One technique for figuring out a soil's consolidated drained shear strength is the direct shear test. In order to conduct the direct shear test, a vertical load is applied to the sample inside a horizontally split box. A shear load is detected on a load measuring equipment when the two sides of the box are "pulled" apart in relation to one another after the vertical force has consolidated the sample.

Failure occurs and the load quickly decreases when the soil has been sheared to its shear strength. Under various vertical weights, this process is repeated (often three times). After that, engineers may design slopes, dams, foundations, and other structures by drawing a "failure envelope" on a graph.

A gear box-type loading jack applies the shear force at rates ranging from 0.001 to 1.2 mm/min in 0.001 increments by setting the appropriate speed rate, which is represented by a crystal display. To measure residual shear, reverse the direction. A proving ring with a dial measures shear force. Vertical loads are applied by attaching weights to a lever with a hanger. The machine is outfitted with micrometer dials and a proving ring complete with dial and weights.