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stop.
(Either normal or emergency methods
can be used.
Refer to Power Off Sequence
paragraph for additional information.)
As
the carriage retracts, the cam surfaces en-
counter the head arms and each head rides
vertically away from the related disk sur-
face.
The carriage continues back to the
retracted position and stops.
Head/Arm Assemblies
Twenty head/arm assemblies are mounted on
the carriaqe.
A read/write head/arm a.sseui:)ly
consists of a read/write head assembly
.
mounted at the end of a supporting arm struc-
ture.
A track servo head/arm assembly con-
sists of a read coil head assembly mounted
at the end of a supporting arm structure.
The head assembly (Figure 3-10), which in-
cludes a cable and pluq, is mounted on a
gimbal rinq which, in turn, is mounted on a
floating arm.
This method of mounting
a.l.lows
the head assembly to pivot (independent of
the arm) tangentially and radially relative
to a data track on the disk surface.
Such
motion is required to compensate for
possible
irreqularities in the disk surface.
The arm structure consists of a floating arm
secured to a heavier fixed arm.
The end of
the fixed arm opposite the head mounts in
the carriage receiver.
The floating arm is
the mounting point for the head and is
necessarily flexible so that it can flex
during load and unload motions, onto and off
of the cam surfaces.
Freedom and mobility of the head are neces-
s~
elements to being able to function with
interchangeable disk packs.
During head
loading, each floatinq arm is driven off the
related cam and unflexes to force a head
toward the air cushion on the spinninq disk
surface.
The force applied by the floating
a~
causes the heads to fly or float on the
air cushion.
Vertical motion by a disk sur-
face (due to warpage or imperfection) is
countered by a move in the opposite direction
by
the gimballed head and/or floating arm.
As
a result, flight height remains nearly
constant.
trOItCC
.~u
IY
"'""ATI .......
~-.~ ~.
tr~
SI""RATm!"uo " -
II ,-OAGID TO Ollie
~
SUlttrACI:
~
)
C"II U;"VIS C""
SUlttrACI- HI"O
alCOIiCS "1 .. 80fUII
\
.....
,
..
~.
CAM:.::?.~~~
. / CAlI SUItf'ACI:-
_
~
"UO IS
UNLOAOm
SUItf'ACI
3-16
"IAo/nlTt
HUO
AND
""1"" SPit,,,, IIOTION
A80UT THIS AXIS ClttAnD
IT
fIlVOTJ ...
A80UT
@
Figure 3-10. Head/Arm Assembly Motion
83318200
A
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