A small component disabled the Kobelco RK 450. The operator wanted to add some more reverse(backup) lamps, and conected 2 piece 70W halogen headlights to the original wiring. This caused an owerload in the printed circuit board, and the system for communication between upper and lower, had an fatal error. The crane was only able to be operated in a emergency mode, and most of the functions were not possible to use, like 4wheel-drive, multi-steering, and all signals from the engine. The outriggers had to be operated from the manual controllers. The problem was located in the card for controlling all relays on the under part of the crane. An output on a relay-driver was short-circuited, and this again caused incorrect combinations in the transmission controllers. A system that watch over all errors in the system, immediately shuts down the data transfer between upper and lower crane-part, to avoid all wrong actions. After locate and replace of the IC (integrated circuit), the communication was back to normal. This is an example where a part costing almost nothing, may stop a big machine.
My personal opinion, regarding all cranes with data-communication between upper and lower is quite simple. Do not become an owner of any crane, without checking the electrical system carefully. www.mobilcrane.com
Rev. 20080224 www.mobilcrane.com