AMT 212 WEEK 3 PPT 1

Question 1

The basic major components of
a reciprocating engine are the :
Crankcase
Cylinders
Pistons
Connecting rods
Crankshaft
Valves
Valve operating mechanism

Answer 1

Engine construction

Question 2

The foundation of an engine
is the ____. It contains
the bearings and bearing
supports in which the
crankshaft revolves.

Answer 2

Crankcase

Question 3

Cast or forged aluminum
alloy is generally used for
_____ construction
because it is light and
strong.

Answer 3

Crankcase

Question 4

In general, a typical radial
engine crankcase separates
into four main sections: the
nose section, the power
section, the supercharger
section, and the accessory
section.

Answer 4

Radial engine crankcase

Question 5

The _______
usually is of cast construction
and the material may be
either aluminum alloy, which
is used most widely, or
magnesium, which has been
used to some extent.

Answer 5

Accessory section

Question 6

The Four Basic Power Delivering Parts

Answer 6

• Cylinder
• Piston
• Connecting Rod
• Crankshaft

Question 7

The part of the engine in which power is
being developed.

Answer 7

Cylinders

Question 8

Four major factors in the design and
construction of the cylinder assembly :

Answer 8

1. Be strong enough to withstand the
   internal pressures.
2. Be constructed of a lightweight
   metal.
3. Have good heat-conducting
   properties.
4. Be comparatively easy and
   inexpensive to manufacture, inspect,
   and maintain.

Question 9

The purpose of the _____
is to provide a place for
combustion of the fuel/air
mixture and to give the _____
more heat conductivity for
adequate cooling

Answer 9

Cylinder Head

Question 10

The _____ of an air-
cooled engine is generally made
of aluminum alloy because
aluminum alloy is a good
conductor of heat and its light
weight reduces the overall engine
weight.

Answer 10

Cylinder Head

Question 11

The ______ in a reciprocating engine is a
cylindrical plunger that moves up and down,
back and forth within a cylinder.

Answer 11

Pistons

Question 12

Two Primary functions of a Piston :

Answer 12

1. It draws fuel and air into a cylinder, compress
   the gases, and purge burned exhaust gases from
   the cylinder.
2. they transmit the force produced by
   combustion to the crankshaft.
   * Usually made of aluminum alloy AMS 4140 for
   forged pistons Alcoa 132 alloy for cast pistons.
   * Piston temperature may exceed 4000°F and
   pressures may be as high as 500 psi or up.

Question 13

Parts of a piston

Answer 13

• Piston Head - The piston’s top surface
  is called the piston head and is directly
  exposed to the heat of combustion.
• Ring Grooves
• Is a cut into a piston’s
  outside surface to hold a set of piston
  rings. As many as six ring grooves may
  be machined around a piston.
• Ring Land
• The portion of the piston
  between the ring grooves.
• Piston pin boss
• Is an enlarged area
  inside the piston that provides
  additional bearing area for a piston pin
  to attach the piston to a connecting
  rod.
• Piston Skirt
• Help align a piston in a
  cylinder, the piston base is extended to
  form the piston skirt.

Question 14

All pistons expand as they heat up
and can cause a piston to take on an
oblong, or oval shape, at normal
engine operating temperatures,
resulting in uneven piston and
cylinder wear.

Answer 14

Cam-Ground Piston

Question 15

A _____ is machined
with a slightly oval shape. That is,
the diameter of the piston parallel
to the piston boss is slightly less
than the diameter perpendicular to
the piston boss.

Answer 15

Cam-Ground Piston

Question 16

• Piston rings - perform three functions in
  aircraft reciprocating engines
  1. They prevent leakage
  2. Reduce oil seepage
  3. transfer heat from the piston to the cylinder
  walls.
• Piston pin - The piston pin joins the piston to
  the connecting rod and sometimes called a
  wristpin.
• Piston pin circlip - Is a small component that
  holds the piston pin in place when the piston
  pin is attached in the piston pin boss.

Answer 16

Piston attachment

Question 17

Piston Ring joints

Answer 17

• Butt Joint
• Step Joint
• Angle Joint

Question 18

Type of piston rings

Answer 18

• Compression rings
• Oil rings

Question 19

prevent
gas from escaping past the
piston during engine
operation and are placed in
the ring grooves immediately
below the piston head.

Answer 19

Compression Rings

Question 20

Oil rings control the
amount of oil that is
applied to the cylinder
walls as well as prevent oil
from entering the
combustion chamber.

Answer 20

Oil rings

Question 21

Types of oil rings

Answer 21

1. Oil control rings
2. Oil scraper ring

Question 22

The primary purpose of oil
control rings is to regulate
the thickness of the oil film
on the cylinder wall.
To allow an oil control ring
to remove excess oil and
return it to the crankcase,
small holes are drilled in the
piston ring grooves, or ring
lands.

Answer 22

Oil control rings

Question 23

• This ring is used to regulate
  the amount of oil that
  passes between the piston
  skirt and the cylinder wall.
• Sometimes called an oil
  wiper ring, usually has a
  beveled face and is installed
  in a ring groove at the
  bottom of the piston skirt.

Answer 23

Oil scraper rings