The combined continuous acting plain line and S&C tamping machine Unimat 09-4x4/4S is the modern successor of the well proven 09- and Unimat 08-4x4 machines.
It represents the results of many years of gaining experience in development and operation of continuous-action tamping machines offering a further rise in performance and quality. A considerable number of these combined machines are performing very well in Europe and North America.
Considering the above mentioned constructional features, the Unimat 09-4x4/4S series represent a further step towards perfecting the maintenance of S&Cs. Apart from the quality of work, which can be reached by the Unimat 09, this is also shown by the increase of working performance. Compared with standard machines of previous designs the time needed for tamping an S&C with the Unimat 09 is up to 40% shorter, which means a great reduction of possession time and therefore a better utilisation of available working windows.
The same principle applies for plain line tamping, because the Unimat 09-4x4/4S offers about 30% more working output compared to conventional cyclic acting single sleeper tamping machines.
The result is a versatile universal high performance tool for plain line and S&C tamping. An important circumstance requiring to be seen in light of achieving higher efficiency and quality of given shift rosters as well as planned reduction of shift patterns in the future.
The existing fleet of Unimat 08-machines operated by various customers in the UK forms the backbone of state of the art S&C maintenance technology on the rail infrastructure of Network Rail.
Amongst other features, these machines are equipped with the “parallel tamping mode” enabling two machines of the same type to work synchronously through S&C layouts with long through bearers. This operating mode has been integrated in the Unimat 09-4x4/4S machine concept as well allowing operating two Unimat 09-4x4/4S machines in parallel.
The 10-axle bogie type Unimat 09-4x4/4S is designed to run self-propelled on track with a maximum speed of 60 mph (96 kph) outside possessions. The machine complies with Railway Group Standard (RGS) GM/RT 2400 in all respects, featuring frame strength to withstand 120 t compression force and 150 t pulling force as well as the front and rear driving cabin designed to RGS requirements.
The Unimat 09-4x4/4S is designed and equipped for operation on standard and 3rd rail track as well. All components, i.e. tamping arms & tines required for operation on 3rd rail are delivered with the machine. Usually, the conversion from one version to the other can be carried out in a suitable workshop within a day. The brush box provided cannot be operated on 3rd rail infrastructure.
The above stated design principles are not the only features of this new machine concept.
Track will always settle under loads following maintenance operations changing the position of the ballast stones, such as ballast cleaning, track lifting & lining or track tamping. This settlement per load unit is considerable at the beginning (immediately following the maintenance activities) and diminishes with passing train loads. The greater the settlements, the more irregular they are.
Furthermore, the change in position of the ballast stones reduces the lateral resistance of the track, which may result in its displacement under train loads or buckling under the influence of heat.