CUTTING EDGE 8K8161 - Caterpillar

Introduction
For Specifications with illustrations, make reference to SPECIFICATIONS for 3500 NATURAL GAS ENGINES, Form No. SENR3103. If the Specifications in Form SENR3103 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.Engine Design
Bore ... 170 mm (6.7 in.)Stroke ... 190 mm (7.5 in.)Displacement: 3512 ... 51.8 liter (3158 cu.in.)3516 ... 69.1 liter (4210 cu.in.)Number and Arrangement of Cylinders: 3512 ... 60° V-123516 ... 60° V-16Valves per Cylinder ... 4Valve Setting: Intake ... 0.51 mm (.020 in.)Exhaust ... 1.02 mm (.040 in.)Compresstion Ratio ... 10:1Type of Combustion ... Spark IgnitedFiring Order: 3512 ... 1-12-9-4-5-8-11-2-3-10-7-63516 ... 1-2-5-6-3-4-9-10-15-16-11-12-13-14-7-8Direction of Crankshaft Rotation (when seen from flywheel end):SAE Standard Rotation ... Counterclockwise Front end of engine is opposite to flywheel end. Left side and right side of engine are as seen from flywheel end. No. 1 cylinder is the front cylinder on the right side. No. 2 cylinder is the front cylinder on the left side.Ignition System
The ignition system has five basic components: a magneto, ignition transformers for each cylinder, wiring harness, spark plugs and instrument panel.
COMPONENT LOCATION
1. Ignition transformer. 2. Wiring harness. 3. Magneto.Fairbanks Morse Magneto
Ignition power is generated in the alternator section (1) of the magneto. This section consists of an eight pole permanent magnet rotor in combination with a four pole stator. The output from the alternator section is three phase full wave rectified and flows into the main storage capacitor (3) on each power pulse. A zener diode located in the end cap with the capacitor is the regulator of the capacitor voltage for proper ignition.The trigger rotor (5) is timed to the distributor rotor (2) which is timed to the engine. The rotation of the trigger rotor (5) in the pulser coil (4) generates properly timed pulses in two series connected trigger coils. The coils energize the ignition triggering circuit by discharging an auxiliary supply capacitor through an auxiliary trigger silicon controlled rectifier (SCR) switch.The voltage generated by both the alternator section and the trigger coil combine and feed into a single triggering circuit that ignites all cylinders. Distribution of the voltage to the proper cylinder is accomplished by the rotation of the distributor rotor which operates as a rotating transformer. It performs no ignition timing, but by mechanical position selects the proper cylinder to which the ignition triggering signal is coupled. The distributor rotor and shaft rotating at engine camshaft speed is positioned so that pulsed triggering energy is transferred from a single coil surrounding the distributor and shaft to a selected coil on a multicoil stator assembly. By this selection, the proper SCR switch ignites the correct cylinder spark plug.
CUTAWAY VIEW OF SOLID STATE MAGNETO (FAIRBANKS MORSE)
1. Alternator section. 2. Distributor rotor. 3. Capacitor. 4. Pulser coil. 5. Pulser (trigger) rotor.Altronic Magneto
ALTRONIC MAGNETO
1. Alternator section. 2. Electronic firing section.The Altronic magneto is made of a permanent magnet alternator section