Chapter 14 PowerPoint

Define these Technical Terms using the textbook:

1. aluminum cylinder block

2. balancer shaft

3. crankshaft end play

4. cylinder sleeve

5. main thrust bearing

6. piston ring gap

7. piston skirt

8. ring land

Answer these discussion questions using the textbook:

1. Explain the construction of engine bearings.

Read the chapter summary below:

■ The basic parts of an engine bottom end are the block, crankshaft, connecting rods, and piston assemblies.

■ Cylinder sleeves, or liners, are metal, pipe-shaped inserts that fit into the cylinder block.

■ Line boring refers to a machining operation that cuts a series of holes through the block for the crankshaft bearings.

■ A two-bolt main block only uses two bolts to secure each main bearing cap to the cylinder block. A four-bolt main block has four bolts holding each main cap.

■ A main bearing bed plate is a large part that fits over the whole bottom of the block.

■ A cam-ground piston is slightly out-of-round when viewed from the top.

■ Piston taper is normally used to maintain the correct piston-to-cylinder clearance.

■ A slipper skirt is produced when the portions of the piston skirt below the piston pin ends are removed.

■ Piston ring width is the distance from the top of the ring to the bottom of the ring.

■ Piston ring gap is the distance between the ends of the ring when it is installed in the cylinder.

■ Case-hardening is a heating and cooling process that increases the wear resistance of the piston pin.

■ A full-floating piston pin is secured by snap rings and is free to rotate in both the rod and piston.

■ A press-fit piston pin is forced tightly into the connecting rod’s small end.

■ Piston pin offset locates the piston pinhole slightly to one side of the piston centerline to quiet piston operation.

■ Connecting rod numbers are used to ensure proper location of each connecting rod in the engine.

■ A broken surface rod is scribed and broken off when manufactured to produce a rough, irregular mating surface between the rod body and cap.

■ A standard bearing has the original dimensions specified by the engine manufacturer and is used for a new, unworn, or un-machined crankshaft.

■ An undersize bearing is designed to be used on a crankshaft journal that has been machined to a smaller diameter.

■ A main thrust bearing limits crankshaft end play.

■ Select fit means that some engine parts are selected and installed in a certain position to improve the fit between parts.

■ Balancer shafts are used in some engines to cancel the vibrating forces produced by crankshaft, piston, and rod movement.