Abstract: A wireline cable length measuring apparatus tracks the length and other parameters of a wireline cable in a well bore. The apparatus has three major components: a rotational distance measuring assembly; a rotation-to-length (rotation:length) calibration assembly; and a processor unit. The rotational distance measuring assembly engages the wireline cable in a manner similar to a standard wireline count wheel, typically receiving the cable from a draw works or a wireline service truck. The rotational distance measuring assembly has a rotation sensor which generates a rotation signal in response to the paying-out and reeling-in of the cable over the count wheel. The rotation:length calibration assembly also engages the wireline cable. However, the rotation:length calibration assembly only intermittently engages the wireline cable, and therefore is subject to substantially less wear than the counter wheel.

Abstract: This is a method and apparatus for monitoring the effective load carried by a crane having a luffing boom of variable effective length. The method includes generating a first signal corresponding to the magnitude of the load supported by the boom and then a second signal corresponding to the effective radius. Calculations are made to calculate a moment value and displaying same. This is then compared with a predetermined maximum permissible moment value and a warning signal is generated it if differs from the maximum load moment value by less than a predetermined amount.

Abstract: A magnetic pick-up device or other electrical output type sensor is operatively situated adjacent to a rotary part of the cable hoist assembly and produces impulses as the part rotates. These are conveyed to electronic equipment which, by use of the necessary calculator networks and the like, displays information such as upper and lower limits or positions of the cable hook and may include automatic cut-off devices for the hoist equipment. Also available is a display showing the total distance travelled by the cable both upwardly and downwardly and means to indicate when a predetermined distance has been travelled. Electronic equipment can also indicate the distance the load travels so that the operator can determine the location of the load relative to a reference point. Furthermore, the rate of travel of the cable as it applies to the penetration of a drill bit can be indicated.