hillhold

Hill hold, also called hill-hold or hill-start assist, is a vehicle feature designed to prevent rollback on an incline during the transition from braking to acceleration. The system detects when the vehicle is stopped on a slope and briefly maintains brake pressure after the driver releases the brake pedal or clutch, allowing a smoother start.

Operation and how it works vary by transmission type. In automatic cars, hill hold typically uses the hydraulic brake system to keep the brakes engaged for a short period after stopping, until the driver applies throttle. In manual transmission vehicles, the function may hold the brakes electronically or engage the parking brake to prevent rollback, releasing when the driver begins to press the accelerator or fully release the clutch. Some implementations hold until a different input is detected, such as vehicle speed increasing beyond a small threshold.

Implementation and usage: Hill hold is common in modern vehicles and is often integrated with other stability and braking systems such as ABS and electronic stability control. It may be branded differently by manufacturers, for example as Hill Start Assist or Hill Hold Control. The hold duration varies by system, typically lasting a few seconds or until throttle input is detected.

Advantages and limitations: Hill hold reduces the risk of rollback, improves starting comfort on slopes, and can reduce clutch wear in manual transmissions. Limitations include potential surprises if the hold disengages unexpectedly, reduced effectiveness on very steep grades or long climbs, and dependence on system reliability. It is not a substitute for attentive driving or appropriate starting technique.

See also: hill-start assist.