OM77

In the early 1930s Daimler-Benz sold its heavy chassis with a choice of fuel rather than a choice of performance: the petrol M 76 and the diesel OM 77 were both in-line sixes of 9,450 cc rated at 110 PS. The OM 77 was a pre-chamber engine of 110 mm bore and a deliberately long 165 mm stroke, water-cooled, fed by a Bosch pump, built at Gaggenau and weighing some 720 kg dry. It went into the L 5000 five-tonner from 1932. The argument for it had already been made by the earlier OM 5 in the three-axle N 56, which customers took to enthusiastically for the simple reason that it burned far less fuel.

The choice did not survive long. For the 1933 model year the petrol engine was struck from the L 8500 and O 8500 range altogether, leaving buyers to pick between the 110 PS OM 77 and the larger 120 PS OM 79 — the moment when Daimler-Benz's heavy program became diesel-only. In 1935 the OM 77 also replaced the OM 67 as standard equipment in the O 4000 low-frame bus chassis, a model kept alive largely because the Deutsche Reichspost went on ordering it in quantity, until the OM 79 took over that duty in 1937.