1. 
   pump jack
   a surface unit similar to a pumping unit but having no individual power plant. Usually, several pump jacks are operated by pull rods or cables from one central power source. Commonly, but erroneously, beam pumping units are called pump jacks. Compare beam pumping unit.
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
2. 
   Pump-jack
   A pump-jack is type of portable scaffolding system. The scaffold rests on supports attached to two or more vertical posts. The user raises the scaffolding by pumping the foot pedals on the supports. The scaffolding is used in construction. ...
   Found op http://en.wikipedia.org/wiki/Pump-jack
   
   
3. 
   Pumpjack
   A pumpjack (nodding donkey, pumping unit, horsehead pump, rocking horse, beam pump, sucker rod pump (SRP), grasshopper pump, thirsty bird, jack pump, popping johnny) is the overground drive for a reciprocating piston pump in an oil well. It is used to mechanically lift liquid out of the well if the...
   Found op http://en.wikipedia.org/wiki/Pumpjack
   
   

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