══════════Frequently Asked Question══════════

Author: Yurran
Noticed that sooner or later many air suspension owners have a similar entry in their logbook. Over time I understood why! Also understood why not all of them are eager to answer questions about the air system. The whole point is that people ask the same questions, and answering the same thing over and over gets tiring. Therefore, in this post I will try to help everyone who has a real interest in compressed air in their vehicle! I do not claim guru status; everything written below is just my experience and knowledge from the internet!
So:
1. The most important thing about an air suspension system are the cushions that replace springs, performing the role of elastic elements! Depending on the type of suspension, cushions can be placed outside or directly on top of the shock absorbers.

Here you have no influence; if a spring is separate from the shock absorber, then you must also install the cushion in this way! In the first case, it's simpler and cheaper; we take a waterproof cushion and place it instead of the spring. With a cushion mounted on the strut, things are more complex.
HOW IS THE CUSHION MOUNTED ON THE STRUT?
It’s very simple - there are grooves in the cushion flanges with rubber rings that tightly grip the strut body and shaft.

Here they are, the rings

AND WILL IT HOLD? It holds for everyone. You just need to ensure that the rings are seated with a press fit of 0.1-0.2 mm.
There are also two types of cushions - silphons and sleeves or in slang terms: donuts and sags. Donuts you saw on the photo above, while sags look like this

Cabin cushion Scania

About how well my suspension donuts bounce and about the need to install additional volumes I wrote here
What do you choose - it's your choice. Personally for me, donuts became a solution due to their low minimum height and close wheel position relative to the strut as well as large diameter of the strut cup. At the rear one could have installed sags but that would require choosing struts from something else due to convex stops on the strut body not allowing to lower the cushion further.
WHAT CUSHIONS DO I HAVE? I settled for Dunlop 6*2 (front) cushions

front strut

and Dunlop 4 1/2*3 (rear)

rear

I only bought the rubber parts, ordered the metal from a turner.
Can I share drawings They have already spread over the internet, here is an example link for instance
pnevmopodveska-club.ru/topic/411-dunlop-6-kh-2/
There is by the way an important moment with McPherson front struts. On mine the shaft turns together with the strut and cushion in a bearing support, therefore there's no friction in the sealing rings of the cushions hence no wear accordingly. If on your strut the shaft stays put only changing angle you'll not fit my design.

2. Air Preparation Block.
I will break it into subitems:
a) COMPRESSOR. There are options - this could be an electric compressor for tire inflation or a mechanical one from the AC system.
For the first option people recommend models BerKut R20, R24 well proven in this topic, or American ViAir.
The air conditioner is another matter that I picked up from jeepers who inflate their tires with them. The productivity is higher than an electric one, so filling the reservoir will be faster. I opted for it since I lost hope to restore my original climate system and planned to remove everything anyway. This choice only makes sense in such a setup.you can read about it here
b) RESERVOIR. Options for everyone's taste - from trucks, fire extinguishers, refrigerant cylinders etc. Mine is from ZIL. I keep 10 atmospheres in it.

c) VALVES. Depending on the number of circuits - two or four you need accordingly four or eight valves. I use ones from gas equipment due to their budget price. They have a small passage (2.5mm), therefore lifting/lowering speed is not high. Want speed? Buy with bigger bore but keep in mind that finding correct position will be inconvenient.

d) MANOMETERS. One of them is needed for the reservoir, for pressure control (just to know). The second one (or several ones) in the cabin. Mine system is two-circuit so I limited myself to a dual-pointer manometer from Kamaz, for four-circuit accordingly you need such 2 or 4 with single pointer. You can if have money install an electronic block with LCD display and sensors freeing yourself from laying extra tubes to manometers in the cabin.
e) CONTROL. I don’t have any electronic brains that automatically maintain clearance etc. Simply two buttons in the cabin which I use to lower or raise front and rear.
f) PRESSURE RELAY. Installed on the reservoir for automatic pressure control. As soon as the pressure drops to 8atm, the relay switches on the compressor, rises to 10 - it turns off. It’s simple.
g) WATER SEPARATOR- is necessary according to name for separating water which inevitably settles when air cools from getting into valves. I think it's clear that it's not needed in this case.
h) CHECK VALVE- necessary so that after the compressor stops, air does not leak back from the reservoir.
i) TUBES - I used plastic tubing of various diameters for pneumatic systems.
j) FITTINGS - exist in different types, I prefer metal ones with threads.
m) A safety pressure relief valve is needed to mechanically release excess pressure in case of uncontrolled pressure increase (when the relay fails), once it reaches preset limits (in my case, 12 atm).
We've figured out about parts, now WHERE TO BUY? HOW MUCH DOES IT COST?
I bought airbags here at a price around 700 rubles per piece; there you can also purchase other parts and ready-made air spring kits. (not an advertisement, just often asked)
Tubes and fittings are available in truck spare parts stores where Scania cab airbags are also sold.
Some plumbing items might be needed (e.g., a half-inch threaded tee.)
I ordered the pressure relay and safety relief valve here
HOW MUCH DID IT COST IN TOTAL? It depends on your choice of components. For me, it cost approximately 30.
Rarely does someone ask WHERE CAN I READ MORE?
But still, here's my answer because after reading this, most of your questions will be answered:
1. A recently emerged but rapidly growing forum air suspension enthusiasts' forum
2. Well-known to all who have built air suspensions Chinese forum
3. And this one forum
Phew, a lot of text, but I believe those with the dream of making pshhh sounds while elegantly lying down will appreciate it.

The price tag: 30,000 rubles