pumping unit 1.standard:API Spec 11E 2.the best price 3.deliver promptly 4.high quality service pumping unitSTRUCTURE FEATURE Based on the original four bar mechanism of walking beam pumping unit,we mount the equalizer on the upwards of walking beam,the rear end of walking beam is bent and adding a barbell at the downwards of walking beam,combined with crank balance to become a compound balance, ...