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DH-Series Automatic Drop Hammers

DH100The days when you had to choose a machine based on whether you wanted to do environmental or geotechnical work are fading fast. Now you can do both.

  • Need SPT blow counts for your customer? Use a Geoprobe® DH-Series Automatic Drop Hammer with your hollow stem augers or with the specially designed dual tube system by Geoprobe Systems®.
  • Going to a job where you won't need the automatic hammer? No problem. A couple of minutes is all it takes to remove it from your machine, or you can swing and secure the drop hammer away from your work spaces.


The Geoprobe® DH-Series Automatic Drop Hammers are an effective tool to collect Standard Penetration Test (SPT) blow counts with your Geoprobe® machine.

SPT BLOW COUNT consists of:

  1. Using a 140 lb. (64 kg) driving mass falling free from a height of 30 in. (762 mm)...
  2. Driving the standard split spoon sampler a distance of 18 in. (457 mm) into the soil, and...
  3. Counting the number of blows (N) to drive the sampler 12 in. (6 in. plus 6 in.) [152 mm plus 152 mm].

The hammer is powered through the auxiliary hydraulics on 66 and 77 Series Machines and is lifted into position using the probing cylinder. The inconsistency that has historically been a problem for the SPT test is minimized with the repeatable, accurate function of this hammer. The 140-pound weight has a 30-inch free fall before making contact with the anvil so every test is performed the same. And safety was a prime consideration during the development of this tool, so all moving parts and impact surfaces are enclosed in a steel housing.

What People Are Saying About the DH-Series Automatic Drop Hammers:

"The Geoprobe® 66 series track machine with the drop hammer has allowed us to complete work we typically would have used our skid rigs for."
-- Chris DeAngelis, Connecticut Test Borings LLC, Seymour, CT

"Our clients are very impressed with it [drop hammer]. We use it on ... inside work with low ceilings, sites with access restrictions, and tight areas."
-- Steve Burck, Env. Field Services, Westfield, IN 

"My clients are very impressed with how accurate the drop hammer is and how safe the hammer is for the operator to use."
-- Graham Bourke, South Western Drilling, Australia 

"The drop hammer is performing well. Sometimes we have to turn down geotech work to focus on our goal of environmental consulting."
-- John Graham, CTL Engineering, Columbus, OH 

"We're using our drop hammer in new developments and we're very satisfied. Our 6620DT leaves no tracks in the grass. We've even moved it on a barge to nearby job sites."
-- Chris Rismiller, Envirocore, Columbus, OH 

Features, Options & Accessories

  • Easy on / Easy off design!
  • Conforms to ASTM Standards D1586-99.
  • Operates from auxiliary hydraulics.
  • Consistent results with no human error.
  • No cables or ropes needed for operation.
  • All moving hammer components are enclosed for operator safety.
  • Hammer swings over hollow stem augers... no need to reposition the whole machine.
  • Operates at up to 60 blows per minute.
  • Throw height can be adjusted within seconds.
  • Use your Geoprobe® track machine for both environmental AND geotechnical projects.
  • Used to perform Standard Penetration Test (SPT) which is the most common in situ geotechnical test in the U.S.
  • SPT blow count results are used by engineers for obtaining strength and density properties of soil, designing foundations, and defining earthquake sensitive soils.
  • Use the Geoprobe® SPT dual tube system with the automatic hammer for SPT testing.
  • Mounts on most Geoprobe® 7730DT, and 6620DT machines with a minimum of initial field modification. 


Geoprobe® DH-Series Automatic Drop Hammer Specifications
  Standard Metric
Weight (hammer only - ASTM D1586) 140 lb. 64 kg
Weight (hammer unit) 470 lb. 213 kg
Height 63 in. 1,600 mm
Width 20 in. 508 mm
Depth 14.5 in. 368 mm
Cabinet Float/Travel Distance 31 in. 787 mm
Percussion Rate 60 blows per minute
Hydraulic Flow Rate 13 gpm 49 Lpm
Hydraulic Pressure Rating 2,500 psi 172 bar

*Unit specifications are subject to change without notice.




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