1. The primary braking system of a vehicle or machine, typically the foot brake that provides the main stopping power
The main brake failed on the truck, causing it to lose stopping power.
O freio principal do caminhão falhou, fazendo-o perder a capacidade de frenagem.
2. In aircraft, the primary hydraulic braking system used for landing and ground operations
The pilot engaged the main brake to slow down the aircraft on the runway.
O piloto acionou o freio principal para desacelerar a aeronave na pista.
3. In mechanical systems, the dominant brake mechanism as opposed to secondary or emergency brakes
The main brake needs adjustment; the secondary brake is working fine.
O freio principal precisa de ajuste; o freio secundário está funcionando bem.