[xGE_97]

Epilogue: Voyage To The Bottom Of The Wallet, seems like a Quinn Martin Production

I had help from Newell, all the way. Broke down on a Sunday and Mark called me back, offered to stop bailing hay, drive to the plant, and send someone to install it. We both agreed that because I was safe, off the road at a truck stop, he would check on Monday. Good thing we did because they did not have the pump in stock. The next day Cambri found a supplier that could send it quick......but where? There was no dependable place that could receive it for me (I checked). Best play was to have Newell deliver it. If I picked it up, an additional day would have been added and we had Dr. appointments for the time after Newell. As long as they were delivering it, I asked them to install it as well. Wow was this a good choice. I did not have all my tools (maiden voyage) and would have needed to make some more as well. Taylor (Newell mechanic) arrived at 6 AM and had those tools. It only took him 2 hours to install. Later that day I was able to call Creslie and tell him to run away fast 'cause I was coming home....Hahahahahaha.

Before Cambri found the supplier, I had 2 roadside help companies searching for the part, I was calling pump suppliers and truck parts places....all came up dry. Many thanks again to Cambri !!!!

So why did it snap? That's the mystery. It looked to me as if the shaft had a rusty spot that started the crack, which ultimately spread and sheared off. The replacement pump's shaft was in good shape, no nicks, and Taylor put assembly grease on it. It went in smooth so maybe this one will be strong. I'm calling it over. I will get 2 new shafts. one to rebuild the original pump and the other as a spare for the current one.

Bottom line, shaft inspection is probably something to add to the annual PM list. Also I could have done it, just buy some more tools and customize a couple. But it was at least a day, maybe 2 days more for me because of the tools issue. We were already there for 5 days and we were getting the "stink eye" from the truck stop. 2 more days seemed stretching it. Now resting at Newell, fixing some small things and waiting for parts and some work for this week.

Also, thanks for all of you guys on this forum. I read a few posts and isolated the pump as the problem, as a result.......'till the next time....

[Latitude 28]

So why did it snap? That's the mystery. It looked to me as if the shaft had a rusty spot that started the crack, which ultimately spread and sheared off. The replacement pump's shaft was in good shape, no nicks, and Taylor put assembly grease on it. It went in smooth so maybe this one will be strong. I'm calling it over. I will get 2 new shafts. one to rebuild the original pump and the other as a spare for the current one.
Bottom line, shaft inspection is probably something to add to the annual PM list. Also I could have done it, just buy some more tools and customize a couple. But it was at least a day, maybe 2 days more for me because of the tools issue. We were already there for 5 days and we were getting the "stink eye" from the truck stop. 2 more days seemed stretching it. Now resting at Newell, fixing some small things and waiting for parts and some work for this week.

While researching another brand of coach, I came across an issue where the hydraulic pump, via a shaft, from a PTO off the transmission was shearing.  One fix was to install a PTO shaft with a zerk fitting to grease the shaft without disassembly.  While that is not possible on the Newell, the key is the type of grease they use at regular intervals.  That special hydraulic pump shaft grease could be applied to the Newell's hydraulic pump's shaft.  Here is the data sheet and part number on the grease itself.

PTO-TEC-085.pdf Size: 130.77 KB  Downloads: 17

[arcticdude]

That's a very interesting find.  I've now had 2 coaches with Chelsea hydraulic pumps.  With the first one, I went to the local Chelsea dealer inquiring about spline grease.  They gave me a little packet that looked exactly like the one shown at the bottom of the spec sheet Steve posted.  Even though the Chelsea sheet says the data sheet is on the back of the packet, there's only what to do if somebody consumes it on the back of the packet I have.


For the second coach, I ordered a tube of spline grease from Chelsea.  I was sent a tube of Schaeffer's #279 Spindle & Coupling Compound NGLI #2 Aluminum Complex.  I have not been able to find a spec sheet specifically for the Schaeffer's grease.  The only place that seems to sell it is either Schaeffer's directly or Chelsea.  Schaeffer's wasn't willing to give me the specs on the grease.

The Wanderlodges have the hydraulic pump driven off the transmission, instead of the engine.  They don't break shafts, but they do have fretting that can occur, so there's all kinds of ideas about how to stop that.  I just grease mine and that seems to be enough to prevent issues so far.

[arcticdude]

With a little searching, I did find the data sheet for the Schaeffer's #279 spline grease.  Now we can look for substitutes.

[Latitude 28]

This is going to be long winded please bear with me on my thought.  Back in my corporate aircraft maintenance days.  We operated three Lear 45s that had Garret engines with the aircraft hydraulic pumps, constant pressure/variable displacement type of pump.  Variable displacement was achieved by a multi piston pump attached to a wobble plate that changed angles as the demand increased.  On the Lear 45s the hydraulic system had this high frequency buzz that would eat o-rings, tubing or anything that touched the tubing.  Needless to say a constant hydraulic issues with this model aircraft aircraft.   A few years later I was working on Cessna Citation Sevens.  Same basic engine model, same basic hydraulic pumps as the Lear 45.  Except the hyd system had one tiny, seemingly insignificant difference.....just a few inches from the pump was an device called an "acoustic ball' about the size of a tennis ball teed off of the pressure output line of the pump.  This stainless steel ball was nothing more than an passive dead space in the hydraulic pressure side of the system.  That device adsorbed the high frequency buzz in the Citation model of aircraft's hydraulic system.  Side note; we had zero issues with the Citation's hydraulic system.

Now having said that....I am thinking by adding a passive dead space as close to the pump as possible (on the pressure line).  It would absorb the pressure impulses from the hydraulic pump as well as the engine and or the PTO i.e. the Wanderlodge and Country Coach. 

This passive dead space needs to be on the high point of the pressure line close to the pump and could be nothing more than a capped tube tee'd into the pressure line. 

Disclosure: I am not a hydraulic engineer take the above based on end user experience living with what engineers designed.

[Richard]

Would a hyd accumulator do the same thing?

[Latitude 28]

Would a hyd accumulator do the same thing?

In essence the acoustic ball was a passive accumulator i.e. no pre-charge or check valves....much like the water hammer device attached to the washing machine hoses in your house.  In the case of the two different aircraft manufactures both hyd systems had accumulators perhaps ten feet of line from the pump close to the reservoirs before it reached the first accumulator.  The Lear did not have the acoustic ball close to the pump and where we had issues....the Citation had the acoustic ball modification installed close to the pump with none of the issues, hydraulically, that the Lear had.  This thing was a stainless steel sphere plumbed into the pressure line.....the shape may have been the magic sauce absorbing the impulses.

   

[[email protected]]

Would a hyd accumulator do the same thing?

In essence the acoustic ball was a passive accumulator i.e. no pre-charge or check valves....much like the water hammer device attached to the washing machine hoses in your house.  In the case of the two different aircraft manufactures both hyd systems had accumulators perhaps ten feet of line from the pump close to the reservoirs before it reached the first accumulator.  The Lear did not have the acoustic ball close to the pump and where we had issues....the Citation had the acoustic ball modification installed close to the pump with none of the issues, hydraulically, that the Lear had.  This thing was a stainless steel sphere plumbed into the pressure line.....the shape may have been the magic sauce absorbing the impulses.

Oh I bet that is a pricey little device, has to be pressure rated for the hydraulic system. Like you said, maybe a piece of pipe will suffice to act as the same thing, much less expensive. As you said, maybe there is something to the sphere shape. Looks like as Richard mentioned there are hydraulic accumulators you can buy, they look like they are similar to the ones that Rolls Royce used on their cars, they are charged on one side with nitrogen, with a diaphragm inside.

[Latitude 28]

Yes sir that little Jewell, rhyming with Newell was intended:-) is about $1,900.  Just like the Rolls Toyota has a Front Suspension Accumulator for the Lexus LX470 Land Cruiser 100 P/N 49141-60010. 

   

[[email protected]]

Yes sir that little Jewell, rhyming with Newell was intended:-) is about $1,900.  Just like the Rolls Toyota has a Front Suspension Accumulator for the Lexus LX470 Land Cruiser 100 P/N 49141-60010. 

Nice, did not know they used them on Lexus. Rolls stole the idea from Citroen is what I understand, I believe they are the ones who first started using the hydro-pneumatic suspension.