HGF jerin guda dunguwa famfo ne mai girma famfo.
Babban aiki sassa ya kunshi da dama sassa kamar conveyor slot, madaidaiciya zagaye shaft, eccentric madaidaiciya jiki da kuma ciki farfajiyar da biyu layi madaidaiciya farfajiyar madaidaiciya bushing.

Ka'idar aikinsa ita ce: Lokacin da motar ke motsa shaft mai juyawa, kafofin watsa labarai yana tura shi a ƙarƙashin aikin mai juyawa, don shiga cikin nau'in rufi na dunƙule da dunƙule na dunƙule. Kowane juyawa na dungulla mako daya, ruwa a cikin rufin rufi yana motsawa da nisan dungulla, tare da ci gaba da juyawa na dungulla, ruwa yana matsa lamba daga ɗayan rufin rufi zuwa wani rufin rufi a cikin nau'i na dungulla, bayan zuyi ya fitar da jikin famfo.