Karcher foam lance

[Diesel_Power]

On my Karcher foam lance theres what looks like a valve which has a "+" & "-".

Does anyone know what this does? Im assuming it alters the mixture of water & soap but when i turn them to max and min it makes absolutely no difference.

The lance gives a nice coating of foam, was just curious as to what it does thats all.

 

[Diesel_Power]

This is the same lance, the bit im refering to is the top nozzle bit.

Cheers.

 

[7MAT]

The strength of the mix can be adjusted by turning the top dial. To add more water to the mix turn the dial to the plus (+) symbol. For a stronger mix turn the dial to the minus (-) symbol.