Sisu S-321

Sisu S-321, S-322 and S-323 is the first lorry and bus model series made by the Finnish heavy vehicle producer Suomen Autoteollisuus (SAT) in 1932–1934. Upgraded models S-341 and S-342 were produced in 1934. The vehicles were heavily based on Volvo components. The two-axle, 4×2-driven lorries were designated with 2,500 kg capacity and total weight of 4,800 kg.

The series was followed by the 1934 introduced Sisu SO-models.

Background

Autoteollisuus-Bilindustri, one of the two predecessors of SAT, had plans about starting automotive industry in Finland. In 1929 the company started negotiations about component supply with the Swedish AB Volvo. Autoteollisuus-Bilindustri made an agreement of equipping lorry Volvo-delivered chassis by locally built cabin and platform. Some chassis were delivered to Autoteollisuus-Bilindustri but the vehicles were not even started before the company put together its operations with its competitor Autokoritehdas, creating SAT. The chassis became owned by SAT thereafter.Blomberg: ''Fleminginkadun koritehtaista syntyi suomalainen autotehdas.'' p. 17–28.

In early summer 1932 SAT announced on main Finnish newspapers starting vehicle production and in the same context set up a competition to select a suitable brand for the products. Eventually, name ''Sisu'' ("stamina; persistence; guts; stubbornness") became selected.Blomberg: ''Mikä autolle nimeksi?'' p. 32.

In the introduced model nomenclature the first two numbers ''32'' or ''34'' mean the year of introduction (1932 or 1934) and the following number indicates the wheelbase. ''E'' at the end means that the vehicle is equipped with single rear wheels and ''D'' stands for double rear wheels; this designation was borrowed from Volvo.

Production

Pre-series

The size of the first Sisu batch remains unclear. According to some sources the first series included 12 vehicles but most likely three of them are actually belong to the production series delivered in the following year. According to the existing sources, the first Sisu's were a series of nine vehicles of which seven were S-323 models built on Volvo LV-66 chassis. Four of these were delivered to the Finnish Defence Forces' Logistics Battalion 1 in Helsinki, two to Logistics Battalion 2 in Viipuri and one unit was handed over to Rovaniemi Infrastructure and Hydro Engineering Bureau. One unit of the series, S-321E based on Volvo LV-71E chassis, was used for displaying.

The ninth vehicle was S-322D with a bus coach; this was built on Volvo LV-72D chassis. This very first Sisu bus was handed over to a Helsinki bus operator in September 1932; during the first two months in service the bus did total 20,000 km which was a significant achievement taking into account the generally poor condition of the Finnish roads back then.

Production series

In spring 1933 the first production series was delivered. Among the first customers were newly founded Oy Alkoholiliike Ab which had ordered two S-322D lorries already in the previous year, as well as a Helsinki firewood distributor, which became an owner of S-321E.

SAT ordered Volvo parts in order lots of ten kits. Each production batch was numbered according to the order lot.Blomberg: ''Ruotsalaista Volvoa ja kotimaista alihankintaa.'' p. 37–39.

The second production series included two combination buses; one ready lorry was converted into combination bus after request of the customer, Imatran Voima Oy. The rest of the second series were exclusively lorries. The customers of the third series were Border Guard, Hietalahti Shipyard and Engineering Works, State Railways, Oy Alkoholiliike Ab, Orimattilan Tehdas and Karhula Oy; the State Railways bought three lorries and Karhula two.Blomberg: ''Kotimaisuus kasvaa.'' p. 44–46; 50.

At this stage SAT had got already so many orders that the customers had to wait for their vehicles.

Both high tolls and transportation costs pushed SAT to start domestic sourcing. The third production batch included parts made by such Finnish companies as Keskusvalimo, Suomen Gummitehdas, Pietarsaaren Konepaja and Kone ja Silta. Five vehicles of the fourth production batch were equipped with frames produced by Crichton-Vulcan. The sixth series got Finnish-made radiators produced by Oksanen & Kumpp., hub caps by Lohmann, headlight brackets by Teräskalustaja, rear axle housing by Karhulan Tehtaat, radiator caps by Metalli-Niklaus and electric cables by Suomen Kaapelitehdas.Blomberg: ''Vielä kolme Volvo-sarjaa.'' p. 50–54. In some cases SAT had to go back to Volvo parts; for example domestically produced track rods turned out to be too weak. Also the first Karhula-produced axle housings did not fulfill the requirements but problems were resolved after. Some of the imported parts were substituted by own component production;Blomberg: ''Tuotanto täysille.'' p. 62–64. fuel tanks as an example.

The weakening of Finnish mark against the Swedish crown made importing increasingly unfavourable, forcing SAT to focus more on local sourcing activities. Designing of the upgraded models S-341 and S-342 had begun already in 1933 but they were introduced in 1934. The content of domestic parts was increased, but they were still powered by Volvo delivered Penta EB engines. Both models were available with single or double rear wheels. An interesting, new variant was ''KV'' which means ''kevyt versio'', "light version". It was delivered without bonnet and wings for DIY customers.

Volvo supplied SAT until autumn 1935; the last delivered components were Timken axles and Ross steering boxes. The last S-341 and S-342 models were powered by domestically made Olympia engines, which were later used in the following Sisu SO-series.

The total amount of Sisus with Volvo parts reached almost 200 vehicles of which 70 first units were practically built on Volvo chassis and additional 12 units were largely based on Volvo components.

Production figures of the pre-series and first serial units

Technical data

Engine

Those pre-series units which were based on Volvo LV-66 were powered by six-in-line, OHV type Penta DC engines. According to Volvo data the displacement is 4,097 cm³ and output 75 horsepower; SAT had exaggerated these figures to 4,100 cm³ and 84 horsepower on its brochures. The serial produced units based on LV-71 and LV-72 had a six-cylinder side-valve 3,266-cm³ Penta EB that produced 65 horsepower at 3000 1/min. The Penta's were expensive but they had a good reputation.Blomberg: ''Ratkaisevana tekijänä käyttö.'' p. 92.

In 1934 SAT started using domestic Olympia engines produced by Suomen Moottoritehdas in Vaasa

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