T-224
19.3.2 Center Distance Error
Even when exaggerated center
distance errors exist, as shown in
Figure 19-7, the results are crossed
end contacts. Such errors not only
cause bad contact but also greatly
influence backlash.
A positive center distance error
causes increased backlash. A
negative error will decrease backlash
and may result in a tight mesh, or
e v e n
m a k e
i t
i m p o s s i b l e
t o
assemble.
19.3.3 Mounting Distance
Error
Figure 19-8 shows the
resulting poor contact from
mounting distance error of the
worm gear. From the figure,
we can see the contact shifts
toward the worm gear tooth's
edge. The direction of shift in
the contact area matches the
d i r e c t i o n
o f
w o r m
g e a r
mounting error. This error
affects backlash, which tends to
d e c r e a s e
a s
t h e
e r r o r
increases. The error can be
diminished by micro-adjustment
of the worm gear in the axial
direction.
Error
Error
Fig. 19-6 Poor Contact Due to Shaft Angle Error
Error
Error
Fig. 19-8
Poor Contact Due to
Mounting Distance Error
Fig. 19-7
Poor Contact Due to
Center Distance Error
RH Helix
LH Helix
RH Helix
LH Helix
(+)
(–)
(+) Error
(–) Error
