Carb Adjustment With 1 Screw vs 2 Screws

[Stihleer]

Hey all, does anyone know the reason for some small engines to only have 1 adjustment screw instead of 2 with a H and L? I am working on an Auger with only 1 adjustment screw, got it running but was curious as to how that 1 adjustment screw manages both high and low speeds?

I have tried to google with no luck, I did watch a video explaining what the screw does but how does it manage both ranges of rpm?

 

[Russ2251]

was curious as to how that 1 adjustment screw manages both high and low speeds?

It's an EPA carb...meaning high speed jet is fixed and is not adjustable.
Usually the low speed screw (if available) has a limiter on it as well.