Tamping machine

As well as being faster, more accurate, more efficient and less labour-intensive, tamping machines are essential for the use of concrete sleepers since they are too heavy (usually over 250 kg or 550 lb) to be lifted by hand.

Some modern machines, sometimes known as tamper-liners or tamping and lining machines, also correct the alignment of the rails to make them parallel and level, in order to achieve a more comfortable ride for passengers and freight and to reduce the mechanical strain applied to the rails by passing trains.

This is done by finding places where the sleepers have sunk from the weight of the passing trains or frost action, causing the track to sag.

[1] Tamper machines are built in many different varieties depending on their purpose: The tamping process from any type of tamper consists of the following basic steps:[1] The basic principles and functions of a tamping machine remain the same regardless of manufacturer with only minor differences in design.

This provides power to the driving wheels via either a hydrostatic circuit or cardan shaft, allowing the machine to propel itself to and around a work-site.

The arm is adjustable so that the unit can be moved clear of small obstructions such as insulated joints or wires.

Depending on type of chord system C point will be either wire anchor with a tensioning cylinder or a photoelectric light receiver.

When working, the machine uses pneumatic cylinders to lightly push these trolleys into the selected datum rail both vertically and horizontally.

When using this method, the tower operator positions A point anchorages according to existing track geometry measurements taken beforehand.

A continuous-action tamping machine (CAT) can pack between one and four sleepers at a time, with outputs between 320 m/h and 2600 m/h generally anticipated.

[3] Tamping and cleaning operations have the adverse effect of reducing the resistance of the track to lateral movement.