In the past years two systems of control lines have approved.
First: A system
where one of the line were replaced of two lines. You can see on the first
picture line 2 and 3.
If the 2 lines
were adjust the lever will move to the arrow position.
That control system is shown on the picture in a assembled status and as individual
parts
The suitable control handle have to include a help segment.
A control handle could be build as the next picture shows.
The activity of
the choke access with the left hand with a mechanical help. This principle
has no disturbing influence through the left hand on the control move with
the right hand.
The last picture shows a handle.
A disadvantage is the different strain to the three control wires.