Shaft current waa hacker-ka nidaamka xajinta eesaddex weji motor alaabta, oo mar haddii shaft-ga hadda la dhaliyo, waxay sababi doontaa in habka wax-qaadista matoorku uu shil galo muddo gaaban gudaheed. Marka loo eego shuruudaha lagama maarmaanka ah ee jiilka hadda jira, korantada iyo wareegga wareegga, wareeggu wuu ka duwan yahay wareegga fudud, ma jiro khad cad oo cad, way adagtahay in la qiyaaso hadda, sidaas darteed ujeedo badan oo la ogaan karo waa ogaanshaha danab usheeda dhexe.
Wixii kala duwan3 wejiga soo saarista matoorkaiyo qaab dhismeedka nidaamka xajinta, farqiga caabbinta ee wareegga waa yar yahay, iyo saamaynta weyn waa danab usheeda dhexe u dhiganta matoorrada kala duwan, marka danab usheeda dhexe gaadho qiimo gaar ah (guud ahaan 300-500mV), waxay keeni doontaa in filimka saliidda ee nidaamka dhalista la jejebiyey, oo ay soo saaraan hadda usheeda dhexe weyn. Voltage shaft waxaa loola jeedaa danabka ka dhasha labada daraf ee shafka mootada ama inta u dhaxaysa shafka wareega iyo kursiga wax lagu qaado. Waxaa sababa isku dheelitir la'aanta wareegga magnetic ee ku wareegsan shafka mootada. Qulqulka birlabeedkan aan dheeli tirnayn waxa uu gooyaa usheeda wareegta oo waxa uu kiciyaa danabka shafka ee labada daraf ee shafka.
Duruufaha caadiga ah, filimka saliidda ee saliidda leh ee u dhexeeya shafka iyo xajinta ayaa ka ciyaara doorka ilaalinta. Marka korantada usheeda dhexe u kordho ilaa qiimo gaar ah, gaar ahaan marka matoorku bilaabmo, filimka saliidda saliidda looma samayn si adag, danab usheeda dhexe ayaa jebin doona filimka saliidda si uu u sameeyo wareeg, soo saara qulqul xoog leh, mararka qaarkood ilaa dhowr boqol ilaa kun oo amps. Marka loo eego xajmiga korantada shafka, waxaa lagu qiyaasi karaa mitir millivolt (sidoo kale loo yaqaan voltmeter iska caabin sare ah). Laga soo bilaabo falanqaynta qaybinta jireed ee qaybaha, usheeda dhexe ee motor iyo guryuhu waxay ku daboolan yihiin dufanka ku jira xajinta, marka korantada mootada uu jiro, taas oo ah, waxaa jira farqi u dhexeeya labada daraf ee mashiinka mashiinka. Marka matoorka la tamarsiiyo, waxaa si toos ah loo cabbiri karaa iyada oo loo marayo baaritaanka cabbiraadda ee voltmeter-ka, taas oo ah, mid ka mid ah baaritaannada ayaa ku jira xiriir firfircoon oo leh shafka (maxaa yeelay shafka ayaa ku jira xaalad wareeg ah), laakiin ka fogow booska muhiimka ah si looga hortago khataraha; Baadhitaanka kale ee voltmeter-ka waa inuu si fiican ula xiriiraa guryaha mootada, taas oo ah, waa lagama maarmaan in laga fogaado booska rinjiga dusha sare leh, iyo in la hubiyo in hoyga matoorka uu si fiican u dhisan yahay.
Inta badan hababka xajinta ee koronto-saresaddex weji matooradaiyo matoorrada soo noqnoqda ee doorsooma waxay qaadeen tallaabooyin lagama maarmaanka u ah usheeda dhexe, laakiin tani ma saameynayso ogaanshaha danab usheeda dhexe.