Chelsea Products' Wet Spline technology addresses spline fretting in PTOs, pumps

Jan. 1, 2011
One of the most common and potentially costly issues surrounding power take-offs is spline fretting. Fretting occurs from corrosion that occurs at the

One of the most common and potentially costly issues surrounding power take-offs is spline fretting. Fretting occurs from corrosion that occurs at the spline where the PTO meets the pump shaft. Torsional vibrations from lower-speed, lighter-weight, and higher-torque engines prematurely wear out the mating shafts between the PTO and pump.

Parker Hannifin's Chelsea Products Division has introduced Wet Spline technology to its PTO product line. Specifically, trucks that run continuously and are lightly loaded suffer from frequent spline fretting. Moreover, work trucks that require long PTO running times and higher torques must also deal with problems associated with increased fretting. The most catastrophic result can be a pump or PTO shaft failure.

Until now, to avoid excessive corrosion, regular maintenance greasing was required. The greasing agent is a high-temperature, high-pressure grease designed to reduce torsional vibration effects. Greasing requires detaching all of the associated parts, cleaning each part, and then separately re-greasing each part before reattaching them. This entire process can take hours and also contributes to downtime. Parker's new Wet Spline technology was designed to eliminate this maintenance requirement.

Many of Chelsea's PTO products feature non-rotatable and rotatable wet spline pump flanges that provide a continuous fresh oil bath at the mating point of the PTO and pump shaft. The cushion of oil virtually eliminates spline fretting and increases shaft life by a factor of 10. The oil in the Chelsea Wet Spline is easily flushed out and refilled during regular transmission flushing, thereby eliminating frequent grease maintenance. Chelsea recommends only a yearly inspection of the mating components when using its Wet Spline technology.

Chelsea's 890 series PTO is a good example of how Wet Spline technology has benefited several industries. The 890 series PTO was designed for the refuse, fire apparatus, and pumper cleaner industry, whose larger pumps and engine torsionals make for challenging applications. Torsional vibrations from diesel engines will often prematurely wear out the mating PTO and pump splines. The 890 not only provides these vehicles with maximum pump clearance, but also with a Wet Spline system to lubricate the mating PTO and pump shafts.

The 890 has been lab- and field-tested using refuse and fire/rescue trucks with superb results.

Another product that the Chelsea has recently introduced is the 277 Series Rotatable Wet Spline PTO. This new option provides solutions for the installer and end users of this product. The rotatable pump flange allows the installer to position his pump in the best position for clearance with obstacles underneath the truck such as frame rail or transmission case interference points. The Wet Spline design provides the end user with all the benefits that have been previously mentioned in extended shaft life and reduced maintenance time.

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