SM53

This article needs attention from an expert in Norway or Trains. The specific problem is: Stockholm closed 1967 not -57, door arrangement obviously 1-2-2 not 2-1-2; it doesn't belong to the "Mustang" tram family, (Hägglunds just built the motors), if that's wrong, how much more?. WikiProject Norway or WikiProject Trains may be able to help recruit an expert. (June 2017)

SM53, originally designed MBO and colloquially known as Høka, were a class of 58 trams and 50 trailers built by

The first series of thirty trams in 1950, with delivery in 1952 and 1953. These were designated MBO50. The next order was for new bodies for used

History

Order and original series

At the end of the

An invitation for tenders was issued in 1947.^[3] Ateliers de Constructions Electriques de Charleroi offered to build a European adoption of the PCC streetcar, although the necessary licenses for Scandinavia were held by Svenska Järnvägsverkstäderna. The trams met all of Oslo Sporveier's demands, except their high power usage.^[4] However, the downside was the high price and that foreign production would require currency exchange licenses, which could be complicated because part of the price was for royalties.^[5]

The second offer came from

Oslo Sporveier opted for Høka and Hägglund's bid and in 1950 signed an agreement to buy thirty motorized units with delivery in 1952, at 250,000 Norwegian krone per unit.^[6] Høka held the Norwegian rights to a Czechoslovakian patent for wooden-filled steel profiles that Hägglund used in its design. The bodies were therefore built by Høka in Hønefoss, while Hägglund built the electrical and mechanical components. Final assembly was carried out by Hägglund and Oslo Sporveier at Sagene Depot in Oslo. The first tram arrived in Oslo on 1 September 1952 and, after final assembly and tests, entered revenue service on 11 November 1952.^[7]

The trams were first used on Line 13, which ran from the

"Chickens"

The original plan was to copy a concept from Stockholm, where the trams were run fast and frequently without trailers. However, Oslo Sporveier soon decided to prioritize operating costs and instead run trams and trailers. At first the company operated Class SS trailers, but these proved unsuitable in combination with the MBOs.^[9] Oslo Sporveier was not willing to pay the price for new trailers and therefore chose a combination whereby new bodies were built atop existing undercarriages. Two such contractions were built at Sagene Depot in 1953, designated TO52 and the first unit can into revenue service on 23 November.^[10] A major issue with the trailers were doors which would not shut properly, often resulting with the trams running with open doors.^[11]

Oslo Sporveier was considering the need for new trams, but were concerned because of the new trams having costs about twice the price of a Gullfisk. This led them into the idea of converting older trams by keeping the most costly parts, such as motors and wheelsets. However, the trams would receive new and larger bodies and interior. The company approved that twenty units be built, stipulating that fifty would be converted should it prove successful.^[11] Of the initial order, twelve were to be built as trailers and eight as motorized trams. They received new controllers and new braking system, and were largely rebuilt from Class U and Class SS units. The motorized version was designated MO52. They quickly received the nickname Chickens (Kylling), as a pun of being smaller than units built at Hønefoss (literally "Hen Falls"). The trailers were nicknamed Stiffsleds (Stivkjelke).^[12]

The first Chicken, no. 33, was met with dissatisfaction by the employees. They were built without

The Chickens were used on a limited number of routes, from 4 July 1954 on lines 0, 8 and 13, variously serving the Vippetangen Line, the Grünerløkka–Torshov Line, the Sagene Line and the Sinsen Line. From 1955 they also started running on the Rodeløkka Line. The TO trailers were usually run with the Chickens, although they were also hauled by the larger Høka units.^[15] The tramway experienced that the Chickens did not have sufficient pneumatic capacity to keep a tram and trailer at ease while stopped on slopes, as separate compressors in the trailers were not installed. This made operating trailers with the Chickens a safety hazard and soon they were only seen i solitude.^[16]

Suburban prologue

The Oslo Metro was approved of by the city council in 1951. It would consist of a common, underground section in the city center and above-ground lines in the suburbs. It was soon evident that one of the suburban lines, the Lambertseter Line, would be completed in the order of magnitude of a decade before it could be hooked to the Common Tunnel.^[16] A similar situation was true for the Østensjø Line, which had been completed as a tramway in 1923.^[16] Oslo Sporveier was therefore given the task of operating the lines as tramways until the metro could open. The company considered building additional MO and TO units and move the new bogie trams to the suburban lines, but the poor performance of the rebuilt units soon made the company change its mind.^[17]

Although Oslo Sporveier was determined to buy bogie trams, it considered options other than additional MBOs. A derivative of Stockholm's A24 was considered,^[17] as was a modernized Gullfisk with Vickers motors and two variations of Hägglund trams. The company considered multiple-unit trams, which would allow for faster speeds, but opted against this due to an increased fault rate and higher maintenance.^[18] A trial with the Gullfisk proved that it had low acceleration and speed and was shaking violently at high speeds, and the option was discarded. The company had two final options, additional MBO units or Vickers-based multiple units with bodies built by Hägglund and Høka, and motors from NEBB.^[19]

The tender was issued in 1953 for twelve trams and thirty trailers. Høka and Hägglund won the bid. All motorized units would be manufactured by Høka, along with twelve trailers. The remaining eighteen trailers would be built by

Early career

With the second series delivered the SM53 units entered service on most of street tram lines. Two exceptions were the Kampen Line and the Vestbanen Line, both which were built for the older narrow profile and could not be used by the wider trams.^[24] As the trams were unidirectional they required a balloon loop at the ends of each line, which was also lacking on the Kampen Line, and new track arrangement had to be built at Vålerenga Depot and Majorstuen Depot. The issue was availed by the 1957 opening of Grefsen Depot, which was built for unidirectional trams.^[25] The MBO50 units were rebuilt in 1959, whereby the back door was closed and the received the same interior as the new trams, with single seats all the way along the door side.^[23]

The city council voted in 1960 to gradually close down the tramway and replace it with the metro and diesel buses.^[23] Operations could continue with the existing rolling stock, although all investments were halted. In the following eight years the least trafficked tram lines were closed.^[26] SM53 was most commonly used on lines 1, 2, 7 and 11 in this period, specifically serving the Briskeby Line, the Frogner Line, the Ullevål Hageby Line, the Sinsen Line, the Grünerløkka–Torshov Line and the Kjelsås Line, as well as the suburban lines. The Chickens were used on the Sagene Line.^[27] The last SM53 ran on the Lambertseter Line on 17 May 1966 and on the Østensjø Line 29 October 1967, as these were converted to metro lines. From then all SM53s were stalled at Grefsen.^[28]

Oslo Sporveier's management attempted to close the tram operations during the late 1960s. However, the "Høka lines" 1, 2, 7 and 11 and the suburban Lilleaker Line and Ekeberg Line exceeded the combined traffic of all city buses. As long as the SM53 units were operational it would not pay to order 300 new buses needed to replace them.^[29] Oslo Sporveier carried out a large-scale retirement of older twin-axle trams during the late 1960s, particularly between 1966 and 1968. By then the only remaining trams were SM53 and the Gullfisk.^[30]

To cut costs, Oslo Sporveier considered during the late 1960s if it could introduce

First retirements

The city council voted in February 1978 to not close the tramway and instead invest in new rolling stock. The first investment was three used M23 units from Gothenburg, which were technically nearly identical to SM53. Except for being underpowered, making them unsuitable for service on the Ekeberg Line, they worked well and Oslo Sporveier therefore decided to retire the Chickens and replace them with additional MBG and TBG trams and trailers.^[34] Four more such pairs were delivered in 1980. The first two Chickens were retired at the end of the 1980 and were chopped in October 1981. With the delivery of the twenty-five first SL79 trams in 1982, the remaining Chickens could be retired on 1 September. No. 38 was preserved by Oslo Tramway Museum, while the rest of the units were scrapped in the course of the month. This was the last twin-axled trams to run in revenue service in Oslo.^[35]

Services on Line 9 were taken over by SL79 and all SM53 units returned to street service. The future of the tramway was still largely based on it being able to reduce costs. The easiest way to rationalize was to introduce one-man operations. The first rebuilt SM53, no. 245, entered one-man service in 1982, and by 19 February 1983 all conductors had been removed. The labor unions agreed to the plan under condition that the motorman's cabins were rebuilt to a more ergonometric layout.^[36] Next the trailers were rebuilt to become unmanned. The first entered service on 22 April 1983, the last manned trailer, and thus last conductor on the tramway, ran on 8 June 1984. The MBG series became superfluous and four pairs were retired on 1 January 1984.^[36] The TO trailers were likewise retired between March 1984 and July 1985.^[37] The last three Gothenburg trailers were kept and rebuilt to run with SM53 trams and remained in service until 1989.^[38]

Modernization

In a move to retire the last Gullfisk before their next main revision, Oslo Sporveier rebuilt some of the SM53 units to allow them again to run on the suburban lines. This time vertical suspension was installed between the bogies and axle box, finally solving the issue with the swaying. Other improvements included a car horn, a new pantograph and

By the 1980s the SM53 units were out of date and were dire need of renewal. Oslo Sporveier therefore carried out a trial with no. 261, which was upgraded at Sagene and completed on 23 June 1985. Conversion took four months and eleven units were rebuilt until 1991. The work involved rebuilding the front, installation of new doors and interior, and a new chopper-based controller and new electronics. They were designated S83.^[40] Only one trailer were similarly rebuilt, and given the designation S86T. This proved to be expensive and gave little advantages and was not carried out on other units. However, smaller upgrades and new interiors were installed on 21 trailers in the same period.^[41]

During the 1980s Oslo Sporveier experimented with their livery. Some received a darker blue, either entirely or with a cream-colored upper section. Consultants had concluded that Oslo Sporveier should introduce a uniform red color with dark blue detailing on all modes of transport: buses, metro trains and trams. This went without protests on the other two modes, but when the trams were painted red it was met with a storm of protests and a unison public demanded that they retain their light blue color. This resulted in a new uniform light blue color scheme which was introduced on the SM83 units. Most of the SM53 retained their original colors.^[42]

Final years

The second batch of SL79 trams was delivered in 1989 and 1990, allowing the first SM53 units to be retired. Three, nos. 237, 244 and 253, were rebuilt to maintenance of way matériel and painted yellow. No. 245 was converted to a school tram. The main concern with the trams was that the insulation on the high-voltage wires was wearing off. They were placed in ducts which were also used for ventilation and heating, giving extra wear. As long as they were not touched the cables would remain intact. This was the start of the process of retiring the SM53 units.^[43]

As part of construction work at

The type classifications were altered in 1992, and the trams renumbered in 1994. MBO50, -55 and -56 were all classified at SM53, S83 became SM83, TBO55 became ST55, S86T became ST86 and TBG became ST89.[39] During the last years SM53s were only to be regularly used on Line 17, serving the Ullevål Hageby and Grünerløkka–Torshov Line. However, they were used throughout the network, in part because almost all motormen had its type certification, in part because SM91 could not enter service on the suburban lines. By 1997 a further set of trams were scrapped, with nine SM53 and ten ST55 units remaining. The 1995 ordering of new SL95 trams was planned as the coup de grâce for SM53.^[45]

Comparison of original and rebuilt cabs

In 1997 the high-voltage cable issue was regarded as so severe that the company decided that they either would have to be replaced for the trams scrapped. On 12 September a tram lost its brakes and the following day all SM53 trams were taken out of service.^[46] Investigations showed that the braking systems would have to be rebuilt similar to SM83. This was too expensive and the trams never ran in revenue service again. One trailer received the new bogies for the SL95 and was hauled around Oslo by a SL79 for testing. The last of the non-preserved SM53s were scrapped in July 1998.^[47] Tram 259 was preserved as it was the only unit to have received a new cable. The only preserved trailer is no. 563, built by Strømmen.^[48]

The SM83, ST86 and ST89 were not subject to the cable and braking issue and were therefore kept in service. Originally Oslo ordered seventeen SL95s and planned to keep either the SM83 or the SM91 units. However, the options for another fifteen SL95s was redeemed, allowing all non-articulated trams to be retired. As the SL95 units were delivered, retirement of SM83 commenced in mid 1999.^[48] The choice to retire SM83 before SM91 was both that the former were in worse technical condition and that the need to raise the voltage on the tramway to 750 volts. SM91 had proven that it could adapt to such in Gothenburg, an outcome that the SM83 could not be sure of duplicating.^[49]

With the completion of the delivery of SL95 in 1999 and 2000 the SM83 units could be retired. No. 207 and 586 were preserved at the Oslo Tramway Museum and tram 210 was passed on to the Djurgården Line. Tram 201 and trailer 589 were sent to a heritage museum in Gothenburg and in the last minute tram 203 was issued to the

The trams each had four Hägglund MBL10 300-volt serial direct current electric motors. They were connected two and two in series to match the system's 600 volt power supply via the

The trams were equipped with two Hägglund-built H-bogies. They had an outer frame with the motor axles parallel with the wheel axles. Each axle had four rubber suspensions as its primary suspension.^[53] The carriage rested on the bogie on rubber plates. Later the bogies were supplemented with a shock absorber. The motors were connected to the wheel axles via a universal joint and a gear. The wheels were rubber suspended, but were later replaced with steel-suspended axle boxes which required less maintenance.^[54]

The trams had a primary

The units have four-abreast seating, with seats originally upholstered in dark blue leather.[59] The interior was largely covered in aluminum and brown-painted plates. The window frames were covered in aluminum. The air ducts were at first painted brown, but passengers had a tendency to rest their feet on them. They were therefore kept unpainted.^[60] The motorman's cab was sealed off with an aluminum and plexiglas wall, later changed to a non-translucent aluminum to avoid reflections.^[59]

The trams were originally constructed with an entrance through the back door and exit through the middle and front doors. The conductor was seated at the back and the passengers would enter a platform before passing by the conductor.^[61] This was opposite on the trailers, which had the entrance at the front. This allowed for a common boarding area, which had the psychological effect of encouraging passengers to a greater extent board the trailer.^[62] The vehicles were equipped with blinker doors. MBO consisted of double doors at the front and back, and a single door in the middle. The first two TO units had the same design, while the remaining trailers had only single exit doors. The vehicles were not built with compartments.^[61]

Ventilation ducts ran through the gaps in the body and through the cable duct under the floor. They had openings in the floor and under the windows. The ventilation system doubled as cooling for the braking resistances. During cold weather the carriage air could be routed via the resistance to heat it, and warm and cold air could be mixed at various levels.^[63] As there was no resistance in the trailers, these were equipped with electric heaters. The trams had a 24-volt lighting system with cabin lighting from fluorescent lamps.^[64]

References

Bibliography

Wikimedia Commons has media related to SM-53.

• Andersen, Bjørn; Kjenstad, Rune (2000). Inngang bak (in Norwegian). Oslo:
  ISBN 82-91223-02-5
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• ISBN 82-91448-03-5
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