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"Thanks to iglidur® plastic bearings and igubal® rod end bearings, the company was able to save at least 15,000 U.S.$ a year in production costs and considerably reduce assembly times."
For this fitness equipment, pivot bearings for the chain tensioner were required on all types. The machine has a drive train consisting of upper and lower pedal cranks for arms and legs. The pedal cranks are connected and drive a resistance load via a rol e-chain®. To ensure alignment between the sprocket teeth, the axial location was adjusted and varied from machine to machine. This increased assembly time and complicated field service. As the teeth wore down, this caused the chain line to vary dynamically during operation and caused excessive noise and possible chain jump out.
In addition, the crank arms also had to be adjusted to the height of the upper body. The earlier bearing design required a high degree of precision that could not be achieved by machine. Therefore, the matching was done by hand to match the crank arm slots with the corresponding dovetail slots. Any small curvature or misalignment due to impact affected the performance of the adjuster.
A third application on a brand new training device involved a dynamically variable length crank arm for use on a training bike. It varies during a cycle depending on the foot position of the user via a cam roller. An earlier prototype optimised an expensive custom in-line roller bearing, but that solution continually failed due to constant misalignment, bending, and noise. Resizing the structure proved to be too expensive. The solution was to find a suitably durable, rigid and tool-free design.
The use of iglidur W300 bearings in the chain tensioner today enables both axial and rotary movement of the roller. This eliminates the need for time-consuming alignment during installation. The result is faster assembly, easier service and no more chain jump out.
For the adjustment of the cranks at the height of the upper body, parallel guide rods have been developed which allow a torsion-resistant linear movement. iglidur W300 bearings were used in pairs, spaced apart for each rod, to enable a linear motion with low friction, high service life and minimum space requirement between bearing and rod. Due to the low installation height, rigidity is achieved, noise is minimised and the steel bars are less susceptible to damage. All crank arms can be connected to each stroke by machine; thus eliminating the need for hand tuning.
For the last application on the prototype, a design consisting of a crank arm bearing with a set of iglidur W300 ball bearings was developed, which slides along a pair of parallel steel rods. Also included is an igubal ball bearing that activates a steel pin attached to the crank arm bearing. The crank arms are now sufficiently stiff and misalignment due to inaccuracies in the bike frame and assembly, as well as user loading, is compensated for without placing extreme stress on the machine and crank mechanism as was the case with previous prototypes.