4TNV98 & 4TNE98 Diesel Engine Section 4. Fuel System175Plunger OperationFigure 7-3The drive shaft simultaneously drives the feedpump, cam disc and plunger. The plunger springpresses the plunger and cam disc onto the roller.When the cam disc turns by means of the driveshaft, the face cam moves on the roller to activatethe plunger’s reciprocating operation. When theinlet port of the plunger barrel being pressed intothe distributor head and the inlet slit of the plungeroverlap, the plunger draws fuel and appliespressure to it.When the outlet port of the plunger barrel and theoutlet slit of the plunger align, the high-pressure fuelopens the delivery valve to be injected into theengine combustion chamber via the nozzle. Whenthe cutoff port reaches the control sleeve, pressurefeeding from the plunger is terminated.
