190201D Pg. 119 Piston, Piston Ring and Connecting Rod Fundamentals

Question 1

Pg. 153
1. List the main components of a piston and connecting rod assembly.
1\_\_\_\_\_\_\_\_\_\_\_\_\_
2\_\_\_\_\_\_\_\_\_\_\_\_
3\_\_\_\_\_\_\_\_\_\_\_\_
4\_\_\_\_\_\_\_\_\_\_\_\_

Answer 1

1. Connecting rod.
2. Piston.
3. Piston pin.
4. Piston rings.

Question 2

What temperature and pressure does a piston encounter in a running diesel engine?

Answer 2

3500 Degrees Fahrenheit

2,000 PSI

Question 3

Give a short example of why aluminum is used in diesel engine pistons.

Answer 3

Aluminum is light weight, reduces engine vibration and has a high rate of heat transfer.

Question 4

Which of the following best describes the design of a trunk type piston?
A. Crown and skirt and be separated for cleaning.
B. Two-Piece construction with a slipper skirt.
C. Three piece construction with a full skirt.
D. Crown and skirt are manufactured as one piece.

Answer 4

D. Crown and skirt are manufactured as one piece.

Question 5

Identify the parts of a piston:
A.
B.
C.
D. 
E.

Answer 5

A. Valve reliefs.
B. crown.
C. Skirt
D. Piston pin bore
E. Compression ring grooves.

Question 6

The purpose of cam grinding a skirt of a one piece aluminum piston is to:
A. fit an oval cylinder.
B. Allow for uneven expansion in the piston pin bore area.
C. Reduce friction when the engine is cold.
D. Allow easier installation of the piston rings.

Answer 6

B. Allow for uneven expansion in the piston pin bore area.

Question 7

What is the purpose of the holes in the oil ring groove of a piston?

Answer 7

Allows oil to flow into and out of the cavity behind the oil ring.

Question 8

Ring groove inserts are used in aluminum piston construction to:
A. Prevent the rings from sticking.
B. Control expansion in the ring grooves.
C. Reduce wear in and reinforce compression ring grooves.
D. Increase oil control ring durability.

Answer 8

C. Reduce wear in and reinforce compression ring grooves.

Question 9

What is the purpose of a slipper skirt piston design?

Answer 9

Provide clearance between the piston skirt and and the crankshaft at BDC.

Question 10

Which of the following best describes an advantage of a two piece piston design?
A. Crown and skirt cannot be separated.
B. Combustion forces are transferred directly to the skirt.
C. The skirt doesn’t have to absorb any side thrust.
D. Combustion forces are transferred directly from the crown to the piston pin.

Answer 10

D. Combustion forces are transferred directly from the crown to the piston pin.

Question 11

If a piston has a semi floating piston pin design, the pin is:
A. Free to rotate in the piston, but fixed to the connecting rod.
B. Held in the piston by a set of internal snap rings.
C. Free to rotate in the connecting rod but fixed to the piston.
D. Free to rotate in the connecting rod and the piston.

Answer 11

A. Free to rotate in the piston, but fixed to the connecting rod.

Question 12

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

Answer 12

Spray through a piston cooling nozzle.

Question 13

List two basic types of piston cooling rings used in an engine.

Answer 13

compression

Oil control

Question 14

The purpose of piston ring end gap is to:
A. Permit removal and installation of rings on the piston.
B. Provide that ring tension necessary for oil control.
C. Allow clearance for ring expansion.

Answer 14

C. Allow clearance for ring expansion.

Question 15

What three factors help a compression ring create an effective seal with the cylinder wall.
A.
B.
C.

Answer 15

A. Ring tension.
B. Cylinder pressure acting on the ring.
C. An oil film between the ring and the cylinder wall.

Question 16

The purpose of an oil ring expander is to:
A. Spread the ring open for installation on the piston.
B. Provide the ring tension necessary for oil control.
C. Hold the ring in place during installation.
D. Allow oil wiped from the cylinder wall to return to the oil pan.

Answer 16

B. Provide the ring tension necessary for oil control.

Question 17

List 2 advantages of a keystone piston ring design as compared to a rectangular design.
A.
B.

Answer 17

A. Stronger ring lands.

B. Greater resistance to carbon buildup and sticking.

Question 18

Chromium plating is used on some compression rings to:
A. Reduce the weight of the reciprocating mass.
B. Decrease heat transfer and increase friction.
C. Increase heat transfer and decrease friction.
D. Reduce the engine break in period.

Answer 18

C. Increase heat transfer and decrease friction.

Question 19

What is the purpose of a connecting rod?

Answer 19

Forms a link between the piston and the crankshaft that transmits the force of the combustion.

Question 20

Identify the parts of the connecting rod.

Answer 20

A. Beam or shank
B. Rod bearing bore
C. parting line
D. Piston pin bushing
E. Piston pin bore

Question 21

List four methods of maintaining connecting rod and cap alignment.

Answer 21

A. Shouldered rod bolts
B. Dowels
C. Tongue and groove joint
D. Serrated joint

Question 22

Identify the two connecting rod designs

Answer 22

A. Straight Cut

B. Bias Cut