Tech Tip #147: Running a Twin Disc/Rockford PTO? Want It To Last Longer?

Dr. Diesel
Written by Dr. Diesel

Running a Twin Disc®, Rockford, AP, Logan or AutoClutch power take off clutch? 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, AP, Logan or AutoClutch PTO (similar to the Stein Manufacturing PTO) clutch. In earlier Dr. Diesel 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 US made or, minimally, a US branded pilot bearing.

See for example

But here is a new way to get more life out of your PTO. It builds on Tech Tip # 116: Tips on Curing Excessive Side Load Problems with Twin Disc and Rockford PTOs.

Here’s the problem. Many people running larger Twin Disc, Rockford and AutoClutch PTO 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. This is most common with Twin Disc models SP211, SP214, and SP314, Rockford PTO models 4-35470 or 4-11060 and AutoClutch models HD1300 and HD1300XT as used in wood chippers, tub grinders, and other difficult applications. Using numerous drive pulleys on a SP214 or SP314 PTO output shaft overloads the clutch.   This leads to excessive side loads on the shaft. This causes the PTO to twist, bind up, and overheat. This ends unhappily with a failed main shaft and a ruined PTO clutch pack.

A Rockford or Twin Disc PTO, even if side load rated, that twists can also have problems with the pilot bearing doing the Texas Two Step in the flywheel housing. This can lead to a ruined flywheel and require not only a new flywheel but also a new pilot bearing holder, some of which are no longer made by the engine manufacturers. (See Tech Tip# 131: Helpful information regarding Perkins 4236 Diesel and Ford 300 Industrial Pilot Bearing Holders for info on our new Foley pilot bearing brackets for the Perkins 4236 and the Ford CSG649 engine.) 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 the new Foley solution for longer PTO life. We have developed a PTO cradle system to prevent your PTO clutch from twisting and binding up. Using two pieces of flat 3/8 to 1/2 inch steel plate you can fabricate brackets, one for each side of your PTO. These steel plates are configured in a curved fashion to follow and bolt to the circular arc of the back of the PTO housing. You can then bolt each bracket to the deck of the machine the Rockford or Twin Disc PTO clutch is mounted on. If bolting each bracket individually to the machine’s deck is difficult, you can connect them with a piece of steel (4′ or 5′ long and 3″ wide) running across the back of the PTO and bolt that to the deck. This makes a rigid cradle for the PTO and prevents twisting when the clutch is engaged. Take a look at the photos presented here of a typical Twin Disc SP214HP1 with this innovative cradle system.

Manufacturers names, symbols and numbers are for reference purposes only and do not imply manufacturing origin.

Dr. Diesel
Written by Dr. Diesel
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