Njirimara nke ngwa ngwa helical:
1. Mgbe meshing abụọ mpụga gia, ntụgharị pụtara na-abụghị direction, mgbe meshing ihe esịtidem giana ihe mpụga gia ntụgharị na-eme n'otu ụzọ ahụ.
2. Ekwesịrị ilebara anya n'ihe gbasara ọnụ ọgụgụ ezé na gia ọ bụla mgbe ị na-ejikọta nnukwu ihe (ime) na obere ihe (mpụta), ebe ọ bụ na ụdị nnyonye anya atọ nwere ike ime.
3. Ọtụtụ mgbe, a na-eji obere ngwo mpụga na-ebugharị gia ime
4. Na-enye ohere maka nhazi nhazi nke igwe
Ngwa nke ngwa ime:Planetary gear drive nke oke mbelata oke, clutches wdg.