Mercedes-Benz SK

Pre-facelift (1989–94)

The trucks of the Mercedes-Benz series Schwere Klasse (SK, for "heavy class") were produced from 1989 through 1998, when they were succeeded by the new Mercedes-Benz Actros truck. The Mercedes Benz SK, in essence is basically a revamped Mercedes-Benz NG chassis with a few added driver comforts and electronic assistance and diagnosis. Therefore, it is a much more comfortable ride than its predecessor.

1989

The SK series is basically a mere evolution of the Neue Generation, which was built up to the year 1989. There were few changes to the cab: radiator grill and wind leading plates were combined optically, and the lower edges of the side windows were made with a progressive incline towards the front. This design feature had already been realized in 1977 with the T1 and in 1984 with the LN series.

1994

Post-facelift (1994–98)

In 1994 the SK series, which apart from the upgraded engines was still based on the NG series from 1973, was facelifted for the last time with a new front design.

Engines

The Mercedes Benz SK were available with the ever popular OM44X series engines. Which were an evolution from the highly respected OM42X series used in the predecessed NG chassis. As a result, the OM4XX series share many similar (not to be confused with identical) components which date as far back to the very early Mercedes Benz OM401 and 402 diesel engines.

These new generation OM44X engines, with their robust cast iron blocks, much like their predecessor engines, were specifically very popular in harsh hot desert climates due to their large displacements and low operating temperatures.

These engines were initially released as two variants:

(Released from 1988 to 1992)

• OM441 Naturally aspirated V6 engine which yielded power at approximately 224 hp
• OM442 Naturally aspirated V8 engine which yielded 290 hp

The later variants (Released from 1992 to 1997) were classed as EURO 1 Emission standard engines.

• OM441 Single Turbo V6 engine which yielded power at approximately 270 hp up to 340 hp when fitted with an intercooler.
• OM442 LA Twin Turbo V8 engine which yielded power between 350 hp to a very respective 500 hp when fitted with an intercooler.

Transmissions

With the introduction of Euro 1 class emission control regulation, it is only understandable that the engines gained a mass disadvantage compared with the earlier models. As the engines were now getting heavier due to Euro 1 class emissions fitting turbos, intercoolers, piping etc., the Mercedes Benz SK moved away from the ZF branded 16s series ecosplit cast iron transmissions used in the late model NG chassis and towards a Mercedes Benz aluminium 16 speed synchromesh transmission of model G155.

These transmissions were much lighter than the 16s transmissions and could also tolerate a greater range of engine power up to 440 hp thanks mostly to their double clutch pressure plate capability and robust gear design.

The transmission was released with one of two versions of gear shift, either the conventional stick shift or the newly developed EPS (Electronic Pneumatic shift) system. However, much like most electronic shift mechanisms of that mid to late 90's era the system did have some mechanical gremlins and reliability issues at times. Although it may have been more comfortable from a drivers point of view, the EPS was not very popular between truck owners and operators, which even led some truck owners sceptical of reliability the later released Actros Telligent transmission.