Piston and Connecting Rod Fundamentals

Question 0

What is the purpose of the piston dome?

Answer 0

Aid in creating turbulence

Question 1

3 functions of a piston

Answer 1

1. Receives the force of combustion
2. Transmits force to con. Rod and crank
3. Dissipates heat

Question 2

What materials are commonly used in piston construction?

Answer 2

Cast Iron
Aluminum
Hypereutectic aluminum

Question 3

4 methods of producing pistons?

Answer 3

1. Sand casting
2. Permanent mould casting
3. Die casting
4. Forging

Question 4

What are 2 common piston designs?

Answer 4

1. Trunk type

2. Two-piece

Question 5

Trunk type piston

Answer 5

Is of one piece construction, the skirt and crown are cast together and cannot be separated

Question 6

Valve reliefs

Answer 6

Notches cut into piston done to provide valve to piston clearance

Question 8

Piston crown

Answer 8

Top portion of piston above ring lands.

Operates at much higher temp. and has reduced diameter to allow for more expansion

Question 9

Tapered Piston Skirt

Answer 9

The Piston Skirt is generally tapered from the top to the bottom. This allows for greater expansion due to extra heat at top of skirt

Question 10

3 types of piston skirts

Answer 10

1. Full skirt
2. Semi-Slipper
3. Full-slipper

Question 11

What are the 2 types of piston pins used?

Answer 11

Full floating

Semi-floating

Question 12

Full floating piston pin

Answer 12

Free to rotate in both the piston and the connecting rod
Retained by a set of snap rings
Pin slowly rotates during operation, changing wear surface

Question 13

Semi-floating piston pin

Crosshead is Semi-floating

Answer 13

Free to move in piston but bolted to connecting rod

Question 14

4 methods of piston cooling

Answer 14

1. Splash
2. Spray
3. Circulation
4. Shaker

Question 15

3 functions of piston rings

Answer 15

1. form a gas tight seal between the piston and the cylinder
2. Help cool the piston by transferring heat to cylinder wall
3. Control lubrication between the piston and cylinder walls

Question 16

Steel alloy rings

Answer 16

most often used for top compression rings, they are usually chrome plated

Question 17

Stainless Steel rings

Answer 17

Used mostly for the rails of multi-piece oil control rings

Question 18

2 coatings used on piston rings

Answer 18

1. Hard chromium plating

2. Molybdenum

Question 19

5 common compression ring designs

Answer 19

1. Rectangular - bears evenly against wall
2. Keystone - more resistant on carbon build up and sticking then rectangular
3. Barrel Face - narrower contact area for greater unit pressure
4. Tapered Face
5. Inside Bevel

Question 20

Oil control Rings

Answer 20

Can be 1,2 or 3 piece, located at bottom of piston in a 2 stroke

Question 21

What are 3 basic types of joints used on piston rings?

Answer 21

Butt joint, angle joint, Step joint

Question 22

Piston ring installation

Answer 22

ID marks installed towards the top

inside bevel up, outside bevel down

Question 23

Connecting rods are made from?

Answer 23

Alloy steel forging

Question 24

What are the 4 different connecting rod configurations?

Answer 24

1. Straight cut - parting line 90* to rod beam
2. Bias cut
3. Articulated
4. Fork and blade

Question 25

List the main components of a piston and connecting rod assembly (4)

Answer 25

Connecting rod, Piston, Piston pin, Piston rings

Question 26

When crown and skirt are manufactured a one, what type of piston is this?

Answer 26

Trunk style

Question 27

What is most common type of piston cooling used in medium and high speed diesel engines?

Answer 27

Spray through a piston cooling nozzle

Question 28

List the 4 methods of maintaining connecting rod cap allignment

Answer 28

1. Shouldered rod bolts
2. Dowels
3. Tongue and groove joint
4. Serrated joint

Question 29

What is the main advantage of using aluminum pistons?

Answer 29

Light weight and good at heat transfer

Question 30

Trunk type piston usually have what type of skirt?

Answer 30

Full skirt

Question 31

What is purpose of slots of in oil control ring?

Answer 31

Allow the flow of oil on upstroke and remove oil on the downstroke