PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620 - LESSON 1/TASK 2
(5) Progressive Linkage Configurations. A carburetor equipped with
progressive linkage is designed so that the accelerator pedal directly
operates the primary throttle valve(s). There are two ways in which the
secondary throttle valve(s) are operated.
(a) Mechanically operated secondary throttle valve(s) (figure 30)
are actuated by linkage from the primary throttle valve(s). The linkage is
designed so that it will not be actuated until the primary throttle valve(s)
are approximately twothirds open. The operating arm on the primary
throttle shaft is made to be approximately three times as long as the arm on
the secondary throttle
FIGURE 30. MECHANICAL PROGRESSIVE LINKAGE OPERATION.