Headlamp range adjuster - How does it work?

[BenH]

Question 2 in my series of 376 questions about how my E-Class works...

The headlamp range adjuster on my W210 E200 is pneumatic, judging by the noise it makes when I adjust the setting. Can anyone tell me the mechanism by which the headlamps are adjusted? How does a pneumatic connection between the switch and the lamp assemblies provide a stepped adjustment?

(Pneumatic systems are either pressurised or not; there are only two states. A variable position setting means there must be some clever way of transmitting a variable signal down the vacuum tube to the lights.)

Thanks in advance for your suggestions!
Ben

 

[BenH]

Headlamp range adjuster

Thinking about it, there are two vacuum tubes leading away from the switch, so perhaps the system uses a cunning binary-type method of controlling the four steps in the adjustment:
0 0
- 0
0 -
- -
When a pipe is 'open' it adds a pull on the actuator by the lights, so if both pipes are 'open' then you get twice the pull and twice the movement. Hmmm.

Is this just barking? I expect so!