The Branch Hydraulic Systems - designed hydraulic power unit shown is one of a number of hydraulic power units designed to operate the emergency braking system on cranes that are used to lift an oxy-acetylene lances adjacent to the furnaces in teel mills.
The areas that the power units are installed in have a number of factors that had to be taken into account during the design process which includes the areas being very dirty and heavily contaminated as well as being very hot and subject to the occasional flash over.
The units were designed to run on Water Glycol to reduce the risk of the hydraulic fluid catching fire, and to improve life with this fluid and resistance to contamination poppet type valves were used. The valves also gave very low leakage rates enabling a very power efficient system to be designed that created little heat with itself which meant that the unit could be totally enclosed in a cabinet to keep it clean and protect it from flash overs.
To enable a high level of serviceability and availability the units were designed to be interchangeable so that a spare unit could be exchanged in the unlikely event of a failure and to aid this hydraulic connections were made via flat face quick release couplings, and all electrical connections were made via two multipole connectors (one 3 phase power and one control connector). Being able to remove the units means that service and repair work can be carried out in a clean environment suitable for the maintenance of a hydraulic system.