Abstract: An inspection device is designed to inspect regions of machines, system components, and/or pipeline systems, the regions being inaccessible to persons. At least one drive carriage, and at least one additional carriage which has an inspection unit can be connected to the drive carriage via a joint unit. The drive carriage includes a housing, two wheels which are rotatably held on the housing about at least two rotational axes that are flush with each other, a first electric motor which has a first motor shaft and which rotates the first wheel, and a second electric motor which has a second motor shaft and which rotates the second wheel. Each electric motor rotates the respective wheel via a respective transmission, and the rotational axes extend between the motor shafts of the electric motors.

Abstract: The invention relates to a process for preparing silica-coated particles of an inorganic expanding agent, the silica-coated particles and their use. The silica-coated particles show a delayed release of the expanding agent particularly in alkaline medium and at elevated temperatures. They are therefore useful in the oil and construction industry.

Abstract: Coated inorganic expanding agent particles comprise a core of an inorganic expanding agent and a sol/gel-formed coating comprising a mixed oxide of two or more metals and/or metalloids, in particular a mixed oxide of silicon and at least one metal and/or metalloid selected from aluminum, boron, titanium, zirconium and zinc. The coated inorganic expanding agent particles are added to cementitious systems to avoid shrinkage during hardening. The coating is effective to delay the expanding effect.

Abstract: The invention relates to a process for preparing silica-coated particles of an inorganic expanding agent, the silica-coated particles and their use. The silica-coated particles show a delayed release of the expanding agent particularly in alkaline medium and at elevated temperatures. They are therefore useful in the oil and construction industry.