Maintenance of rolling gates is a major consideration since many of the components are underwater. This can be up to 70% of the components depending on the gate design. As such, rolling gates need to be designed to minimize maintenance requirements. The wear of the lower rail tracks is a major problem for many rolling gates including the Belgian locks. Therefore, like in Germany, special maintenance cofferdams were developed to provide access to these tracks and to enable the change of rails. The gate recess should also be designed as a dry dock with bulkhead provisions. Sediment and debris needs to be controlled as the gate moves across the lock chamber. The Belgian locks in Antwerp utilize mixers and a venturi system to keep sediment from settling as the gate is moved across the lock chamber. Condition monitoring of equipment is recommended for the drive machinery. Items of major and recurring maintenance include gear boxes, wire ropes, bearings (greased or greaseless), wear surfaces, lubrication, paint, anodes, and rails. Wire rope supports include both rollers and wear pads and both need to be designed to prevent damage to the wire rope. The guide roller system will reduce friction compared to a sliding system and will reduce the required power for the driving machinery. The wear on a guide roller is limited and the life time expectancy is high. Disadvantage for such a system is its reliability and required maintenance. For rack and pinion driven rolling gates, the alignment is a critical consideration and needs to be verified on a periodic basis. The lubrication of the drive system on rolling gates is a significant maintenance effort. Drive systems need to be designed with maintenance considerations in mind. The use of environmentally acceptable lubricants is recommended. The Port of Antwerp utilizes a maintenance frequency for their rolling gates. This includes moving the rolling gate with the emergency driving unit every 3 months, testing the emergency power supply (diesel generator) every 2 weeks, visual inspection of the 4 installed mixers every year, visual inspection of wire rope every 2 months plus re-tensioning as required, change the under carriage wagon every 20,000 movements, remove the accumulated debris with crane and divers every 6 months, and inspection of the ballast chambers every 6 months.