DER FRÜHE MERCEDES 170V (1936-1938)
The dynamo and regulator / die Lichtmaschine


The succession of dynamo types used is as follows:

-Bosch RJH 90/6 1800 RS 189 (source: Ersatzteilliste- Ausgabe A, dated 20.06.1936). This is the earliest reference I found and it was the type used in early 1936. A Bosch list of equipment used in Mercedes cars (issued March 01, 1943) mentions RS 189 as the dynamo equipping 1936 cars. The same source lists the regulator as Bosch SSM 81/ 13Z;

-Bosch RJH 90/6 1800 RS 222 (source: Ersatzteilliste- Ausgabe B, dated 19.03.1937 and Ersatzteilliste- Ausgabe C, dated 25.04.1938). In this last source the regulator is individualized for the first time as Bosch Type SSM 81/ 13Z. The Bosch listing omits any reference to 1937 models;

-Bosch RJH 90/6 1800 RS 235 (mentioned in a MB source and also in the Bosch listing as the type used in 1938). The regulator is SSM 23/58Z;

-Bosch RJH 90/6 1800 RS 262 (mentioned in a MB source as the type used in 1939). The Bosch 1943 listing mentions that this regulator was also used in 1940-41. The regulator is still Bosch type SSM 23/58Z throughout 1941;

-Bosch RJHK 130/6 2200 R3P (starting at car NR 136.050/0001- source: Reparatur Handbuch Ausgabe C dated 1943). The same source mentions that the previous type was RS 262 of 1939. The 130Watt dynamos that superseeded the 90W models were considered necessary on account of an increased power need (e.g. because of the introduction of radios) and continued being used after the war. They are immediately distinguished by the louvered brush cover and by the "fat" regulator mounted on them, similar to the one used in early Volkswagens.

Note: An Ersatzteilliste published 31.01.1941 mentions two other different dynamo types in gas cars presumably for military use, both of 12V..


All RJH 90 dynamos used, at least until 1938 and probably always until the introduction of the 130/6 types, an unventilated brush cover. The following images depict early dynamos mounted in cars.

Above: factory photo, probably 1936 (notice integral Mercedes star), Below: 1936 catalogue

Above: factory photo from the 1936 Owner's Manual; below: Bosch voltage regulator geometrically similar to the one originally used in the 170V (albeit slightly more rounded in the edges). Notice also the shape of the curved tensioning bar. At this time there was an alternate option that was still longer and allowed the use of a wide range of replacement belt lengths.
Below: a typical Bosch RJH130 dynamo (from the 1950 Bosch parts manual). The most obvious differences are the louvered brush cover (part #45) and the Type RS/G voltage regulator. further down a comparison of the RJH 90 (Part # 46) and the RJH 130 brush covers.
Index of Mercedes 170V pages

Joao-Manuel Mimoso

Aug 18, 2009