Problem

The fact that there are no road traffic regulations on construction sites makes it all the more important for construction machine drivers to have good all-round visibility. That's not always easy. The field of vision is very limited, especially in very wide excavators or wheel loaders. To achieve a full view of his surroundings, the driver must stop the vehicle and leave his seat. The operating concept from Gessmann is based on offering the driver the highest possible flexibility by moving his control position
W. Gessmann GmbH's development objectives were clear: the driver's seat should be rotated around its own axis and also moved transversely to the direction of travel. The operator should be able to change position within seconds in order to regain an overview of the entire machine environment as quickly as possible. In addition to the high level of flexibility, the operating concept must also withstand the harsh construction site conditions and be extremely low-maintenance. 
Originally, the design was to be guided using recirculating ball bushings and a stainless steel guide shaft. However, due to the hardened steel balls rolling over the polished stainless steel guidance, this system was not ideal for the planned application. Because construction machines vibrate strongly, which can cause the steel balls to damage the stainless steel shaft, thereby increasing the displacement force and greatly reducing the service life.

Solution

Instead of recirculating ball bushings, Gessmann uses drylin W guide rails for seat adjustment, on which drylin hybrid double roller bearings run. These prove to be a long-lasting solution, especially when it comes to use on construction sites. The tribologically optimised high-performance plastics are light and corrosion-free and, above all, do not require external lubrication. This increases the service life in moving applications because no adhering dirt affects the bearing point. The Gessmann developers also came to this conclusion after the first tests with the bearings. But advantages in construction were also achieved. The small installation space of the drylin W series allows the guide system to be attached below the machine base. This means the system is better protected from the weather and heavy contamination. Overall, the drylin bearings are also cheaper compared to recirculating ball bushings with stainless steel guide shafts. Both in terms of the purchase price and ongoing maintenance costs.