Buses have historically used the same underpinnings as trucks. This also applied to the apparently most famous bus of Czechoslovak production, the Škoda 706 RTO, which was based on the 706 R truck model. However, even at the time of its creation, a unique base with a self-supporting body was considered. In the end, it was only the successor of the “er-té-óčka”, called Karosa of the Š series, that got it.
A brand new foundation
Its development began at the end of the 1950s, in the national company Karosa Vysoké Mýto, where RTO was produced from 1958. At the same time, the developers had the task of designing a completely new vehicle, designed from the beginning as a bus, which resulted in a self-supporting body. And this was a major difference against the Škoda 706 RTO with its semi-self-supporting body combined with a modified 706 RT truck chassis.
The first functional piece of the new bus was produced in 1961, under the designation ŠM 11. The letter Š referred to the Škoda engine in the guts, while the M referred to the urban use of this specific vehicle. The eleven then determined the approximate length.
The resulting rendering was adapted to urban use. Therefore, ŠM 11 had three doors to speed up the exit and boarding of passengers. This was also facilitated by the lower floor compared to the previous RTO. Abundant glazing in turn helped the view outside, while the short wheelbase in combination with the split front axle had a positive effect on maneuverability.
Serial production itself started in 1965. The first functional sample still used a number of components from foreign suppliers, but later prototypes increased the proportion of domestic parts.
The new construction base made it possible to build diverse versions. One of them took over the name of the original prototype – the urban ŠM 11. The range was supplemented by the Karosa ŠD 11, a long-distance coach, nicknamed the Eurobus, which had a more powerful 154 kW engine and only one pair of doors for long routes or tours. Later, however, there was also an alternative with a second door behind the rear axle.
There were 47 seats inside with a 2+2 layout, while the interesting thing was the LP 30 trailer, which, in addition to 30 beds, also included a washroom, dressing room or toilet. Karosa eventually built eight pieces of this nine-meter-long and three-meter-high “rotel.”
The ŠL 11 body had two doors, one in front and the other between the axles. It was an intercity, “line” bus primarily for ČSAD with space for up to 75 people, of which 45 are seated.
The trolley bus and the accordion didn’t make it
In the end, the other derivatives did not see the realization, or rather remained only with prototypes. The ŠM 16.5 body from 1965 was an articulated city bus with three axles and a length of 16.6 meters. Unfortunately, serial production did not take place, due to the insufficient production capacity of Karosa, as well as the fact that the production of double-decker buses within the framework of RVHP was taken over by the Hungarian company Ikarus. However, a few built prototypes eventually got into service, for example in Bratislava or Pardubice.
A trolleybus called Škoda T11 was also intended. It was supposed to be a joint project with the Škoda engineering company. His plant in Ostrov nad Ohří was to supply electrical equipment, while Karosa was to supply bodywork.
However, it quickly became clear that the construction was not very suitable for this solution. The foundation was too fragile to support electrical weaponry. After all, even the starting bus earned the infamous nickname harashito. In addition, the then era of cheap diesel was not very kind to trolleybuses.
The ŠD 11 Lux project had a completely different design. The distinguishing feature was the auxiliary reflectors, filmed together with the steering wheel.
Younger siblings were also considered. The considered ŠL/ŠD 9, with a total length of approximately 9.1 meters, was intended to be used for regular and long-distance routes, while the ŠM 8 was to be only an eight-meter-long bus for urban environments. In the end, however, these projects remained only on the drawing boards.
The Š-series Karosa was eventually produced until the early eighties, when it was replaced by the 700-series Karosa with its characteristic angular body. Between 1965 and 1981, 26,544 examples of this series were produced. In Czechoslovakia, most of the units traveled in Prague, but the bus was also exported – for example to Poland, Mongolia or Bulgaria. ´