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  1. #61
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Just for reference an extraction from the RAVE manual on the P38 EAS.

    Regarding the comment by Fluffy, I find it quite amusing that they also see the need to use "complex" devices like non return valves in there to ensure a wanted flow direction.


    There is no mention in the description of the working of the system, that it is able to compensate for side slopes - and that would have been listed as one of the main features if it was the intend.

    This is nothing more than a height control system with some integration with other vehicle systems to reduce driver input.
    Err, please read my post again properly. The P38 EAS can’t compensate for sideslopes, I said the system I designed could/can.

    “nothing more than a height control system” is a HUGE oversimplification. Not only does it control height, but it also does auto leveling. This is not trivial because you need to know what the chassis is doing and you need to integrate over the appropriately time the complex inputs from the wheel sensors.

    I’m pretty sure that you understand what closed loop control systems are all about and the work involved in tuning PID loops. Now try applying that to four interacting loops, each influencing the others, on a moving platform like a car.

    Oh, and there are no nonreturn valves in the wheel circuits.
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  2. #62
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by grips View Post
    Very basic pneumatics in the attached PDF document. One can build that circuit walking in your sleep.
    Exactly my point that I made right at the beginning. It is mechanically easy to do.

    But the overall problem is not simple, it is deceptively complex.

    Understanding pneumatics and physics is only half the problem. The real work starts with making it work on a very dynamic moving platform.

    The first air suspensions where horrible and they have evolved over time becoming more and more complex, out of necessity, to provide the ride and capabilities that they now possess.
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  3. #63
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Fluffy View Post
    Err, please read my post again properly. The P38 EAS can’t compensate for sideslopes, I said the system I designed could/can.
    Yes and what is the relevance in that? Just because you wanted the function, does not mean I need it too.



    Quote Originally Posted by Fluffy View Post
    “nothing more than a height control system” is a HUGE oversimplification. Not only does it control height, but it also does auto leveling. This is not trivial because you need to know what the chassis is doing and you need to integrate over the appropriately time the complex inputs from the wheel sensors.
    I do not disagree with you. I just can't understand why you make such a big deal of it.

    This is part and parcel of the game of control, and if you think this will be the first complex system I have ever done, you are making a big mistake.

    That is why when I design, I often bring in components that passively takes care of some physical behaviour that is very hard to sort out with direct electronic control.


    Quote Originally Posted by Fluffy View Post
    I’m pretty sure that you understand what closed loop control systems are all about and the work involved in tuning PID loops. Now try applying that to four interacting loops, each influencing the others, on a moving platform like a car.
    Jip. I have spend more than enough hours tuning loops. Initially I thought anything could be sorted with PID. That is not the case. If you have a system that inherently has poor mechanical response, you are wasting your time.

    One example is to temper flow with an orifice. The logarithmic response of the device makes it so much easier to get the PID to do the job.

    And that is then the difference I guess in our design styles. I like to use physical components in addition to the electronics to make the system behaves smoothly, because it works and increase the resilience of a system.



    Quote Originally Posted by Fluffy View Post
    Oh, and there are no nonreturn valves in the wheel circuits.
    Why is that significant?

    You made it out to be complex devices. So I am confused. The same part in a different line and all of a sudden it becomes a complex device?

    I think you really need to reconsider the apparent hyperbolic and irrelevant examples you want to accuse me of, because there is no relevance in the above.


    You designed your system with certain goals in mind. Maybe you achieved that, maybe you still want to make it better.


    I have different goals for the system I want, and if you cannot accept that this is different than yours, stop arguing all together.

    If you can accept that I have different outcomes in mind, and you would like to make suggestions, it obviously has to be within that frame of reference.
    1999 Discovery 1, 300 Tdi - "Tink Tanky"
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  4. #64
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Yes and what is the relevance in that? Just because you wanted the function, does not mean I need it too. (How on earth can you make that statement, I didn't say you need to. I said I did it, and as a consequence there off gained real in depth understanding of how EAS is implemented, which ironicaly I am offering/offered to share with you, but instead get attacked..)







    I do not disagree with you. I just can't understand why you make such a big deal of it.

    This is part and parcel of the game of control, and if you think this will be the first complex system I have ever done, you are making a big mistake. (How on earth can you make that statement)



    That is why when I design, I often bring in components that passively takes care of some physical behaviour that is very hard to sort out with direct electronic control.




    Jip. I have spend more than enough hours tuning loops. Initially I thought anything could be sorted with PID. That is not the case. If you have a system that inherently has poor mechanical response, you are wasting your time.

    One example is to temper flow with an orifice. The logarithmic response of the device makes it so much easier to get the PID to do the job.

    And that is then the difference I guess in our design styles. I like to use physical components in addition to the electronics to make the system behaves smoothly, because it works and increase the resilience of a system. (How on earth can you make that statement)





    Why is that significant?

    You made it out to be complex devices. So I am confused. The same part in a different line and all of a sudden it becomes a complex device?

    I think you really need to reconsider the apparent hyperbolic and irrelevant examples you want to accuse me of, because there is no relevance in the above.


    You designed your system with certain goals in mind. Maybe you achieved that, maybe you still want to make it better.


    I have different goals for the system I want, and if you cannot accept that this is different than yours, stop arguing all together.

    If you can accept that I have different outcomes in mind, and you would like to make suggestions, it obviously has to be within that frame of reference.
    Aay - ya - ya - yay.

    My point is that a calibrated orifice or a nonreturn valve or what ever, is way more complex than a piece of pneumatic line. The real point being that by the time you have completed adding addition components, complex or not, to try and make an inherently floored and unstable design work you may just as well simplify things and do it properly with a simple valve for each corner.

    See next post.
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  5. #65
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Here is a simple air suspension system that works.

    How do I know it works. Because it is the emergency bypass mode in my P38 air system.

    Use a common and garden car tyre pump, and use a tape measure to set each wheel height.

    As long as there are no leaks you can drive like this for months.

    When you get to a trail set an offroad height.

    Simple ne.

    But I promise you there are slagata.
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    Cheers

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  7. #66
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Fluffy View Post
    Aay - ya - ya - yay.

    My point is that a calibrated orifice or a nonreturn valve or what ever, is way more complex than a piece of pneumatic line. The real point being that by the time you have completed adding addition components, complex or not, to try and make an inherently floored and unstable design work you may just as well simplify things and do it properly with a simple valve for each corner.

    See next post.

    Phew! I don't know what is wrong with me then. I find these things to be no more complex than a piece of pneumatic line.
    1999 Discovery 1, 300 Tdi - "Tink Tanky"
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Fluffy View Post
    Here is a simple air suspension system that works.

    How do I know it works. Because it is the emergency bypass mode in my P38 air system.

    Use a common and garden car tyre pump, and use a tape measure to set each wheel height.

    As long as there are no leaks you can drive like this for months.

    When you get to a trail set an offroad height.

    Simple ne.

    But I promise you there are slagata.

    Simple yes. Exactly what I said.

    I will do no more than automating the manual valve a bit - and that manual valve will in any case be there.

    Want to do self leveling? Cool. Hitch the trailer, press the button, let it lift. Shut off and go. No more constant adjustments needed.

    Want to let your mother get in like a lady. Press button, let it drop. She gets in. Press button, back to ride height. Shut off and go.

    Once the air in there, don't mess with it.
    1999 Discovery 1, 300 Tdi - "Tink Tanky"
    2004 Discovery 2 Td5 - "Blink Tanky"

    "Logic is a systematic method of coming to the wrong conclusion with confidence."

    "A technician will let a system degenerate to the level of his understanding and maintain it there."

    "...it is abundantly clear that you are an arrogant C-nut." - Estee. (I was overwhelmed. It was the nicest thing someone has said to me in a week!)

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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Simple yes. Exactly what I said.

    I will do no more than automating the manual valve a bit - and that manual valve will in any case be there.

    Want to do self leveling? Cool. Hitch the trailer, press the button, let it lift. Shut off and go. No more constant adjustments needed.

    Want to let your mother get in like a lady. Press button, let it drop. She gets in. Press button, back to ride height. Shut off and go.

    Once the air in there, don't mess with it.
    OK, sorry that i interviened from the beginning cos i thought that you want to fit air springs on the front of a D2 and make it with functional SLS that's why i said it's complicated, from the bolded part i can deduce that you dont want anything like that cos as long as you push buttons so often it has nothing to do with Self levelling(which is about continuous automatic adjustemnts based on loads removed or added. From the last posts it's clear for me that you only want air springs instead of coils not an automatic SLS so a rudimentary air suspension which i not complicated. I rest my case and i'll not participate anymore in this discussion though i'll watch with interest how you'll make the system work in real life cos in theory you are covered. Good luck
    Last edited by sierrafery; 2019/08/19 at 01:28 PM.
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Simple yes. Exactly what I said.

    I will do no more than automating the manual valve a bit - and that manual valve will in any case be there.

    Want to do self leveling? Cool. Hitch the trailer, press the button, let it lift. Shut off and go. No more constant adjustments needed.

    Want to let your mother get in like a lady. Press button, let it drop. She gets in. Press button, back to ride height. Shut off and go.

    Once the air in there, don't mess with it.
    Yes pushing buttons is simple. Making the buttons do the job is where the fun starts.

    Getting the right amount of air in there is the real scary part.
    Cheers

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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by sierrafery View Post
    OK, sorry that i interviened from the beginning cos i thought that you want to fit air springs on the front of a D2 and make it with functional SLS that's why i said it's complicated, from the bolded part i can deduce that you dont want anything like that cos as long as you push buttons so often it has nothing to do with Self levelling which is about continuous automatic adjustemnts based on loads removed or added. From the last posts it's clear for me that you only want air springs instead of coils not an automatic SLS. I rest my case and i'll not participate anymore in this discussion though i'll watch with interest how you'll make the system work in real life cos in theory you are covered. Good luck
    Automatic Self leveling does not imply that it has to happen while the vehicle is moving.

    That is not what self leveling does.

    All that self leveling does, is to compensate for load and adjust the sag out of the suspension. That is it. Nothing more, noting less. It is not as if you load and unload while the vehicle is moving. The load is constant.

    Anything beyond that, and you move into active suspension control. Like ACE.

    And then you need hydraulics. Air is simply too slow for that.
    Last edited by biltong; 2019/08/19 at 01:35 PM.
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Automatic Self leveling does not imply that it has to happen while the vehicle is moving.

    That is not what self leveling does.

    All that self leveling does, is to compensate for load and adjust the sag out of the suspension. That is it. Nothing more, noting less. ...
    I can't let that unanswered, I say again i interviened cos i thought that you want SLS on your D2 with front on air too , based on your own statement from post #3:
    I am just thinking how incredible the D3 rides on air. It really is magic carpet.

    And I think the D2 will feel the same with all corners on air.
    then you said you'll do that with one "equalised channel" then i replied ... if i knew that you are speaking about simple air suspension i wouldnt have said it's complicated

    As about your simplistic view about SLS here's some quotes from the WSMs so you'll see that it does more:

    D2 SLS Description and operation 64-21:

    "Extended mode

    The extended mode is automatically operated by the ECU and requires no input from the driver. Extended mode

    operates when the chassis is grounded causing the rear wheels to spin. This information is generated by the ABS
    function of the SLABS ECU.
    When the ECU senses that the chassis is grounded and the vehicle speed is less than 6 mph (10 km/h), the ECU will
    operate the compressor and energise the air control valves for 25 seconds to raise the rear of the vehicle. This
    operates irrespective of the mode that the SLS system is in at that time. To inform the driver, the ORM warning lamp
    will flash continuously at all times that the system is in extended mode.
    The driver can exit the extended mode by depressing the ORM switch for not less than 0.5 seconds or by exceeding
    8 mph (13 km/h)."

    you mentioned D3 yourself how incredible it rides but what you explained untill now about how you'll make your system it has nothing to do with that. ... that's what i said it's complicated and not doable with one "equalisd channel"

    from D3 VDS description(WSM 4479)
    .....
    The four corner air suspension system maintains the vehicle height under all operating conditions by controlling the mass of air in the air springs. The air suspension control module uses signals from the four height sensors to maintain the correct suspension height. This is achieved by operating pneumatic control valves to increase or decrease the mass of air in the air spring damper modules.
    .....
    If the air suspension control module senses that the vehicle has grounded and lost traction, the control module can temporarily increase and/or redistribute the volume of air supplied to the affected air spring(s) to maximize the available traction. This is known as extended mode and will be indicated to the driver by the lamps on the air suspension switch flashing, and messages displayed in the instrument cluster message center.
    If the air suspension control module senses that the vehicle is prevented from moving upwards or downwards during a height change or leveling correction, the control module will adopt a safe state and further height changes will be suspended.
    ACCESS MODE

    Access mode lowers the vehicle body height by 50 mm (2 in) and provides easier entry, exit and loading of the vehicle. Access mode can be pre-selected when the vehicle is moving. The vehicle will partly lower as the vehicle speed decreases, lowering to the full access mode height when the vehicle reaches 5 mph (8 km/h). If the required road speed is not reached within a predetermined time, the air suspension will return the vehicle to the previously selected height.

    Access mode can be selected at any vehicle speed. When access mode is selected, the response of the air suspension system will depend on the vehicle speed:


    • If the vehicle speed is more than 12.5 mph (20 km/h), the air suspension control module will wait for up to one minute for the vehicle speed to be reduced. The access mode lamp and the lowering lamp will flash while the air suspension control module waits for the vehicle speed to be reduced, the on-road mode lamp will remain illuminated. If the vehicle speed is not reduced sufficiently, the access mode request will be cancelled after 1 minute.
    • If the vehicle speed is less than 12.5 mph (20 km/h), the air suspension control module will lower the suspension to a part lowered height and will remain at this height for up to one minute. The on-road mode lamp will extinguish as the air suspension control module lowers the suspension to the part lowered height. The access mode lamp and the lowering lamp will illuminate. When part lowered is reached, the 'lower' lower lamp will flash. If the vehicle speed is not reduced to less than 5 mph (8 km/h) in the one minute period, the access mode request will be cancelled.
    • If the vehicle speed is less than 5 mph (8 km/h), the suspension will be lowered to access mode immediately. The access mode lamp and the lowering lamp will illuminate. When the access mode height is reached, the lowering lamp will be extinguished.


    Access height may be selected up to 40 seconds after the ignition is turned off, provided that the driver's door has not been opened within this time.

    The suspension will automatically rise from access mode when the vehicle speed exceeds 6.2 mph (10 km/h). If access mode was selected directly from off-road mode then the system will return to off-road mode when the vehicle speed exceeds 6.2 mph (10 km/h). Otherwise the system will lift the suspension to On-road height.

    ....
    Now i really rest my case cos i dont want to annoy you or other forum users with my interventions which were meant to help you develop a well working SLS cos i've read page by page all the D2 and D3 WSMs in the last 12 years but it became clear to me that you want something else for which i wish you good luck again.
    Last edited by sierrafery; 2019/08/19 at 02:13 PM.
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  15. #72
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post
    Automatic Self leveling does not imply that it has to happen while the vehicle is moving. (Land Rover seems to think that it does.)

    That is not what self leveling does.

    All that self leveling does, is to compensate for load and adjust the sag out of the suspension. (What sag and from where/what. Are you saying air gets old and loses its physical properties??) That is it. Nothing more, noting less. It is not as if you load and unload while the vehicle is moving. The load is constant. (Its varying, all the time. dynamically. DUH )

    Anything beyond that, and you move into active suspension control. Like ACE. (ACE is a Toyota word, its the same wolf in different clothing)

    And then you need hydraulics. Air is simply too slow for that. (Or you could go Hydropneumatic like MB and Citroen to get the best of both worlds. These are the real kings of the hill.)
    One of the reasons for on the go self leveling is dynamic changes in load mass. Like cornering and braking and accelerating.

    But yes, I know you proposed a simple system.

    So lets start with that.

    So start with my system above. Four simple stopcocks (valves are bad) , one on each bellow, and a car compressor.

    Suck it and see. Learn how a car responds to air suspension. Learn for yourself some of the issues we have described. Especially learn the triangle leveling problem - not dynamically but even statically..

    Then design and come up with YOUR solution.

    ---------------------

    Hell heres an olive branch, organise a courier and you can have two P38 front bellows and two rear P38 bellows for free.
    Cheers

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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?


    I wonder if this system was ever implemented in production vehicles.
    Would not mind having this system in my bakkie.
    2004 Technology.

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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Fluffy View Post
    One of the reasons for on the go self leveling is dynamic changes in load mass. Like cornering and braking and accelerating.
    Help me if I am wrong. I think you are confusing SLS with active suspension. There is a huge difference.

    Any system that needs to react on dynamic changes like for cornering, braking and accelerating, needs to be real fast - and that is what we call active suspension. It has to be hydraulic. There is no other way. You just can't get that response with compressible media under the mediocre working pressures of air suspension, and secondly, the air consumption will be rather high.

    ACE is an excellent example of how Land Rover applied active suspension.

    They had a good look at the dynamics and figured that they can capitalise on the 80/20 principle. (This might be a little enthusiastic, but you get my drift)

    They did ACE, which is a very simple, 20% application that gives an excellent 80% effect by simply eliminating body roll - which on this kind of vehicle is by far the dominating problem.

    Your P38 has it. I am sure of it. And you can certainly vouch that the system is so damn quick that you don't even notice it. It works brilliant, but for that, you need hydraulic actuation.





    Quote Originally Posted by Fluffy View Post
    Hell heres an olive branch, organise a courier and you can have two P38 front bellows and two rear P38 bellows for free.
    If you are willing to accept a bottle or two of that guest house room whisky that evaporated last time you were there, we have a deal.
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by sierrafery View Post
    I can't let that unanswered, I say again i interviened cos i thought that you want SLS on your D2 with front on air too , based on your own statement from post #3: then you said you'll do that with one "equalised channel" then i replied ... if i knew that you are speaking about simple air suspension i wouldnt have said it's complicated

    As about your simplistic view about SLS here's some quotes from the WSMs so you'll see that it does more

    I honestly think that you are under the impression that SLS is a super quick acting all the time working kind of system.

    That really is not the case.

    All the things that are mentioned, are simply spinoffs from having electronic control on the air suspension.

    SLS is primarily a level control system and that is it. Whether it can set one level or 10 different levels each with a pretty name behind it, does not matter.


    Let me put it in further perspective. SLS will NOT start raising the backside of the vehicle if you go up a 45° slope to get it back to 0°. It has zero sense that you are at an angle. All it cares about is the distance of the axle from the body.

    The same goes for side slopes. It is not meant to compensate for that - but it will try on a side slope if you give it long enough.


    SLS cannot in any way, handle instant dynamic loads. The best it can so, is take an average over some time and act on that.


    Sorry Buddy. It really is as simple as that.
    1999 Discovery 1, 300 Tdi - "Tink Tanky"
    2004 Discovery 2 Td5 - "Blink Tanky"

    "Logic is a systematic method of coming to the wrong conclusion with confidence."

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  19. #76
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Fluffy View Post
    ---------------------

    Hell heres an olive branch, organise a courier and you can have two P38 front bellows and two rear P38 bellows for free.
    Quote Originally Posted by biltong View Post
    If you are willing to accept a bottle or two of that guest house room whisky that evaporated last time you were there, we have a deal.
    Way to go guys!
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  20. #77
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by biltong View Post

    Sorry Buddy. It really is as simple as that.
    Off course, simple as that if you deny all the engineering involved and confuse the Dicovery's SLS/VDS with a truck's air suspension(even those are a bit more complicated than you think): http://www.stengelbros.com/air-ride-suspensions/

    compared to this:


    WSM-14233 - Workshop manual Discovery 3 / LR3




    ......................


    INPUTS AND OUTPUTS

    The air suspension control module uses four harness connectors for all inputs and outputs.
    The air suspension control module uses inputs received on the CAN bus from other vehicle systems. The system uses longitudinal acceleration, lateral acceleration, steering angle and wheel speed data to control the suspension operation in differing driving conditions.
    The system will react differently if one or more of these data inputs is missing or incorrect, for example, if the steering angle sensor is missing or incorrect, the air suspension control module assumes a default value of zero which may result in some unnecessary leveling activity.
    .....

    Cornering
    If the air suspension control module registers a cornering force greater than 0.2g it will inhibit all height changes and corrections. The system will remain inhibited until the cornering force falls to less than 0.15g. The air suspension control module receives a message from the lateral acceleration sensor (which is an integral part of the ABS yaw rate sensor) on the high speed CAN bus for the cornering force.
    Rapid Acceleration
    If the air suspension control module registers a rapid acceleration greater than 0.2g it will inhibit all height changes and corrections. The system will remain inhibited until the rapid acceleration falls to less than 0.15g. Acceleration is calculated by the air suspension control module from a vehicle speed signal received via the high speed CAN bus.
    Rapid Deceleration
    If the air suspension control module registers a rapid deceleration smaller than -0.2g it will inhibit all height changes and corrections. The system will remain inhibited until the rapid deceleration rises above -0.15g. Deceleration is calculated by the air suspension control module from a vehicle speed signal received via the high speed CAN bus.



    Last edited by sierrafery; 2019/08/21 at 03:20 AM.
    2000 Discovery Td5 ES manual, tuned

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    i DON'T ANSWER TO TECHNICAL QUESTIONS IN PM'S

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  21. #78
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by sierrafery View Post
    Off course, simple as that if you deny all the engineering involved and confuse the Dicovery's SLS/VDS with a truck's air suspension(even those are a bit more complicated than you think): http://www.stengelbros.com/air-ride-suspensions/
    You are basically under the impression that SLS is performing dynamic functions - which it simply cannot do. Air is waaaaaay too slow for that.


    The examples that you quoted from the D3 manual, are all fieterjasies. It is all just electronic manipulation of a basic function - SLS.

    To make an SLS act on speed sensors, or door open switches as input is really nothing exceptional. You have controller, you have I/O's that are all physically independent of each other, and all that you have to do is bind the I/O's with programming in any way you like.


    So, I will make my point clear for you again:

    SLS can NOT under ANY circumstances be used to perform DYNAMIC vehicle control. FFS buddy, it takes a few seconds for a Disco to raise a couple of centimeters and with that you simply cannot act on dynamic suspension behavior, not even if you are God himself. Physics governs that.

    To control dynamic behavior, there is only one way: Hydraulics. It has always been like that, and always will be like that - at least with the technology we have right now.

    So I would suggest that you spend some time to read up on the brilliant ACE system, which is designed exactly for dynamic control. You can spend 12 years on that if you want to. The maths behind (even though it is elegantly simple for what it achieves) that will certainly be cool.

    In the past two weeks that I have my D2, I have at times really hammered it through corners and the levels of grip and handling behaviour is simply staggering for a vehicle of this type - especially since it has solid axles. (If I go air, there will undoubtly be a sacrifice there)



    To make SLS drop a wheel when traction is lost, or lower when the speed goes above X, is nothing but programming. It happens slowly - fast enough for that specific situation, but way too slow for any dynamic actions that occurs at road speeds.


    I said I wanted Air suspension, and that SLS will be inherently part of it.

    1. I do not have to do ANYTHING to improve the riding comfort of air vs steel at a specific height. The air does the job. That is why one would go air.

    2. SLS knows about nothing else than axle to chassis distance. That is the nature of SLS. One can now go in all sorts of ways to control that specific distance with electronic algorithms, but the bottom line is you are limited to the slow speed this system offers and regardless how good the software is, it cannot override physics.


    Based on your perception of SLS, I can very well understand how you can be so puzzled that it could be possible to achieve what I want to with a 2-channel system - and that is only one of a few concepts I am evaluating.

    I never said there is never ever a possibility that I will do a 4-channel system. But that system has some disadvantages, of which pretty vulnerable ride height sensors (which are core to the control) are one of them.

    Break a sensor like that at the wrong time and wrong place and suddenly have a wheel drop away at a precarious slope, is definitely something that worries me. With a 2-channel system a sensor can be placed in a lot better protected area.

    In fact, something like that is so serious to me, that I would in fact HARD-WIRE a micro switch which will electrically disable any action the controller can take, when low-range is selected.



    I have spend my whole life double shifting to gain engineering experience in both mechanics and electronics, and I am sorry if you find it disappointing that this problem might not be so daunting for me.

    I have no idea what you are, but if you are an engineer of any kind, I surely would not take you in on my team of designers. In certain environments, one can simply not work with people who are overwhelmed by technical challenges.


    If you want a real challenge, go and study active suspension - maths and all. Then come back and tell me what you think of SLS.
    Last edited by biltong; 2019/08/21 at 05:23 AM.
    1999 Discovery 1, 300 Tdi - "Tink Tanky"
    2004 Discovery 2 Td5 - "Blink Tanky"

    "Logic is a systematic method of coming to the wrong conclusion with confidence."

    "A technician will let a system degenerate to the level of his understanding and maintain it there."

    "...it is abundantly clear that you are an arrogant C-nut." - Estee. (I was overwhelmed. It was the nicest thing someone has said to me in a week!)

  22. #79
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Biltong, getting back to the title of the post, I suppose you could fit the RR P38 Air Suspension to the D2 due to the design and parts commonality of both vehicles. This would be ''relatively'' straight forward for someone with your level of knowledge and experience in these matters.

    It would be an interesting, self-indulgent project if one were so inclined to fit a totally unnecessary and unreliable yet critical system to a vehicle that would be used for over-landing and where reliability would be an important consideration. Thats just my experience as a user or ex-user.

    Designing one from scratch might require a change of title to this post. I think the last 3 pages of banter between you guys stems in part, to the title of this post and the Mental Modes of the reader resulting from the title. Change it to something like Biltong's Air Suspension Build.

    On separate note, it is abundantly clear that you are an arrogant C-nut. However, just my opinion here, but I would have thought that if you are so brilliant you wouldnt be stuck in a technological back water like Bloemfontein. Again, my opinion, I firmly believe you suffer from the Dunning Kruger Effect.

    Remember, in the land of the blind the one-eyed man is king.
    There is no such thing as inclement weather, only poor selection of clothing.... or Vehicle

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  24. #80
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    Default Re: I can't sleep so I thought: What about fitting RR P38 Air suspension in a D2?

    Quote Originally Posted by Estee View Post

    On separate note, it is abundantly clear that you are an arrogant C-nut.
    ouch
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