GCSE Engineering Theory Work (14 X 1 Hour Lessons)

GCSE Engineering Theory work (14 x 1 hour Lessons) There are 36 GCSE Engineering lessons this term that you would received in school under normal circumstances. You have been set a 22 hour NEA project (similar to what you will be examined on next year that forms 40% of your finalgrade). This is compulsory and must be handed in on your return to school. Please see other PowerPoint for thisinformation. In this PowerPoint you will find 14 x 1 hour lessons (including questions that must be completed). The exam you will sitnext June will count for for 60% of your final grade. Each set of questions shows you where a lesson starts and finishes. You are all different abilities so how long you take depends on your working speed. For some, this will take longer than 14hours- work at your own pace. Work your way through these chronologically. Write the answers on a separate PowerPoint or Word document as youprefer. These will be submitted on your return to school. Watch the videos an read the information before answering questions. Most answers come straight from these 2 sources,but you may need to do additional research using google.Best of Luck and enjoy your summer as best you can. Tricky times, but lock down won’t last forever.Mr Corkin and Mr Kennedy

Cams and FollowersA CAM changes the inputmotion, which is usuallyrotary motion (a rotatingmotion), to a reciprocatingmotion of the follower.They are found in manymachines and toys

KEY PHRASESONE CYCLEOne rotation/revolution of the cam.DWELLWhen the cam rotates but the followerdoes not rise or fall.THE RISEThat part of the cam that causes thefollower to rise

In diagram 1 the cam is in a vertical position and itslow rotates in an anticlockwise direction. As it rotatesthe follow drops down. In diagram 4 the follower is in its lowest position. The cam continues to rotate and the follower begins torise in diagrams 5 and 6 until it returns to its originalposition

There are different types offollower but they all slide or rollon the edge of the cam. Varioustypes are shown below.

The cam seen below is a'pear shaped cam'. As thehandle is turned the camprofile rotates.The model moves forwardsand backwards as a result.The movement is gentlealthough the faster thehandle is turned the fasterthe movement of the modelbecomes.

Cams Questions 1 : Lesson 1 (1 hour)1.2.3.4.5.6.7.8.Explain what is a Cam?Explain what is a follower?What is does ‘one cycle’ mean?What does ‘the rise’ mean?What does ‘the dwell’ mean?Explain how the cam and follower mechanism works?Name( and get photos) of products that use cams and followers?Explain how this mechanism can be used in an engineering context?

Cams Questions 2 : Lesson 2 (1 hour)Look at the Automata . Explain what would happen to thefigure if you put each different cam in :Example: Egg shaped CAM:1) Egg shaped CAM Answer. In this automata when youturn the crank with a egg shaped CAM inside nothinghappens to the figure for half the revolution. This isknown as the dwell . Therefore the crank rotates (rotarymotion) and the figures leg doesn’t move for this period.Then the crank rotates the pointed part (rotary motion)and this causes the leg to go up and down (reciprocatingmotion). This is known as the rise. The figure moveforwards and backward lifting one leg. The automataturns rotary motion into reciprocating motion.

4 Types of motion https://www.youtube.com/watch?v OfOQKv1mjks

Cool motions that combine manymechanisms!! https://www.youtube.com/watch?v ruiQR3CZE7k

Motions Questions 1 : Lesson 3 (1 hour)1.2.3.4.5.6.7.Explain what a mechanism is and does?What is meant by mechanical advantage?Explain what motion is ?Explain what oscillating motion is and used for?Explain what a rotary motion is and used for?Explain what a linear motion is and used for?Explain what a reciprocating motion is and used for?Hint: Use photos and real world examples for each.At least separate PowerPoint slides would be best

www.Technology Student.com http://www.technologystudent.com/cams/link1.htm web site https://www.youtube.com/watch?v xh1jTtAxs Q Linkages video

Linkages Questions 1 : Lesson 4 (1 hour)1.2.3.4.Explain what linkages areExplain what a parallel linkages is and does?Explain what a reverse motion linkage is and does?Explain what a bell crank motion is and does?Hint: Use photos and real world examples for each.At least 3 separate PowerPoint slides would be best

Mechanical Understanding Questions 1 : Lesson 5 (1 hour)1.2.3.4.5.6.7.8.9.10.11.12.13.What are mechanisms design to do?What are the four main types of motion?Describe the different ‘orders of lever’ and provide exampled oftheseWhat are linkages and what do they do?Describe push/ pull leversHow do you change the magnitude of these levers?Describe bell crank leversHow do you change the magnitude of these levers?What are gears and what do they do?What is a gear train?What is meant by the term ‘gear ratio’?Copy down both formulae to calculate gear ratios and output speedCopy the example worked out to aid your revision notes

Mechanical Understanding Questions 1 : Lesson 6 (1 hour)1.What are rotary systems?2.What is a pulley and what are theyused for?3.What is a one pulley system used for?4.What are 2 pulley systems used for?5.What does a belt drive do- give anexample of where one was used.6.What is the formula to calculate thevelocity ration?7.What is the formula to calculate theoutput speed?8.What two parts make a cammechanism?9.What are the 4 different types of cams?10. How can the magnitude of outputmotion be changed?

Gear trains Gears can be found in many machines in a workshop or factory and athome they are often an important part of mechanical devices. In a carthe gears help the driver to increase and decrease speed as he/shechanges the gears with the gear stick.

Simple Gear Train1. Large Gear driving a small gear results in increased speed butdecreased torque2. A smaller gear driving a larger gear results in decreased speed andincreased torque

Torque is a twisting or turning force that tends to cause rotationaround an axis, which might be a centre of mass or a fixed pointTorque is the turning force about a point.This is also known as a moment or coupleThe SI unit for torque Is Newton metre (Nm).0.5mA1.0mBIf a force of 1 Newton is applied at point A, the torque appliedto the beam about the pivot point is 0,5 Nm.

This is a good example of a ‘gear train’. Agear train is usually made up of two ormore gears. The driver in this example isgear ‘A’. If a motor turns gear ‘A’ in ananticlockwise direction;Which direction does gear ‘B’ turn ?Which direction does gear ‘C’’ turn ?Does gear ‘C’ revolve faster or slowerthan gear ’A ? - explain your answer.’

Gear Ratio: Learn!The Gear or Velocity ratio of a simple gear train is calculated by dividingthe number of teeth on the driven gear by the number of teeth on thedriver gearGear Ratio Number teeth driven gearNumber of teeth driver gear

Video Explaining Gears https://www.youtube.com/watch?v OaujUXfDVGE

Gears Questions 1 : Lesson 7 (1 hour)1.2.3.4.5.6.7.8.9.10.11.What do gears do?What is a spur gear?Explain what a gear train does?Explain what a simple gear train is?Explain torque?What does a larger gear driving a smaller gear achieve?What does a smaller gear driving a larger gear achieve?What is the driven gear?What is the driver gear?What is the idler gear?What is the calculation for working out gear ratio?

Gears Questions 2 : Lesson 8 (1 hour)1.Simple gear train2.Idler gear3.Compound gear train4.Bevel gears5.Mitre gears6.Rack and pinion7.Worm and worm wheel gears8.Helical gears

Chain and Sprocket

Friday, 24 April 2020Think about the levers .HardEasierWhat happens tothe number ofteeth when theradius doubles?

Gears Larger gears will: Have a larger moment Turn slowerLOW GEAR: Low speed HighturningeffectHIGH GEAR: Highspeed Lowturningeffect

GearsLOW GEAR: Low speed HighturningeffectHIGH GEAR: Highspeed LowturningeffectDriverLOW GEARDrivenHIGHGEAR

GearsQuick Tip Gears in line changedirection with eachgear wheel If faced with aquestion like this,draw in thedirectional arrows foreach cog!

Chain and Sprocket Everyone has seen a bicycle or used oneand noticed that it is driven by a largedriver gear wheel with pedals attached. Smaller gears at the back are drivenround, in turn driving round the backwheel. As the back wheel turns the bicyclemoves forwards. Gears driven by chains are used inmachinery, motorcycles, in car enginesand have many more applications.

Chain and Sprocket A chain is made up of a series of links withthe links held together with steel pins. This arrangement makes a chain a strong,long lasting way of transmitting rotarymotion from one gear wheel to another. Chain drive has one main advantage over atraditional gear train. Only two gear wheels and a chain areneeded to transmit rotary motion over adistance. With a traditional gear train, many gearsmust be arranged meshing with each otherin order to transmit motion.

Chain and Sprocket When working out gear / velocity ratiochain driven gears it must be rememberedthat the chain is ignored. This means the you simply find out the teethper gear wheel use the same method ofcalculating as you would with a normal,meshing gear

Gear Ratio: Learn!The Gear or Velocity ratio of a simple gear train is calculated by dividingthe number of teeth on the driven gear by the number of teeth on thedriver gearGear Ratio Number teeth driven gearNumber of teeth driver gear

Chain and Sprocket Questions 1 : Lesson 9 (1 hour)1.2.3.4.Explain what a chain and sprocket gear is?What products use this type of gear used?What advantages does this have over spur gears?What is the calculation for working out gear ratio for a chain andsprocket?5. How important is the length of chain when working out gear ratio?

Gear Systems

Where do we find a gear systems?Gear systems are found in machines everywhere

What are gear systems used for? Gear systems are one of the best methods fortransmitting rotary motion from one shaft to another.Are there other methods? A gear system allows the torque, rotational speedand direction of the output shaft to be varied.

Gear Types Spur Simplest tooth form of allthe gear types Good efficiency Parallel Shafts Suitable for a widerange of gear ratiosand loadsNoisy, especially at highspeeds

Gear Types Helical Quieter than spur gear Load spread over longerteeth Parallel Shafts Suitable for higherspeeds and loadsthan spur gear Not as efficient as a spur gear Thrust forces along the shafts

Gear Types BevelSuitable for non parallelshaft applications Non Parallel Shafts Can have helical gear form Noisy, especially athigh speeds Not suitable for veryhigh gear ratios

Gear Types Worm Suitable for non parallelshaft applications High gear ratios can beachieved Quiet Non Parallel Shafts The worm shaft is alwaysthe driver Low efficiency Sliding action of teeth

Gear Types Rack and PinionPinion GearRackFor converting between rotatory and linear motion

Gear Types Epicyclic Suitable for high torqueapplications Compact design Gear ratio can be variedwithout the need toengage gearsParallel Shafts Complexity

Can you recognise these gears?

Can you recognise these gears?AB

Analysis of a gear systemA gear system (sometimes called a gear train) is an arrangementof gears used to transmit rotational power from the driving shaftto the driven shaft. In doing so the speed, torque and directionof the driven shaft can be varied to that of the driving shaft.Output/Driven shaftSpeed No r.p.m.Torque To NmDirectionInput/Driving shaftSpeed Ni r.p.m.Torque Ti NmDirection

Think about the levers .HardFriday, 24 April 2020Easier

LeversA spanner is a lever that can be used to unscrew a nut.The spanner exerts a moment or turning effect on the nut.pivotdistancefrom forceto pivotforceIt is important to be able to identify where the pivot is, wherethe force is being applied as a distance from the pivot, and thesize of that force