The grab slewing crane in the Hildesheim port, manufactured in 1988, is primarily used for the loading of scrap metal. In the autumn of 2006 it was taken out of operation due to technical defects.
Emotron was contracted to develop a completely new drive concept. The solution was based on Emotron VFX variable speed drives and a unique grab control system.
Ralf Teichmann GmbH, a long-time partner of Emotron, was the subcontractor for the assembly. The employees of the port company lent a helping hand during the disassembly of the old motors and the cabinets as well as during the installation of the new equipment cabinets.
Only four signals are required for the grab operation: hoist, lower, open and close
The commissioning of all drives, including a load test, took three days.
Included in the delivery was the complete cabinet equipment for the engine room, Emotron VFX variable speed drives and grab control system, brake resistors, standard asynchronous motors as a replacement for the old slip-ring motors, disassembly respectively assembly, wiring of the new motors and commissioning.
Existing components incorporated in the new concept were crane disconnection switches, long travel motors, slip-ring system, illumination and climate-control in the engine room, the cabin and the complete mechanical system including the brakes, the magnet system and the wiring.
The employees of the port company lent a helping hand during the disassembly of the old motors and the cabinets as well as during the installation of the new equipment cabinets
The four-rope grab is controlled by the Emotron electro-nic grab control. It coordinates the two drives controlling the hold and close motors. For the crane operator, the crane works as if there were only a single hoisting device with the additional functions of “open” and “close”.
Setting the nominal grab positions only has to be performed once after a change of a rope or grab unit. Only four signals are required for the grab operation: hoist, lower, open and close. A joystick with the corresponding contacts delivers the signals.
The individual functions can be combined in any order. An integrated position control ensures that the two hoisting devices move correctly towards each other at the correct rate at all times.
To reduce cycle times and reduce stress on ropes, the grab can be closed or opened while being hoisted and lowered. Furthermore, a slightly opened grab can be hoisted and lowered.
The grab slewing crane in the Hildesheim port, manufactured in 1988, is primarily used for the loading of scrap metal. In the autumn of 2006 it was taken out of operation due to technical defects
In order to keep the grab securely closed, the torque of the close motor must always be slightly higher than the torque of the hold motor.
The application was configured using Emotron’s combined crane control system and operator panel PP41 that is built into the crane cabinet. The operator can adjust the grab settings as well as monitor control signals and current values. Parameters are set during commissioning of the system.
