AGRICULTURAL TECHNOLOGY
GRADE 12 
AMENDED SCE PAST PAPERS AND MEMOS
MAY/JUNE 2018 2018

MEMORANDUM

SECTION A 
QUESTION 1 
1.1
1.1.1 C✔✔ (2)
1.1.2 D✔✔ (2)
1.1.3 B✔✔ (2)
1.1.4 B✔✔ (2)
1.1.5 C✔✔ (2)
1.1.6 D✔✔ (2)
1.1.7 A✔✔ (2)
1.1.8 B✔✔ (2)
1.1.9 C✔✔ (2)
1.1.10 D✔✔ (2)  (10 x 2) (20) 
1.2
1.2.1 yellow✔✔ (2)
1.2.2 cell phone/two way radio✔✔ (2)
1.2.3 smart controller✔✔ (2)
1.2.4 oil✔✔ (2)
1.2.5 zinc✔✔ (2) (5 x 2) (10) 
1.3
1.3.1 D ✔✔ (2)
1.3.2 G✔✔ (2)
1.3.3 A✔✔ (2)
1.3.4 B✔✔ (2)
1.3.5 E✔✔ (2) (5 x 2) (10) 

 TOTAL SECTION A: 40

SECTION B 
QUESTION 2: MATERIALS AND STRUCTURES  
2.1 The alloy metal that is specifically used to manufacture the following  products and TWO reasons why that metal is used. 
2.1.1 Milk tanks 
Stainless Steel✔ (1) 

• Resistant to air, water and many chemical acids and alkali.✔ 
• Resistance against corrosion.✔ 
• Can be welded well.✔ (Any 2) (2) 

2.1.2 Fittings for hot water copper pipes 
Brass✔ (1) 

• Strength✔ 
• Machinability✔ 
• Wear resistance✔ 
• Hardness✔ 
• Corrosion resistance✔ (Any 2)  (2) 

2.1.3 Hammering tools that can be used in explosive atmospheres.
Bronze(Beryllium Copper)✔ (1) 

• Does not generate sparks✔ 
• Low friction✔ 
• Resist corrosion✔  (Any 2)  (2) 

2.2 TWO hot working processes that can be used to change the structural  properties of brass. 

• Annealing✔ 
• Stress relieving✔ 
• Tempering✔ (Any 2) (2) 

2.3
2.3.1 TWO reasons for preferring fibre-glass troughs instead of concrete  troughs for cattle. 

• Easy to move around. (Light)✔ 
• Easy to fix/repair✔ 
• Rust resistance✔ (Any 2) (2)

2.3.2 Description of 'resin' as used in the manufacturing in fibreglass  products. 

• They are low viscosity fluids✔that can be transformed✔to tough  flexible solids by adding✔a hardening agent.   (Any 2) (2) 

2.3.3 TWO methods used to join fibreglass parts. 

• Pop rivet✔ 
• Bolt and nut✔ 
• Fibreglass✔  

2.4 FIVE reasons why Vesconite is proven as the best material in the  manufacture of bushes. 

• It is ideal for many marine applications.✔ 
• It does not swell and seize.✔ 
• It remains hard.✔ 
• It does not delaminate.✔ 
• It has low friction.✔ 
• It does not corrode.✔ 
• Bushes can easy be removed.✔ 
• Does not contain any asbestos (healthy)✔/Safer to work with. 
• Easy to machine.✔  (Any 2) (2) (Any 5) (5) 

2.5 Description of how an adhesive should be applied to a surface to ensure  sufficient cohesion. 

• First clean the surface properly.✔ 
• If the surface is very slippery, the surface can be sanded to make it coarse.✔
• Apply a thin base coat if the surface is very porous.✔ 
• Apply only a thin layer of adhesive because a thick layer of adhesive will result  in a weak joint.✔ 
• Apply adhesive to both surfaces.✔ (Any 4) (4) 

2.6
2.6.1 The procedure that must be followed when testing the earth system  of an electric fence. 

• Firstly short out the live fence line to the ground.✔ 
• Switch the energizer ON.✔ 
• Measure the voltage between the GROUND and the Earth Spike with  a meter.✔ 
• If this is above 200 volts the earth installation is inefficient.✔ (4)

2.6.2 TWO examples of the application of electric fences on the farm. 

• Protection✔/Farm security purposes. 
• Temporary fences.✔ 
• Fencing dangerous animals.✔   (Any 2) (2) 

2.6.3 THREE alternative energy sources that can be used to provide  energy for an electrical fence.  

• Wind✔ 
• Solar✔ 
• Water✔ (3) [35]

QUESTION 3: ENERGY 
3.1 The TWO parts labelled as A and B of the turbine, and the function of each. 

3.2 3.2.1 The working of the solar hot water geyser. 

• The sun heats the water in the glass tubes, the heated water rise to  the highest point in the system.✔ 
• The heated water enters the geyser through a closed copper pipe  network that runs through the geyser.✔ 
• The hot water inside the copper pipes heats up the cold water inside  the geyser.✔ 
• The cooled water flows downwards back to the solar tubes where it is  reheated.✔ (4)

3.2.2 FOUR benefits of using solar energy to heat water. 

• Environmentally friendly energy source/No pollution.✔ 
• Installation is relative cheap and simple.✔ 
• Solar power is limitless.✔ 
• Transition losses are limited.✔ 
• Does not use a lot of space.✔   (Any 4) (4) 

3.3
3.3.1 TWO geological aspects that should be investigated to determine  the specific area to construct a geothermal energy plant. 

• Rocks that is soft enough to drill✔/Type of rock 
• Volcanic activities✔ 
• Accessibility✔ (Any 2) (2) 

3.3.2 TWO advantages of a geothermal energy plant. 

• A geothermal system does not create any pollution.✔ 
• The cost of the land to build a geothermal power plant on is usually  less.✔ 
• Because geothermal energy is very clean, you may receive tax cuts,  and/or no environmental bills.✔ 
• No fuel is used to generate the power.✔ 
• The running costs for the plants are very low.✔ 
• The overall financial impact of these plants is positive.✔ (Any 2) (2)

3.4
3.4.1 TWO alternative fuels that are obtained from plants. 

• Ethanol✔ 
• Methanol✔ 
• Biodiesel✔ (Any 2) (2) 

3.4.2 TWO crops that can be used to produce bio-fuel. 

• Sugar cane✔ 
• Sunflower✔ 
• Maize✔ 
• Vegetables✔ 
• Sorghum✔ (Any 2) (2) [20]

QUESTION 4: SKILLS AND CONSTRUCTION PROCESSES  
4.1
4.1.1 The origin and purpose of the cloud formed around a welding area. 

• The inserted gas✔is fed through the pipe and nozzle and exit  through the holes in the nozzle.  
• The function is to shield the molten puddle✔from oxygen  contamination.✔ (3) 

4.1.2 The procedure that must be followed when the feed wire burns  onto the copper welding tip. 

• Release the trigger.✔ 
• Take a plier and cut the blob from the welding tip.✔ 
• Use a file and file the welding tip.✔ 
• Ensure that the feeding wire is separated from the tip and continue  welding.✔ (4) 

4.1.3 TWO circumstances that can cause the feed wire from melting  onto the welding tip. 

• Gap between the nozzle and work piece is too small.✔ 
• Wire feed is too slow.✔ 
• Welding too close to your material.✔ 
• Building up too much heat on the tip of the welding torch.✔ (Any 2) (2)

4.1.4 THREE causes of cracks forming on the welding bead when  performing MIG welding. 

• Root gap too small in restrained joint.✔ 
• Current too high.✔ 
• Deep narrow weld bead. ✔(with centre line cracking) 
• Inadequate filling of crater.✔ 
• Inadequate pre-heat on high tensile and low alloys.✔ 
• Incorrect composition of electrode.✔   (Any 3) (3) 

4.2
4.2.1 Description of 'shrinking' as it occurs in a welding joint. 

• When metal is heated it expands and when cooling down it  shrink.✔ 
• The shrinking of welded metal and weld runs cause distortion of  metal when they cool down.✔ 
• Shrinking take place in all directions simultaneously and therefore  cause various kinds of distortion.✔ (3)

4.2.2 A free hand drawing to illustrate angular shrinking longitudinally  on a welded project. The dimensions of the two flat bar pieces that  must be welded together is 50 mm x 10 mm x 100 mm. 

• Two pieces of metal✔ (1) 
• Welding bead✔ (1) 
• Shrinking✔ (1) 
• Original shape of the metals✔ (1) 

4.2.3 Prevention of metal distortion when welding on metal. 

• Pre-setting✔ 
• Welding of patch work✔ 
• Clamping✔ 
• Spot welding✔  (Any 2) (2) 

4.3 4.3.1 Reasons why sunglasses are not recommended when cutting with  the oxy-acetylene set. 

• They do not filter the ultraviolet light effectively.✔ 
• Sunglasses will not protect your eyes sufficiently from flying sparks.✔ (2) 

4.3.2 The possible end results for the gas cylinder when it accidentally topples over. 

• The main valve may break off.✔ 
• The cylinder will turn into a missile and cause extreme  damage.✔ (explodes) (2)

4.3.3 TWO types of metals that can be cut with an oxy-acetylene welding  set. 

• Mild steel✔ 
• Carbon steel✔ 
• Cast iron✔ 
• Stainless steel✔  (Any 2) (2) 

4.4 Technical advice to a farmer who wants to purchase a plasma cutting  machine for general use on the farm. 

• Buy a machine according to the thickness of the metal that must be cut.✔
• You need a compressor large enough for the required working pressure✔ 
• Buy a well-known brand/quality.✔  (Any 2) (2) 

4.5 FOUR pieces of personal protective equipment (PPE) that must be used when doing plasma cutting. 

• Fireproof gloves✔ 
• Face shield✔ 
• Flame resistant clothing✔ 
• Leather shoes✔ (4) 

4.6 Factors that cause poor cutting performance when using the plasma  cutting machine. 

• The working pressure of the machine is too low.✔ 
• A too small compressor that provides insufficient air pressure.✔ 
• Water in the air system.✔ 
• Electrode and tip are worn.✔ 
• Use of a too thin air hose.✔ 
• Blocked air filters.✔ (Any 2) (2) 

[35]

QUESTION 5: TOOLS, IMPLEMENTS AND EQUIPMENT  
5.1
5.1.1 TWO disadvantages of mechanization on the farm. 

• High initial input cost✔ 
• Higher salaries✔ 
• Skilled labourers are needed✔ 
• Labour regulations✔ 
• Loss of jobs✔  (Any 2) (2)

5.1.2 TWO examples of fixed capital on the farm. 

• Land✔ 
• Buildings✔ 
• Kraals✔ 
• Boreholes✔ 
• Pumps✔  (Any 2) (2)

5.2 TWO functions of a shear bolt used in the drive system of a baling machine.  

• Prevents heavy objects from being taken into the baler.✔ 
• Protects the pick-up if it is impeded by anything.✔ 
• Protects the auger if it becomes overloaded.✔  (Any 2) (2) 

5.3 THREE parts of a clutch assembly A, B and C. 

A = Pressure plate✔ 
B = Release bearing✔ 
C = Clutch plate✔ (3) 

5.4 Is it possible that a vehicle can turn around a bend if the differential is locked?  Explain your answer.  

• No✔ 
• When the vehicle turn around a bend the wheels will momentarily turn around a  common centre,✔ 
• but when the differential is locked this cannot happen because the half axle shaft  of the outer wheel cannot revolve faster than that of the inner wheel.✔ (3) 

5.5 TWO advantages of using a bearing in a drive system. 

• Bearings increase efficiency.✔ 
• Bearings reduce friction and wear.✔ 
• Allows extended use at high speeds.✔ 
• Avoids overheating and premature failure of a drive system.✔  (Any 2) (2)

5.6 TWO advantages of thermoplastic universal joints.   

• They are light weight✔ 
• They have negligible backlash✔ 
• Are corrosion resistant✔ 
• They have the capability for high-speed operation✔ 
• They are self-lubricating✔ 
• Does not delaminate or soften✔ 
• Easy removable✔ 
• Easy to machine✔ 
• Does not swell or seize✔ (Any 2) (2) 

5.7 Freehand drawing of a ratchet type slip clutch and indicating of the following  components. 

• Ratchet plate (1) 
• Pressure spring (1) 
• Driven gear with ratchet plate (1) 
• Adjusting nut (1)
  (4) 

5.8 Reasons why it is better moving heavy loads with a rear attachments rather  than with the front-end loader. 

• Rear tyres are better suited/stronger to carry the extra weight.✔ 
• There is less chance of side overturns because the bale is not lifted high.✔ 
• More stress on the front wheels causes difficult steering.✔ (Any 2) (2)

5.9 The situation in case the top link between a tractor and plough are removed  when ploughing. 

• The back of the plough will tend to lift up out of the soil✔or the nose of the  tractor will tend to lift up.✔ (2) 

5.10 Parts where a quick coupling can be connected to a tractor. 

• Two lifting arms✔ 
• Top link✔ (2) 

5.11 THREE systems on a combine harvester that must be set to prevent the loss  of cornels during harvesting. 

• The pickup system must be set correctly.✔ 
• Set the drum speed correctly.✔ 
• Sieves must be set correctly.✔ 
• Gears/pulleys.✔ (Any 3) (3) 

5.12 THREE aspects to consider in order to prevent a hammer mill from vibrating. 

• Hammers should be checked to ensure that their mass is the same.✔ 
• When replacing hammers, the whole set of hammers should be replaced at the  same time.✔ 
• Hammers that are reversed should be replaced in its original place.✔ 
• Nothing should be added or removed from the rotor.✔ 
• Run the hammer mill at the correct speed.✔ 
• The hammer mill must be properly anchored.✔ (Any 3) (3) 

5.13 TWO places on a tractor where the automatic depth control mechanism can be  installed. 

• Where the top link is fitted.✔ 
• In the differential housing.✔ 
• At the base of the lifting arms.✔  (Any 2) (2) 

5.14 THREE advantages of transmission oil in tractor hydraulic systems. 

• Not compressible✔ 
• Good lubrication qualities✔ 
• Remains liquid over a large temperature range✔ 
• Not volatile✔ 
• Relatively cheap✔ 
• Easily conductible in pipes✔  
• Flows through filters, pipes, oil pumps and cylinders with ease✔ 
• Contains detergents that keeps parts clean✔ 
• Contains anti-foam detergent✔ 
• Good cooling qualities✔ (Any 3) (3)

5.15 A diesel tank with a surface area of 9 m² needs to be painted. Use a  corrosion resistant paint with a covering capability of 3 m² per litre.  
Determine how much paint is required by showing all calculations, if TWO  coats of paint are required on the tank. 

• Paint required = 9 m² / 3 m² (covering capability per litre)✔ 
  = 3 litres needed 
  = 2 coats X 3 litres per coat✔ 
  = 6 litres of paint✔ (3) 

[40]

QUESTION 6: WATER MANAGEMENT 
6.1 Completion of the table regarding different irrigation systems. 
6.1.1 Centre pivot irrigation✔ (1)
6.1.2 PVC pipes with plastic or brass sprinklers✔ (1)
6.1.3 Sprinklers can irrigate areas such as small farms, parks and pastures✔ (1)
6.1.4 Lateral wheel line irrigation✔ (1) 
6.2 FOUR disadvantages of flood irrigation. (4) 

• When water supply is weak flood irrigation is impossible.✔ 
• Surface gradient (steep) leads to erosion.✔ 
• Infiltration tempo not constant.✔ 
• Drainage problems.✔ 
• High costs of levelling of land.✔  
• Increase salinity in soil.✔  (Any 4) (4) 

6.3 The functions of the following irrigation system parts. 
6.3.1 Sand filter Prevent blockage of sprinkler nozzles / filters the  water.✔ (1) 
6.3.2 Sprinkler Provide water to plants.✔ (1)
6.3.3 Pump Provide water to the system / sprinklers.✔ (1)
6.3.4 Solenoid valve Controlling the water flowing through the system.✔ (1)
6.3.5 One way valve Prevent water from flowing back to the pipe.✔ (1)
6.4
6.4.1 TWO devices, A and B. 

A Tensio meter✔ 
B Evaporation pan/Class – A pan✔ (2)

6.4.2 The main purpose of the devices shown. 

• To determine the water evaporation rate in a specific field.✔ (1)

6.5 TWO devices that are used to control garden watering systems. 

• Electronic irrigation timer✔ 
• Mechanical timer✔ (2)

6.6 Operation of a septic tank system. 

• Sewage is broken down by anaerobic bacteria in the first tank.✔ 
• Very little solids remain when the watery sewerage flows to the second tank.✔
• Only liquid sewage remains and drains away through the outlet pipe or stone  trench.✔ (3) 

6.7 THREE points to consider when choosing a suitable location for installing a  septic tank. 

• The tank should not be built near boreholes and drinking water  installations.✔(water source) 
• A suitable distance away from the house.✔ 
• Not near traffic.✔ 
• Not near where people eat, wash or work regularly.✔  (Any 3) (3) 

6.8 The operation of a pipe drainage system. 

• The water drains through the surface gravel✔and seeps into the pipe's  perforations✔before traveling out the end of the pipe into an area that can accommodate extra water.✔ (3) 

6.9 THREE types of water purification systems that make use of a membrane to  purify household water. 

• Reverse osmosis✔ 
• Faucet filters✔  
• Jug or pitched filter✔ 
• Inline filter✔ 
• Whole house purification system✔  (Any 3) (3)

[30] 
TOTAL SECTION B: 160
GRAND TOTAL: 200