control units that allow or stop airflow to the PTO engagement system. When electrically stirred, they either open or close. Essentially, the solenoid controls the flow of air to the PTO. When the operator triggers the PTO control, it opens up the solenoid valve for air to enter the clutch chamber, which then engages the PTO.

A damaged or malfunctioning solenoid valve can inhibit correct PTO engagement by preventing air from reaching the clutch chamber.

Fix

Inspect the solenoid valve for signs of wear or damage. Listen for a solenoid click when you attempt to engage the PTO. The absence of a solenoid click may indicate a faulty solenoid valve. If the solenoid valve is why your air-operated PTO will not engage and power your equipment, you must replace it with a new one.

3) Clogged Air Lines and Filter

Some lines move compressed air around when you try to engage the PTO. These air lines can become clogged or plugged by dirt, debris, and moisture. Supposing the pipes are clogged, the required compressed air for the machine to engage an air-operated PTO will not reach the clutch chamber and cause PTO engagement failure.

Another thing that can cause failed PTO engagements is the air filter. The air filter removes contaminants and prevents them from clogging lines and the system. However, as time passes, contaminants can clog the air filter and restrict airflow to the PTO system.

Fix

Inspect lines and air filters for clogs. If there are any blockages in the air lines, clear them and retest the PTO. In the case of a clogged air filter, you will need to clean or possibly replace it, then test the PTO to see if it will engage.

4) Faulty Clutch or Mechanical Components

The clutch in an air-operated PTO is a clutch type used in engaging or disengaging a PTO shaft from the engine. Compressed air forcibly initializes the clutch, which moves the piston that engages the clutch plates. So, the clutch is what engages the PTO to the driveline. Worn out or damaged clutch can stop the PTO in your machine from engaging successfully.

Besides the clutch, other mechanical components function to engage and disengage the PTO, like gears, springs, air cylinders, and more. Damage or fault with any of these components can cause PTO engagement failure.

Fix

Depending on the nature of the issue, the clutch might be repairable. However, leave such repairs in the hands of a professional due to how complex they can get. If a repair is impossible, to fix the PTO engagement problem, you will need to replace the clutch. Air-operated PTO clutches can be more expensive than other types.

In case other mechanical components are responsible for the PTO engagement problem, repair or replace them to fix the problem.

5) Poor Installation

An air-operated PTO poorly mounted or incorrectly installed on a machine can cause engagement problems. You or the contracted technicians must strictly adhere to the manual of the particular air-operated PTO installed to ensure you connect plugs to the correct ports.

In addition, many modern machines come with Engine Control Units (ECU) that can complicate PTO installation. You must install the PTO correctly and use a compatible diagnostic tool to program the ECU. Failure to configure such ECUs can cause engagement problems later on.

Fix

In the case of improper air-operated PTO installation, seek the help of a qualified technician to correctly install the PTO. If you have an ECU in your machine, program it correctly to support your air-operated PTO.

If after looking through all the likely reasons we mentioned above for the PTO in your machine not engaging and you still cannot solve the problem. Then it might be best to find expert assistance in fixing the PTO engagement problem.

Preventing Air-operated PTO Engagement failure

There are some measures you can adopt to prevent air-operated PTO engagement issues; they include:

• Regularly check the air-operated PTO system for symptoms of wear and tear, damage, or leaks. Inspect components like the solenoid valve and air lines frequently. Fix any issues you notice as soon as possible so they don't become more significant and cause the PTO not to engage later.
• Ensure there is adequate air pressure. The air supply system has to supply air at a specific pressure level to engage the PTO. So, to guarantee PTO engagement, the air compressor must be functional. Regularly monitor the air pressure gauge to ensure it is within the recommended range. There is no point in engaging the PTO if the air pressure is too low.
• Lubricate the moving parts of the air-operated PTOs mechanism in line with the manufacturer's recommendations. Lubrication will help reduce friction, prevent premature wear, and guarantee optimal operation.
• Clean air lines, fittings, valves, and filters of contaminants as part of maintenance procedures. Pollutants like dirt and debris can restrict airflow and prevent PTO engagement.
• Use the air-operated PTO correctly. Get training for all operators of the PTO on the appropriate method to engage the PTO. Operators should understand the proper sequence and timing for engaging and disengaging the PTO.
• The PTO should not be engaged if the attachment is not correctly connected or installed. Likewise, operators should not engage the PTO while moving the machine at high speed, as this can damage the PTO. Also, disengage the PTO before shutting off the engine to prevent damage.
• Follow the manufacturer's recommendations for maintaining and servicing the air-operated PTO in your machine. Regular maintenance will help identify and fix issues before engagement problems occur in an air-operated PTO.

Conclusion

An air-operated PTO uses compressed air to engage the PTO in various machines. The air-operated PTO may fail to engage when triggered by the operator. Several reasons can cause this, and this article identifies some. Common causes include low air pressure, a bad solenoid valve, clogged air lines, a faulty or worn-out clutch, and poor installation. We also discussed how you can fix these issues.

You can prevent air-operated PTO engagement failure with regular inspection and maintenance. Also, lubricate moving parts, clean air flow components, and ensure adequate air pressure for PTO engagement. Furthermore, you should train operators on the proper PTO engagement and operation procedures. If you have difficulty in fixing air-operated PTO engagement failure problems or maintenance. In that case, consult with a qualified technician to help you out.