Track brakes are shunting technology in tracks at marshalling yards , i.e. H. built-in shunting equipment (RTE). They reduce the kinetic energy of the wagons running down the mountain . There are energy conversions through impacts, friction and electrodynamic operating principles on the wheelsets or buffers. The types are differentiated according to function and principle of action.
- Hill brakes
- Valley brakes
- Directional track brake
- Slope compensation brake
- Wagon holding brakes
- retractable and erecting buffer stop
- Hydraulic rail brakes
- Pneumatic rail brakes
- Electrodynamic rail brakes
- Braking by putting on drag shoes with mechanical ejection
- Braking by placing the brake shoe
Differentiation according to function
Hill brakes and ramp brakes in large marshalling yards (usually with more than 40 to 48 directional tracks , in systems with Russian shunting technology, however, often also with fewer directional tracks) after the speed measurement has been carried out, so that the valley brakes can fulfill their function. They also represent a braking force reserve when carrying out heavy wagon group processes.
Hump retarders delay car in front of a direction track group, so that the distance to the previously-running car is large enough so that the switch can be changed over in the gap. A valley brake supplies about 6 to 12 (in Europe mostly 8) connecting tracks.
Directional track brakes are used to regulate the speed in the directional track, depending on the fill level of the wagons in the directional track to ensure the defined approach speed.
Slope compensation brakes are brakes that are intended to regulate the approach speed of trolleys on a slope. They are specially installed in downhill stations with inclined directional tracks or in flat stations with a roll-out system.
Differentiation according to type
Valley and ramp brakes
Skid release brakes (also called Büssing brakes after the most important manufacturer in the past ) are not actual track brakes, but stop the braking of a car by throwing the underlying skid through a soft-like construction laterally into a catch box.
A three-force brake is a bar track brake that works depending on the weight of the wagon. The flange runs on a braking element. Due to the weight of the car, which exerts a vertical force, the braking effect of the brake beams is proportional to the weight of the car.
Bar track brakes slow down the wagon speed by pressing brake bars with wear brake strips against the side of the wheel tires. A distinction is made according to the type of drive:
- hydraulic : z. B. Systems
- pneumatic : e.g. B. Westinghouse or Kompass systems
- electrical: e.g. B. Electrodynamic track brake type FEW . They are stationary eddy current track brakes .
Bar track brakes are also divided into two and three-force brakes. While the brake bars of two-force brakes are only pressed against the wheels from both sides, with three-force brakes the weight of the car is also used. In some countries there is only one system and in other countries different systems are in use.
With some brakes, the brake carrier with the brake strips can be lowered for the passage of locomotives ( locomotive driving position ).
In the braking position, rubber track brakes allow the wagons to roll over rubber bodies, which reduce / absorb the kinetic energy of the wagons through flexing . In the release position, the rubber bars remain sunk and the carriages pass the brakes continuously on the wheel flanges. A second type is the non-lowerable FEW rubber track brake , in which the rail web is replaced with a flex rubber element. However, it is only used as a gradient compensation brake.
Slope compensation brakes
Screw track brakes are cylinders with an internal hydraulic braking device, which are provided with a helical bulge on the outside. In the braking position, they are placed on the running edge of the rails in such a way that the flanges of wheel sets running over them turn the cylinder. The hydraulic braking device generates higher braking forces the faster the vehicle rolls. Slowly moving wagons are braked little or not at all. Screw track brakes are used as directional track brakes, they can be folded down and thus rendered ineffective for traction vehicle journeys or for poor walkers.
Dowty retarders are piston-shaped elements that are depressed when driven over and thereby absorb energy. In contrast to most other rail brakes, they cannot be switched off, but always effective. Screw brakes and Dowty retarders work depending on the speed, so the faster the vehicle driving over them, the harder they brake. You brake it to an adjustable steady speed , e.g. B. 1 m / s. In the controllable version as a "dowty booster", the wagons that run down can not only be braked, but also accelerated as required.
Relay rail brakes combine several Dowty retarders in a foldable swivel element and can therefore be switched off.