During the 1930s and 1940s, Hilding Carlsson made a long series of railcars for SJ. The bodies of these consisted of metal clad wood which was very maintenance intensive. SJ, therefore, began in the mid-1940s, looking at solid steel construction and came after various tests to what they wanted. SJ ordered a small series of narrow gauge railcars from Märstaverken for delivery from 1949, and designated type YCo4p (for 891mm gauge) and YCo4t (for 1067mm gauge). In 1944, SJ set up a working-party to produce guidelines for the construction of a new batch of standard gauge diesel railbuses. The group examined the few modern steel-bodied designs that were in use in Sweden at that time and was particularly impressed by the three railbuses built by Nydqvist & Holm AB (NOHAB) for the Halmstad-Nässjö Järnväg (HNJ) in 1938. It also used some of the older wooden-bodied railbuses to try out such ideas as Scharfenberg couplings, fluorescent lighting and hydraulic gearboxes. The following year, the group produced its report, which recommended steel-bodies and multiple-working for future orders; and design work began. In 1950 they ordered 40 standard gauge railbuses and 35 trailers with AB Hägglund & Soner (Örnslöldsvik). In 1951 and 1952 they ordered additional vehicles from ASJ (AB Svenska Järnvägsverkstäderna – with plants at Arlöv and Linköping), KVAB (Kalmar Verkstadsaktiebolag, Kalmar) and AB Eksjöverken (Märstaverken, Eksjö) (formerly Märsta works). Hilding Carlsson wanted to build his own design – basically a steel version of his wooden-bodied railbuses, and therefore didn’t receive an order.

The first railbuses were delivered in 1953 as type YCo6 (later Y6) and was on among other routes, the Boden-Haparanda line. In order to be used in longer trains up to eight railbuses could be run in multiple. They got a characteristic colour with black frame, orange bottom, yellow upper and grey roof. The railbuses soon proved to have a lot of teething problems which caused SJ much headache. Engines were wrecked when gravel penetrated through the underfloor air intakes, cracks occurred in the bogies and even the Atlas gearbox malfunctioned. The first vehicles had to be rebuilt while those which had not yet been delivered could be changed at once (and Wilson gearboxes were provided instead). After these changes the railbuses worked as expected.

Deliveries to SJ continued during the 1950s and lasted until 1961. From 1956 they changed the interior construction for larger and more comfortable chairs arranged 2+2. These railbuses were type YBo7 (later Y7). In Y6 the seats were smaller and placed 3+2. The Y6 had 53 seats against 47 in Y7. In the 1960s, there were built some railbuses with even more comfortable chairs to be used on longer routes particularly in the north. They got 36 seats and new type, Y8. For regional transport on electrified lines there were also built electric versions of Y6 and Y7, see “An electric Y6,” below.

A large number of trailers and control trailers without motors were manufactured and built in different versions (see list below). With these you could combine the train as required. A total of 373 diesel units, 30 electric units and 321 trailers and control trailers was delivered to SJ and this is the largest Swedish series of carriages ever. In addition, Hilding Carlsson (who missed out on the standard gauge railbus orders) built a series of narrow gauge railbuses of similar type, YP, see below.

Railbuses were used all over the country and made for a long time its mark on the passenger traffic on the non-electrified routes. They were cheap in operation and rescued or postponed the closure of the traffic on many railway lines. During the 1970s, many of the railbuses were converted to track-work vehicles, some of which are still used today, such as lift motor coaches. Some railbuses were also sold to the Danish private railways as their type MB (and assorted trailers BDS/YBM/S), and others loaned to Norway as their class Bm89. From 1979, when Y1 was delivered many more were withdrawn and the last passenger railbuses were taken out of service 1989. A fair number of railbuses, trailers and control trailers remain as museum vehicles.

Over the years there have been a number of modifications to the standard design. The first of note was in late 1954 when 1000 and 1001 were fitted with a second toilet, a pantry and aircraft-seats of blue DC-4 type in 1000 and red DC-6 type in 1001; reclassified YCo8, they were used in the ‘Härjedalingen’ night service from Stockholm to Hede. The service did not last ling and they ended up at Kalmar working on a special diagram to Nässjö until reverted to YBo7 standard in 1960. In the late 1950s a few trailers were rebuilt with first-class seating and a pantry for use on the Blekinge Kustbana (Malmö-Kristianstad-Karlskrona), a few more were later converted for Göteborg-Kalmar and Stockholm-Mora services, in the latter case without a pantry. In 1959/60 a number of non-driving passenger-trailers (UCo6) were rebuilt as driving-trailers. In late 1963 the classification YBo8 was applied to four YBo6 refurnished with more comfortable seating for use on the lines from Oskarshamn to Linköping and Nässjö, a further twenty-three railbuses and four trailers were similarly dealt with late the following year, mostly for use in northern Sweden. Many vehicles were given new interiors and changed classification, most commonly from YBo6 to YBo7 and there were many minor or temporary alterations, including three vehicles refitted as inspection vehicles (YS). During the 1960s a handful of vehicles received a large ‘panorama’ end-window to eliminate the vertical support between two of the smaller windows that had been directly in front of the driver, a further fifty were dealt with during the 1970s.

From their introduction the railbuses were used on local stopping and semi-fast services on both electrified and non-electrified lines throughout Sweden. Many of the early YCo6 were sent to northern Sweden to replace the older railbuses and steam locos, but in turn they were displaced southwards by the more comfortable YBo7. The closures of the 1960s resulted in many withdrawals. By the time the Y1 railbuses were ordered in 1977 the run-down had reached such a state that repair had to be carried out on a number of Y7 and Y8 to keep them running and some withdrawn examples had to be reinstated to cover shortages. The Y1s started arriving in 1979 and were initially sent to northern Sweden to displace Y7s and Y8s southwards. Continued deliveries of Y1s and further closures reduced the requirement for older vehicles; the last Y6 was withdrawn in 1983, the last Y8 in 1984 and the last four-wheeled trailer in 1985; the last trailer vehicle of all (UBF7Z 2069) was withdrawn in 1987. The last railbuses went in 1989, their last regular working having disappeared when the Sjötofta-Ulricehamn line closed on 12 June 1988, although three had been kept as an emergency reserve at Borås during the winter of 1988/89, although they were not used; and a handful were used on the Mellerud-Bengtsfors summer service in 1989. As early as 1966 a YBo6 was rebuilt as a mobile workshop and over the years over one hundred have gone into engineering department – later Banverket – service as workshops, stores vehicles, personnel-carriers and OHL maintenance vehicles, including two of the latter on the (narrow gauge) Roslagsbanan (one having replaced the other).

A number of other Swedish railways have owned railbuses of this type or similar; TGOJ (Trafikaktiebolaget Grängesberg-Oxelösunds Järnvägar) had four examples of the original Hilding Carlsson design and four similar trailers, all were gradually sold after being rendered surplus by electrification in 1956. Between 1956 and 1959 Hilding Carlsson also sold three four-car and ten two-car e.m.u. sets with bodies based on his diesel designs to TGOJ (see “An electric Y6” below). In 1985/1986 TGOJ bought four electric railbuses and one trailer from SJ (X16 959/974/975, X17 976 and UBF7Z 2076); all were withdrawn before the end of 1988. The GSJ (Göteborg-Särö Järnväg – “Säröbanan”) ordered five railbuses and three trailers of YCo6/UCoy type from ASJ in mid 1952, they were delivered in 1953/1954 as YCo6 1-5 and UCoy 11-13 (later YBo6 and UBoy). These were in a colour scheme of blue and beige-yellow. As a result of the GSJ’s closure at the end of 1965 all, except for UBoy 13, were sold to LAMCO (Liberation American-Swedish Mining Company) for personnel transport in Liberia; LAMCO also bought TGOJ YBos 54 and SJ YBo6 827.

The Finnish Railways (VR) had a Valmet-built (under licence) version for their slightly broader track gauge, and several detail differences do exist. The motorised unit was classified Dm7, and the trailer (which had seating and goods capacity, but no driving controls) was the EFiab.

An electric Y6

In addition to the diesel Y6/Y7 railbuses, SJ ordered also an electric version from ASJ with ASEA for the electrical equipment. They were divided into two classes with different interiors, X16 with seating similar to Y6 and X17 with more comfortable chairs. X17 was therefore fewer seats than the X16, 49 instead of 55.
Electric railbuses’ type designation was originally YBoa6 and YBoa7. They changed to X16 and X17 in 1970 when SJ decided to dedicate X for electric motor coaches and Y for diesel motor coaches. Some of the driving trailers built for use with the Y6 were adapted so that they could also be used in conjunction with the electric motor cars (including a button to operate the pantograph). These driving trailers had type designation that ended at Z. A typical X16 or X17 railbus could take one driving trailer. X16 and X17 were also multiple wired with each other (up to 8 units).
Electric railbuses were also problematic in the early days, as it turned out that some of the electrical equipment was undersized, but after the renovations they worked fine. X16 and X17 were used mostly in Svealand, but Värmland and Gävle region were the last service areas before withdrawal in the mid-1980s. Some of them were sold to TGOJ for traffic in Mälardalen but were abandoned after a few years. Two X16 units are held by Swedish railbus club and Bergslagen Railway Society and an X17 unit at Dellenbanans Vänner.
There were also electric multiple units of type X20 (4-car) and X21 (2-car), delivered to the TGOJ. The outer ends have the rounded appearance of the YCo6, but the inner ends are flat for closer coupling.

Hilding Carlsson’s NG railcars

YP railbuses were built in the 1950s, and look very similar to the standard gauge Y6. But there are several differences between types, both for manufacturers and construction. The first railbuses were delivered 1952 and received type designation YCo5p (only passenger compartment) and YFo5p (only cargo space) and the trailers UCFo3yp (driving trailer with a passenger and cargo space), UDFo13p (post trailers) and UFo1p (freight trailers). The railbuses could work in multiple (max 6). After 1956 when the third class had been abolished and the letter C became B there were a few more trailer types: UBo3yp (driving trailer exclusively for passengers) and UBFo4yp (driving trailer with a passenger and cargo space). After type changes from 1970, railbuses became YP (and should not be confused with its predecessor Yp) and the remaining control trailers UBYP and UBFYP.
The four freight railbuses YFo5p were built for rapid transportation of smaller goods and used in Västergötland and Östergötland. One is preserved at the railway museum Uppsala Länna.
The narrow-gauge railbuses were mostly Hilding Carlsson’s own design, but many impressions had been taken by SJ’s standard gauge railcars. Unlike Y6, they had air cooling in the front and the bogies were also of a different type. Instead of having a motor bogie and a trailing bogie as Y6, YP got a driving shaft to one axle and a trailing axle on each bogie. The bearings in the bogies proved to give less good running characteristics and was therefore modified on the last-built vehicles. The railbuses that had already been delivered were rebuilt later on.
There were no electric single railbuses for the narrow-gauge, but the 891mm gauge NKlJ (Nordmark Klarälvens Järnvägar) did receive two 3-car electric multiple units of Hilding Carlsson design called ‘Uddeholmaren’ which were only used in passenger service between 1956 and 1964. They had the rounded ends outer-most, but the inner ends were flat, rather like with the standard gauge X20 and X21.

Originally narrow gauge railbuses got a colour scheme of yellow-white with green decor. When Y6 railbuses were delivered, they were however, a new colour scheme of yellow and orange and it was introduced soon in the narrow-gauge vehicles. The decor was similar to that of Y6, but the comfort improvements in Y7/Y8 was never made in YP.
Until 1958 there were delivered a total of 72 railbuses for passenger, four freight railbuses and 75 trailers of various types. The vehicles were spread across almost all lines with 891 mm gauge. In the 1960s, there were also six railbuses and five trailers modified for use on the 1067mm gauge railways in Blekinge and Småland. These were abolished already in 1970 when the last passenger 1067mm network was shut down. At the same time traffic was lost on the Västgöta Line (Göteborg-Skara) and then there were only railbuses left on the Roslagsbanan and on the lamented Växjö to Västervik route.
The use of YP on Roslagsbanan ceased in the early 1980s, and by 1984 passenger numbers between Växjö and Västervik were down. The remaining railbuses ended up in various museum railways. Most were bought by the newly formed company Västervik-Hultsfred-Växjö Railway (VHVJ) who began driving museum traffic on that line. When VHVJ after a few years went bankrupt, the vehicles spread to several locations. Today’s YP railbuses are only as museum vehicles including the museum railways Uppsala Länna and Hultsfred to Västervik. In total there are around fifteen narrow gauge railbuses and trailers preserved.

Understanding the Varieties

• YCo6-YBo6-Y6 = Original diesel railbus (256)
• YBo7-Y7 = Modified diesel railbus (129)
• YCo8-YBo8 = Exclusive diesel railbus (2)
• YBo8-Y8 = Exclusive diesel railbus (29)
• YSo6-YS = Special diesel railbus (3)
• YCoa6-YBoa6-X16 = Electric railbus based on the Y6 (18)
• YCoa7-YBoa7-X17 = Electric railbus based on the Y7 (12)
• UAFo6y-UAFY = Trailer first-class with cargo space (3)
• UAFo7ye-UAFZ = Trailer first-class with cargo space, adapted for X16/X17 (5)
• UABFo7y-UABFY = Driving trailer first and second class with freight space (8)
• UCo6-UBo6-UB = Trailer second class (15)
• UCoy-UBoy = Driving trailer second class (3)
• UCFo6-UBFo6-UBF6 = Trailer second-class with cargo space (48)
• UCFo6y-UBFo6y-UBF6Y = Driving trailer second-class with cargo space (112)
• UBFo6ye-UBF6Z = Driving trailer second-class with cargo space, adapted for X16/X17 (26)
• UCFo7y-UBFo7y-UBF7Y = Driving trailer second-class with cargo space (14)
• UBFo7ye-UBF7Z = Driving trailer second-class with cargo space, adapted for X16/X17 (31)
• UBFo8 = Trailer second-class with cargo space (4)
• UBFo8y-UBF8Y = Driving trailer second-class with cargo space (4)
• UBF8Z = Driving trailer second-class with cargo space, adapted for X16/X17 (2)
• UDFo15 = Trailer for mail and luggage (25)
• UDFo20-UDF20 = Trailer for mail and luggage (16)
• UFo6-UF = Trailer for Freight (30)
• UF6-UFV = 2-axle trailer for goods (50)

Note 1: The total number of each type includes rebuilds, so there are more listed than actually built.
Note 2: Numbers 6, 7 and 8 of the type states that the interior is similar to Y6, Y7 and Y8.
Note 3: Type designation for SJ was changed from 1970; the UDFo15 was withdrawn before they could be changed, hence the old type only.
Note 4: The total for YCo6 includes the five for the Säröbanan.
Note 5: The YCo8 which became YBo8 are completely different vehicles to the YBo8 which became Y8.
Note 6: The UCoy was unique to the Säröbanan.
Note 7: Alignment with the X16/X17 meant there was a switch between diesel and electric drive and a control button for the pantograph.

Narrow Gauge (all 891mm unless stated otherwise):

• YCo5p-YBo5p-YP = Diesel railbus for passengers(76)
• YCo5p-YBo5p-YBo5t-Y5T = Diesel railbus for passengers – later converted to 1067mm gauge (6)
• YFo5p = Diesel railbus for cargo only (4)
• UCFo3yp-UBFo3yp-UBFYP = Driving trailer for passengers and cargo (44)
• UBo3yp-UBYP = Driving trailer for passengers only (7)
• UBFo3yp-UBFo3yt-UBFYT = Driving trailer for passengers and cargo – later converted to 1067mm gauge (2)
• UBFo4yp-UBFYP = Driving trailer for passengers and cargo (6)
• UDFo13p = Non-driving post trailers (9)
• UDFo13p-UDFo13t = Non-driving post trailers – later converted to 1067mm gauge (3)
• UFo1p-UFP = Non-driving freight trailers (7)

Note 8: Some narrow gauge units delivered to the south were painted in a white and green livery for a while! (The TGOJ’s two-tone green (standard gauge) units actually belong to an earlier (but similar) design!)
Note 9: The NKlJ received two 3-car electric multiple units based on the YP design (Yoap-Uoap-Yoap).

FLMJ (& guest) Model Details

• 764 built by H&S in 1953 as type YCo6-YBo6-Y6; withdrawn 1971 – scrapped 1971
• 1109 built by ASJ-L in 1957 as type YBo6-Y6; withdrawn 1983 – Preserved (Järnvägsmuseum)
• 1136 built by ASJ-L in 1957 as type YBo6-YBo7-Y7; withdrawn 1981 – Preserved (DVVJ?) but looking derelict
• 1201 built by ASJ-L in 1958 as type YBo7-Y7; withdrawn 1986 – Service vehicle, then scrapped 1997
• 1949 built by EV in 1955 as type UCo6-UBo6-UB; withdrawn 1980 – Scrapped 1982
• 1956 built by EV in 1955 as type UCo6-UBo6-UB; withdrawn 1973 – Exported, then scrapped in Denmark
• 2048 built by EV in 1957 as type UF6-UFV; withdrawn 1983 – Preserved (SMoK), then Scrapped 2002
• 2051 built by EV in 1957 as type UF6; withdrawn 1968 – Preserved (SMoK) as Qgu-e 945 0981 from 1969
• 2052 built by EV in 1957 as type UF6; withdrawn 1969 – Scrapped 1970
• 5 built by ASJ-L in 1954 as GSJ type YCo6-YBo6; withdrawn 1964 – Exported, then scrapped in Liberia
• 11 built by ASJ-L in 1954 as GSJ type UCoy-UBoy; withdrawn 1964 – Exported, then scrapped in Liberia

Notes:
SJ-L = AB Svenska Järnvägsverkstäderna – Linköping
EV = Eksjöverken (Märstaverken, Eksjö)
H&S = Hägglund & Söner
Thus, all our railbuses except one were built by ASJ (Linköping) along with the GSJ trailer.
All other trailers were built by Eksjöverken.
The one railbus exception was built by Hägglund & Söner.

Final note: Due to their intriguing shape, these railbuses (all gauges) have become affectionately known as “dateboxes!”

Information from “Rälsbussar,” “Lok & Vagnar 3,” “Scanrailsoc.org.uk,” and “Järnväg.net.”