The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure Dry PTO The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure

You realize you have a dry PTO and fix it before it fails. The Good You realize you have a dry PTO and fix it before it fails.

The Bad It fails on the road, but you’re OK.

The Ugly It fails on the road and you lose steering control at a critical time.

Objectives – we will answer these questions: How do I know if I have a PTO? What is a PTO? Where is it located? What’s the problem? What’s the fix? Who can do it? What does it cost?

What is a PTO ? PTO stands for “power take off.” It is a mechanical device that takes power from the transmission and directs it to drive a hydraulic pump. In our case the PTO drives a hydraulic pump that powers the radiator fan and the power steering in Cummins engines, and fan only in CAT engines. Failure of the PTO is very dangerous because if you lose power steering the coach is almost impossible to steer.

Which Country Coaches have PTO’s? John Davis of JDRV Services in Oregon has compiled a list of CC’s he’s seen with dry PTO’s. The best thing is to look. All Chelsea PTO’s are red. The PTO’s used depend on what pump you have.

PTO port on Allison transmission There are 10 15 mm bolts Torque: 40-50 ft-lbs Be sure to use thread locker on These bolts

PTO mounted right side of coach - Can be either side. Pump Wet Kit PTO

The problem is the dry PTO. CC says to “inspect” every 5,000 mi Male spline gear on pump Female spline gear on PTO

The pump is heavy and difficult to remove for greasing, but Chelsea does make a special grease. Wet Kit PTO

Diesels produce a characteristic vibration that can lead to gear fretting. New spline gear on PTO Dry spline gear @ 45,000 mi

Same fretting wear on pump spline gear New pump and spline gear Dry pump spline gear @ 45,000 mi

The Solution: The Chelsea Wet Kit Kit is pump specific The Solution: The Chelsea Wet Kit Kit is pump specific. Parts in the kit: Flow Restrictor Shim gaskets Gasket to trans. Pump Wet Kit PTO Female output shaft to pump Gasket to PTO Oil Reservoir Flange

Dry PTO vs. Wet Kit Installed No Wet Kit Wet Kit Installed

Oil is Pumped up to the PTO From the Transmission Pan Wet Kit PTO

This hole drains the wet kit so that the Spline Shaft is half submerged in oil all the time. Pump Wet Kit PTO

How the wet kit works: Oil to PTO @ 250 psi (Allison) Restrictor reduces to less than 10 psi Gravity drain hole keeps spline shaft half submerged in oil Oil drains to PTO main body and back to transmission

The Restrictor is very important… Omitting restrictor results in high pressure that blows out seals.

Crushable gasket recommended at pump. Cummins 3008400 crushable (L) Vs. Chelsea pump gasket Use high temp RTV on pump but not transmission gasket

Expect to lose three quarts of ATF when removing the PTO.

What about the pumps? The pump will need to be replaced if the gear is worn. Country Coach used 25-30 different pumps. All pumps are now available within a week (John Davis).

How to get the repair done? Options: Let a shop do everything Do it yourself Play contractor and sub it out

CC Techs listed on CCI website:

What’s this going to cost? Chelsea wet kit: about $ 300. Pump: $900 - $3,000. Labor: about four hours.

The End - Happy Camping… georgeharper@comcast.net

Questions? georgeharper@comcast.net