Additional Notes for AB Power Engineering

Tractive work

requiring pulling or drawing efforts. Ex. plowing or land preparation,

planting and seeding, crop cultivation, harvesting, and hauling

Stationary work

- usually accomplished by means of belt, gears, pto, direct drive, electric

motors.

Ex. Water pumping, threshing, milling

0.7 to 1.3 hp

Power range of farm animals

P = force * speed

Power (watt) = Voltage (volt)*current(amp)

Power =

Mass

quantity of matter a body contains irrespective of the kind of material of which it is composed

Inertia

property of matter by virtue of which a body tends to remain at rest or

continue in motion in a straight line

Momentum

-a term applied to a body in motion,

it is the product of its mass and

velocity at any instant

Force

an action exerted upon a body that changes or tends too change to its natural state of rest or uniform motion in a straight line

Work

if a force is applied to a body changing its state of motion or

if it is in motion, its rate or direction of travel is changed- then work is done

W = Fd

formula of Work

P = W/t

formula of power

Energy

possessed by a body is defined by its capacity for doing work

Potential energy

- energy possessed by virtue of its position. (kg-m, ft-lb)

Kinetic energy

- energy possessed by virtue of its motion

Torque

- a turning or twisting effort or action.

Power

-rate at which work is done (ft-lb/min, kg-m/min)

Horsepower

- a unit of measurement of power (English) equal to doing work at the

rate of 33,000 ft-lb/min or 550 ft-lb/sec

Electrical work (joules)

Amount of work done by a current of 1 ampere flowing for 1 second under a

pressure of 1 volt.

Electric Power (Watt)

Electrical work (joules) per unit time (sec)

Indicated Hp (ihp)

the power generated in the cylinder and received by the piston.

Belt or Brake hp

power generated in the belt pulley (measured by a suitable

dynamometer) and available for useful work

Friction Hp (fhp)

power the engine consumes in operating itself at a given speed

without any load.

Drawbar hp

- power developed at the hitch or drawbar and available for pulling, dragging

or similar tractive efforts

PTO hp

- power developed at the PTO shaft of the tractor and available for driving

rotovators and other implement

Hydraulic hp

- the fluid power required by the implement from the hydraulic system of

the tractor.

Volumetric Efficiency

refers to the relationship of the quantity of fuel mixture actually

drawn into the cylinder by the piston on the intake stroke and producing power to the actual

volume of space displaced by the piston on this stroke (range 75 to 85%).

Thermal Efficiency

- ratio of output in the form of useful mechanical power to the power

value of the fuel consumed.

Mechanical Efficiency

ratio of the useful mechanical power to the total power generated

by the engine (range 75 to 90%)

FIRING ORDER

The order or sequence in which the engine cylinders fire or generate & deliver power

FIRING INTERVAL

The arc of travel of the crankshaft between successive explosions in an engine

Firing interval = 360/no. of cylinders - for 2sce

Firing interval = 720/no. of cylinders - for 4sce

Firing interval of 2 stroke and 4 stroke engine

VALVE CONSTRUCTION

The usual face and seat angle is 45 degrees.

• However, a 30-deg angle is frequently used for intake valves

• The four-cycle engines have inlet and exhaust ports at each combustion chamber

at the upper section of the cylinder.

• The inlet and exhaust ports are equipped with inlet valves and exhaust valves

INTAKE/EXHAUST VALVE

TIMING GEAR

CAMSHAFT

TAPPET

PUSH ROD

ROCKER ARM

VALVE SPRING

VALVE TIMING

Valve Mechanism

INTAKE/EXHAUST VALVE

• Allows the fuel mixture to enter/exit the combustion chamber on the

intake/exhaust stroke.

• Intake valves are larger in diameter than exhaust valves

TIMING GEAR

• Drives the camshaft that opens and closes the valves.

CAMSHAFT

• Driven by the camshaft gear.

• Held by the camshaft bearings so that it can smoothly rotate between the

camshaft journals and bearings

• On the cam surface, tappets are mounted which move vertically

• The rotating movement of the camshaft is converted into vertical movement to

open and close the valves

TAPPET

• Used to convert camshaft rotation into reciprocating movement.

• The overhead valve type tappet is cylindrical or cup-shaped, and includes a push rod which connects the cam to the rocker arm

PUSH ROD

• Push rods are simply hollow steel pipes machined at both ends

• The bottom contacts the tappet interior and the top contacts the rocker arm

ROCKER ARM

• One end is pushed up by the push rod which is moved by cam rotation.

• The other end directly contacts the end of the valve stem, and functions as a lever

to push the valve up.

• The rocker arm shaft is mounted on the cylinder head, using bracket bearings

• the push rod movement is transmitted to the rocker arm via an adjustment screw for valve clearance

VALVE SPRING

Keep the valve pressed firmly on the valve seat to maintain air-tightness when the

valve is closed.

• Quickly return the valve to its original position after it has been pushed down by

the rocker arm

VALVE TIMING

The timing of any valve is specified with respect to the instant it begins to open

and the instant it closes in relation to the crankshaft rotation and the piston

position.

• If a valve starts to open and then closes at the specified time with respect to the

crankshaft and the piston position for that cylinder, it is said to be correctly timed.

• It would be assumed, ordinarily that a valve would start to open at the beginning

of its stroke and be completely closed at the end.

• Most engines operate efficiently only when the valves open and close at certain

points in the cycle and remain open a certain length of time.

FUEL TANK ASSEMBLY

FUEL PUMP

FUEL PIPES/LINES

FUEL FILTER

CARBURETOR

Fuel Supply System

FUEL TANK ASSEMBLY

Made from pressed steel and coated inside to prevent corrosion, or a synthetic rubber

compound or flame resistant plastic. Fuel gauge sender unit and electrically driven fuel

pump are usually located inside the fuel tank.

FUEL PUMP

This supplies fuel under high pressure to the fuel injection system, or under low pressure

to a carburetor.

FUEL PIPES/LINES

Made from steel or Plastic. Secured by clips at several points along the underside of the

vehicle.

FUEL FILTER

Prevent dirt and fluff entering the fuel pump. Fuel filter is fitted on the suction side of the

pump. Fuel filter is fitted on the suction side of the pump. Fuel filter should be changed

according to manufacturer recommendation

CARBURETOR

atomizes the fuel and mixes it with the correct amount of air

- assist in properly vaporizing the fuel

-mix the vaporized fuel in the correct proportions of air

-supply the correct air-fuel mixture to the engine

Functions of carburetor

-air fuel ratio

-catalytic converter

-turbo charger/ supercharger

-euro emission standard

Fuel supply system terminologies:

air fuel ratio

the proportion of air and fuel mixture maintained by the fuel supply

system for maximum power and economy. (15:1)

catalytic converter

- a device added to the exhaust system to reduce hydrocarbon

and carbon monoxide pollutants in the exhaust gas.

Turbocharger/supercharger

a device that forces more air or fuel mixture into the

cylinder than would be drawn under normal condition, thus increasing the volumetric

efficiency and power output of the engine

Euro emission standard

- seek to limit the vehicle's toxic gas in hope to attain a

cleaner, breathable air.

Euro 1

Euro ___ was introduced in 1992 as an initiative by the EU.

Euro 6

Euro __ was the latest and was introduced in 2014.

Euro4

DENR pushed for the implementation of Euro _ in July 2015. Oil and car manufacturers

preferred to follow DOE timeline - Jan 2016

Euro 4 emission standard

Gasoline:

CO - 1.0g/km, THC - 0.10g/km,

NOx -0.08g/km.

For diesel;

CO - 0.50g/km,

HC+NOx -0.30g/km,

NOx - 0.25g/km,

PM -0.025g/km

(CO - Carbon Monoxide,

HC - Hydrocarbon,

THC - Total Hydrocarbon,

Nox- Nitrogen Oxide,

PM - Particle matter

Euro 2 emission standard

for gasoline;

CO - 2.2g/km,

HC+NOx - 0.5g/km.

for diesel;

CO - 1.0g/km,

HC+NOx - 0.7g/km,

PM - 0.08g/km

Catalytic converter

- are used in exhaust systems to provide a site for the oxidation

and reduction of toxic by-products (CO, NOx and HC) into less hazardous substance

such as carbon dioxide, water vapor and nitrogen gas using redox reaction (redox

reaction - oxidation reaction and reduction reaction occurring simultaneously

Bad effect of high temperature in engine

1. Cylinder and piston may expand to such an extent that the piston would seize in the

cylinder and stop the engine.

2. Lubricating quality of the oil inside the cylinder would be destroyed due to high

temperature and there may not be sucking of air in the cylinder.

3. Pre-ignition of fuel mixture would take place and would cause engine knocking as

well as loss of power

Purpose of cooling

1. To maintain optimum temperature of engine for efficient operation under all

conditions.

2. To dissipate surplus heat for protection of engine components like cylinder, cylinder

head, piston, piston rings and valves.

3. To maintain the lubricating property of the oil inside the engine cylinder for normal

functioning of the engine

Ignition and electrical system terminologies

-Primary cells

-secondary cell

-lead acid battery

-electrolyte

-sulfation

-CDI

-ignition voltage requirement

-cold plug

-condenser/capacitor

-distributor

-Primary cells

a type of cell that is when fully discharged or dead, can only be restored

to its original condition by renewing the materials that had been so changed (e.g.

common dry cells).

Secondary cell

- a type of cell that can be restored to its original condition by sending

an electric current through it in the direction opposite to that of discharge.

Lead acid battery

- a type of battery commonly used on tractors. 2 volts/cell (2.2volts

max'm)

Electrolyte

- solution used on lead acid batteries. It consist of 2 parts sulfuric acid (SG

= 1.835) and 5 parts distilled water (SG=1). The specific gravity equals 1.300 at 21*C.

Sulfation

- most common type of battery trouble. It is the formation of lead sulfate

(discharged battery) at the bottom of the container due to delayed charging

- capacitor discharge ignition

CDI stands for

25,000 to 40,000 volts

Ignition voltage requirement

Cold plug

- a type of spark plug used on high compression, high speed engines with

short heat path for quick heat dissipation

Condenser/capacitor

- a device connected to the ignition that eliminates arcing of the

breaker points

Distributor

- a device necessary in multi cylinder ignition system to distribute the

secondary voltage to each spark plug.

1. To eliminate friction and wear of moving parts and loss of power.

2. To absorb and dissipate heat.

3. To serve as piston seal.

4. To act as cushion to deaden the noise of moving parts and absorb shock.

5. To keep the engine working parts clean and free of dirt, gum, corrosive acids, and

other contaminants.

Functions of Lubrication: