I-phrettle yivalve elawulwayo elawula ukuhamba komoya kwi-injini. Xa irhasi ingena kumbhobho ongathahlikiyo, iya kudityaniswa ne-petroli ibe ngumxube onokutsha, oya kuthi utsha kwaye wenze umsebenzi. Iqhagamshelwe kwisihluzo soMoya, ibhloko ye-injini, eyaziwa njengomqala wenjini yemoto.
I-threttle iinjini ezine zepetrol zikhangeleka ngolu hlobo. I-throttle yenye yezona ndawo zibalulekileyo zenkqubo ye-injini ye-injini yanamhlanje ye-injini. Inxalenye ephezulu yayo yifiltha yomoya, indawo engezantsi yibhloko ye-injini, kwaye ngumqala wenjini yemoto. Ukukhawulezisa imoto kuyaguquguquka, kwaye iflethi emdaka inobudlelwane obukhulu, ukucocwa kwenkunkuma kunokunciphisa ukusetyenziswa kweoyile kunokwenza injini iguquke kwaye yomelele. Iqhinga alifanele lisuswe ukuze licoceke, kodwa kunye nokugxila kwabanini ukuba baxoxe ngakumbi
