| Author |
Message |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 10:05 am: | |
40' bus conversion
Two choices are as follows;
1) Build a leveling system using the air bags.
2) install a set of Power Plus electric leveling feet and the control unit which I found new in the box at $2000.00 from a friend. (I guess the retail was around $3800
Need opinions before he sells them to someone else! |
James Maxwell (Jmaxwell) (66.81.51.21)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 12:15 pm: | |
No doubt about it, you can build a premium leveling system with the existing air system for much less money. However, the available range of the air suspension system is limited, generally 4-5 inches tops. They work in most situations, but occasionally you find yourself on a site that places you out of their range of operation. Another advantage to the air is that u have only 1 system to maintain. I built the manual/automatic system on my Grumman and am satisfied with it, but it does have it's problems (primarily leaking solenoid valves). For now, my Neoplan is converted to strictly manual until such time as I find some electric valves that come with a guarantee to not leak for a reasonable number of years.
On the other hand, the electric jacks that I have seen are not adequately rated to handle the weight of a bus, especially the rear, even though the range of the jacks is greater than that of air springs. The big negative here that I see is having another system to maintain, providing the jacks will handle the weight. To me, hydraulic has the same drawback; just something else to maintain when you can do an adequate job with what the bus was equipped with. |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 12:30 pm: | |
Mr.Maxwell,
Thank you for the reply. I do, however have a few questions for you if it is not too much bother.
1) Which Neoplan do you have? I am converting a 1985 Cityliner built in Stuttgart.
2) My air bags leak down overnight, I spoke ot the local diesel shop (Pacific Torque Burien, WA.) and they told me that it is nearly impossible to stop all the little leaks in the air suspension and that as long as the system worked it was best to just leave it. It was explained to me that the system was never intended to hold the bus up for days...is this true?
3) The jacks I found are rated at 8,500 lbs each, seems to me that 4 should do the trick for a bus with an empty weight of 14,000.....What do you think?
4) how does the air bag system work if the system has a leak? Aux air compressor?
chris |
Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 3:14 pm: | |
Go with the mechanical system and try to leave the air bags alone. Gives you a redundant system should anything fail. Air can leak out over time. Good luck. |
Sam Sperbeck (204.248.119.254)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 3:28 pm: | |
Hi Chris,
We have had our airbag leveling system for years and it will stay up for months. We have a manual system with 4 air ride seat valves and 4 100 psi gagues, without the original automatic suspension valves. When we eliminated the suspension valves our leaks went away, however if I were doing it over I would replace the original suspension valves and isolate them with solonoid valves for campground leveling. On our GM4106 we have 7" of travel on the rear and about 6" on the front. We have never been in a situation where we have not been able to get comfortably level, I'm not saying we were always perfectly level, but we were comfortable. With airbag leveling you will still feel some motion as people move around inside the bus or in a strong wind, but that has never bothered us too much. With the electric jacks you would have better stability when parked.
I am suprized that your bus only weighs 14,000 lbs as our GM4106 weighed a little over 20,000 stripped and it is 35' long, but I am not familiar with Neoplan construction.
Thanks, Sam Sperbeck
La Crescent, MN |
H3jim (68.107.62.94)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 3:35 pm: | |
Are you sure that's not 14,000 kilos? or about 31,000 lbs |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 4:52 pm: | |
I am in fact not sure about the weight, could be Kilos...I better look.
I kind of like the idea of more stability when parked as I hae a small child and once she is asleep I like to try and keep her that way. I'll look inot the weight and go from there.
chris |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 4:57 pm: | |
Looks like it is Kilos, but at 8600lbs a leg X 4 legs I would have 34,400 lbs of capacity which would be cutting it pretty close....
Chris |
Jim Ashworth (Jimnh) (172.158.243.193)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 5:23 pm: | |
I vote for the air bags. With jacks you can only level by raising the bus. Sometimes puts the front end way up in the air. Using air bags, you usually lower the bus to level. Norgren makes a spring centered air or electric operated solenoid valve. About $60 each. My bus stays up for 4 months. That's an entire winter without dropping.
Yes, there is a little movement with air bags and tires, but I found that when my kids were little, noise or movement didn't bother them because they were used to it. They frequently went to sleep with a dot matrix printer running all evening because of my computer business. Same with movement. I've watched them bounce clear of the rear bed by about 6" in a Southwind motorhome. Never woke up. Boy am I glad I got a bus now. That Southwind was a real piece of crap.
Jim |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 9:06 pm: | |
Jim,
Funny you should say that... I am now trying to sell my 1989 Southwind. You should buy it just for the memories...interested?
Chris |
Sean Welsh (Sean) (64.81.73.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 9:28 pm: | |
Chris,
Your German Cityliner has rolling lobe bags identical to those on my Spaceliner.
If you use hydraulic or mechanical levelers, you run the very real risk of breaking the seal on the roller bags when you jack in the up direction, and the roller bags are very, very difficult to re-seat (trust me on this -- I've been stuck on the side of the road for hours trying to do just that).
Consequently, I suggest air. With your particular air setup, this presents yet a different set of challenges, as the Neoplan air system is very different from any other coach on the road. If you want to go the traditional route of tapping into the air lines ahead of the bags, you'll need six three-way valves, eight one-way valves, and two proportioning valves, in addition to whatever gauges and sensors you use to determine where everything is set. On top of this, all the valves will need to be metric!
What I did was to use the existing coach ride-height valves (one in the rear, two in the front) and build a system to control these using linear actuators. If you search back through the archive here, there is a whole thread on this with more detail.
HTH,
-Sean |
James Maxwell (Jmaxwell) (66.81.60.148)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 10:01 pm: | |
I have a 40' 1990 Jetliner, built in Lamar, CO. I would respectfully disagree that the air suspension system was never intended to stay inflated for long periods; if it doesn't then something is not sealing as it was designed to do. I finally found the 2 or 3 small leaks in the front-end of mine, fixed them, and now they stay where I put them for weeks at a time. The rear four springs still have some minor leaks that I have not had time to address yet but I have located a couple that would account for the loss of air I am having: 36-48 hr. bleed-down on the rear.
Apparently, somewhere between Stuttgart and Lamar Neoplan modified the suspension air distribution system because mine was not designed like Sean's, nor did it use the same components, such as the leveling valves. Everything about the system is comparable to what was found on US built units of the era.
My Grumman system incorporates the kneeling system that came with it, and it has several leaks, mostly in the $100 3-way spindle valves that I bought. I use a 3/4hp DeVilbiss Oil-less compressor as an aux. air source in it.
On the Neoplan, I will use electric valves for the road/parked leveling system, when and if I find some with a semblance of a guarantee. Until then, I am strictly manual, with 3 way manual valves on a 3-point system (entire rear and each front corner; just the opposite of the Grumman).
The 8500# jacks will not work for the rear of your bus. My Jetliner was 28.5k (lbs)stripped and only 7800 of that was up front. The remaining 20k+ was at the rear. Have not weighed it since building, but the rear is heavier now. |
James Maxwell (Jmaxwell) (66.81.60.148)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2004 - 10:07 pm: | |
Jimnh: Thanks for the tip on the Norgren valves: I'll seek a source and check them out. |
Sean Welsh (Sean) (64.81.73.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 1:53 am: | |
James,
Indeed, major changes were made between Germany and Lamar. There is, in fact, no relationship or connection between Lamar and "Neoplan" Germany (now part of MAN, formerly Auwaerter). "Neoplan USA" merely licensed the name and the original designs.
When Lamar ramped up production, they changed as many components as they could to US-spec items without compromising their investment in the original structural design. So German units have, for example, Mercedes or MAN axles, while US units have Meritor axles. German units use metric air line and fitting, US units use DOT/SAE lines, etc. etc.. Running gear is generally not interchangeable between the two. Looking at two cityliners side by side, one from Stuttgart and one from Lamar, it's hard to notice the difference, but they can't even swap lug nuts.
By the way, my Spaceliner was built in Pilsting, while Chris's Cityliner was built in Stuttgart. Both models were also built in Plauen for import to the US. All highway coaches made in the US were built in Lamar -- Brownsville only ever made transits.
-Sean |
GWH (209.121.201.59)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 1:57 am: | |
Sean, your description of the Neoplan air circuitry sounds very interesting. Do you know if there is a schematic of it available on the internet anywhere? |
Sean Welsh (Sean) (64.81.73.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 3:18 am: | |
GWH,
Not as far as I know. I have it in hardcopy, though.
The Neoplans use an active ride-height system -- air moves into and out of the front bags when cornering, helping to reduce body roll. The front suspension is fully independent, and each front bag has its own ride-height valve. Intercepting the lines to the front air bags to insert three-way valves to build an air-operated leveling system would be straightforward, as long as these valves did not impede the free flow of air while underway.
The rear suspension ride height is controlled by a single valve. The valve actuator is attached to the drive axle transverse support beam. This single valve controls air flow to all four rear bags (two large ones on the drive axle, and two smaller ones on the fully-independent tag axles), as well as proportioning the air pressure between the drivers and the tags. Because of this six-way interconnection and proportioning, the only way to intercept the lines to install a traditional (parked) air leveling system is to intercept the individual line to each bag from this valve, and do your own proportioning between drive and tag.
In addition to all this, many Neoplans, mine included, have lift/lower solenoids that can over-ride the ride-height system and either empty the bags completely (to clear a low bridge, for example) or fill them to maximum capacity (to clear a deep gutter or other low-end obstruction). These solenoids send air "signals" to the ride-height valves to either dump or fill the bags completely irrespective of actuator position. This system further complicates the installation of an air leveling system.
-Sean |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 11:21 am: | |
Sean,
I still do not understand why I could not used hydraulic or eceltric levelers or how the use of such would damage the bags... I have actually been trying to contact you but lost your number. Mine is 206-227-7355 and it would be great if I could ask you a few hundred more Neoplan questions, it took about 3 days for me to process the information I got from you last time!
Kindest regards,
chris |
Sean Welsh (Sean) (64.81.73.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 1:11 pm: | |
Chris,
I will try to call you this week -- I'm on the road.
The bags are not attached at either the top or the bottom. If you took one out, it would look like a small tire (like a golf cart tire), with holes on both ends and a "bead".
The bag is sealed against the top and bottom posts the same way a tire seals against the rim. The seal is maintained strictly by air pressure, and this depends on gravity holding the coach down to the suspension.
If you jack the coach up until the suspension "tops out" without increasing the pressure in the bags, the bead can unseat and the bag can come loose. This will not damage the bag, but now you have a problem getting the bag to re-seat and getting air into it. Just as with beading a tire onto its rim, it takes a huge inrush of compressed air while holding the bags to the seats. The ride-height valves usually will not deliver enough flow to seat the bag. So if your bag unseats, then you may end up with the coach sitting on the bottom stop when you lower it back to the ground.
Seating the bags often requires removing the fitting at the top of the bag (sometimes difficult to reach) and giving it a big squirt of air.
-Sean |
cgoodwin (208.12.28.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 2:25 pm: | |
OK how about this idea..
Build a leveling system using the stock air bags and add a set of stabilizing jacks to limit movement (wind, walking, etc). With the weight being born by the airbags the stabilizing jacks could be fairly light duty, perhaps even 4 electric jacks like the ones found on the corners of over-cab campers. I could park, level the bus with the air bags then deploy the jacks to stabilize the whole thing?
See any issues with this type of arrangement?
chris |
Tom Caffrey (Pvcces) (65.74.65.65)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 06, 2004 - 5:27 pm: | |
Chris, if your automatic leveling system should detect that the bus body is too high FOR ANY REASON while you are supporting the body with the jacks, it will attempt to lower the body by letting air out of the airbags.
This means that any kind of blocking of the body with any attempt to carry any weight on the jacks will result in the jacks carrying the full weight of the body. The jacks will need to be capable of carrying the full body weight.
This is why you never want to attempt to jack up the body of any automatically leveled vehicle unles you are prepared for your jack or jacks to lift all the weight of the body.
Blocking the body, leaving a slight clearance between blocks and body should not pose the same problem.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
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