Vehicle hydraulic brake booster system and method

A vehicle comprising:

• a plurality of drive wheels;
• an engine for powering the drive wheels to move the vehicle along the ground;
• a brake booster system including:
• a reservoir;
• a pump operable to drive a hydraulic fluid from the reservoir;
• a brake booster;
• a supply line coupling an outlet of the pump to an inlet of the brake booster;
• and
• a return line coupling an outlet of the brake booster to the reservoir;
• and
• a steering gear operable to reduce a required steering effort of the vehicle, the steering gear in communication with the brake booster via a connection line and with the reservoir via a steering gear return line,
• wherein the brake booster includes an input member adapted to receive a manual braking input force from a vehicle operator and an output member adapted to apply a braking output force to a master cylinder,
• wherein a flow of hydraulic fluid pumped to the brake booster by the pump provides a boost factor by which the braking output force exceeds the braking input force, and
• wherein the brake booster is hydraulically lockable by a first valve in the supply line and a second valve in the return line such that when the first and second valves are closed, a quantity of hydraulic fluid is trapped within the brake booster to maintain operation of the brake booster without continued operation of the pump, and
• wherein a third valve in the connection line is operable to lock the quantity of hydraulic fluid within the brake booster when the pump is non-operational.