The three uncooled fuel injection valves in each cylinder cover
have nozzle tips sufficiently long for the cap nut to be shielded by the
cylinder cover and not exposed to the combustion space. The camshaftdriven
fuel injection pumps are of the double-valve controlled type,
traditional in Sulzer low speed engines. Injection timing is controlled
by separate suction and spill valves regulated through eccentrics on
hydraulically-actuated lay shafts. Flexibility in timing is possible through
the variable fuel injection timing (VIT) system for improved part-load
consumption, while the fuel quality setting (FQS) lever can adjust
timing according to the fuel oil quality. The valve-controlled fuel
injection pump, in comparison with a helix type, has a plunger with a
significantly greater sealing length. The higher volumetric efficiency
reduces the torque in the camshaft; additionally, injection from a
valve-controlled pump is far more stable at very low loads, and rotational
shaft speeds down to 15 per cent of the rated speed are achieved.
Valve control also has the benefits of less deterioration of timing over
the years owing to reduced wear and freedom from cavitation.