The tasks of cranes in picking up loads and setting them down gently at a precise location requires special drives and integrated brakes as well as a frequency inverter technology, which ensures a soft start and generator braking via defined adjustable ramps. Smooth motion with high positioning accuracy is essential - and is often required with the simultaneous movement of the crane and the trolley as well as the control and synchronous operation for travelling drives. This places the very highest demands on the drive systems used.
Throughout the world, manufacturers of cranes and trolleys rely on parallel shaft geared motors from NORD DRIVESYSTEMS with power ratings up to 200 kW and a wide range of gear ratios. Speeds are around 80 m/min for crane movement and 32 m/min for trolley movement, with accellerations of 0.2 m/sec. Two or three-stage basic types are available with hollow or solid shafts, in foot mounted, flange mounted or face mounted versions, each with the same housing. The unicase concept enables parallel shaft gear units with high output power and extremely compact gear unit dimensions. These in turn can be combined with many elements of the NORD modular system.
A further emphasis is on bevel gear units, usually with hollow shafts and torque arms. With this drive version, the large range of standard components also allows the gear unit to be precisely matched to the requirements of the application. In addition to the high efficiency of gear units with helical, parallel shaft, bevel and worm gears, there are further decisive benefits to operators: highest operational reliability, high output torques, high axial and radial load capacity, quiet running, high efficiency, reduced maintenance and longer operating life. Additionally, products with protection classes IP55 and IP66 as well as rust and dust-protected versions with a special coating are used. Furthermore, gear units may are also befilled with synthetic oil if the cranes are to be used at high temperatures, for example in foundries.