In most cases, when two spur gears are in mesh, the apparatus with more teeth is called the "equipment" and the main one with small number of teeth is named the "pinion."
Guud ahaan marka laba spar gears ay ku jiraan mesh, qalabka ilkaha oo badan waxaa loo yaqaan "gear" halka midka ugu yar ee ilkaha ah waxaa loo yaqaan "pinion."