The present invention relates to a side-bar chain for infinitely variable cone pulley transmissions of the type composed of packs of side bars forming the chains links articulatedly connected with one another and thrust pieces acting transversely of the longitudinal direction of the chain for the transmission of friction force between cone pulleys and side-bar chain.
Such side-bar chains are known in many forms. Thus, as disclosed for example in U.S. Pat. No. 3,089,346, they can be composed of thrust pieces for friction force transmission between the articulation points formed by rocker piece pairs, which thrust pieces extend transversely through the pack of side bars, and clamp straps which laterally hold these thrust pieces together, transversely of the longitudinal direction of the chain, in an aperture formed for this purpose, in order to come into frictional contact via their ends with the cone pulleys.
In other known chains as disclosed, for example, in U.S. Pat. No. 3,364,767 where the packs of side bars forming the chain links are articulatedly connected with one another by joint bolts and then between the respective joint bolts for example T-shaped thrust pieces serving for friction force transmission are pushed into the packs of side bars.
More recently proposed side-bar chains, such as those disclosed in U.S. Pat. Nos. 3,353,421 and 3,916,709 make use of pairs of rocker pieces forming the joint at the same time as thrust pieces, which also come into frictionally engaging contact with the cone pulleys, for power transmission.
Another form of construction is described in Federal Republic of Germany Gebrauchsmuster (Utility Model) No. 1,979,429. Here again there are packs of side bars which form each chain link and are connected with one another by joint bolts. Between the joints the side-bar packs are surrounded by thrust rings which are rotatable about the side-bar pack about an axis parallel with the longitudinal direction of the chain, and come into frictional contact with the cone pulleys.
The above-mentioned examples of the prior art show that fundamentally with the initially stated classification all side-bar chains for cone pulley transmissions are to be covered, irrespective of the details of their construction.
One burdensome phenomenon in cone pulley transmissions where the force transmission takes place through individual thrust pieces of a chain is the noise which is generated. Its occurence is mainly attributable to the fact that impacts occur between the thrust pieces and the cone pulleys when the chain enters the V-gap of a pair of cone pulleys. On account of their high quality, the cone pulleys are predominantly bodies of good resonance which correspondingly promote the generation of noise. These noises become especially burdensome if the frequency of the entry impacts of the chain stimulates the cone pulleys into sympathetic, or resonant vibrations.
Apart from the burden of noise, a further trouble consists in that the irregular movements caused by sympathetic vibrations are transmitted further from the transmission and, for example in a production process, can impart corresponding irregularities to a workpiece being machined or the like.