What does
आयताकार कुंजी जो पहिए की हब और घूरे की झिरी में फिट रहती है ताकि दोनो एक साथ घूम सके (Āyatākāra kun̄jī jō pahi'ē kī haba aura ghūrē kī jhirī mēṁ phiṭa rahatī hai tāki dōnō ēka sātha ghūma sakē) mean in Hindi?
English Translation
a rectangular key that fits in the hub of the wheel and the zigzag so that both can move together