Apparatus for generating an electrical signal which is proportional to the tension in a bridle

In a pump jack unit having a motor controlled by a switch means, said pump jack unit includes a bridle which has two spaced load carrying bridle cables, the improvement comprising:

• an apparatus for generating an electrical signal which is proportional to the tension in the bridle cable, said apparatus includes a main frame, a load cell which generates an electrical signal proportional to the load imposed thereon when the load cell is placed in compression, means by which said load cell is supported by said frame;
• means including a first attachment arm extending perpendicular to one bridle cable by which said frame is connected to said one bridle cable, means including a second attachment arm by which the other bridle cable is attached to the load cell to cause the load cell to be placed in compression when the bridle cables are placed in tension;
• means for adjusting the effective distance between the outer ends of said first and second attachment arms so as to bias the bridle cables within a plane which is perpendicular to the bridle cables;
• and further including a circuit means for controlling the switch means to the motor of the pumpjack unit;
• said circuit means is responsive to said signal for actuating said switch means when said signal is of a predetermined configuration, so that said circuit means can be used to de-energize the motor of a pumpjack unit whenever a pump-off condition is encountered.