Mechanical engineering

1. ASSOSA UNIVERSITY
COLLEGE OF ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING
Course Title: Heavy duty and construction equipment
(MEng5411)
Chapter – 3
Technologies in Construction Equipment
By: Usman F.

2. 1. Engine
❑ Engine is a device that transforms one form of energy into another form. It is any
device that is capable of converting the chemical energy of the fuel into thermal energy
which is again converted to mechanical energy (useful work).
✓ Most engines convert thermal (heat) energy into mechanical energy (work) and
therefore they are called Heat engines.
✓ Heat is generally generated by chemical reaction, typically from combustion of all
sorts of fuels.

3. Types of Heat Engines
❑ Heat Engines can be broadly classified into two categories
✓ External Combustion Engine (EC Engine): is a heat engine in which the burning of
fuel takes place outside the engine cylinder.
➢ A working fluid is utilized to transfer the heat of combustion to the engine where this
heat is transformed into mechanical energy.
➢ An example of this type is the steam power plant employing a boiler and a turbine.
➢ Such an arrangement is not generally desirable for mobile power plants, since it entails
the use of heavy and bulky heat exchangers, as well as the transportation of the supply
working fluid.
✓ Internal Combustion Engine (IC Engine): is a heat engine in which combustion of a
fuel occurs in a combustion chamber (the portion of the engine which converts heat
energy into mechanical energy).

4. ➢ There is no necessity for an intermediate heat transferring apparatus, thus eliminating
the need for heavy and bulky heat exchangers and the necessity of transporting the
working fluid. into
Working principle of IC engine
➢ Chemical energy of the fuel is first converted to thermal energy by means of
combustion or oxidation with air inside the engine cylinder.
➢ This thermal energy raises the temperature and pressure of the gases within the engine,
and the high-pressure gas then expands against the mechanical mechanisms of the
engine.
➢ The expanding gases drive the engine directly and the products of combustion are
rejected back to the atmosphere.
➢ This expansion is converted by the mechanical linkages of the engine to a rotating
crankshaft, which is the output of the engine.

5. ➢ The crankshaft, in turn, is connected to a transmission and/or power train to transmit
the rotating mechanical energy to the desired final use.
➢ For engines this will often be the propulsion of a vehicle (i.e. automobile, truck,
locomotive, marine vessel, or airplane).
Classification of IC Engines
❑ Engines can be classified according to the following criteria:
1. Application
2. Basic Engine Design
3. Operating Cycle
4. Working Cycle
5. Valve/Port Design and Location
6. Fuel
7. Mixture Preparation
8. Ignition
9. Stratification of Charge
10. Combustion Chamber Design
11. Method of Load Control
12. Cooling

6. 1. Application
❑ Automotive, Locomotive, Light Aircraft, Marine, Power Generation, Agricultural,
Earthmoving, Home Use and Others.
2. Basic engine design
I. Reciprocating
(a) Single Cylinder
(b) Multi-cylinder
i. In-line
ii. H, U,V, W & X
iii. Radial
iv. Opposed Cylinder
v. Opposed Piston
II. Rotary
(a) Single Rotor
(b) Multi-rotor

8. 3. Operating cycle
✓ Otto (for the conventional SI engine)
✓ Atkinson (for complete expansion SI engine)
✓ Miller (for early or late inlet valve closing type SI engine)
✓ Diesel (for the ideal diesel engine)
✓ Dual (for the actual diesel engine)
4. Method of increasing inlet pressure (power boosting)
✓ Naturally Aspired: No intake air pressure boost system
✓ Supercharged: Intake air pressure increased with the compressor driven off of the
engine crankshaft
✓ Turbocharged: Intake air pressure increased with the turbine-compressor driven by the
engine exhaust gases.
✓ Crankcase Compressed: Two Stroke cycle engine which uses the crankcase as the
intake air compressor.

9. 5. Fuel
✓ Conventional fuel: crude oil derived (petrol, diesel)
✓ Alternate fuel: bio-mass derived (alcohols such as methyl and ethyl, vegetable oils,
producer gas and biogas, hydrogen)
✓ Blended fuel
✓ Dual fueling
6. Mixture preparation
✓ Carburetion
✓ Fuel injection (Diesel, Gasoline)
7. Based on the type of ignition
a) Spark ignition (SI): the engine starts the combustion process in each cycle by use of a
spark plug.
b) Compression ignition (CI): the combustion process starts when the air-fuel mixture
self-ignites due to high temperature in the combustion chamber.

10. 8. Based on engine cycle
a) Four-stroke cycle: Four piston movements over two engine revolutions of each cycle
b) Two-stroke cycle: Two piston movements over one revolution for each cycle
9. Based on the cooling system
a) Direct air-cooling (air-cooled)
b) Indirect air-cooling (liquid cooling, or water-cooled)
c) Low heat rejection (semi-adiabatic) engine.
Basic Engine Components
a) Cylinder Block
b) Cylinder Head
c) Crankshaft
d) Camshaft
e) Timing Chain
f) Bearing shell
g) Oil pump
h) Water pump
i) Fly wheel
j) Valves
k) Valve Springs
l) Pistons
m) Connecting Rod
n) Piston Ring
o) Cylinder sleeve
p) Inlet manifold
q) Exhaust manifold
r) Rocker Arm

11. ❑ Engine components can be broken down into two broad categories:- Stationary parts
and Moving parts.
✓ Stationary parts: The stationary parts of an engine include the cylinder block,
cylinders, cylinder head, crankcase, exhaust and intake manifolds.
➢ These parts furnish the framework of the engine.
✓ Moving parts: This part includes the Piston, Connecting Rod, Crankshaft, Flywheel,
Valve Train, Camshaft & Cams, Valves, etc.
➢ All movable parts are attached to or fitted into the stationary parts.

13. A heavy-duty engine
❑ This is a type of internal combustion engine that is designed for heavy-duty
applications such as construction equipment, mining trucks, buses, and long-haul
trucks.
✓ They are the backbone of the transportation and construction industries, powering a
variety of vehicles and equipment.
✓ These engines are designed to withstand extreme conditions, high temperatures, and
heavy loads, making them suitable for heavy-duty applications.
✓ They are characterized by their high torque and power output.
✓ They can also withstand heavy loads and extreme temperatures.
✓ Heavy-duty engines are available in a variety of configurations, including diesel and
gasoline-powered engines.
✓ The various benefits of diesel engines like greater torque and compression resistance
make them the superior choice for heavy construction machinery and vehicles.

14. Types of engines used in heavy-duty vehicles
❑ Heavy-duty vehicles such as trucks, buses, and construction equipment use a variety of
engines.
✓ The most common types of engines used in heavy-duty vehicles are:
▪ Diesel Engines: are commonly used in heavy-duty vehicles because they are more
fuel-efficient and have more torque than gasoline engines.
➢ They are also more durable and can last longer than gasoline engines.
▪ Gasoline Engines: are less commonly used in heavy-duty vehicles because they are
less fuel-efficient and have less torque than diesel engines.
➢ However, gasoline engines are quieter and smoother than diesel engines.
▪ Natural Gas Engines: are becoming more popular in heavy-duty vehicles because
they are cleaner and produce fewer emissions than diesel or gasoline engines.

15. Top 10 heavy-duty engine brands
There are many heavy-duty engine brands on the market, but some stand out above the
rest.
▪ The top 10 heavy-duty engine brands are:
➢ Cummins
➢ Caterpillar
➢ Perkins
➢ Isuzu
➢ Komatsu
➢ Volvo
➢ John Deere
➢ MTU
➢ Doosan
➢ Scania

16. Heavy Duty Engine Stand
❑ A heavy-duty engine stand is a specialized piece of equipment designed to hold,
position, and rotate an engine block or transmission during maintenance, repair, or
assembly.
❑ It typically consists of a metal frame with adjustable arms or brackets that can
accommodate various engine sizes and weights.
❑ Most engine stands have casters or wheels for easy mobility and a swivel head for 360-
degree rotation.

17. 2. Drive train

18. ❑ A drivetrain is a group of components that deliver mechanical power from the prime
mover to the driven components.
✓ These components usually include the transmission, differential, driveshaft, axles, CV
joints, and wheels.
✓ In automotive engineering, the drivetrain is the component of a motor vehicle that
delivers power to the drive wheels.
❑ The construction equipment is equipped with power trains that are similar in many
ways to the automotive vehicle power trains.
✓ However, factors, such as size, weight, design, and use of the construction equipment
require power trains that vary greatly in configuration.
✓ The most common drive trains used in modern construction equipment are the
mechanical and the hydrostatic drive trains.

19. a) Mechanical drive train: The mechanical drive train found in construction equipment
is similar to that of the automatic transmission in that a transmission is used in
conjunction with a torque converter and shifting is accomplished hydraulically.
❖ Power Shift Transmission
✓ The power shift transmission uses a torque converter and is designed to provide high-
speed shifting through hydraulically actuated clutches.
✓ It uses a dual-clutch system; in which the advanced gearbox pre-selects the next gear
for you so that you don't lose power when you change.
✓ The first clutch handles gears one, three, and five; while the second clutch handles
gears two, four, and six.
b) Hydrostatic drive train: The hydrostatic drive train is an automatic fluid drive that
uses fluid under pressure to transmit engine power to the drive wheels or tracks.
✓ The hydrostatic drive functions as both a clutch and transmission.

20. ✓ Mechanical power from the engine is converted to hydraulic power by a pump-motor
team and this power is then converted back to mechanical power for the drive wheels
or tracks.
✓ The pump-motor team is the heart of the hydrostatic drive system.
✓ Basically, the pump and motor are joined in a closed hydraulic loop; the return line
from the motor is joined directly to the intake of the pump, rather than to the reservoir.
✓ A charge pump maintains system pressure, using supply oil from the reservoir.
Working principle of drivetrain:
▪ The engine will generate power to power a flywheel
▪ That flywheel works with the transmission to control the quantity of power distributed
to other parts of the drivetrain
▪ The driveshaft rotates to create power for a differential
▪ After that the differential provides power from all those driveshaft parts and transmits
to the wheels to make it rotate.

21. 3. Hydraulic Systems

22. ❑ A hydraulic system is an operation that utilizes pressurized fluid to power the motion
based on the principle of fluid pressure flowing through a closed-loop circuit.
✓ It is a type of mechanical design used in equipment manufacturing to provide lift,
reach, tilt, and other functions the equipment needs.
✓ Defined simply, hydraulic systems function and perform tasks by using a pressurized
fluid.
✓ Heavy equipment relies on hydraulics rather than electricity or pneumatics because a
hydraulic system is capable of lifting heavier loads at a greater force.
✓ Fluid pressure can power heavier loads at a constant rate of force and torque, which is
not possible with other mechanical systems.
✓ Other power systems use various mechanical components, such as pulleys, gears, or
electrical circuits to achieve the same amount of power for a particular function.
✓ On account of this liquid-based system, heavy machinery can utilize small operator
movements to make huge attachments and things they hold.

23. Working principles of hydraulic system
✓ Hydraulic systems operate based on the principle of fluid pressure flowing through a
closed-loop circuit.
✓ Inside a hydraulic system, some parts put the incompressible fluid under pressure. The
machine contains a reservoir of hydraulic oil that gets pumped through a valve and into
the cylinder of the hydraulic system.
✓ The pressure of the fluid being pumped toward the cylinder forces the component to
move. i.e. Since the hydraulic oil doesn’t press into a more modest space, its power
gets moved to the opposite end of the oil region.
✓ The pressure applied from the oil moves a piston that can work alone or with extra
cylinders to move things requiring additional power
✓ A hydraulic system involves this fluid in cylinders or hydraulic power units to take
care of operations like stopping a vehicle through its brakes, lifting a crane and its
load, or moving a bucket on a loader.

24. Basic components of a hydraulic system
❑ Hydraulic systems operate using a few key components, each playing a vital role in
supplying and converting power to achieve load-handling functions.
✓ Below are the five main components of the hydraulic system an equipment contains.
1. Reservoir: is what holds the hydraulic oil.
✓ It’s a protective container that keeps the hydraulic fluid readily available for use by the
hydraulic system components.
✓ The reservoir itself is sealed and designed to prevent hydraulic fluid from becoming
contaminated with foreign materials, dirt, and condensation through its filters.
2. Pump: is the component of the hydraulic system that converts mechanical energy into
hydraulic energy.
✓ It generates power based on its ability to overcome the pressure of the fluid induced by
the weight load.
✓ A hydraulic pump contains both an inlet and an outlet.

25. ✓ By mechanical or electrical motor, the pump creates a vacuum and forces the hydraulic
liquid from the reservoir into the inlet line, then finally forced out through the pump
outlet into the hydraulic system.
✓ In earthmoving equipment, such as excavator hydraulic systems, the type of pump used
is a variable displacement pump.
✓ Variable displacement provides more control over the amount of power needed for load
handling.
3. Valves: play the role of controlling the direction of hydraulic oil flow.
✓ They help in starting, stopping or directing the hydraulic fluid based on the amount of
power required for handling the load.
✓ Valves are categorized based on their function and can be directional control, pressure
control or flow control valves.
✓ Complex hydraulic systems employ a series of valves to ensure optimal pressure
regulating efficiency.

26. ✓ The ability of valves to control the flow of the hydraulic fluid is essential in regulating
the amount of pressure through the hydraulic lines.
✓ Improper valve function can lead to leaking or bursting lines.
4. Actuator: Hydraulic actuators are the moving component of the hydraulic system that
activates the lifting.
✓ Once it reaches a certain level of pressure, the actuator uses the fluid pressure to
convert it into mechanical energy.
✓ The actuator of a hydraulic system in earthmoving equipment moves linearly, though
other actuators can provide rotary or oscillatory motions.
✓ Actuators consist of a cylinder, piston, rod, and seal. The seal may need to be replaced
eventually, but the main components of the actuator should last if properly maintained.
✓ The biggest risk with this component is a hydraulic cylinder leak, which occurs when
the seal wears out or the cylinder or rod develops cracks.

27. 5. Pressure Regulator (Relief valve): is a control mechanism that regulates how hydraulic
fluid pressure is maintained throughout the system.
✓ The pressure regulator helps to ensure that the appropriate amount of fluid is released
from the reservoir to achieve the desired pressure level.
✓ If fluid pressure reaches a certain threshold, the pressure regulator ensures that the
excess fluid returns back to the reservoir until the pressure level drops again.
✓ Pressure regulators maintain output pressure values at a certain level to minimize the
amount of fluctuation in pressure levels throughout the system.
✓ In a hydraulic system a pressure regulator can be repaired or replaced, depending on
the issue.
✓ A properly maintained pressure regulator can last the life span of the equipment.

28. Common causes of hydraulic systems failures
❑ Hydraulic system failures can range from a repairable degradation failure to a sudden
catastrophic failure, depending on the cause.
✓ Some of the common causes of hydraulic system failures include:
▪ Fluid contamination: caused by impressed dirt and dust particles or air and water
molecules.
▪ Extremes temperature in the hydraulic fluid: causing changes to the viscosity of the
fluid that strains the system.
▪ Abrasions and tears: that cause hydraulic hose leaks.
▪ Incorrect amount and quality of hydraulic fluids.
▪ Improper maintenance and repairs: such as not using and installing the correct
components or failing to replace faulty and worn components in a timely manner.
✓ Of the above causes of hydraulic system failures, fluid contamination is the leading
cause.

29. ✓ Contaminants, including air and water, enter the system and wear down the pump and
other hydraulic system components over time leading to a system failure if not filtered
properly.
✓ Changing the hydraulic fluid filter regularly is a key practice in how to maintain a
hydraulic system.
Features of Hydraulic Systems for Heavy Equipment
❑ The hydraulic system offers three real benefits when industries use it with heavy
equipment:
✓ Reliability: Hydraulic systems offer reliable operation if the system remains closed and
the fluid stays free of contaminants.
✓ Power density: The output of hydraulics is many times greater than the force put into
the system of heavy construction equipment.
✓ Versatile control: Innovations allow hydraulic systems that move in multiple directions
and have electronic controls.

30. The Hydraulic Systems Operation
Hydraulic systems work with one of two strategies: cylinders or hydraulic power units.
Hydraulic Systems With Cylinders: Cylinders are the primary parts used to duplicate
power with hydraulic liquid.
✓ Hydraulic systems have small and large cylinders. The smaller one has a piston for
work put into the system.
✓ The piston pushes down on hydraulic fluid in the little cylinder and streams into the
bottom of the huge cylinder.
✓ The large cylinder has a piston that moves based on the power of the oil.
Hydraulic Systems With Hydraulic Power Units: The other kind of system that
equipment uses is a hydraulic power unit that expands the system’s abilities by using a
pump and pressurized fluid to replace the small cylinder.
✓ This kind of system is frequently utilized on heavy equipment to accomplish enormous
work and lifting abilities.

31. 4. Undercarriage
❑ An undercarriage is the supporting framework of a vehicle that is underneath the main
cabin of any vehicle, whether it's an excavator, car, or tractor-trailer. For trucks and
automobiles, it contains the chassis.
✓ The undercarriage of heavy equipment refers to the set of components that support and
propel the machine, including the tracks or wheels, and associated parts. It is what
keeps the equipment up and running.
✓ Underneath every vehicle is a complex system of parts that are exposed to the road;
some of these car parts include the exhaust system, suspension, and gas tank. These
parts are designed to be tough in order to handle constant exposure to the road.
✓ Any wheels or tracks get attached or fitted to the undercarriage to help the machine
move.
✓ The undercarriage protects the vehicle's underbody and is usually under a lot of stress.

32. ✓ Undercarriage damage is any harm to the parts of a vehicle below the chassis that
affects how it performs on the road, including suspension, brakes, wheels, tires, and
axles.
✓ This damage can be caused by various incidents, and if left unaddressed, it can lead to
accidents that result in personal injury.
✓ Driving with undercarriage damage can be dangerous as it can lead to more significant
problems down the road.
✓ The brake system under the car is one of the most critical systems to maintain.

33. Components of undercarriage
❑ The undercarriage includes various components that are simple on their own but are
assembled to help the machine move over all types of terrain.
✓ The undercarriage of heavy equipment comprises several components, each with its
specific function. Here are the main parts and their function:
▪ Track Shoes: These are the plates that make direct contact with the ground. They
provide traction to propel the equipment forward or backward.
▪ Track Chains: These are a series of interconnected links that hold the track shoes in
place. They help in the movement of the machine.
▪ Rollers: These are cylindrical wheels that support the weight of the equipment and
guide the track chains as they move.
▪ Idlers: These are stationary wheels that guide the track chains and help maintain the
tension in the undercarriage.

34. • Sprockets: These are gears that engage with the track chains and propel the equipment
by rotating them.
• Track Adjusters: These are hydraulic or mechanical devices that maintain the tension
in the track chains. They ensure proper track alignment.
✓ Many of these parts are kept together by bushings and pins, however, these can become
complicated to repair when faced with a breakdown.
✓ It is important to perform preventative maintenance and to have the correct
maintenance equipment to keep all these parts in order.

35. 5. Work tools

36. ❑ Construction tools: are an important part of anyone who works in the industry, so they
play an important role in building construction.
✓ These tools are particularly important in construction work and are primarily used to
put things together or to take them apart.
✓ From the use of wood, bones, and stone in ancient times to more modern power tools,
they made it possible for activities to be performed more quickly, efficiently, and
accurately
❑ Some of these tools include but may not be limited to:
a) Hand tools: include a wide range of all non-powered tools that must be operated by
hand (such as screwdrivers, brushes, trowels, wrenches, and clamps).
✓ These tools have been in use since the Stone Age, but they have evolved from stone
tools that were used for hammering and cutting to more durable tools that can perform
a variety of tasks for both indoor and outdoor applications.

37. ✓ The use of hand tools can cause some problems which are caused by using the wrong
tool for the job or a tool that has not been properly maintained.
b) Power tools: are divided into classes, depending on the power source: electrical tools
(powered by electricity), pneumatic tools (powered by compressed air), liquid-fuel tools
(usually powered by gasoline), powder-actuated tools (usually powered by explosive and
operated like a gun) and hydraulic tools (powered by pressure from a liquid).
✓ They can be either stationary or portable, with portable having more advantages in
terms of mobility.
✓ Stationary power tools have more of an advantage in terms of speed and accuracy.
▪ Pneumatic tools: include chippers, drills, hammers and sanders
▪ Gas-powered tools: present fuel explosion hazards, particularly during filling.
➢ They should be filled only after they have been shut down and allowed to cool off.
▪ Powder-actuated tools: are like loaded guns and should be operated only by specially
trained personnel.

38. ▪ Hydraulic power tools: should use a fire-resistant fluid and be operated under safe
pressures.
❑ Power tools, in general, are more dangerous than hand tools, because the power of the
tool is increased and the power source itself can cause injuries or death.
c) Machine Tools: can be used to shape materials by cutting, boring, or grinding.
✓ They’re powered by something other than human muscle, and they’re often used in
manufacturing.
d) Generic Tools: A variety of tools (such as shovels and hammers) that can be used for
any number of tasks that relate to construction.
❑ In general, tools should be inspected before use, be well-maintained, be operated
according to the manufacturer’s instructions and be operated with safety systems.