Power transmission belt

A power transmission belt comprising:

• a body having a length, a width between laterally spaced side surfaces, an inside and an outside,
• the body comprising a first rubber composition in which at least one load carrying member is embedded and extends in a lengthwise direction,
• the body comprising a plurality of laterally spaced ribs extending lengthwise of the body and having exposed surfaces on one of the inside and outside of the body to engage a complementarily-shaped pulley to drive or be driven by the pulley,
• the ribs comprising a second rubber composition in which:
• a) a plasticizer of 8.3 to 10.7 (cal/cm3)1/2 in solubility parameter;
• and b) solid lubricant are respectively blended in an amount:
• i) 5 to 25 pts.wt.;
• and ii) 5 to 50 pts.wt. per 100 pts.wt. ethylene-α-olefin elastomer,
• the body further comprising short fibers in the second rubber composition implanted at the exposed, pulley-engaging rib surfaces directly against the second rubber composition without being mixed with and fully embedded in the second rubber composition,
• the ribs having a composition causing bleeding of the plasticizer to the exposed pulley-engaging rib surfaces and into the implanted short fibers to thereby reduce a coefficient of friction between the exposed pulley-engaging rib surfaces and cooperating pulley surfaces as the power transmission belt is operated.