Pfaff 260 Service Manual page 27

As the regulating slide is moved to the left, the roller rides up on the conical
port of the driving eccentric. The farther the regulating slide is moved to the
left, the larger will be the throw of the driving lever ond the higher the rota-
tional speed of the com assembly. This speed, in turn, determines not only the
length o·f the design, but also the number of stitches it contains.
A Iorge throw of the driving lever causes the com assembly to rotate quickly,
thus producing fewer stitches and a shorter des.ign (Figs. 46 and 50).
And conversely, a small throw of the driving lever causes the com assembly
to rotate slowly, thus producing more stitches and a longer design (Figs. 47
and SO).
The rotational speed of the com assembly con thus be varied between 25 and
100 stitdhes per com revolution and design. The role of speed is controlled by
lever E (Fig. 113) which is arranged on the top cover and has eight graduations.
As this lever is turned from one graduation to the next, on eccentric pin on the
pattern length regulating crank (50561) engages in the fork of the regulating
slide (c in Fig. 109) and moves this slide lengthwise of the machine arm.
Fig. 48 Cam assembly backlash retainer
3
5 7
26
fig. 49 Cam assembly feed clutch
Fig. 50 Various pattern lengths as are ob-
tained by setting lever E (4 in
Fig. 46) at positions 1, 3, 5 and 7,
respectively.