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| [GMCnet] Propane airbags [message #267950] |
Sat, 20 December 2014 20:57  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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One thing to keep in mind when considering the wireless air vs stock system is the ride height control units themselves when new kept ride to within +- 3/8". The ride height spec listed was +- 1/4" so even if the stock system ride height control unit works perfectly after nearly 40 years (doubtful) it still has a wider band around the actual ride height than the ride height spec itself. So, if staying right at the actual "correct" ride height is essential to you, best use some non-stock ride height control unit with a closer tolerance than the one the factory used.
What most seem to be looking for is a control system that will keep ride height at the preferred level independent of weight load. On most coaches there is enough hysteresis in the rear suspension that it takes quite a weight change to effect ride height much at a given inflation pressure in the air bags. Easy to test. Fill your bags to the pressure required to reach and maintain the desired ride height after you drive for a mile or two and park on a level spot. Now put a person of a known weight as far back as you can inside your coach and drive a mile or two returning to park on the same level spot. Re-measure ride height and note the change if any. Add 5 PSI to the air bags on each side and repeat the drive two miles, stop on the same level spot and re-measure ride height. Now you know quite a bit about how your particular coach responds to weight and air pressure in the bags. From that info it is easy to calculate the change in air pressure required to compensate
for a given change in weight (assuming that is a linear function within a normal weight change range).
One of our coaches has the wireless air system (the Royale) and the other (Clasco) has the first generation of the solenoid operated air valve system with stock ride heigh controllers and a modern compressor. Both have the stock one air bag on each side. The Royale maintains ride height over a wider range of weight change than does the Clasco. It also leaks down less than the Clasco. Both work. When I get in the Clasco I know the compressor will have to run several minutes to overcome the overnight leak down. When I get in the Royale and activate the wireless air system it usually is good to go or only needs a small amount of run time on the compressor to get both bags back to the set air pressure. Is one better than the other? Do I like one better than the other? No is my answer to the first question and yes is my answer to the second question. I am having that stock system in the Clasco changed out in favor of the wireless air system so I no longer have to overcom
e the leaks that seem to pop up after every time I chase a previous leak.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Propane airbags [message #267960 is a reply to message #267950] |
Sun, 21 December 2014 06:28  |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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Jerry, I would say right on with your evaluation. You are disguising
quality evaluation on the resr suspension under an odd title. I had not
even pulled this thread up until I saw you had a comment.
I would like to add to your thoughts, my Dad drove Greyhound buses, I lived
at the garage and in the backside of the terminal. It was expected not
just because it was good for the motors to warm up before you cracked the
whip but that warm up time gave the air syspension time to pump up, this
was the cas on @ every bus. "AIR WANTS OUT" and engineering in the 70's
expected some seepage of fluids, pressures, etc. . Don't know but many of
the retired engineers of that time may say no but from the garage side of
it things sure felt that way. Look at Harley...
The original systems are a chore to "keep up with". There is no doubt that
there are too many failure possibilities and bad logic to where is most any
components has a problem the system fails. Today, you can redesign the
system to "fail safe". You can also design it to where the basic function
of it is not electronic, electro-mechanical pneumatic device. If basic
operation could only be in one operation path you would have a more
reliable and maintainable system. All that said, there are several systems
out there that answer issues in different ways. Up until recently, I have
occupied my work in reproducing the original Power & Electrolevel systems
switching any ELII systems back to a reproduction Power Level design when
doing restorations. This seemed to be @ the most practical, serviceable
thing to offer someone who may not want to mess around with his coach just
for fun.
Recently however I too have thought about the problem and am doing my own
rendition because no matter which way you go, it's getting difficult to
just keep doing as before. I am not recommending nor want to throw my
solution in the frey. The system a new contributer here has suggested
sounds very interesting. I love new stuff and always want to hear about
it. To this point, systems have had to rely upon the traditional height
sensors that relate the suspension to the frame or with preset air
pressures. Having measuring sensors to the actual road outa make the
retired engineer and gearhead types here salivate.
It's alote safer playing with the rear suspension. When it fails, your
coach simply sits down! Lets give this new idea some ear..
On Sat, Dec 20, 2014 at 9:57 PM, Work Jerry wrote:
>
> One thing to keep in mind when considering the wireless air vs stock
> system is the ride height control units themselves when new kept ride to
> within +- 3/8". The ride height spec listed was +- 1/4" so even if the
> stock system ride height control unit works perfectly after nearly 40 years
> (doubtful) it still has a wider band around the actual ride height than the
> ride height spec itself. So, if staying right at the actual "correct" ride
> height is essential to you, best use some non-stock ride height control
> unit with a closer tolerance than the one the factory used.
>
> What most seem to be looking for is a control system that will keep ride
> height at the preferred level independent of weight load. On most coaches
> there is enough hysteresis in the rear suspension that it takes quite a
> weight change to effect ride height much at a given inflation pressure in
> the air bags. Easy to test. Fill your bags to the pressure required to
> reach and maintain the desired ride height after you drive for a mile or
> two and park on a level spot. Now put a person of a known weight as far
> back as you can inside your coach and drive a mile or two returning to park
> on the same level spot. Re-measure ride height and note the change if
> any. Add 5 PSI to the air bags on each side and repeat the drive two
> miles, stop on the same level spot and re-measure ride height. Now you
> know quite a bit about how your particular coach responds to weight and air
> pressure in the bags. From that info it is easy to calculate the change in
> air pressure required to compensate
> for a given change in weight (assuming that is a linear function within a
> normal weight change range).
>
> One of our coaches has the wireless air system (the Royale) and the other
> (Clasco) has the first generation of the solenoid operated air valve system
> with stock ride heigh controllers and a modern compressor. Both have the
> stock one air bag on each side. The Royale maintains ride height over a
> wider range of weight change than does the Clasco. It also leaks down less
> than the Clasco. Both work. When I get in the Clasco I know the
> compressor will have to run several minutes to overcome the overnight leak
> down. When I get in the Royale and activate the wireless air system it
> usually is good to go or only needs a small amount of run time on the
> compressor to get both bags back to the set air pressure. Is one better
> than the other? Do I like one better than the other? No is my answer to
> the first question and yes is my answer to the second question. I am
> having that stock system in the Clasco changed out in favor of the wireless
> air system so I no longer have to overcom
> e the leaks that seem to pop up after every time I chase a previous leak.
>
> Jerry
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple
> building in historic Kerby, OR
> Visitors always welcome!
> glwork@mac.com
> http://jerrywork.com
>
>
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Propane airbags [message #267961 is a reply to message #267960] |
Sun, 21 December 2014 07:58 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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Jim, height sensor could become pure electronic with the cheap and easy microprocessors. Only problem might be keeping sensors free of road grit and dirt. Read the actual road surface and run air pressure to an relative accurate height.
Add a fail-safe path with predetermined height in case of sensor path failure. "Limp home mode".
Lots of smart guys on this forum could do this in their sleep.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] Propane airbags [message #267969 is a reply to message #267950] |
Sun, 21 December 2014 09:21 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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...Or, just disconnect the leveling bars and air up the coach to the desired ride height after you load it and forget about it for the rest of the trip.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Propane airbags [message #267976 is a reply to message #267971] |
Sun, 21 December 2014 11:24 |
bdub
Messages: 1578
Registered: February 2004
Location: Central Texas
Karma: 5
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Senior Member |
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Kieth
WOW! I can't wait! How much?
Can I be the test dummy? :-)
I'm qualified, bonafied,
bdub (certified "DIY for Idiots" test dummy)
On Sun, Dec 21, 2014 at 10:14 AM, Keith V wrote:
> As I have talked about before I have a true height measuring controller
> that works.
> I have a prototype system running on my coach.
> I have been working with another GMCer, introduce yourself if you dare :),
> and we have PCBs in fab as I write this, they are due for Christmas.
>
> It uses any of multiple options for ride height. Any Analog sensor such as
> those used on GM or available from Dakota digital, Ride pro etc will work.
> It uses 4 air solenoids of most any type, from the expensive Air Ride
> blocks to cheap SMC valves, what ever you want to use. There are only 2
> lines
> running to the air bags from the valve block.
> The height sensors are mounted to the original mounting points using a
> custom bracket.
>
> The controller itself is an 8 bit Atmel Automotive grade MCU, not an
> Arduino, running fully custom C++. All the code is ours as is the PCB
> design. (I
> write firmware for a contact house doing everything from sprinkler systems
> to Avionics to Medical if you worry about my credentials ) It has FET
> drivers to control the solenoids. The controller fits into the stock
> location and uses high end rocker switches and push buttons. It has LED
> indicators to show you what it is doing.
>
> It has 2 RF remotes. One that is a keyfob, It provides up and down for
> each wheel. This allows you to have complete manual control for dumping,
> tire
> changing etc.
>
> The other remote is for the steering wheel. it can control the coach
> height up and down ( but not side to side ) for traversing speed bumps and
> steep
> drive ways. It also can enable travel mode or camp mode.
>
> Travel mode is a calibrated height for travel. Setting travel height is as
> simple as using the keyfob to set height while you are at the back of the
> coach measuring the actual height! No driving around or settling the
> suspension is required. it just works.
>
> Camp mode is new. This is a feature found on high end systems where when
> you pull into the campsite it will level you coach for camping. No Guessing,
> no levels required. just press the button and it will adjust until the
> coach is level.
>
>
> It performs exceptionally well. It is capable of detecting you Leaning
> from side to side standing by the dinnette, no it doesn't adjust that
> closely.
> I ran the prototype last summer and had no issues. I had it at the GMC
> convention last fall.
>
> There is still work to be done, but I'm hoping to be delivering units in
> the spring to a restricted set of installers.
>
> --
> Keith Vasilakes
> Mounds View. MN
> 75 ex Royale GMC
> 69 Vette
> 29 Dodge
>
>
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bdub
'76 Palm Beach/Central Texas
www.bdub.net
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| Re: [GMCnet] Propane airbags [message #267979 is a reply to message #267950] |
Sun, 21 December 2014 11:49 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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glwgmc wrote on Sat, 20 December 2014 19:57One thing to keep in mind when considering the wireless air vs stock system is the ride height control units themselves when new kept ride to within +- 3/8". The ride height spec listed was +- 1/4" so even if the stock system ride height control unit works perfectly after nearly 40 years (doubtful) it still has a wider band around the actual ride height than the ride height spec itself. So, if staying right at the actual "correct" ride height is essential to you, best use some non-stock ride height control unit with a closer tolerance than the one the factory used.
What most seem to be looking for is a control system that will keep ride height at the preferred level independent of weight load. On most coaches there is enough hysteresis in the rear suspension that it takes quite a weight change to effect ride height much at a given inflation pressure in the air bags. Easy to test. Fill your bags to the pressure required to reach and maintain the desired ride height after you drive for a mile or two and park on a level spot. Now put a person of a known weight as far back as you can inside your coach and drive a mile or two returning to park on the same level spot. Re-measure ride height and note the change if any. Add 5 PSI to the air bags on each side and repeat the drive two miles, stop on the same level spot and re-measure ride height. Now you know quite a bit about how your particular coach responds to weight and air pressure in the bags. From that info it is easy to calculate the change in air pressure required to compensate
for a given change in weight (assuming that is a linear function within a normal weight change range).
One of our coaches has the wireless air system (the Royale) and the other (Clasco) has the first generation of the solenoid operated air valve system with stock ride heigh controllers and a modern compressor. Both have the stock one air bag on each side. The Royale maintains ride height over a wider range of weight change than does the Clasco. It also leaks down less than the Clasco. Both work. When I get in the Clasco I know the compressor will have to run several minutes to overcome the overnight leak down. When I get in the Royale and activate the wireless air system it usually is good to go or only needs a small amount of run time on the compressor to get both bags back to the set air pressure. Is one better than the other? Do I like one better than the other? No is my answer to the first question and yes is my answer to the second question. I am having that stock system in the Clasco changed out in favor of the wireless air system so I no longer have to overcom
e the leaks that seem to pop up after every time I chase a previous leak.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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In a real world sense, I think any of the working systems will be OK. However, from a technical standpoint I think the systems designed by GM have real advantages. They are all closed loop so there is a feedback system to try to get you to the correct height. I can't imagine too many of you managing your checking accounts without looking at the balance. Everything has a tolerance and the static adjustment tolerance has nothing to do with the hysteresis of the system. I also think that well maintained older systems still have the capability of controlling the height as originally designed--esp the EL II. An EL II system will still adjust for a person walking from the front to the rear. I suspect the others will but it will be less obvious since the compressors in the EL II have no reservoir and act on demand. I recall many years ago when GM tried to develop a low cost automatic HVAC system without the feedback loop--needless to say it was a just a low cost system that didn't work.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Propane airbags [message #268015 is a reply to message #267979] |
Mon, 22 December 2014 08:16 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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Senior Member |
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Man, I need a life vest, the creative juices are flooding in! How many
posting here have a design on a better mousetrap or time piece?
Certainly not wanting to squelch this exchange, I love going to "Skycraft"
here in Orlando -- I always come out with a handbasket of cool little
things I can make round tuits with!
Here is something though you may want to consider with working with a coach
you may not have competent expertise as yourself to trouble shoot, repair
or maintain:
I want any design to be with readily available from most anywhere "off
shelf parts". I mean YOU will be the only tech that will be able to work
on a specialty system as you propose. Hey someone smart could understand
and work the system but there would be discovery time on it which the owner
would need to pay for every time someone ran a diagnostic on the syste. If
that would be you fine but something like this would only be for you
technogeeks.
We are installing a full manual up/down system with air rocker valves from
Air Lift. Big business who has been around -- repair parts are
distributed. Added to the failsafe manual system we add 4 solenoids (most
any brand or style will work), 2 back to back to created a gate valve on
both sides and to that we connect the original air height control vales
which are also off shelf available. One switch fires all 4 solenoids which
puts the "auto segment of the system in line. If you have air in the tank,
you can pump the system up no matter what has failed in the electrical
system. To this, we always have some sort of air bag shut off valve and a
filler Schrader valve on each side to isolate the system in event of a
catastrophic failure. That way, no matter what happens you can pump air
into each bag an hnker down for a ride to safety. This is what we must
have -- these things are too big to push, even a short tow bill will melt
your wallet -- no, you have to make it work again where the air ride system
squatted you.
This is what I would call reliable. If you include a cool doodad to
control the system function when it fails -- and you know most anything
made by man will -- it won't be a lookup on the internet for an obscure
page with some even more obscure components no matter how cool and accurate
they are. Remember who you are designing this system for and how it will
be maintained and problems discovered.
This is the way I must think when designing things we can include in a
restoration,
Jim Bounds
------------------------
On Sun, Dec 21, 2014 at 12:49 PM, Bob de Kruyff wrote:
>
> glwgmc wrote on Sat, 20 December 2014 19:57
>> One thing to keep in mind when considering the wireless air vs stock
> system is the ride height control units themselves when new kept ride to
>> within +- 3/8". The ride height spec listed was +- 1/4" so even if the
> stock system ride height control unit works perfectly after nearly 40 years
>> (doubtful) it still has a wider band around the actual ride height than
> the ride height spec itself. So, if staying right at the actual "correct"
>> ride height is essential to you, best use some non-stock ride height
> control unit with a closer tolerance than the one the factory used.
>>
>> What most seem to be looking for is a control system that will keep ride
> height at the preferred level independent of weight load. On most
>> coaches there is enough hysteresis in the rear suspension that it takes
> quite a weight change to effect ride height much at a given inflation
>> pressure in the air bags. Easy to test. Fill your bags to the pressure
> required to reach and maintain the desired ride height after you drive for
>> a mile or two and park on a level spot. Now put a person of a known
> weight as far back as you can inside your coach and drive a mile or two
>> returning to park on the same level spot. Re-measure ride height and
> note the change if any. Add 5 PSI to the air bags on each side and repeat
> the
>> drive two miles, stop on the same level spot and re-measure ride
> height. Now you know quite a bit about how your particular coach responds
> to
>> weight and air pressure in the bags. From that info it is easy to
> calculate the change in air pressure required to compensate
>> for a given change in weight (assuming that is a linear function within
> a normal weight change range).
>>
>> One of our coaches has the wireless air system (the Royale) and the
> other (Clasco) has the first generation of the solenoid operated air valve
>> system with stock ride heigh controllers and a modern compressor. Both
> have the stock one air bag on each side. The Royale maintains ride height
>> over a wider range of weight change than does the Clasco. It also leaks
> down less than the Clasco. Both work. When I get in the Clasco I know the
>> compressor will have to run several minutes to overcome the overnight
> leak down. When I get in the Royale and activate the wireless air system it
>> usually is good to go or only needs a small amount of run time on the
> compressor to get both bags back to the set air pressure. Is one better
> than
>> the other? Do I like one better than the other? No is my answer to the
> first question and yes is my answer to the second question. I am having
>> that stock system in the Clasco changed out in favor of the wireless air
> system so I no longer have to overcom
>> e the leaks that seem to pop up after every time I chase a previous
> leak.
>>
>> Jerry
>> Jerry Work
>> The Dovetail Joint
>> Fine furniture designed and hand crafted in the 1907 former Masonic
> Temple building in historic Kerby, OR
>> Visitors always welcome!
>> glwork@mac.com
>> http://jerrywork.com
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> In a real world sense, I think any of the working systems will be OK.
> However, from a technical standpoint I think the systems designed by GM have
> real advantages. They are all closed loop so there is a feedback system to
> try to get you to the correct height. I can't imagine too many of you
> managing your checking accounts without looking at the balance. Everything
> has a tolerance and the static adjustment tolerance has nothing to do with
> the hysteresis of the system. I also think that well maintained older
> systems still have the capability of controlling the height as originally
> designed--esp the EL II. An EL II system will still adjust for a person
> walking from the front to the rear. I suspect the others will but it will be
> less obvious since the compressors in the EL II have no reservoir and act
> on demand. I recall many years ago when GM tried to develop a low cost
> automatic HVAC system without the feedback loop--needless to say it was a
> just a low cost system that didn't work.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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