12225-ZY3-A01ZA Honda SEE PART DETAILS - PRI; CYLINDER HEAD-CAM ASSY. *NH8* (DARK GRAY)

1.1 Starter
The starter is an overhang type in which the pinion sliding surfaces are not exposed to the outside. Major components include: the motor that develops a high torque required to get the engine started; overrunning clutch that transmits torque and prevents the starter from overrunning; magnetic switch that brings the pinion into mesh with the ring gear, while turning on/off the load current to the motor; and, the reduction gear which boosts the armature torque.(1) Reduction Gear The gear at the end of the armature is in mesh with the reduction gear. This amplifies the turning force of the armature and the resultant greater force is transmitted to the pinion.(2) Overrunning Clutch The overrunning clutch is of the roller type mounted to the pinion shaft assembly.There is a wedge-shaped gap between the outer race and the inner race (sleeve), which contains rollers held by spring force.When the starter begins to rotate, the rollers are pressed to the narrow end of the gap, acting as keys to transmit outer race revolution to the pinion. When the engine starts and the pinion is driven by the engine, these rollers compress their springs, moving towards the wide end of the gaps, thereby preventing the transmission of power from the pinion to the outer race.(3) Operation The 24 V starter has a starter relay. When the starter switch is turned ON ("START" position), current from the battery flows from the SW terminal to terminal L of the starter relay to close contact P1. When this contact closes, the battery current flows from terminals of the magnet switch to the pull-in coil (P) and the holding coil (H). The reduced current then flows from terminal M to the motor. The plunger is attracted by the magnetic force of the holding coil and pushes out the pinion by means of a lever.The 12 V starter does not have a starter relay. When the starter switch is turned ON ("START" position), the battery current flows from terminals of the magnet switch to the pull-in coil (P) and the holding coil (H), which cases the same reaction as in 24 V type starter. As the pinion comes into complete mesh with the ring gear, the contact P, closes allowing a large current to directly flow from the battery to motor to turn the pinion powerfully.At the time, no current flows to the pull-in coil (P), the plunger being retained by the holding coil (H) alone. The moment the starter switch is turned OFF, the battery current flows from terminal B to the pull-in coil (P) and the holding coil (H) to cancel the magnetic flux force of the plunger. As a result, the return spring moves the plunger back to its original position and contact P2 opens to shut off current to the motor.1.2 Alternator
This is a brushed alternator that uses a slip ring to draw current for supply to the field coil in the rotor. It is divided structurally into: the rotor that generates a magnetic field; the rectifier that rectifies the electromotive force; and the regulator that keeps the generated voltage constant.Some alternators have a vacuum pump installed on their back. (1) Charging Circuit(a) Set the starter switch in ON position. (b) Start the engine. After engine start, when the alternator starts power generation and the voltage at alternator B terminal becomes higher than the battery voltage, current flows as shown below, starting battery charge. Thus the charging to battery is started, and the charge lamp turns off.(2) Rotor When the rotor is driven by the pulley rotation, a current flows from the brushes, through the slip ring, to the rotor coil. The rotor core tabs then become magnetic poles.(3) Stator Together with the rotor core, the stator core forms the magnetic flux path. The magnetic flux lines in the stator core are affected by the passage of the rotor core field and generate electricity.(4) Rectifier The rectifier mainly consists of 3 diode trios, 6 diodes and 2 heat sinks. It rectifies the AC stator output to DC power.Each heat sink has the (+) or (-) leads from 3 diodes attached to it, performing full wave rectification for 3-phase AC.(5) Regulator The IC regulator keeps the generated voltage constant, which would otherwise change with the engine speed. For this purpose, the regulator changes the intensity of the field coil magnetic force as the engine speed changes. The regulator and the brush holder (holding the brush and brush spring) are integrated into one unit.1.3 Vacuum Pump
The vacuum pump is installed on the back of the alternator and has its rotor coupled to the alternator shaft for simultaneous rotation with the alternator. Within its cylindrical housing, the rotor has three movable blades which are pressed onto the housing inner wall by centrifugal force generated as the rotor rotates, thus producing pumping action. The vacuum pressure generated by this action evacuates the vacuum tank. The rotor is positioned eccentrically to the housing cylinder. The air from the vacuum tank is sucked through the suction port and compressed gradually before it is discharged from the discharge port. From the suction port, engine oil is also sucked in to keep the housing oil tight and to lubricate and cool the housing. The oil is discharged from the discharge port and is returned to the oil pan with compressed air. At the suction port, a check valve is provided to prevent air and engine oil from flowing back from the vacuum pump to the vacuum tank when the engine is stopped.1.4 Safety Relay
The alternator rpm is detected and when it exceeds the reference level, the safety relay prevents the starter from operating even if its switch is accidentally turned on during engine revolution. Operation (1) When the starter switch is set to ON, current flow from the starter relay to terminal "S" and to terminal "E" of the safety relay, closing contact P1.(2) As the starter runs and the engine starts running, pulses of frequency 1/10th of the