Tamping - Universal Tamping Machine

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 determines the amount of slewing required and measures the subsequent adjustments applied by the lining bogie. The lining bogie also lifts the track to make it level. The tamping bank behind the lining bogie has a vibrating motor and four arms for each rail.

A tamping cycle comprises three operations:

1. Penetration – the arms are pushed down vertically into the ballast either side of a sleeper
2. Squeezing – the arms squeeze the ballast under the sleeper, packing it together
3. Moving – the arms are lifted and the machine is moved to the next sleeper to repeat the cycle.

The operations are controlled from the control cabin by an operator using three pedals, while the lining bogie holds the track in its lifted and slewed position.