A line-locking brake system consists of a brake pressure generator which, in conjunction with a brake fluid solenoid isolates the front brake circuit from the master cylinder while maintaining a precise brake pressure in the front brake hydraulic system. The brake pressure generator consists of a pressure amplifier having a high pressure chamber located in the flow path from the master cylinder to the front brake cylinders and a low pressure chamber in fluid communication with a regulated gas pressure source. When activated, the brake pressure generator applies a pressure to the front brake circuit that is directly proportional to the pressure of the regulated gas and therefore is precisely controllable irrespective of wear on parts, driver fatigue or other variables.