Power Steering Pump Location?

[dreamchasers]

I have discovered I have a very slight power steering (hydraulic) oil leak. I can see the results of oil wet wiring on the forward, right side of the engine compartment, viewing from underneath. I have read references to o'ring leaks on the power steering pump. Is this reference made to the 8V92 or the Series 60 engine that I have?

And where is the Series 60 hydraulic pump located?

Yes, I am very green.

Hector

[Jon Wehrenberg]

Hector.....

If the leak is in the front (actually the motor is backwards in a bus so it would be the rear) it may not be from the pump. Check at the reservoir, and if not there it may be from the air over hydraulic system that supports the coach when the tag lifts automatically on hard turns.

Here's the pump....

[dreamchasers]

Hector.....

If the leak is in the front (actually the motor is backwards in a bus so it would be the rear) it may not be from the pump. Check at the reservoir, and if not there it may be from the air over hydraulic system that supports the coach when the tag lifts automatically on hard turns.

Here's the pump....

Humm, Air over hydraulic system.... So that what those things are. I have two 'large shock absorber look alike devices' connected to the bus frame and the rear axle, near the rear pumpkin. They have, what looks like air lines and other lines connected to a device mounted under the floor of the bus. Whew!

Where can I find information concerning this system? Is this a Prevost system? I have noticed that one of 'shocks' has a ruptured seal and evidence of oil leaking. So it is on the list for replacement.

As a newbie, I am quickly learning the majority of maintenance and repairs are done 'underneath' the bus. That pit option is looking better and better in my soon to be built storage building.


Any help appreciated.

Hector

[truk4u]

OK Jon, air shocks or ?

[Jon Wehrenberg]

The air over hydraulic is part of a tag lift system Prevost has on 45 foot coaches. Obviously hector has it because his description is correct.

When the 45' coach steering wheel is turned to the full extent in either direction, a device on the steering arm up front actuates a microswitch lever arm. This is to facilitate sharp turns. The tag axle air is dumped with the actuation of the switch, but if that were to occur while the bus had minimal clearance at the rear, the dumping of air in the tag axle air bag would cause the rear to drop and the bus could end up scraping the ground or a driveway.

To prevent the rear from sagging as an additional 12000 pounds from the tag is now shifted to the drive axle air bags the air over hydraulic system is actuated and hydraulic pressure to the devices that look like shock absorbers is used. The system uses the same fluid as the power steering system and the reservoir is on the forward bulkhead in front of the drive axle.

I think Prevost calls them "stabilizators".

I do not think the system is engaged when the tag is manually lifted. Because of this I would suggest anyone with this system on a 45' coach to not lift the tag axle manually as is often suggested, but to let the system function automatically.

[truk4u]

Hmm, was that year specific, I sure don't have those..

[Jon Wehrenberg]

Tom,

I do not know if it was year specific, or if it was an option. It is not on 40 foot coaches to the best of my knowledge. I was under the impression that feature was standard on the 45' coaches because when they first were introduced by Prevost the automatic tag lift was incorporated to improve the turning radius.

When Prevost came out with the IFS, and the greater angle of front tire cut, the feature may have been eliminated because of the improved turn radius. If that is the case it would be on all 45' coaches up to around serial number T5870 or T5880 (I don't know the exact serial number for the first IFS)

[nrhareiner]

Hello Jon,

Just a quick question, did Liberty negate that feature? I remember Frank telling me that they had stopped that function so no automatic tag axle dump at full turn.

[Jon Wehrenberg]

Kim,

There was a post sometime back about Marathon negating it, but I have not heard that Liberty disabled the feature. I do not know if Marathon did disable it or if that was rumor.

I have no idea why anybody would want it disabled because if the tag axle airbags are dumped about 12000 pounds is added to the drive axle air bags and the rear of the coach drops. That might not seem like a big deal, but if your exhaust pipes or hitch or oil pan are already close to the ground, they suddenly hit the ground, and with the coach moving and turning that cannot be a good thing.

[truk4u]

Jon,

I was the one that told you about Marathon not using the system after a certain year, as was told to me by the folks in San Antonio. The reason stated was they had some bad experiences with guys pulling huge stacker trailers where the tag dumped and lots of damage was done to the undercarriage when the whole ass end hit the ground.

Yea I know, common sense out the window....

[Jon Wehrenberg]

Tom,

If you analyze that it makes zero sense.

The lifting of the tag manually is not to be confused with the automatic feature, unless there is a version in which there is no hydraulic "stabilizator".

The hydraulic stabilizers "lock" up when the tag axle air bags have their air dumped. That keeps the ass from dropping. I know from experience that if I manually dump air to the tag axle the ass will drop because the stabilizers are not "locked".

Where logic flies out the window is assuming the automatic tag air dump makes the bus drop in the rear. Unless the hydraulic system is absent then that feature is better than having to manually lift the tag to make a sharp turn.

When this feature was introduced Prevost indicated that they wanted the longer wheel base 45' coaches to turn as well as the 40 foot coaches. So they improved the angle of cut the front wheels would make slightly, and made the tag air dump automatically. They considered all of the other ways other bus shell manufacturers were addressing the issue of turn radius, and concluded a steerable tag was too complex and prone to many problems, hence the system they used.

If in fact Marathon knows the shell better than Prevost (sarcasm here) they are telling their customers "we are going to make sharp turns harder because we will not dump tag air, and if you manually dump tag air we will assure you that your tail will fall to the ground". I for one would want someone in the know on this issue to jump in here and explain what is going on.

[dreamchasers]

Does anyone know the manufacturer or brand name of this stabilizer system? I am looking for information for maintenance and rebuild. One of the pistons is leaking. I am looking through the Prevost Car service section in the manufactures publications for info, but knowing the system manufacturer would help in narrowing the search.

Any ideas?

Hector

[Jon Wehrenberg]

Hector...

All the parts to rebuild are available through Prevost. JDUB supplied us with CDs with Prevost parts list on them, or perhaps if you contact Prevost parts (I call Elgin) they can either send a CD to you or just walk you through what you need. My parts book is in the bus and I'm up in my office otherwise I would be able to give some part numbers right now. If I forget remind me and I will post enough info to get you started.

Sometimes the entire assembly is cheaper than the parts.

[dreamchasers]

I also have a CDROM I requested and received from Prevost. I have not sorted out exactly how the CD works (Too much in a hurry!), but I will concentrate on it after Christmas. The CDROM seems to have plenty of infomation available.

Thanks for pointing me in the right direction.


Merry Christmas.

Hector

[Jon Wehrenberg]

Hector,

You just have to load Cat Base Viewer from the CD and then you can cruise the parts lists. It takes a while to figure it out, but once you do there is a wealth of information.