Prelim Revision : SHORT ANSWER QUESTIONS

Q21. Landscape product

1. Function and quality of different types of Lawn Mowers

• John Ferrabee (1830)

• Follows and Bate (1900)

• Royal (1936)

• Victa 2 Stroke (1950)

• Victa 2 stroke (1960)

• Sunbeam 2 stroke (1974)

• Honda 4 stroke (2011)

1. John Ferrabee ( materials and Quality + Function of mower)

• The first push mower invested by Edward Budding in 1830

• Roller for regulating the height to prevent the machine from dropping into ground

• Front Mounted Catcher

Wrought Iron

- Ductile, tough and strong, so it can withstand bending and impacts without easily cracking.

Cast Iron

• Hard, strong in compression and wear-resistant, making it suitable for parts exposed to vibration

2. Follows and Bate

• Catcher behind the main body of the mower

• Gear driven

• Timber Handles

Lightweight and easy to shape with the tools available in 1900.

Steel frame and gears

High strength and toughness, allowing the mower to handle mechanical loads.

3. Royal

• Petrol engined domestic mower

• Chain drive and front mounted catcher

- Fabricated steel frame, engine uses cast iron

- Steel reel → tough + sharp

4. Victa 2 stroke (1950)

• Cast iron base plate with no provision for catcher

• Handles painted tube steel

FUNCTION

• Started by using a rope wrapped around a pulley at the top of the motor

• Tiresome, took many pulls

5. Victa 2 Stroke (1960)

• Self propelled model

• Fuel tank and impulse starter

• Polyethelene catcher

6. Sunbeam Mower

• 160 cc two stroke motor

• Fuel tank, recoil starter

• Pipes exhaust fumes to reduce airbone pollution

7. Mulch and catch mower (HONDA 4 STROKE)

• Offer choice between mulching and catching

• More versatile

• Base plate is cast aliminium

• Catcher is Poleyethelyne Terephtalte

Safety Features of Lawn Mowers (2 AND EXPLANATION)

• Operator presence control: Stops the engine or blades when the operator releases the handle.

• Blade guard: Covers the blade to prevent contact with the operator and reduce objects being thrown

Quality of materials used on Landscape product

• Cast Iron

• Wrought Iron

• Mild Steel- Deck

• Die cast Aliminium Deck

• Poleyehtylne terephtlate (PET) fabric

Cast Iron

• High strength, hardness and wear resistance are important.

Wrought Iron

• Ductile, tough and strong, so it can withstand bending and impacts without easily cracking.

Mild Steel DECK (Advantages and Disadvantages)

Advantage

• Strong and durable – can withstand impacts from rocks and other object

Disadvantage

• Can rust/corrode when exposed to moisture and grass

Die cast Aliminum Alloy Deck (Advantages and Disadvantages)

Advantages

• Lightweight – much lighter than steel

Disadvantages

• Less tough than mild steel and can crack under severe impact

Poleyehtylne terephtlate (PET) fabric

• High strength

• Fabric is durable and resistant to tearing

• Lightweight

Forming methods of Lawn mower components

• What forming process are used to make lawm mower components

1. Aliminium Deck (Die- casti…)

• defintion of die casting

• 2 types of die casting

• how does it help w lawn mower deck

• Die casting is the forming process

• Diecasting involves when molten metal is forced under high pressure into a reusable metal mould . The metal cools and solidifies, then the finished component is removed.

Gravity die casting and Pressure die casting

Helps with lawn mower deck by..

• Produces denser, stronger castings with excellent surface finish.

• The process allows a complex, rigid deck to be produced accurately while keeping it lighter and corrosion-resistant

2. Lawn mower wheels ( Plastic process) - injec… m

• define forming process

• how does it help w lawn mower wheels ( 2 advanatges , fast prod.. , consisten..)

• Forming process= Injection Moulding

Injection moudling: .Molten plastic is injected under pressure into a mould, where it cools and solidifies into the required wheel shape.

How does it help

• Fast production – ideal for producing large quantities of wheels.

• Consistent dimensions – every wheel can be produced to the same size.

3. Blade

• forming process (forg…) meaning

• how does it help “blade” ( 3 advantages), high stren, high toug, better grai..

Forming Process

- Forging: Proccess of shaping a metal with forceful blows usually by hammering or pressing

- Produces high strength to withstand the forces from cutting.

- Improves toughness, helping the blade resist impact from small objects.

- Creates a strong grain structure in the steel.

Punching Shear FORMULA

PUNCHING SHEAR = FORCE/ CIRCUMFERENCE X THICKNESS

Q22.

Pascals Principle Calculation

Pressure 1= Pressure 2

Quality and and microstructure of materials used in Braking System

refer to other slides

BRAKING SYSTEM: From flashcard 33-72

Stress and Strain Graph

Features of Stress and Strain

Proportional Limit (Hookes Law) - SHOWS STIF..

- Straight line relationship between stress and strain

- E= STRESS/ STRAIN ( E = Young’s Modulus (Pa))]

SHOWS STIFNESS

Elastic Limit, what happens beyond this point

Beyond this point plastic deformation will occur

Ultimate Tensile Strength

Maximum stress a material can withstand

Necking:

Undergo localised deformation

Toughness

Toughness: The area under the whole curve, resistance to shock loading

Resilience:

The area under the curve ONLY in Elastic Deformation region, It is also the amount of strain energy stored

Components method

Calculationn- practise in book

Q23