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Quiz 2
Cylinder
Crankcase
Crankshaft
Connecting Rod
Pistons
Valves
Valve-operating mechanism
Engine Basic Parts
crankcase,
cylinders,
pistons,
connecting rods,
valves,
spark plugs, and
crankshaft
Engine Components
Crankcase
Foundation of a reciprocating engine
Provides tight enclosure for the lubricating oil
Contains the engine’s integral parts
Mounting surface for the engine cylinders and external accessories
Cast or forged Aluminum Alloy
Crankcase
It contains the bearings in which the crankshaft revolves.
It provides a tight enclosure for the lubricating oil.
It supports various internal and external mechanisms of the powerplant to the airplane
Front or Nose
Main or Power Section
Fuel Induction and Distribution Section
Accessory Section
In Line and V type Engine Crankcase
four major sections
Front or Nose Section (In Line and V type Engine Crankcase)
Directly behind the propeller in most tractor type airplanes.
Its function is to house the propeller shaft, the propeller thrust bearing, the propeller reduction gear train, and sometimes a mounting pad for the propeller governor.
Main or Power Section (In Line and V type Engine Crankcase)
Where the cylinders are normally mounted.
Made up of two separates parts that supports each halves of the crankshaft bearing.
Fuel Induction and Distribution Section (In Line and V type Engine Crankcase)
Normally located next to the main or power section.
This section houses the diffuser vanes and supports the internal blower impeller.
Contains the induction manifold.
Accessory Section (In Line and V type Engine Crankcase)
It contains the accessory drive gear train.
Has mounting pads for the fuel pump, coolant pump, vacuum pump, oil pump, magnetos, tachometer generator.
nose section
power section
supercharger section
accessory section
radial engine crankcase separates into four sections:
Nose Section (radial engine)
The nose section is mounted at the front of a _engine crankcase and bolts directly to the power section.
The nose section usually houses and supports a propeller governor drive shaft, the propeller shaft, a cam ring, and a propeller reduction gear assembly if required.
In addition, many nose sections have mounting points for magnetos and other engine accessories.
Main or Power Section (radial engine)
Represents the section of the crankcase where the reciprocating motion of the pistons is converted to the rotary motion of the crankshaft.
Supports crankshaft bearings,
Contains cylinder pads where cylinders are mounted.
Diffuser/Blower Section/Supercharger Section (radial engine)
Located directly behind the power section and is generally made of cast aluminum alloy or magnesium.
As its name implies, this section houses the supercharger and its related components.
Also called “Fuel induction and distribution section”. Provides housing for attachments of induction pipes, manifold pressure lines.
Accessory Section (radial engine)
A typical ___ houses gear trains containing both spur- and bevel-type gears that drive various engine components and accessories.
Has mounting pads for fuel pump, oil pump, tachometer generators etc.
Crankshaft
The backbone of a reciprocating engine.
Receives linear power pulse and changes it into rotary motion.
The basic parts of a crankshaft include the main bearing journal, the crankpin, and the crank cheek.
Main Bearing Journal/Main Journal
Represent the centerline of a crankshaft and support the crankshaft as it rotates in the main bearings. Center of rotation of the crankshaft. All crankshafts require at least two main journals to support the crankshaft, absorb the operational loads, and transmit stress from the crankshaft to the crankcase
Crankpin/Throw/Crank throw/Connecting-rod Bearing Journal
Serves as attachment points for the connecting rods. To reduce total crankshaft weight, crankpins are usually hollow. This hollow construction also provides a passage for lubricating oil.
sludge chamber
a hollow crankpin serves as a collection chamber for sludge, dirt, carbon deposits, and other foreign material. This is called_
Crank cheek/Crankweb/Crank arm
Required to connect the crankpin to the crankshaft. The solid section of the crankshaft that connects the crankpin to the main journals. The crank cheek is also where counterweights might be mounted to help balance the engine and reduce vibrations.
Counterweights and dampers
Helps balance the crankshaft. Its function is to relieve the whip and vibration caused by rotation of the crankshaft. A counterweight in a reciprocating aircraft engine is a mass attached to the crank cheek (or crankweb) to balance the crankshaft, reduce vibrations, and offset the inertia of reciprocating components like pistons and connecting rods.
Static Balance
When the weight of an entire crankshaft assembly is balanced around its axis of rotation.
Dynamic Balance
Refers to balancing the centrifugal force created by a rotating crankshaft and the impact forces created by an engine’s power impulses.
dynamic dampers
The most common means of dynamically balancing a crankshaft is through the use of__.
is a weight which is fastened to a crankshaft crank cheek assembly in such a way that it is free to move back and forth in a small arc.
Single Throw
Two Throw
Four Throw
Six Throw
Crankshaft Types
single-throw, or 360-degree crankshaft.
The simplest crankshaft is _
bearing
is any surface which supports and reduces friction between two moving parts. Typical areas where bearings are used in an aircraft engine include the main journals, crankpins, connecting rod ends, and accessory drive shafts.
Plain Bearing
Friction | Higher (needs constant lubrication) |
Load Capacity | Very High |
Durability | High, but can wear over time |
Complexity | Simple, easy to manufacture |
Roller Bearing
Friction | Lower |
Load Capacity | High (especially radial loads) |
Durability | Very durable under heavy loads |
Complexity | More complex design |
Ball Bearing
Friction | Lowest |
Load Capacity | Moderate (handles both radial & axial) |
Durability | Durable, but balls can wear out faster |
Complexity | Simple, but precision-made |
Connecting Rod
The link which transmits the force exerted on a piston to a crankshaft.
Made of forged durable steel alloy.
One end of a connecting rod connects to the crankshaft is called the crankpin end, while the other end connects to the piston is called piston end.
Plain type,
Master and Articulated rod Type,
Fork and Blade Type.
Types of connecting rod
Plain Rod
used in opposed and in line engines. The piston end of a plain connecting rod is fitted with a bronze bushing to accommodate the piston pin. The crank pin end is usually fitted with a two piece bearing end cam which is held on the end of the rod by bolts or studs.
Master and Articulated Rod
Commonly used in radial engines. With this type of assembly, one piston in each row of cylinders is connected to the crankshaft by a
knuckle pins
Articulated rods are attached to the master rod by , that are pressed into holes in the master rod flanges during assembly. A __ lock plate is then installed to retain the pins.
Fork and Blade Rod
Used primarily in V-type engines and consists of a fork connecting rod and a blade connecting rod. The forked rod is split at the crankpin end to allow space for the blade rod to fit between the prongs. The assembly is then fastened to a crankpin with a two piece bearing.
Piston
Cylindrical plunger the back and forth.
Primary Function: draw fuel and air into a cylinder, compress the mixture, and purge burned exhaust gases from the cylinders.
Secondary Function: Transmit the force produced by combustion to the crankshaft.
Machine aluminum alloy forging.
Piston Head,
Ring Groves,
Piston Pin Boss,
Piston Skirt.
Four parts or piston:
Ring Grooves
are then cut into a piston’s outside surface to hold a set of piston rings.
ring land
The portion of a piston between the ring grooves is commonly referred to as a
piston head
The piston top surface is called the _ and is directly exposed to the heat of combustion.
piston pin boss
is an enlarged area inside the piston the provides additional bearing area for a piston pin which passes through the _ to attach the piston to a connecting rod.
piston skirt
To help align a piston in a cylinder, the piston base is extended to form the __
Flat Head
Flat Head with Valve Recessed
Cupped Head
Domed Head
Piston Head Designs
Flat head
are the simplest type of piston head design. They are typically used in older engines.
Recessed head
have a small depression in the center of the piston head. This depression helps to improve the combustion process.
Concave head
have a larger depression in the center of the piston head than recessed head pistons. This depression helps to further improve the combustion process and can also help to reduce emissions.
Domed head
have a raised area in the center of the piston head. This raised area helps to increase the compression ratio of the engine, which can lead to more power.
Piston Rings
Performs three functions in aircraft reciprocating engines.
Prevent leakage of gas pressure from the combustion chamber.
Reduce Oil Seepage into the combustion chamber
Transfer heat from the piston to the cylinder walls.
Compression Rings
Prevent gas from escaping past the piston during engine operation and are placed in the ring grooves immediately below the piston head. However, most aircraft engines typically use two or three
Oil Rings
Controls the amount of oil that is applied to the cylinder walls as well as prevent oil from entering the combustion chamber.
Oil scraper rings
Used to regulate the amount of oil that passes between the piston skirt and the cylinder wall.
Butt Joint
Angle Joint
Step Joint
Piston ring Gaps example
cam-ground piston
piston pin
joins the piston to the connecting rod. It is sometimes called wrist pins.
Stationary
Semi-floating
Full-floating
PISTON PIN types
CYLINDER
provides a combustion chamber where the burning and expansion of gases takes place to produce power.
It houses the piston and connecting rod assembly, as well as the valves and spark plugs.
Valve Assembly
Intake Port
Exhaust Port
Spark Plug Port
Fuel Injector Port
Cylinder Head
Cylinder Barrel
Mounting Base
CYLINDER PARTS
valves
regulate the flow of gases into and out of a cylinder by opening and closing at predetermined times in the combustion process.
Flat Head
Semi-Tulip Head
Tulip Head
Mushroom Head
Valve Head Types
Head
Stem
Tip
Valve Parts
Valve Seat
Valve Guide
Valve Springs
Valve Spring Retainers
VALVE SEATING COMPONENTS
Valve Seat
A circular ring of hardened metal that provides a uniform sealing surface for the valve face.
Valve Guide
A cylindrical sleeve that provides support to the valve stem and keeps the valve face aligned with the valve seat.
Valve Springs
Helical-coiled springs that are installed in the cylinder head and provide the force that holds the valve face firmly against the valve seat.
Valve Spring Retainer
Holds the valve springs in place.
Camshaft
A device for actuating the valve lifting mechanism. Consists of a round shaft with a series of cams, or lobes, that transform the circular motion of the crankshaft to the linear motion needed to actuate a valve.
Tappet or Valve Lifter
A mechanism to transmit the force of the cam to the push rod.
Push Rod
A steel or aluminum alloy rod or tube situated between the valve lifter and the rocker arm to transmit the motion of the valve lifter.
Rocker Arm
A pivoting lever located in the cylinder head that changes the lifting movement of the push rod into the downward motion needed to open a valve.
