Transcript The Good, The Bad, and The Ugly George Harper Rome, GA 2004 Allure.

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 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?
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 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.
Pump
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. Parts in the kit:
Flow Restrictor
Shim gaskets
Gasket to trans.
Pump
Wet Kit
PTO
Gasket to PTO
Oil Reservoir Flange
Female output
shaft to pump
Dry PTO vs. Wet Kit Installed
No Wet Kit
Wet Kit Installed
Oil is Pumped up to the PTO
From the Transmission Pan
Pump
Wet Kit
PTO
This hole drains the wet kit so that
the Spline Shaft is half submerged in oil all
the time.
Drain
Hole
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?
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 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…
[email protected]
Questions?
[email protected]