A combination of telephoto lens and camera with 4 kg of weight is in 45 degree angle still held, even if one the Friktionsknopf follow suit well after the locking knob. With a bit of finger pressure on the lens of the head are but by now. The 18kg Belastbatkeit sound like "Manufacturers imagination", but probably come from a standard measuring method in which a corresponding weight will be attached directly to the adapter plate. A lens needs with its 'arm' a much smaller force to twist the ball head against the arrest.
