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<p>The thumpers, or as Geophysical Services Inc. called them,
stompers, replaced the use of explosives for taking readings of
what was down below the surface, particularly oil, and possibly
natural gas. GSI was a division of Texas Instruments where I
worked from 1968 until 1987. We occasionally had articles about
what they were doing in our company newsletter.</p>
<p>Phil in TX<br>
</p>
<br>
<div class="moz-cite-prefix">On 7/25/2020 7:44 PM, Howard Pletcher
wrote:<br>
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<div class="gmail_default"
style="font-family:tahoma,sans-serif">Very interesting.
Thanks for your info. When I was at IH/Navistar, I know
some trucks were used as thumpers, but had no idea just what
they did--and after a little searching, now see what is
being done, but still don't begin to understand how it tells
the geologists anything. </div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif">Where are the trucks
you worked with built? What engine powers them?</div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif">I am continually
amazed by the wide variety of expertise accumulated by us
"dumb farmers that play with old tractors", haven't seen any
brain surgeons on here yet, but I wouldn't be surprised if
one pops up. Very interesting group.</div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default"
style="font-family:tahoma,sans-serif">Howard</div>
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<div dir="ltr" class="gmail_attr">On Sat, Jul 25, 2020 at 1:08
PM ustonThomas Mehrkam <<a
href="mailto:tmehrkam@sbcglobal.net" target="_blank"
moz-do-not-send="true">tmehrkam@sbcglobal.net</a>>
wrote:<br>
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Neue",Helvetica,Arial,sans-serif;font-size:16px">
<div dir="ltr">The ones we used in the vibrator trucks
were rated for over 300 hp and cost only $32,000 each.
We used them to make it easyier to control the spacing
between trucks. Had ultrasonic sensors to measure the
distance between the trucks. They operated as an array
and spacing was important. Some array designs had
different spacing between each truck.</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">The hydrstatic transmission was much easier
to precisely control spacing between trucks. Three to
five trucks in an array was common and there would be
multiple fleets of trucks that would stop shake the
ground then pull up the pad and move forward to the next
shot point. While they were moving another fleet would
shake the ground. Speed things things up a bit. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">The older trucks were built on Mac Truck
chases with normal transmissions. Not having a drive
shaft from the front and rear drive allowed putting a
bigger vibrator in the middle to get more signal. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">In the US the wheeled version is common.
Some places use the tracked version.</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">This is the company I use to work for. The
name changed many times. When I joined the name changed
to Geosource that was the name it was know by for many
years.</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><span><a
href="https://www.inovageo.com/products/category/source-products/vibrators"
rel="nofollow" target="_blank"
moz-do-not-send="true">https://www.inovageo.com/products/category/source-products/vibrators</a></span><br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr"><span><a
href="https://www.youtube.com/watch?v=8EVilzqcggk"
rel="nofollow" target="_blank"
moz-do-not-send="true">Seismic Vibrator truck</a></span>
<div><br>
</div>
<div
id="m_-4842885578549511306m_1472968588542696885gmail-m_4105975687844552525ydp799752a1enhancr_card_5974204822"
style="max-width:400px;font-family:YahooSans,"Helvetica
Neue","Segoe
UI",Helvetica,Arial,sans-serif"><a
href="https://www.youtube.com/watch?v=8EVilzqcggk"
style="text-decoration:none;color:rgb(0,0,0)"
rel="nofollow" target="_blank"
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style="background:rgb(255,255,255);width:100%;max-width:400px;border-radius:0px
0px 2px 2px;border-top:1px solid
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cellpadding="0" align="center"
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<tbody>
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<td
style="background-color:rgb(255,255,255);padding:16px
0px 16px
12px;vertical-align:top;border-radius:0px
0px 0px 2px"><img
src="https://s.yimg.com/nq/storm/assets/enhancrV2/23/logos/youtube.png"
style="min-width:36px;margin-top:3px" moz-do-not-send="true" height="36"></td>
<td
style="vertical-align:middle;padding:12px
24px 16px
12px;width:99%;font-family:YahooSans,"Helvetica
Neue","Segoe
UI",Helvetica,Arial,sans-serif;border-radius:0px
0px 2px">
<h2
style="font-size:14px;line-height:19px;margin:0px
0px
6px;font-family:YahooSans,"Helvetica
Neue","Segoe
UI",Helvetica,Arial,sans-serif;color:rgb(38,40,42);max-width:314px">Seismic
Vibrator truck</h2>
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</a></div>
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