▁may ▁be ▁carried ▁efficiently ▁over ▁short ▁distances ▁by ▁a ▁wave guide ▁or ▁in ▁free ▁space ▁via ▁wireless ▁power ▁transfer . ▁ ▁Mechan ical ▁power ▁▁ ▁Elect rical ▁power ▁transmission ▁has ▁replaced ▁mechanical ▁power ▁transmission ▁in ▁all ▁but ▁the ▁very ▁short est ▁distances . ▁▁ ▁From ▁the ▁ 1 6 th ▁century ▁through ▁the ▁industrial ▁revolution ▁to ▁the ▁end ▁of ▁the ▁ 1 9 th ▁century ▁mechanical ▁power ▁transmission ▁was ▁the ▁norm . ▁The ▁oldest ▁long - distance ▁power ▁transmission ▁technology ▁involved ▁systems ▁of ▁push - rod s ▁or ▁j er ker ▁lines ▁( st äng enk unst ▁or ▁f eld st ängen ) ▁connecting ▁water w he els ▁to ▁distant ▁mine - d rain age ▁and ▁br ine - well ▁p umps . ▁A ▁surv iving ▁example ▁from ▁ 1 7 8 0 ▁exists ▁at ▁Bad ▁Kö sen ▁that ▁transm its ▁power ▁approximately ▁ 2 0 0 ▁meters ▁from ▁a ▁water w heel ▁to ▁a ▁salt ▁well , ▁and ▁from ▁there , ▁an ▁additional ▁ 1 5 0 ▁meters ▁to ▁a ▁br ine ▁ev apor ator . ▁ ▁This ▁technology ▁surv ived ▁into ▁the ▁ 2 1 st ▁century ▁in ▁a ▁hand ful ▁of ▁oil fields ▁in ▁the ▁US , ▁transm itting ▁power ▁from ▁a ▁central ▁p ump ing ▁engine ▁to ▁the ▁numerous ▁p ump - jack s ▁in ▁the ▁oil ▁field . ▁ ▁Mechan ical ▁power ▁may ▁be ▁transm itted ▁directly ▁using ▁a ▁solid ▁structure ▁such ▁as ▁a ▁driv esh aft ; ▁transmission ▁g ears ▁can ▁adjust ▁the ▁amount ▁of ▁tor que