In 1932 the double jib system for slewing cranes was invented and patented. By slewing, the excavator can reach through a horizontal range. An example is a radar scanning 360 degrees by slewing around the z axis. A more sophisticated process involves a controlled process using slewing jacks in addition. This destabilized the Pontic army, slewing it towards its right flank. Moving to the location is called "slewing". The term slewing is also found in motion control applications. Slewing bearings often use two rows of rolling elements. Slewing in a complete rotation takes a similar time. There are slight differences between different amplifier designs in how the slewing phenomenon occurs. The slewing ends are also wound on to another half-barrel. Slewing refers to rotating the excavator's house assembly. Slewing is driven by large gears, while hoisting generally makes use of a cable system.