Piston and Connecting Rod Fundamentals Flashcards
What is the purpose of the piston dome?
Aid in creating turbulence
3 functions of a piston
- Receives the force of combustion
- Transmits force to con. Rod and crank
- Dissipates heat
What materials are commonly used in piston construction?
Cast Iron
Aluminum
Hypereutectic aluminum
4 methods of producing pistons?
- Sand casting
- Permanent mould casting
- Die casting
- Forging
What are 2 common piston designs?
- Trunk type
2. Two-piece
Trunk type piston
Is of one piece construction, the skirt and crown are cast together and cannot be separated
Valve reliefs
Notches cut into piston done to provide valve to piston clearance
Piston crown
Top portion of piston above ring lands.
Operates at much higher temp. and has reduced diameter to allow for more expansion
Tapered Piston Skirt
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
3 types of piston skirts
- Full skirt
- Semi-Slipper
- Full-slipper
What are the 2 types of piston pins used?
Full floating
Semi-floating
Full floating piston pin
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
Semi-floating piston pin
Crosshead is Semi-floating
Free to move in piston but bolted to connecting rod
4 methods of piston cooling
- Splash
- Spray
- Circulation
- Shaker
3 functions of piston rings
- form a gas tight seal between the piston and the cylinder
- Help cool the piston by transferring heat to cylinder wall
- Control lubrication between the piston and cylinder walls
Steel alloy rings
most often used for top compression rings, they are usually chrome plated
Stainless Steel rings
Used mostly for the rails of multi-piece oil control rings
2 coatings used on piston rings
- Hard chromium plating
2. Molybdenum
5 common compression ring designs
- Rectangular - bears evenly against wall
- Keystone - more resistant on carbon build up and sticking then rectangular
- Barrel Face - narrower contact area for greater unit pressure
- Tapered Face
- Inside Bevel
Oil control Rings
Can be 1,2 or 3 piece, located at bottom of piston in a 2 stroke
What are 3 basic types of joints used on piston rings?
Butt joint, angle joint, Step joint
Piston ring installation
ID marks installed towards the top
inside bevel up, outside bevel down
Connecting rods are made from?
Alloy steel forging
What are the 4 different connecting rod configurations?
- Straight cut - parting line 90* to rod beam
- Bias cut
- Articulated
- Fork and blade
List the main components of a piston and connecting rod assembly (4)
Connecting rod, Piston, Piston pin, Piston rings
When crown and skirt are manufactured a one, what type of piston is this?
Trunk style
What is most common type of piston cooling used in medium and high speed diesel engines?
Spray through a piston cooling nozzle
List the 4 methods of maintaining connecting rod cap allignment
- Shouldered rod bolts
- Dowels
- Tongue and groove joint
- Serrated joint
What is the main advantage of using aluminum pistons?
Light weight and good at heat transfer
Trunk type piston usually have what type of skirt?
Full skirt
What is purpose of slots of in oil control ring?
Allow the flow of oil on upstroke and remove oil on the downstroke
