C3.3B Tier 4 Interim and EU Stage 3A Engines for Caterpillar Built Machines – Basic Engine

Cylinder Block

Illustration 1g03002479

(1) Crankcase upper section

(2) Crankcase lower section

The cylinder block is the main housing of the engine and supports the other main parts. The cylinder blocks utilize a ladder frame structure type crankcase design. The cylinder block is made of cast iron and includes complete passages for coolant and lubricating oil.

The ladder frame structure design includes the following benefits:

  • Minimizing Parts

  • Noise reduction

  • Reduction of loss and dispersion on friction through accuracy of axial concentricity

This engine does not utilize cylinder liners. The following benefits include improved cooling operation, less strain on components and improved abrasion resistance

Illustration 2g03002661

The cylinder block has a hollow core already cast inside the cylinder to cylinder water jacket.

This engine utilizes coolant evenness distribution type cooling jacket inside the top section of the crankcase.

Half-Floating Valve Cover

Illustration 3g03002718

(4) Valve cover

(5) Rubber packing

The rubber packing is attached to keep the cylinder head cover approximately 0.5 mm (0.02 inch) off the cylinder head. The rubber packing decreases the noise from the cylinder head.

Closed Crankcase Breather

Illustration 4g03331967

(6) Breather

(7) Breather tube

Illustration 5g03007176

(8) Breather valve

(9) Oil shield

Closed breather system has been adopted to prevent the release of blow-by gas into the atmosphere.

After the oil content is filtered by oil shield (9) , the blow-by gas is fed back to the intake manifold through breather valve (8) to be used for combustion.

Combustion Chamber

Illustration 6g03007042

(10) Injection nozzle

(11) Glow plug

(12) Combustion chamber

(13) Piston

Fuel is injected directly at the center of the cylinder. This allows uniform mixture of injected fuel and inlet air, which leads to more stable, higher combustion performance. The benefits include: cleaner emissions, higher power output, lower fuel consumption, lower operating noise and higher start-up performance


Illustration 7g02792771

The crankshaft converts the up-and-down motion of the pistons into rotary motion. The crankshaft ties together the reactions of all the pistons into one rotary force that drives the machine.

The crankshaft is made of tough special alloy steel, and the journals, pins, and oil seal sliding portions are induction hardened to increase the hardness for higher wear resistance.

The front journal is supported by a solid type bearing (tunnel type cylinder block) or by a split type (hanger type cylinder block), and the intermediate journal by a split type, and the rear journal by a split type with thrust bearings.

The crankshaft is provided with an oil gallery, through which engine oil is fed to the crankpin portion, and lubricates.


Illustration 8g03007258

(14) Camshaft gear

(15) Camshaft

The camshaft is normally driven by gearing from the crankshaft.

The camshaft is made of special cast iron, and the journal and cam sections are chilled to resist wear. One intake and one exhaust cam is provided for each cylinder.

The journal diameters are large in order to permit removal of the shaft from the bore. The journal sections are force-lubricated.

Note: There are no camshaft bearings for these engines.

Gear Train

Illustration 9g03007499

Rear view of gear train

(16) Fuel pump gear

(17) Camshaft gear

(18) Idler gear

(19) Crankshaft gear

The gear train is located on the flywheel side of the engine.

The crankshaft is the hub around which other parts of the engine can be timed and driven. This is done by the meshing of gears as shown in the Illustration 9.

The timing gears transmit torque from the crankshaft to the oil pump and injection pump and, at the same time, correctly control fuel injection to the cylinders and valve timing.

Each gear has an inscribed mating mark for correct and easy assembly and is spherical with teeth set obliquely to the axis of rotation to rotate smoothly and reduce noise.


Illustration 10g03007836

(20) Crankshaft

(21) Flywheel ring gear

(22) Flywheel

The flywheel is made of heavy cast iron or steel, and has gear teeth around the outer rim of the flywheel, which mesh with the drive pinion of starter.

The flywheel mounted on the rear of the crankshaft is a stabilizer for the whole engine.

The flywheel stores the rotating force in the combustion stroke as inertial energy, reduces crankshaft rotating speed fluctuation and maintains the smooth rotating conditions.

The flywheel periphery is inscribed with the marks showing fuel injection timing angle lines and top dead center mark TC.

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