each vehicle, which applies the brakes if pressure/vacuum is lost in the train pipe. Automatic brakes are thus largely "fail safe", though faulty closure of hose taps can lead to accidents such as the Gare de Lyon accident. The standard Westinghouse Air Brake has the additional enhancement of a triple valve and a local reservoir on each wagon, enabling the brakes to be applied fully with only a slight reduction in air pressure, reducing the time that it takes to release the brakes as not all pressure is voided to the atmosphere. Non-automatic brakes still have a role on engines and first few wagons, as they can be used to control the whole train without having to apply the automatic brakes. Types Mechanical brake Most tractive units, passenger coaches and some freight wagons are equipped with a hand-operated parking brake (handbrake). This acts directly (mechanically) on the vehicle's brake linkage. The activation of such a brake prevents wheel rotation independently of the pneumatic brake and is therefore suitable for securing parked wagons and coaches from unintentional movement. Only mechanical brakes can be used for this purpose, since the holding power of air brakes can decrease due to unavoidable leaks. There are two types. The handbrake that can be operated on board the vehicle is used firstly to prevent it from rolling away and secondly to regulate the speed for certain shunting operations and to stop trains if the automatic brake fails. It is usually designed as a screw brake and is operated from a brakeman's platform or, in the case of passenger coaches, from inside the coach, usually from an entrance area. On UIC freight wagons, this braking weight is framed in white (white like the rest of the brake inscription, alternatively black on a white or light-coloured background). Hand brakes on tenders and tank locomotives are often designed as counterweight brakes. The manually operating parking brake is only suitable for securing static railway vehicles from rolling away. It can be designed as a hand wheel or as a spring-loaded brake, the operating handles are marked in red frames on freight wagons. A direction-dependent pawl brake is often installed in vehicles on rack railways. It only brakes when going downhill. When driving uphill, the applied ratchet brake is released by a ratchet mechanism and prevents the train from rolling backwards. Air versus vacuum brakes In the early part of the