First of all, proceed to a trial assembly of a wheel without ring on the axle.
Horizontal positioning of the rim
First side ring positioning
Second side ring positioning
Conical ring positioning
Careful positioning of the O-ring
Locking ring positioning
Proceed to the mounting on a flat wheel
Don’t use lubricant
Contact areas between the conical ring and the locking ring must be as clean as possible, without paint, in order to get a better “gripp”.
The bearing surface of the conical ring and the O-ring must be very clean, without grease, with the O-ring perfectly positioned in its well during the mounting.
So that the wheel elements can block each other, the inflation can be done momentarily at a higher pressure than the nominal pressure needed.
It is highly recommended to make the machine move enough, with respect to the safety rules and areas, to be sure all the parts and the O-ring are perfectly positioned.
Once the manoeuvres are done, put the recommended pressure back.