Bridgeport Interact 2 - The Milling, Drilling and Boring Head; Transmission; The Quill and Spindle

4,5
THE MILLING,
DRILLING AND
BORING HEAD
4.5.1
Transmission
The
prime mover
is a
3
phase, 2
h.p.
(t.5
kw) A.C.
induction motor.
The motor
incorporates
Bridgeport's
unique
patented reverse
flow air
cooling system.
This
system
ensures
that the
heat build up
in the spindle
bearings,
belt and
quill area
is kept
to
an
absolute
minimum.
Distortion is thereby
avoided
by maintaining
the operating
temPerature
to
within
20oF
of ambient
resulting in increased
belt
and bearing
life and maintained
accuracy.
The speed changer control is
provided
by
factory
balanced, cast
iron
varidiscs.
Each varidisc
assembly
is
precision dynamically balanced.
The
careful
balancing diminishes
vibration
and
promotes long belt
life.
When
the
high/low shifter
is in high, the output
varidiscs
drives the spindle
directly through
the
clutch. Shifting
into back
gear
(low)
disengages the
clutch
and
engages the bull
gear.
The power
travels through a toothed
belt drive to a counter shaft
and
back to
the
spindle
through
the
bull
gear.
4.5.2
The
Quill
and Spindle
The
quill
is an 86
mm
(3
3/8")
diameter steel tube
ground
and
chrome
plated to a
tolerance
of
.005
mm
(.0002").
The
quill
secures the outer
races of
the angular contact Class
7
preloaded
bearings
mounted
to the spindle. The spindle
itself is
alloy steel hardened and
ground
with
an
involute
spline at its
upper end
to slide
internally
in the
power
transmission train.
At
the lower
end of the
spindle
a taper is
ground
for Erickson No.
30
Quick
Change Tool
Holders.
CAUTION: Because of
tbe matcbed
fit
of
quill
to
quill
bousing and because tbe spindle
taper
is
ground
in
its own
bearings any
field
cbange of spindle must
be
performed
as a
spindle cartridge sub assembly
consisting
of
spindle, bearings, spdcers and
locknuts
+-3