1. 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

2. 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.

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

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

5. 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?

6. 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.

7. 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.

8. PTO port on Allison transmission
There are mm bolts
Torque: ft-lbs
Be sure to use thread locker on
These bolts

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

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

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

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

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

14. 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

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

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

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

18. 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

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

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

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

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

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

24. CC Techs listed on CCI website:

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

26. The End - Happy Camping… georgeharper@comcast.net

27. Questions? georgeharper@comcast.net