The non-destructive inspection of large concrete walls is still an unsolved problem. One possible technique is to use driven wheels for the propulsion and a vacuum system for the adhesion. The seals for the vacuum chambers are slipping over the rough surface, therefore it is not guaranteed that the chambers are always airproof. Especially over concrete walls a special seal construction must be found to make the adhesion more safe. On the other side the propulsion system must be able to produce enough force for carrying and accelerating the robot to a suitable velocity. This paper will present the climbing robot Cromsci which uses the described techniques. The propulsion system consists of three omni directional driven wheels which are airproof and completely rotatable and has been presented in earlier papers before. For adhesion a vacuum system of seven controllable vacuum chambers and one reservoir chamber is used. This system including chambers and seals will be discussed in more detail. The rough and sharp-edged surface of concrete walls cause strong requirements to the sealing concerning leak tightness and attrition. Therefore, each sealing must be flexible to allow a good adaption to the ground but also let the robot slip when the wheels are turning.

Nowadays, radial shaft seals are more and more used in many products with a short or very short life cycle. As a consequence of the reduced durability, the demands on the sealing system decrease so that system components with a significantly lower resistance against wear can be used compared to conventional components. However, changing the resistance against wear of the radial shaft seals does not lead to any cost advantage. The situation in the production of the mating surface of the seal is quite different. Conventional manufactured shaft surfaces, for the use of dynamic radial seals have to be hardened and ground in a complex way, which increases the costs. By reducing these manufacturing processes to a pure turning procedure, a large part of the production costs can be saved.

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