Abstract
Loading problems on cam, follower, pump, and tappet are frequently encountered in high-output engines. The main parameters are Hertzian stresses, bouncing tendencies, and cam profile design. Rising speeds, line pressures, and injection rates have brought about major changes in pumping element design, and in this paper plunger and sleeve materials and their failures are discussed.
Hydraulic considerations determine the fuel pump delivery valve design, and the chief mechanical problem is fatigue failure. Body redesign has accommodated the increased clamping and sealing loads which higher line pressures demand.
Causes and prevention of fuel pipe breakage are described.
In the injector assembly the major mechanical problems are the inertia of moving parts, spring stresses, and sealing.
As regards future designs, are there ultimate hydraulic or mechanical limitations to conventional jerk pumps and, if so, what are the alternatives ?
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