| Loosening by cutting
Boring grab
This method
was developed from the form of a shovel. Thus, the semicircular shaped
shovel of a grab penetrates into the soil, whereby the dead weight of
the grab compensates the upward directed forces caused by the closing
action of the shovels.
Driving the shovels into the soil can increase grab penetration. If the
shovels are properly supported on the main frame of the grab, they can
also be successfully used in very stiff strata as a form of a chisel.
Cutting
teeth for rotary drilling
During rotary
drilling, inclined cutting teeth are rotated horizontally. The quantity
of soil loosened during each rotation varies in accordance with the incline
of the teeth. The incline of the teeth also causes the drilling tool to
pull itself downward into the soil, provided adequate torque is applied.
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