A baling machine including: a knotter and needle combination, the combination comprising one or more knotters corresponding in number to the needles; a cyclic needle drive (77, 78, 43); a bale-forming chamber that supports a longitudinally reciprocable bale-forming plunger, the bale-forming chamber being penetrable by the one or more needles supporting one or more lengths of twine for knotting bales, the one or more needles being pivotably mounted via the cyclic needle drive (77, 78, 43) for reciprocal movement into and out of the bale-forming chamber, and a knotter drive shaft supporting and driving the one or more knotters the knotters each being capable of engaging twine supported by a respective needle penetrating the bale-forming chamber and describing a knot-forming locus when driven by the knotter drive shaft, wherein: a. the cyclic needle drive (77, 78, 79, 43) and the knotter drive shaft include one or more drive train permitting selective independence of the cyclic needle drive (77, 78, 79, 43) from movement of the knotter drive shaft and/or adjustment of timing of the cyclic needle drive (77, 78, 79, 43) relative to activation of the knotter drive shaft; b. the baling machine includes one or more sensors (40, 45, 46, 51, 52, 53, 54, 57, 62) for sensing conditions prevailing in the baling machine and generating one or more signals indicative thereof; c. the baling machine includes one or more control devices that determine, based on the one or more signals, the operational status of the knotter and needle combination and that command operation or deactivation of one or more sub-systems of the baling machine in dependence thereon; and d. the one or more control devices is configured to control motion of the needles 38 and action of the knotters 39 in dependence on the sensed conditions and/or operational statuses of parts of the baling machine characterized in that the baling machine further includes a trip drive motor that is selectively operable and that when operated completes a drive cycle that causes engagement of driving of the knotter drive shaft and activation of the cyclic needle drive (77, 78, 79, 43); and wherein the one or more sensors includes a sensor sensing operation of the trip drive motor. a knotter and needle combination, the combination comprising one or more knotters corresponding in number to the needles; a cyclic needle drive (77, 78, 43); a bale-forming chamber that supports a longitudinally reciprocable bale-forming plunger, the bale-forming chamber being penetrable by the one or more needles supporting one or more lengths of twine for knotting bales, the one or more needles being pivotably mounted via the cyclic needle drive (77, 78, 43) for reciprocal movement into and out of the bale-forming chamber, and a knotter drive shaft supporting and driving the one or more knotters the knotters each being capable of engaging twine supported by a respective needle penetrating the bale-forming chamber and describing a knot-forming locus when driven by the knotter drive shaft, wherein: a. the cyclic needle drive (77, 78, 79, 43) and the knotter drive shaft include one or more drive train permitting selective independence of the cyclic needle drive (77, 78, 79, 43) from movement of the knotter drive shaft and/or adjustment of timing of the cyclic needle drive (77, 78, 79, 43) relative to activation of the knotter drive shaft; b. the baling machine includes one or more sensors (40, 45, 46, 51, 52, 53, 54, 57, 62) for sensing conditions prevailing in the baling machine and generating one or more signals indicative thereof; c. the baling machine includes one or more control devices that determine, based on the one or more signals, the operational status of the knotter and needle combination and that command operation or deactivation of one or more sub-systems of the baling machine in dependence thereon; and d. the one or more control devices is configured to control motion of the needles 38 and action of the knotters 39 in dependence on the sensed conditions and/or operational statuses of parts of the baling machine a. the cyclic needle drive (77, 78, 79, 43) and the knotter drive shaft include one or more drive train permitting selective independence of the cyclic needle drive (77, 78, 79, 43) from movement of the knotter drive shaft and/or adjustment of timing of the cyclic needle drive (77, 78, 79, 43) relative to activation of the knotter drive shaft; b. the baling machine includes one or more sensors (40, 45, 46, 51, 52, 53, 54, 57, 62) for sensing conditions prevailing in the baling machine and generating one or more signals indicative thereof; c. the baling machine includes one or more control devices that determine, based on the one or more signals, the operational status of the knotter and needle combination and that command operation or deactivation of one or more sub-systems of the baling machine in dependence thereon; and d. the one or more control devices is configured to control motion of the needles 38 and action of the knotters 39 in dependence on the sensed conditions and/or operational statuses of parts of the baling machine characterized in that the baling machine further includes a trip drive motor that is selectively operable and that when operated completes a drive cycle that causes engagement of driving of the knotter drive shaft and activation of the cyclic needle drive (77, 78, 79, 43); and wherein the one or more sensors includes a sensor sensing operation of the trip drive motor.