Patent ID: 7178273

Claim:
A trench wall cutter comprising: trench cutting means for cutting trenches of rectangular cross-section in the ground in order to carry out underground construction work, the trench cutting means including: first, second, third, and fourth cutting wheels drivable in rotary manner in first and second oppositely directed rotation directions, wherein the first and second cutting wheels are arranged in a first pair in rotary manner about a first common rotation axis, the third and fourth cutting wheels are arranged in a second pair in rotary manner about a second common rotation axis, and the first and second common rotation axes are parallel to each other, at least one first cutting means, located on each cutting wheel, for removing soil material during a rotation of the cutting wheel in a first rotation direction, and at least one second cutting means, located on each cutting wheel, for removing soil material during rotation of the cutting wheel in an oppositely directed, second rotation direction, at least one of the cutting means on each cutting wheel being displaceably mounted between a first position for removing soil material and a retracted, second position and control means for displacing the cutting means between the first position and the second position.