An **ABS brake pump**, also known as an **ABS hydraulic pump**, is a crucial component in a vehicle's **Anti-lock Braking System (ABS)**. The ABS is designed to prevent the wheels from locking up during hard braking, especially in slippery conditions, by modulating the brake pressure. The pump is part of the ABS module that helps maintain optimal braking pressure and ensures the system functions effectively.

Here's a breakdown of the ABS brake pump's role:

1. **Brake Pressure Regulation**: When the ABS system detects that a wheel is about to lock up (i.e., it's losing traction), it momentarily reduces the braking force to that wheel. The ABS pump helps to restore the brake pressure to the correct level, ensuring maximum braking force without losing control of the vehicle.

2. **Pulsation Control**: The pump works with valves to modulate brake fluid pressure in real-time, allowing for rapid changes in brake force during an ABS intervention (when the system is actively controlling wheel slip). This is typically done in a fast, rhythmic pulsing pattern, which is felt as a vibration in the brake pedal.

3. **Hydraulic Pressure Maintenance**: It ensures that there is sufficient hydraulic pressure in the ABS system to handle these changes. If a hydraulic pump fails, the ABS system may not function properly, potentially compromising vehicle safety.

4. **Integration with Other Components**: The ABS pump works in conjunction with other ABS components such as pressure sensors, control valves, and the Electronic Control Unit (ECU), which monitors the wheel speeds and decides when ABS activation is needed.

In short, the ABS brake pump helps maintain consistent brake pressure and allows the ABS system to control wheel slip, improving vehicle stability and safety during emergency braking.