| 摘要 |
<p>A pump jack pole (62) is comprised of an elongated metal tube (32) of rectangular configuration and a resiliently yieldable elastomeric strip (34) which is secured to one side of the tubing. The tubing (32) is comprised of an aluminum extrusion whereon there is formed a plurality of longitudinally extending closely-spaced parallel protrusions (40). The strip (34) is formed with a plurality of similarly spaced longitudinally extending grooves (50) of complementary configuration to the protrusions (40) which are interdigitated with the grooves (50).</p> |
