TheInternational Union of Railways groups all special classes of railwaygoods wagon (less those in classes F, H, L, S or Z) intoClass U in itsgoods wagon classification system.
These are:
Between 1964 and 1979 bulk goods wagons for liquid and gaseous materials (tank wagons) were included in Class U before being reclassified in 1980 as Class Z.
The powder wagon is a special form of bulk goods wagon designed to transport goods in powder form. These wagons are pneumatically unloaded, usually by using compressed air. For goods that might react with oxygen in the compressed air, nitrogen is used instead. These wagons are used for bulk commodities, such as cement, that are so fine-grained they cannot be poured, or at least do not pour very well, and so cannot be emptied under gravity. Under the UIC system they are given the category letter U and index letter c. They do not normally have their own compressors but must be unloaded using external equipment.
![[icon]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg) | This sectionneeds expansion. You can help byadding missing information.(September 2021) |
![Semi-trailer on a Kangourou wagon[2]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aHUA-168077-Afbeelding_van_enkele_opleggers_van_vrachtauto%2527s_op_speciale_wagons_van_de_S.N.C.F._(z.g._Kangourou-_of_Huckepack-vervoer)%2c_op_het_terrein_van_de_Veilinghaven_te_Utrecht%2c_bedoeld_voor_een_tentoonstell.jpg)
→
This group has a large variety of different types of wagon that range from the two-axlelow deck wagon to the 36-axleSchnabel wagon.
The currentdesignation for all low deck wagons isUi, which can be supplemented as necessary by theindex lettersa,aa,k,kk ors. The load limits on low-loading wagons are not indicated by letters. The formerGerman wagon classes wereSt andSSt.
In 1998 theDeutsche Bahn had a total of 180 well wagons of 43 different types. They are used to move very large and heavy goods that would exceed theloading gauge onflat wagons. Such loads typically include:combine harvesters,generators ornarrow gaugevehicles.
| Class number | Maximum carrying capacity | Tare weight | Wheelsets | Quantity (DB as at 31 Dec 1997) | Length overbuffers | Bogie pivot spacing or wheelset spacing | Length of low loading bay |
|---|---|---|---|---|---|---|---|
| Uis 632[5] | 25 t (24.6 long tons; 27.6 short tons) | 14,500 kg 32,000 lb | 2 | 25 | 12,240 mm 40 ft1+7⁄8 in | 9,000 mm 29 ft6+3⁄8 in | N/A |
| Uiks 635[6] | 19 t (18.7 long tons; 20.9 short tons) | 12,800 kg 28,200 lb | 2 | 27 | 15,590 mm 51 ft1+3⁄4 in 15,760 mm 51 ft8+1⁄2 in | 9,000 mm 29 ft6+3⁄8 in | 7,450 mm 24 ft5+1⁄4 in |
| Uais 732[4] | 50 t (49.2 long tons; 55.1 short tons) | 29,500 kg 65,000 lb | 4 | 16 | 19,940 mm 65 ft 5 in | 14,900 mm 48 ft10+5⁄8 in | 10,000 mm 32 ft9+3⁄4 in |
.jpg)
The largest low-loading wagons are designed asSchnabel wagons, made from two completely separate sections. Each section rests on multiple-axlebogies or groups of bogies. The two sections each support a beak-shaped carrying arm which, in turn, supports one side of a low-loading platform or is directly fixed to the outsize load to be transported. In the latter case the load becomes temporarily part of the vehicle itself. The wagons havehydraulic equipment with which the load can be raised or lowered in order to manoeuvre it past obstacles. There are about 30 examples ofSchnabel wagon inEurope,North America andAsia.
Typical loads for these vehicles are largeboilers forpower stations,turbine components or power stationtransformers. Due to their heavy weight and outsize dimensions these goods are not usually transported in normalgoods trains, but are moved in special trains and need careful preparation. Whenever transportation restrictions arise with a wagon and its load due to its weight and size, it is designated as an abnormal load and must be labelled in accordance with theRIV as aU type. When the vehicle is unladen the two carrying arms are joined directly to one another; the wagon can then travel in goods trains at normal speeds.
A range of funnel-shaped self-discharging wagons is also classed as special wagons. Their external shape resembles theopen hoppers, but they have an enclosed roof with loading hatches or in some other way do not fulfil the criteria for awagon with opening roof.
TheDB has grouped several of the lime wagons with four hatches taken over from theDR intoClass Uaoos-y. Some of these wagons have since been fitted with swing roofs.
In theSNCF there is a large number ofgrain wagons in service that are classed as special wagons.