TM 5-3895-363-13&P
16. SAXIMETERTM
16.1 INTRODUCTION
The SAXIMETERTM stroke indicator is an electronic
instrument that (a) detects the occurence of an
impact; (b) determines the duration between con-
secutive blows, At; (c) converts At to the corres-
ponding fall height or stroke of an Open End Die-
sel ram; (d) counts blows; and (e) determines
average stroke values. The current model contains
two methods by which the occurrence of the blow
is detected; the first is a manual pushbutton and
the second is a sound recognition circuit.
The conversion from At to the fall height is made
using an equation derived from both field observa-
tion and laboratory analysis and is based on a free
fall assumption with a built in correction for fric-
tion and precompression. Comparisons with field
results indicate that the equation predicts well
within ±0.3 feet.
It must be emphasized that only open end diesel
hammers have both upward and downward free
fall ram motion. However, the SAXIMETERTM
Stroke Indicator can effectively be utilized to moni-
tor other hammer types by converting the indicat-
ed stroke value to blow rate, BR, using either Fig-
ure 39 or 40 on page 25. Blow rate has the
dimension blows per minute (BPM). The highest
blow rate measurable by the SAXIMETERTM Stroke
Indicator is 85 BPM.
16.2 OPERATION
Several circuits and controls are built into the
SAXIMETERTM stroke indicator. The following de-
tails for proper operation are dealt with in this sec-
tion (see also Figure 37).
(1) Power Switch (BAT)
(2) Microphone Switch (MIC) and External
Microphone
(3) Sound Level Adjustment (I, II, III)
(4) Manual Trigger (M)
(5) Average Display Mode (A)
(6) Blow Display Mode (B)
(7) Warning Signals
16.3 DISPLAY MODES
16.3.1 MANUAL TRIGGER
There may be instances when no distinct
hammer sound can trigger the instrument;
for example, the hammer may be visible but
not audible, or the background noise ex-
ceeds the hammer SPL. In those cases the
instrument can be triggered manually by
depressing M quickly and firmly. “MIC”
should be switched off.
16.3.2 DISPLAY MODE B
All time increments,
, recognized by the
instrument and converted to stroke cause
the blow number to be incremented by one
and to display the the new stroke and its cor-
responding blow number. Note that the
blow number displayed is one less than the
number of actual impacts. Thus, if the blow
counter is used to obtain a driving log, one
blow has to be added to the number dis-
played. The maximum blow number is 999.
After exceeding this upper limit, counting
restarts at 0.
Figure 37
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