fig1 a , 1 b show a perspective representation of the ballast apparatus 10 in accordance with the invention . it is suitable for attachment to the rear of a crane superstructure so that the ballast apparatus 10 or the ballast 23 taken up is arranged at the crane in the opposite direction to the payload and counteracts the tilting torque active by the load . the ballast apparatus 10 is consequently a rear ballast . the apparatus 10 comprises a base plate 20 at which two ballast towers 21 , 22 are pivotably arranged . the ballast towers 21 , 22 each comprise a plurality of ballast plates 23 stacked on one another . the ballast apparatus 10 can be installed at the crane superstructure in a conventional manner with the aid of the base plate 20 and can , for example be bolted to the superstructure frame via suitable bolting positions . the representation of fig1 a shows the ballast apparatus 10 in the regular starting position in which the ballast towers 21 , 22 are pivoted to the side . in this state , the ballast apparatus 10 corresponds with respect to the physical dimension to a conventional rear ballast in crawler - mounted cranes which is installed at the rear of the superstructure . fig1 g reflects the key idea of the present invention according to which both ballast towers 21 , 22 can be pivoted to the rear . in this position , the spacing between the superstructure and the ballast plates 23 is at a maximum so that the total center of gravity of the ballast plates is changed with respect to the crane . it is thus possible to react flexibly to changed payload situations of the crane by pivoting the ballast towers 21 , 22 and indeed all the more since the pivot mechanism of the ballast towers 21 , 22 allows a continuous pivoting over a pivot radius of approximately 90 °. the possibility of a flexible displacement of the center of gravity increases the stability of the machine and as a further consequence reduces the ground pressure present or distributes it more evenly over the contact area . conversely , larger tilting torques can be transmitted with an unchanged stability . a further substantial advantage can also be found in the fact that the base ballast can be reduced with the same stability . this reduces the machine &# 39 ; s own weight and thus the ground pressure overall . the significantly reduced machine width with outwardly pivoted ballast towers 21 , 22 ( fig1 b , 2 b ), which allow a passing through of narrow points without a complex and / or expensive dismantling of the rear ballast , is to be listed as an important secondary function . this saves equipping time and thus increases the operation readiness of the machine . the specific design of the ballast apparatus 10 will now be explained further with reference to fig2 and 3 . the pivotable rear ballast 10 is based on the base plate 20 to which carrier arms 24 , 25 are connected in an articulated manner pivotable about the vertical axes a , a ′ via a finger - type fork connection 27 . carrier plates 7 , 8 , on whose surface ballast plates 23 can be stacked , are provided at the free end of the carrier arms 24 , 25 . the base surface of the carrier plates 7 , 8 substantially corresponds to the base surface of the ballast plates 23 . both carrier arms 24 , 25 are thus connected in an articulated manner pivotable about vertical axes a , a ′ offset laterally from one another . a lift cylinder 9 serves the actuation of the ballast towers 21 , 22 in the embodiment of fig2 and 3 . the piston rod or the eye of the piston rod of the lift cylinder 9 is connected in an articulated manner pivotably at an actuation lever 11 of the first pinion 1 at the end side . the linear movement of the lift cylinder 9 is thereby converted into the required rotational work of the pinion 1 . a coupling rod 6 , which serves the force transmission of the force applied via the lift cylinder 9 to a second pinion 2 , is likewise rotatably supported at the actuation lever 11 . this pinion 2 likewise comprises an actuation lever 26 which is pivotably connected at the end side to the coupling rod 6 . the toothed arrangement of the pinion 2 engages into a further gear 4 such that the toothed arrangement 5 of the left carrier arm 24 meshes . the pinion 1 accordingly meshes with a toothed arrangement 3 of the right carrier arm 25 . the ballast towers 21 , 22 are pivoted behind the base plate 20 by the extension movement of the piston rod of the cylinder 9 , while the retraction movement of the piston rod results in the position of the ballast towers in accordance with fig1 a , 2 a . alternatively to the variant shown , rotary drives can also be provided instead of the lift cylinder 9 which drive corresponding pinions 1 , 2 , 4 directly . in this respect , either a separate rotary mechanism is provided for each pinion 1 , 2 , 4 or the pinions 1 , 2 , 4 are mechanically coupled as shown via a linkage 6 so that one common rotary drive is sufficient . the effects on the crane payloads due to the continuous displacement of the center of gravity of the ballast are calculated online and output via the crane software . the load torque limitation of the crane control can thus be ideally utilized in every ballast position . either the stroke of the hydraulic cylinder 9 or the angle of rotation of the ballast towers 21 , 22 can be measured for the calculation of the position of the ballast towers 21 , 22 . to hold the arbitrary continuous location of the ballast towers 21 , 22 in a secure position , the hydraulically actuated lift cylinder 9 is equipped with a lowering brake . the rotary encoder is equipped with a redundant cam limit switch to secure the angle measurement .