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The Mercedes-Benz L 6600

Posted: Sun 24 Aug, 2008 8:20 am
by Des
eMercedesBenz Feature: The Mercedes-Benz L 6600, The First Newly Designed Post-War Heavy Duty Truck
Posted August 22, 2008 At 5:45 PM CST by C. Danielson


http://emercedesbenz.com/Aug08/22_00135 ... _6600.html

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At Daimler-Benz, the first newly developed heavy-duty truck after the war was the L 6600. Large-scale production of this untiring workhorse with a payload capacity of 6,600 kilograms began in October 1950. The L 6600 with its OM 315 pre-chamber diesel engine – 145 hp, 8.3 liters – originated from the Gaggenau plant which would fully concentrate on the heavy-duty class from then on.

With respect to the engine, the plant promised that it would “not be unusual for the L 6600 to cover 200,000 kilometers or more without any engine repairs.” Chrome-plated top piston rings were to double the service life of the cylinder liners; the crankshaft was running in seven “hardened lead-and-bronze bearings” which, prior to installation, were subjected to painstaking x-ray checks in final inspection. The sales strategists enthused about the “completely vibration-free suspension of the engine in rubber mounts, realized for the very first time in an engine of this size.”

Another modern feature of the L 6600 was a thermostatically controlled cooling system with heat exchanger, which would warm up or cool the engine oil more efficiently. An engine brake was optionally available for the L 6600. The new truck was fitted as standard with a central lubrication system to which “all the important bearings” were connected, as a contemporary brochure ensured.

The “Six-Six”, as it was commonly known at the time, did not deny its ancestor, the L 6500, which had been built in Gaggenau from 1935 until 1940. The chassis and cab were modified only slightly, while the hood and bumper received the curvatures that were popular at the time and also gave the vehicles greater aerodynamic efficiency.

Sound engineering, fantastic start

Right from the start, the L 6600 established itself as the best-selling truck in its class. The vehicle reached absolute-majority market shares at times even though its segment was served by another six manufacturers in Germany: Büssing, Faun, Henschel, Kaelbe, Magirus, MAN and Krupp were (in alphabetical order) the companies which competed for buyers of trucks with permissible gross vehicle weights between 13 and 15 tons at the time.

This was not yet the juggernaut class but one that was clearly more popular among customers. In the early 1950s, as many as six German manufacturers offered trucks in the 16 ton GVW category and with engines in the 200 hp range – but only few operators opted for these vehicles even though the latter already weighed in at 40 tons (as they do again today) and were permitted to pull two trailers (only until 1953, however). What’s more, the payload capacity of the 13- to 15-tonners was between one and one-and-a-half tons lower than that of the juggernauts.

And yet, the somewhat lighter vehicles were a lot less expensive for operators. While a 16-tonner with 180 – 200 hp engine cost around DM 50,000 in 1954, just about DM 35,000 had to be paid for an L 6600 with 145 hp engine. The difference of DM 15,000 bought a complete three-axle trailer at the time. Hence, companies preferred the lower-cost alternative which they would then overload mercilessly, however. In this way, they tried to compensate for the shortcomings that arose from this tight-fisted approach to freight calculations.

Uphill in first gear

However, this approach was frequently penalized in checks by the authorities. And every pedestrian was capable of overtaking these trucks when they labored up steep gradients. This meant drivers had to change back into first gear of the AK 6-55 from ZF, an unsynchronized six-speed constant-mesh transmission whose first gear permitted a maximum road speed of 7.5 km/h. The climbing ability of a 40-ton L 6600 was a meager 7.3 percent in second gear. Not to forget the very special soundscape at a snail’s pace: only “second to sixth gear inclusively” were rated as “low-noise gears” in the model sheet.

Long-distance haulage thrived nonetheless. The Federal Republic of Germany was heading straight on towards the economic miracle with trucks like the Six-Six. In spite of this, the plant still refrained from producing a long cab with a bunk, permitting the driver of the L 6600 to sleep in the truck. These versions were contributed by bodybuilders such as Wackenhut, Schenk, Kässbohrer and Kögel. More often than not, however, the additional space offered by the bodybuilders’ long-distance cabs was no more than a “swallow’s nest”, as it was called at the time, a coffin-type contraption protruding rearwards into the load compartment. From an operator’s perspective, this had the advantage that the load volume was reduced to a lesser extent than by a long-distance cab extended over its entire length.

Continuous increases in payload

By the end of 1953, Daimler-Benz was producing platform trucks with two wheelbase lengths and dump truck versions of the L 6600. The permissible gross vehicle weight rose from 12,500 kilograms in 1950 and 1951 to 12,750 kilograms in the two following years and reached 13,250 kilograms in 1953. This was accompanied by a continuous increase in payload capacity, from initially 6,500 kilograms to finally 7,200 kilograms. At the end of 1953, an all-terrain all-wheel drive version was added to this well established truck family which also included a panel truck version – made possible by the O 6600 low-frame chassis developed for buses.

From 1953, this illustrious lineup was joined by a slightly exotic cousin named LG 6600. This was an all-wheel-drive truck with high off-road mobility and a payload of five tons for military operations, designed for the German Armed Forces which were in the process of being established at the time.

In 1956, when the vehicle had already been renamed LG 315, Daimler-Benz started testing two versions of this vehicle – a platform truck and a semitrailer tractor. These vehicles with single tires all round were, however, powered by the new OM 315 V multi-fuel engine. Between 1958 and 1964, the Federal Armed Forces ordered large numbers of the versions with open-top cab, folding top and dif-ferent bodies – after the Royal Air Force had procured a larger number of LG 6600 vehicles as early as around 1954.