BRUEL & KJAER 2305 - Page 16

connected to Drive Shaft I via a special Flexible Shaft VB 0040 or in the
case of the combined instruments, which are mounted together in a steel
cabinet, via a chain drive. When the B & K Audio Frequency Spectrometer
Type 2112 or the Band·Pass Filter Set Type 1612 are employed the filter
switching of th ese apparatuses is also con troll ed from Drive Shaft I but in
this case electrically via a microswitch (vide Figs. 1.6 and 1.8). The switch can
be removed from touching the cam disc by the screwdriver· operated Out-In
Control S accessible on the plate where the pilot lamp is situated, see also
Fig. 2.3. As both the speed of Drive Shaft I and the paper is controlled by
a single knob ( PAPER SPEED), Ihe speed may be changed during the
reeording of frequency response curves or spectrograms without upsetting
the synchronism between the Oscillator/Analyzer and the recording paper.
To avoid damage to the gear wheels , the torque supplied from Drive Shaft I
should not exceed 2 kg cm.
FrictIon Clutch. 'Vilh a view to giving easy and exact synchronization
he tween the starting point of a recording on the recording paper and the
sca nning device of the connected oscillator or analyzer the paper rlrive
sprocket can be mo ved with respect to the position of Drive Shaft I by means
of a grooved finger wheel Z (vide Figs . 1.8 and 2.3) . This has been made
possible by the use of a friction clutch, see Figs. 1.6 and 1.8.
Single Chart. An important device which is controlled via the paper drive
spin(lIe is the automatic stop switch . This switch is operated by a cam disc
on the 1 : 10 Gear axle when the Gear is engaged (Lev er X pulled out) and
activates the electromagnetic clutch after one complete rot a tion of the axle.
Each rotation of the cam corresponds to one chart length of preprinted
reco rding paper (250 mm). Thus . as the automatic stop switch is connected
in the start-slop circuit of th e electromagnetic clutch the recording of single
cha
rts is made possible .
DrIve Shaft II. Since the speed of this shaft is independ e nt of the paper
speed as is mentionl'd previously, any frequency response curve or spectro·
gram ('an he recorderl in an en la rged or compressed fr e quency scall'. providing
the Oscillator or Analyzer controlling the Recorder input signal is driven
from Drive Shaft 11 instead of from Drive Shaft T. The DRIVE SHAFT
SPEED and the PAPER SPEED have the same numher of positions, Ihal
means if they are bolh se t in the same position (examp le PAPER SPEED on
"10/1" and DrnVE SHAFT SPEED on "12") the two Drive Shafts T and IT will
rolale at Ihe same speed.
The safe torque supplied from Drive Shaft II is the same as specified for
Drive Shaft T.
It is also possible to us e DRIVE SHAFT II with the combined units when the
accesso ries VT 0018 are fitt ed to the Level Recorder. See rlescriplion at the
beginning of chapter 5.
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