Ballast tamper
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A ballast tamper or tamping machine is a machine used to pack the track ballast under railway tracks to make the tracks more durable. Prior to the introduction of mechanical tampers, this task was done by manual labour with the help of beaters. As well as being more accurate, more efficient and less labour-intensive, tamping machines are needed for the use of concrete sleepers since they are too heavy (usually over 250 kg) to be packed into the ballast by hand.
The machines also correct the alignment of the rails to make them parallel and level, to minimise jerks and bumps experienced by passengers whilst travelling and to reduce mechanical strain put on the rails.
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[edit] Types
Tamping machines are built in many different varieties depending on their purpose:
- Straight track tamping machines
- Universal tamping machines (U.T.)
- Unomatic
- Duomatic
- Continuous action tamping machines (C.S.M.)
- Tamping express
- Points and crossing tamping machines
- Multi-purpose tamping machines
[edit] Prime movers
Basically the prime mover in all tampers are diesel engines which convert chemical energy of the fuel to mechanical energy. This mechanical energy is transmitted to wheel axles through gear boxes, cardan shafts, and axle gearboxes etc as mechanical power.
For working operations such as vibration, penetration, squeezing, lifting, etc, (tamping) hydraulic power is used through pumps coupled with gear boxes.
Pneumatic power is also used for brakes, horns etc. through a compressor. The main advantage of hydraulic and pneumatic power is flexibility.
Electric power is used for valve operations, various sensors, lights etc. from a battery which gets charged through alternators
[edit] Tamping Units
For each rail there is a tamping unit attached to the main frame by means of vertical guide columns and a lifting / lowering cylinder
[edit] Universal tamping machine
This type of straight track tamping machine is the oldest of the varieties. It uses a two chord lining system for alignment of track (for slewing the track to left or right as and when required). This type of lining is controlled mechanically. The machine has four bogies, one at the front, one at the rear, a third in the centre and a fourth in between the centre and the rear. They are called: front-tightening, rear-tightening, lining bogie and measuring bogie, respectively.
The measuring bogie measures the amount of slewing to be done and the subsequent slewing done by the lining bogie. The lining bogie also lifts the track to make it level. The tamping bank rear to the lining bogie has a vibrating motor and four arms for each track. These arms while tamping, will penetrate the ballast and pack the ballast under the sleepers by squeezing while the track is in a lifted and slewed condition by the lining bogie. After packing of one sleeper the machine moves to the next sleeper.
These operations — penetration, squeezing and moving — are controlled by an operator with the help of three pedals from his cabin.
[edit] Two Chord Lining System
[edit] See also
