TM 5-3810-306-20ELECTRICAL SYSTEMGeneralThe electrical system is 24-volt operation, consisting of an alternator and four lead-acid batteries, series-parallelconnected. The system is the single wire ground return, utilizing the crane’s superstructure as ground.BatteriesThe 12-volt batteries are located in a box on the left side of the machine behind the rear axle. Two batteries areconnected in parallel to make two parallel sets. Both parallel sets are connected in series to provide the necessary 24-volts for the system.StarterWhen the start button is depressed, the coils in the solenoid are energized creating a magnetic field. This field pulls in theplunger which causes the shift lever to push the drive assembly in mesh with the ring gear in the engine. At this time theplunger closes the circuit between the "BATTERY" terminal and the field coil.The current passes through the field coil, then through the brushes until it reaches the armature. The current formscounteracting magnetic fields around the field coil and the armature, causing the armature to turn. The armature turns thedrive assembly which cranks the engine through the ring gear.When the engine starts, the start button is released. This causes the magnetic field in the solenoid to collapse and areturn spring forces the plunger back to its original position. As this happens, the shift lever disengages the driveassembly from the ring gear teeth. The contact from the "BATTERY" to the field coil is also broken by the returningplunger, which causes the armature to stop turning.AlternatorThe alternator is mounted on the engine and is belt driven. It is a 65 amperage alternator with a 24-volt output terminal.The 24 volts from the alternator is supplied by a transformer rectifier unit mounted on the end frame of the alternator.When the engine is running, the 24-volt terminal supplies the voltage to recharge the batteries and maintain them at a fullstate of charge.1-19
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