This is primarily a points and crossing tamping machine. Tamping unit of this machine is designed in a manner to allow independent operation of individual tamping tool. This helps in tamping of almost all the sleepers in points and crossings. Tamping tool(s), which infringes any track component, can be tilted individually or in pairs and rest of the tools tamps the sleeper. Tamping unit in most of these machines can be rotated to align with the sleepers. These machine have the arrangement for lifting of third rail as well. It does twist correction also.
The tamping units work according to the asynchronous constant pressure tamping principle. The tamping tools penetrate the ballast and perform a closing movement with sinusoidal vibrations. The tamping tools continue to move, pressing the ballast till desired force is reached and thus each of the tools applies the same force on the ballast. Since each of the tools continue to move for different durations and presses the ballast till the desired pressure is reached, the process is known as asynchronous constant pressure tamping operation.
All tamping tools, therefore, apply the same amount of pressure to the ballast being tamped; thus there is equilibrium of forces between the individual tool pairs and the specific surface pressure of all tools. During tamping of ballast, resistance gets built up in front of each pair of tools. The movement of the tool is completely independent, according to the resistance encountered from the ballast. Once the resistance reaches the pre-selected value (hydraulic pressure in the squeezing cylinder), the corresponding tool pair stops squeezing automatically, however other tool pair(s) continue to squeeze till the resistance for those also becomes equal to preselected pressure.