A wheelchair ramp was developed and installed at the front entrance of a low-floor bus. It is folded up after use. It contains one bearing for the drive unit, 2 bearings that are used as hinge points on the ramp and a cylindrical plain bearing in the chain tensioner.
Criteria for the application of plastic plain bearings were:
exposure with road environment outdoors
Insensitive to dirt
lubricant-free operation required
plastic bearings reduce the maintenance costs and are more cost-effective than bronze, bearing for bearing