Tamping is the most frequent maintenance action on railway track. Tamping refers to lifting and correcting the longitudinal and vertical alignment of the track by squeezing ballast stone into the void created under the sleeper due to the lift. Tamping machines are either of the index or, for high production, continuous action design. Index tamping machines stop at every sleeper or sets of sleepers to be tamped whereas continuous action tamping machines separate the main frame and a satellite frame on which the tamping units are mounted to allow continuous motion of the main frame while the cyclic braking and acceleration for the tamping action is performed by the much lighter satellite frame. This together with the number of sleepers tamped per insertion determines the production of the machine. Many different specialised machines have been developed by Plasser & Theurer to address the various aspects of tamping but are basically divided between plain track and universal machines.
Plain Track Tamping Machines
Plain track tamping machines are more cost effective where turnouts are limited and/or where high speed tamping is required.
The 09-3X Dynamic Tamping Express continuous action tamping machine tamps three sleepers at a time using a total of 48 tines with a production rate of up to 55 sleepers per minute. These machines have been operating in South Africa for almost a decade, achieving the desired results on heavy haul and high traffic density lines.
The 08-series fills the gap where ultra high production tamping is not always required due to the lower demand by smaller rail networks. This index tamping machine is available with either 1 or 2 sleeper tamping units producing high quality at competitive unit costs. Similar machines have been operating for a number of decades in South Africa and have a proven track record for good quality, extreme reliability and maintainability.
Universal Tamping Machines
Universal tamping machines may be equipped with a combination of special features, depending on the intended application of the machine, such as sliding tamping units to find the best area to enter the ballast in the restricted turnouts, rotating tamping units to ensure right angles to the sleeper when the turnout section is tamped, a third rail lifting unit to allow uniform lifting across the whole turnout without stressing the fastenings and split tamping units with 16 tines which split in half (field side and gauge side) which can be individually lowered for unparalleled versatility. When plain track is tamped, the tamping units are locked in position.
These features are fitted to a variety of machines, each with a specialised function in mind. The 08-series is also offered with split tamping units and is the smallest in the range designed for cost effective day to day maintenance where high lifts and large slews are not required such as general freight lines.
The Unimat Universal Tamping machine is a heavy duty machine suitable for all types of work especially on heavy haul lines where high production capabilities and high lifts are required of heavy turnouts and where there are many turnouts on the line. These machines have a proven track record on the Coal Export Line where one has been on contract for the last decade on construction and maintenance projects, carrying out extensive lifting and slewing of heavy concrete turnouts and open track.
The 09-Dyna-C.A.T. is also a heavy duty machine with the added advantage of high production on plain track due to its continuous action feature and two sleeper tamping arrangement. It also incorporates integral dynamic track stabilising. These machines have achieved exceptional results on the Iron Ore Export Line and high density lines where they have been on contract for almost a decade, carrying out day to day maintenance of heavy concrete turnouts and open track.