the frequency required for the desired speed. Most systems were out of service by the mid-20th century and relatively few remain in the 21st century, even fewer in their original location and configuration. Disadvantages and alternatives Disadvantages Compared to individual electric motor or unit drive, line shafts have the following disadvantages: Power loss with line shafts varied widely and was typically 25% and often much higher; however, using roller bearings and good quality lubrication could minimize losses. Roller and spherical bearings gained acceptance in the decade before electrification of factories began. Continuous noise Maintenance costs were higher. The systems were more dangerous. Down time due to mechanical problems was higher. It was not as easy to change speed. Factory layout was designed around access to the line shafts, not in the most efficient manner for the work flow. The line shafts and millwork took up a lot of space; Baldwin Locomotive Works estimated 40% more than electric drive. The shafts and belting were in the way of lighting, overhead cranes and ventilation ducts. Alignment of the system was critical and problematic for long shafts that were subject to expansion and contraction, settling and vibration. The belting shed dust and kept it continuously circulating in the air. Oil dripped from the overhead shafting. Firms switching to electric power showed significantly less employee sick time, and, using the same equipment, showed significant increases in production. Writing in 1909, James Hubbart said that "We can scarcely step into a shop or factory of any description without encountering a mass of belts which seem at first to monopolize every nook in the building and leave little or no room for anything else." Historical alternatives to line shafts To overcome the distance and friction limitations of line shafts, wire rope systems were developed in the late 19th century. Wire rope operated at higher velocities than line shafts and were a practical means of transmitting mechanical power for a distance of a few miles or kilometers. They used widely spaced, large diameter wheels and had much lower friction loss than line shafts, and had one-tenth the initial cost. To supply small scale power that was impractical for individual steam engines, central station hydraulic systems were developed. Hydraulic power was used to operate cranes and other machinery in British ports and elsewhere in Europe. The largest hydraulic system was in London. Hydraulic power was used extensively in