4805 Body; Insert Installation And Replacement; Fixtures - BRUEL & KJAER System V Instruction Manual

3.3.2.
4805 Body
Place the Exciter Head on top of the Exciter Body with the connector to the rear (the cool­
ing air hol e is also to the rear). The lower edge of the Head Protective Can will slip over
the Upper Wheel of the Exciter Body and the Head Alignment Pins will rest on the upper
surface of the Upper Wheel. Rotate the head until the Head Alignment Pins drop into the
holes in the Upper Wheel and lower the Head until it is fully engaged . The Split Hub of
the Head will prov ide close concentricity guidance. The magnetic field should be suffi­
cient to hold the Head in place, but 3 x 4 mm screws are also provided, which can be
screwed into the space normally used for the Head Latches .
Attach the cable from the Power Amplifier to the connector on the Head . The Exciter is
now ready for operation.
To remove an Exciter Head, remove the hold-down screws from the Head Latch slots .
Place your feet against the base on either side, take hold of the Head and jerk it upwards
a few centimeters. This will pull the Driver Coil free of the magnetic field, after which the
Head can be lifted off easily and smoothly.
3.4. INSERT INSTALLATION AND REPLACEMENT
Exciter Heads which use inserts are supplied with a mounting tool, a bott le of thread
locking cement, and two boxes of inserts. One box contains inserts with metric internai
threads and the other contains inserts with imperial internai threads.
To install an inser!, the insert is placed on the tool, with the pin of the tool inside the in­
sert internai thread and with the blade of the tool in the slot of the insert. Both the insert
and the hole should be thoroughly cleaned with a solvent to remove all traces of oil or
contaminants from fingerprints. A drop of cement is placed on the insert· externai
threads, and the insert is screwed into the hole.
If properly installed, the upper surface of the insert should be about 0,1 mm (0,005 in)
below the surface. If an insert is damaged, it can be unscrewed with the same tool. It is
advisable to heat the insert with a soldering iron to weaken the cement before unscrew­
ing the insert.
3.5. FIXTURES
It will almost always be necessary to prepare some sort of fixture to act as a transition
from the Exciter to the test object. This is because the test object is usually attached at
those places where it will be fixed in service, in order to duplicate field conditions, and
these attachment points will seldom match those of the Exciter.
The fixture may be a simple plate with holes for bolting to the Exciter and for mounting
the test object, or it may be a very complicated structure. Whether simple or complex, its
main function is to convey the force generated in the Exciter to the test object, and there­
fore its performance can be crucial to the test .
It is beyond the scope of this book to do a comprehensive study of fixtures . However, if
there are enough interested persons in a given geographical area, courses in fixture de­
sign can sometimes be arranged. Contact your B & K representative for more informa­
tion.
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