The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure.
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Dry PTO The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure
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Transcript of The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure.
Dry PTOThe Good, The Bad, and The Ugly
George HarperRome, GA
2004 Allure
The GoodYou realize you have a dry PTO and fix it
before it fails.
The BadIt fails on the road, but you’re OK.
The UglyIt 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?
o John Davis of JDRV Services in Oregon has compiled a list of CC’s he’s seen with dry PTO’s.
o The best thing is to look. All Chelsea PTO’s are red.
o The PTO’s used depend on what pump you have.
PTO port on Allison transmission
There are 10 15 mm boltsTorque: 40-50 ft-lbs
Be sure to use thread locker onThese bolts
PTO mounted right side of coach -Can be either side.
PTO
Pump
Wet Kit
The problem is the dry PTO.CC says to “inspect” every 5,000 miMale 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.
PTO
Pump
Wet Kit
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. Parts in the kit:
PTO
Pump
Wet Kit
Gasket to PTO
Oil Reservoir Flange
Female outputshaft to pump
Gasket to trans.
Flow Restrictor
Shim gaskets
Dry PTO vs. Wet Kit Installed
No Wet Kit Wet Kit Installed
Oil is Pumped up to the PTOFrom the Transmission Pan
PTO
Pump
Wet Kit
This hole drains the wet kit so thatthe Spline Shaft is half submerged in oil all the time.
PTO
Pump
Wet Kit
DrainHole
How the wet kit works:Oil to PTO @ 250
psi (Allison)Restrictor reduces
to less than 10 psiGravity 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?o The pump will need to be replaced if the gear is worn.o Country Coach used 25-30 different pumps.o All pumps are now available within a week (John Davis).
How to get the repair done?Options:Let a shop do everythingDo it yourselfPlay 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…[email protected]
