Chapter 08: Final Review & Key Terms

cavitation erosion Pinholes produced in cylinder block walls, heads, and liner sleeves as a result of the collapse of tiny water vapor bubbles formed when coolant vaporizes on hot cylinder wall surfaces.

compacted graphite iron (CGI) A material produced from powdered iron alloys squeezed into molds at high pressures and then heated to bond the metal particles together; also known as sintered graphite.

cross-bolted block A variation of the deep-skirt block that uses additional horizontally placed bolts to connect the crankcase walls of the block to the main bearing caps; also known as a tie-bolted or bolster-bolted block.

deep-skirt block A block configuration with a bottom edge that extends well below the crankshaft’s centerline.

downspeeding An operating strategy to further reduce engine speed by intentionally lowering driveline gear ratios (even further than already traditionally low gear ratios) to take advantage of diesel’s high torque output at low engine speeds.

dry sleeve cylinder block A block designed with a bored or honed hole in the block that allows no coolant contact with the cylinder sleeve.

dual mass flywheels (DMF) Two-piece flywheel designs that incorporate specialized torsional damping springs.

fillet radius A circular machining applied to the surface between the journal and the crankshaft cheek that strengthens the crankshaft and minimizes the possibility of a fracture.

harmonic vibration A vibration that sends pressure waves moving back and forth along the axis of a shaft, particularly the crankshaft.

induction hardening A heat treatment process that involves passing alternating electric current through coils of heavy-gauge wire surrounding the material to be hardened; through magnetic induction, heat is produced in the metal, which is then quenched with water to produce a hard, wear-resistant metal surface.

ladder-frame block A block design with sides that extend exactly to the centerline of the crankshaft bearings and a separate, additional section that attaches to the crankcase and the oil pan and incorporates the main bearing caps into a one-piece component.

Nanoslide technology A plasma-spray welding technique developed by Mercedes-Benz to coat cylinder walls with a tool-grade hardness iron alloy.

nitriding A crankshaft hardening technique that involves heating the shaft and introducing cyanide salt or liquid into the heating chamber with the crankshaft; slowly cooling or quenching the crank with these substances in its heated condition causes the nitrogen and carbon to molecularly bond with metal surfaces to create an extremely hard journal.

parent bore block A block design that has holes cast and bored in the block for the cylinders with the pistons inserted directly into these holes; also known as a no-sleeve block.

pendulum vibration absorber A damper that provides torsional vibration control by producing forces that directly cancel the forces producing torsional vibration.

physical vapor deposition (PVD) A process used to add layers of new, hardened polymer coating to the surface of a plain bearing.

primary balance The balance achieved when the crankshaft counterweights offset the weight of the piston and connecting rod assembly.

scissor gear Two separate spring-loaded gears incorporated into a single unit to reduce gear rattle caused by torsional vibration.

secondary balance The balance achieved when the movement of one piston counterbalances the movement of another, resulting in smoother-running engines.

sputter-coated engine bearings Also called a sputter bearing , it is a bearing using a hardened overlay material using physical vapor deposition. This bearing has one of the highest capabilities to support a load compared to other bearing technologies.

tension bolts A feature of aluminum block construction where a single bolt is used to clamp both the cylinder head and the main bearing caps together.

torsional vibration The speeding up and slowing down of the crankshaft caused by alternating compression and power strokes of the engine cylinder.

tunnel-bore block A block that has the main bearing bores and block formed into one solid structure for maximum block rigidity and strength.

warp anchor A block design that has the cylinder head and the cylinder block bolted together by tie bolts; sliding steel sleeves, which are locked in the block, accept the cylinder head bolt from one side and the tie bolt from the other.

wet sleeve block A block designed with large holes into which the cylinder sleeves are inserted; coolant has direct contact with the outside of the sleeve and there is no supporting cylinder bore structure.