Importance

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Abstract

A dual automatic leveling system for a blast hole drill during raising and lowering which includes 'fine' level sensors to detect an attitude within a fine level range and 'coarse' level sensors to detect an attitude outside a coarse level range which is greater than that of the first. A controller is connected to the sensors as well as to appropriate valving with a pressurized fluid source so as to operate hydraulic jacks. The jacks are activated in a first mode in conjunction with the 'fine' sensors and in a second mode in conjunction with the 'coarse' sensors. In a preferred manner, the 'fine' and 'coarse' level sensors are positioned as front, rear, and end level sensors mounted on the main frame of the blast hole drill. The 'fine' level sensors in conjunction with a programmable logic control will initially level the drilling platform within a .+-.0.5.degree. (both transverse and longitudinally). If during the raising or lowering process the platform becomes out of level by 2.degree. or more, the 'coarse' level sensors in conjunction with the programmable logic control will cause the raising or lowering process to stop and a re-leveling to .+-.0.5.degree. is effected before a raising or lowering is continued.

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First Claim