Not getting much life out of your PTO?
Foley can help. This Tech Tip presents a new way to prolong the life of your Twin Disc®, Rockford™, NACD or WPT Power PTO clutch. In earlier Tech Tips, we presented several ways to get more life out of your industrial clutch. These included the proper adjustment of the over center PTO clutch, not over greasing it, and using a quality pilot bearing.
See for example:
- Tech Tip# 48: Maintaining Your Twin Disc, Rockford, NACD or WPT Power PTO Clutch,
- Tech Tip #73: 3 Ways To Make Your Twin Disc, Rockford, NACD or WPT Power Clutch Last Longer
- Tech Tip #118: Supersizing Power Pilot Bearings; Can It Prolong The Life Of Your PTO?, and
- Tech Tip # 93: What Do I Need To Find The Right Parts For My PTO Clutch?.
But with a little ingenuity there is a way to more life out of your PTO.
Here’s the problem: Many people running larger PTOs install as many as 7 or 8 drive pulleys on their output shaft. Some OEMs will even underdrive the system by using a smaller diameter pulley than what is recommended. This allows the machine manufacturer to get more torque out of a smaller power plant at the expense of added sideload pressures on the PTO. We have seen this more often in wood chippers, tub grinders, and other aggressive applications. This can lead to excessive side loads on the PTO shaft, which in turn can put excess force on the clutch pack and bearings which can cause overheating and the excess friction that quickly wears discs and bearings and in extreme cases can even cause the main shaft to fail.
Even if the PTO is “side load rated”, it is only rated to handle a certain range of load. If operated continuously at the outside edge of that range and/or if surges in torque (ex. from equipment bogging down) push the PTO outside of it design range, you can have a pilot bearing doing the Texas Two Step in the flywheel housing. This can lead to a ruined pilot bearing, bearing carrier and perhaps even a flywheel. All in all, if your PTO clutch is allowed to twist or bind up, you’re not going to have a productive day and your crew may be going home early.
Here is a solution that should prolong your PTO life if your application generates heavy side loading. We have seen many customers effectively develop a PTO cradle system to provide added support to the PTO and resistance to sideload pressures which can reduce the twisting and binding up that can quickly wear or damage a PTO. These support brackets might be fabricated using two pieces of flat 3/8 to 1/2 inch steel plate ; one for each side of your PTO. Often these steel plates are configured in a curved fashion to follow and bolt to the circular arc of the back of the PTO housing. Then each bracket is bolted or attached to added supports on the deck of the machine the PTO clutch is mounted on. When properly executed, these supports create a rigid cradle for the PTO that helps to reduce twisting when the clutch is engaged.
Manufacturers names, symbols and numbers are for reference purposes only and do not imply manufacturing origin.
