An auxiliary diesel engine on your towboat is equipped with an electric starting motor such as is shown in the illustration. For what reason is there a significant gap in distance between the start solenoid plunger (C) and the rod that is used to close the starter motor contacts? Illustration MO-0051
⢠Operation sequence of an electric starter solenoid and pinion engagement (what moves first: the pinion or current to the armature?) ⢠Mechanical linkage in the illustration between plunger (C), lever (F), and pinion gear (H) ⢠Purpose of delaying either pinion engagement or contact closure to protect gear teeth and electrical contacts
⢠Trace, in the illustration, what part actually meshes the pinion with the flywheel ring gear and which part closes the heavy current contacts. Which motion must be completed first to avoid gear damage? ⢠If the starter motor armature were energized before the pinion is fully engaged, what mechanical problem could occur? Conversely, if the armature were never energized until after engagement, what electrical effect does that have? ⢠Look at where the gap is drawn between the plunger (C) and the contactâclosing rod. What does that gap allow the plunger and shift lever to do before the contacts can move?
⢠Identify in the figure which component moves the pinion into mesh and which piece actually closes the highâcurrent starter contacts. ⢠Confirm whether the gap would logically cause a delay in current flow or a delay in gear engagement when the solenoid is energized. ⢠Eliminate any option that talks about armature reaction or effects that are not clearly related to the visible mechanical gap between (C) and the contactâclosing rod.
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