Following are the main categories of Rolling Stock
Basic components of Rolling Stock
1. Under Frame : Made out of steel members of channel, Angle or required section. These members are joined together by riveting or welding, capable to accommodate all other components and to withstand the load and other forces acting on it while on the run.
2. Running Gear : Consists of pair of wheels connected firmly by an axle with a provision for a bearing at both ends and its housing and guide arrangements. Cartridge bearings are used of late which are more reliable and require no lubrication.
3. Spring Gear : Cushioning arrangements between the Wheel (Axle) and the body of the Rolling Stock to absorb the vertical shocks coming to the wheel while on the run due to unevenness in the track and also to transmit the load vertically from body to Axle. There are laminated bearing springs (Self damping) and coil spring with separate damping arrangements (Shock absorbers) used in rolling stock. The spring arrangement in a Rolling stock is generally called as suspension system. In case of Goods stock only one suspension is provided – Primary or Secondary. In case of coaching stock both primary and secondary suspensions are provided to give more comfortable ride.
4. Draw Gear : An arrangement provided in the Rolling Stock at its both ends at the centre to couple several rolling stock together and to make a string of suck Rolling Stock in a formation and to haul the formation as one unit by the Train Engine draw gear arrangement is provided. A drawbar hook with a set of screw coupling and straight “U” shackles and coupling screw rod, two drawbar with springs and cotter are assembled at both ends of the rolling stock at its centre. The “U” shackle of the screw coupling is put on to the hook of the adjacent wagon or coach and tightened with the screw rod thereby transmitting the draft force to the rear through the under frame members. To haul heavy loads we have developed high capacity draw gear – Centre Buffer Coupler (CBC) It is important that the draw gear arrangement permits gradual increase of draft force to the locomotive while starting the train from the stabled position and transmitting the draft at the time of acceleration of the locomotive to attain higher speeds.
5. Buffing Gear : To absorb the linear forces coming into the Rolling Stock while on run and during shunting, buffers are provided at the end body at both sides. This consists of two buffer casing fitted at headstock at sides and a plunger with a coil spring or hard rubber pads inside is assembled into this casings and secured. The buffer plunger projecting at the ends will come in contact with the adjacent rolling stock and will absorb the linear shocks coming to the headstock while on run ad during shunting thereby protecting the underframe and body from heavy shock. In the advanced Rolling stock the draw gear and buffing gear are combined together and made as one unit which is called as Centre Buffer Coupler (CBC) which is provided at the headstock at its centre. It serves both the purpose of draw gear and buffing gear. In case of MG a Centre Buffer Coupler with hook and yoke end known as ABC (Automatic Buffer Coupler ) is used.
6. Brake gear : Brake gear is an arrangement to retard the momentum of a Rolling Stock. Brake gear applies a force on the rotating wheel thereby retarding the motion of a rolling stock. It comprises of pull rod, levers and links, brake beam and brake block. The force developed for brake application maybe manual, vaccum system or by compressed air depending upon the type and design of brake system in the Rolling Stock.
7. Body and other Fittings: Over the under frame body is built according to the nature of utilization of the Rolling stock utilization – goods or passenger carrying etc. Floor, side body, end body and doors, securing arrangements for goods stock, and other items like seats, berths and amenity items like fan, lights, toilets, Air Conditioning and others are provided according to the requirements of rolling stock.
In case of Locomotive apart from these arrangements a driving mechanism with an engine, Generator, Motor, Air Compressor, Vacuum Exhauster Plant and other Control, auxiliary equipments are provided. Similarly for coaches accommodation of passengers in different classes and amenities are arranged. For wagons necessary body design to accommodate the goods is provided according to the necessity.
In case of EMU/DEMU/MEMU – These are units consisting of 3 or 4 coaches with a power car in first coach with Loco Pilot/Guard’s cabin in leading end and other 2 or 3 coaches trailing. All these coaches are interconnected by special coupling called “SHAKHOO” coupling . At the end IRS screw coupling is available. Two or three such units form a train in which both the ends have Loco Pilots cabin and the power car controls interconnected. Loco Pilot/Guard interchange their position according to the direction of movement. This is used for suburban/local passenger trains in which engine turn round, shunting can be avoided, runs as a set rake without any disturbance. Two or more units can be coupled and controlled from one point at the leading end. In case of any emergency, a unit containing 3 or 4 coaches is to be isolated from the train. It is not easy to uncouple a coach from the unit.