Exciter Support; Base; Side Supports; Trunnion Springs - BRUEL & KJAER System V Instruction Manual

If any of these malfunctions is detected the Exciter protection circuit operates, cutting off
the drive coil power and field coil power . The indicator lamp "Exciter" on the front panel
of the Power Amplifier will be lit to indicate that the malfunction is confined to the
shaker.
4.
4.3. EXCITER
S UPPO RT
The Exciter Support consists of three large parts , the Base and the two Side Su pports,
and a number of smaller parts associated with the connection of the Side Supports to
the Magnet Assembly of the Exciter Body .
4
4.3.1. Base
The Base , with the two Side Supports, provides the frame for th e exciter . 15 mm
(0 , 59 in) holes are provided in each corner of the Base on a 305 mm (12 in) square (see
Fig.2.4). These holes typically may be used to attach the exciter to a reaction mass to re­
duce Exciter Body motion , or alternatively , to hang the exciter upside -down from shock
cords for structural testing .
4.3.2. Side Supports
The Side Supports are bolted to the Base . These Side Supports provide the bearing sur­
face for the exciter trunnion assembly and act as a protective cover for the trunnion
springs .
4.3.3. Trunn ion S p ri ng s
The Trunnion Springs permit relative motion along the axis of the exciter , but restrict mo­
tion radially. When the exciter is used with slip tables, it is important that the table loca ­
tion is accurately repeatable . The high radial stiffness satisfies this requirement. In the
axial direction, th e resonance frequency of the unloaded exciter on the Trunnion Springs
is about 14Hz.
4 .3 .4 .
High Frequency Suspen sion Engagem ent Knob
The smaller of the two knobs in the top centre of each Side Support (Fig.4.3) is the High
Frequency Suspension Engagement Knob. When both of these controi knobs are at their
counterclockwise limit , the low frequency suspension is engaged. At the clockwise limit
a highly damped high frequency suspension is engaged .
These knobs should both be either fully clockwise or f u lly counterclockwise at all times .
There is no advantage to be had by leaving them in an intermediate position .
NOTE: The knobs should always be fully clockwise during transport.
4.3 .5 .
R otation Bearin g /Bra k e
The Rotation Bearing/Brake is a four segment wide rimmed wheel that acts both as a
bearing and as rotationai brake. As abearing, it rotates freely in a brass liner in the Side
Support.
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