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Geoprobe® Automatic Drop Hammer Overview


The DH105 Automatic Drop Hammer is equipped for Standard Penetration Testing (SPT) work. The easy-to-use drop hammer hydraulically swings out over the borehole after the combo head is sideshifted away from the tool string. The DH105 comes standard with a 140 lb. slug, or can be equipped with slugs ranging from 100 to 340 lb., depending upon your needs.

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Geoprobe® automatic drop hammer are used to collect Standard Penetration Test blow counts for geotechnical projects. The results of the blow counts are used by engineers for obtaining strength and density properties of soil, designing foundations, and defining earthquake sensitive soils. An SPT test is the most common in situ geotechnical test in the US.

The optional automatic drop hammer is easily mounted on most Geoprobe® rigs, ranging from the smaller 6712DT up to the larger sonic rigs. The automatic drop hammer swings into place, allowing for quick and easy changes between environmental and geotechnical applications. This also allows you to move the drop hammer into place over hollow stem augers without repositioning the whole machine.

All automatic drop hammers from Geoprobe® conform to ASTM standard D1586, which specifies using a 140 lb. weight. Expansion kits are available to meet weight requirements for other specifications. For the ASTM D1586 method, the 140-pound weight has a 30-inch free fall before making contact with the anvil. This is repeated at a rate of 60 blows per minute. The SPT blow count is the number of blows of the automatic hammer required to advance the split spoon sampler 6 inches (305 mm).

A weight throw height window at the top of each drop hammer allows operators to visually verify that the weight is falling from the height specified by ASTM D1586. The drop hammer is operating within this specification as long as the drop height begins within the shaded area.

Each hammer operates in a consistent manner that provides repeatable, accurate results. No cables or ropes are needed for operation as it is powered by the auxiliary hydraulics on the rig.

Safety was a prime consideration during the development of the Geoprobe® automatic drop hammer. All moving parts and impact surfaces are enclosed in a steel housing for safety. When not in use, you can swing and secure the drop hammer away from your work spaces or remove it completely from the machine within minutes.

Geoprobe® rigs are designed for flexibility on a job site, allowing for environmental and geotechnical applications to be completed with the same rig. As the drop hammer is designed to hydraulically swing into place, SPT tests can be completed quickly alongside additional applications.

For more information, visit our website or call us at 785-825-1842.

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