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Copyright © 2021 Quality Machine Tools, LLC
PM-1228VF v3 2021-05
Figure 3-20
External drive components
This is the typical as-shipped configuration, with 30T upper gear, good
for power feeding, and cutting more than 20 U.S. and metric threads.
Numbers 1, 2 & 3 are clamp screws for adjustable components. The
lower gear, always 90T, is held in place by a keyed spacer bushing
outside the gear, as shown here. For metric thread cutting the spacer
bushing is inside the gear.
Figure 3-21
Other change gears
Alternate sizes for the upper gear are at right, 19
mm bore. The 56T gear at left is an alternate mid-
dle gear, bore 30 mm, for 13 TPI threading only.
Figure 3-21
Shifter assembly
This assembly transfers drive from the spindle
gear (not shown) to the upper change gear, typi-
cally 30T. To reverse the gearbox input the shifter
assembly is pivoted upwards, adding the second
46T idler (B) to the drive train.
Figure 3-22
Quadrant & middle gears
The middle gears, 86T and 91T, known as
metric translating gears
,
run on a threaded sleeve. The sleeve runs on a movable axle post
(19 mm head) that is clamped by a T-nut on the inside surface of the
quadrant. To exchange the 86T gear for 56T (13TPI only), loosen the
ring nut by tapping with a soft metal rod.
Slotted ring nut
Shifter assembly
Upper gear (varies)
Middle gears
86T & 91T
90T lower gear
(gearbox input)
Cover
safety
switch
Spindle pulley
Idler assembly
Quadrant
1
1
2
2
3
3
M6
M8
M8
M10
Middle gear axle
post (19 mm)
Reverse
idler
A
B
