POWER MECHANICS PAPER 2 - 2019 LAINAKU JOINT MOCK EVALUATION EXAMINATION

STATION 1
Instructions:
The figure below shows a piston assembly of a single cylinder engine. In the space below, sketch an exploded view of the assembly and label all the parts. (10 marks)

STATION 2
Instructions
The figure below shows a shaped block drawn in third angle orthographic projection. In the space provided below, draw the oblique view of the block in good proportion.( 10 marks)

STATION 3
Instructions:
From the manual provided, look for and record all the information required to complete the following table for models HONDA G35 (APPENDIX A) and CLINTON ENGINE (VS 2100)(10 marks)

HONDA G35                     (Standard)

1. Exhaust valve stem O/D ………………………
2. Valve spring free length ……………………….
3. spark plug gap.   …………………………………
4. Piston O/D at skirt ………………………..
5. Cam height …………………………………….

CLINTON   VS 2100

1. Carburetor float setting ……………….max
2. Ring end gap in cylinder ……………….max
3. Spark plug gap …………………….min
4. Piston O.D. at skirt ……………..min
5. Point setting …………………

STATION 4
Instructions
Make a good proportion sketch of a two-leading shoe design of a drum brake on the space provided below and also label it .

STATION 5
Instructions:
Identify the tools labeled A to J and state the use of each. (10 marks)

STATION 6
Instructions
Using the conventional ignition system components and the wires provided. Connect a complete ignition circuit as found in a vehicle.(10 marks)
Let the examiner inspect your work and disconnect the circuit.

STATION 7
Instructions
The single cylinder engine provided has a clearance volume of 48cm3.

1. Measure the bore……..mm
2. Measure the stroke……mm
   Calculate
3. the cubic capacity of the engine
4. The compression ratio of the engine
5. The amount of fuel the engine consumes in 10 minutes if its air fuel ratio is 15:1 and the engine is running at 1200 has a volumetric R.P.M and efficiency of 80%.

STATION 8
Instructions:  
Identify the components numbered 1 to 10 and complete the table given below. (10 marks)

STATION 9
Instructions
The engine provided has faults in its basic system indicated below. Identify the faults and state the effect of each on the performance of the engine. (10 marks)

SYSTEM                     FAULTS           EFFECTS

1. Fuel
2. Ignition
3. Lubrication
4. Cooling
5. Exhaust

STATION 10
Instructions
On the gas welding equipment provided:

1. identify the parts labelled A to E
2. Light the equipment and set the torch to a carburizing flame.
   (NOTE: The regulator pressures are already set).
   Let the examiner check your work. (10 marks)

MARKING SCHEME

STATION 1
Instructions:
The figure below shows a piston assembly of a single cylinder engine. In the space below ,sketch an exploded view of the assembly and label all the parts.(10 marks)

STATION 2
Instructions
The figure below shows a shaped block drawn in third angle orthographic projection. In the space provided below, draw the oblique view of the block in good proportion. ( 10 marks)

STATION 3
Instructions:
From the manual provided, look for and record all the information required to complete the following table for models HONDA G35 (APPENDIX A) and CLINTON ENGINE (VS 2100)(10 marks)

HONDA G35                     (Standard)

1. Exhaust valve stem O/D …6.910mm(0.2702)……………………
2. Valve spring free length …27.9mm (1.098)…………………….
3. spark plug gap.   …………0.7mm (0.0281)………………………
4. piston O/D at skirt …0.03mm(0.001)…………………..
5. Cam height ………28.1mm (1.106)…………………………….

CLINTON   VS 2100

1. Carburetor float setting 11/64……………….max
2. Ring end gap in cylinder ………0.017……….max
3. Spark plug gap ………0.025…………….min
4. Piston O.D. at skirt …2.3690…………..min
5. Point setting …0.021 max………………

STATION 4
Instructions
Make a good proportion sketch of a two-leading shoe design of a drum brake on the space provided below and also label it .

STATION 5
Instructions:
Identify the tools labeled A to J and state the use of each.( 10 marks)

1. correct Identification of the tools (5marks )
2. Correct use of tools (5marks)

STATION 6
Instructions
Using the conventional ignition system components and the wires provided. Connect a complete ignition circuit as found in a vehicle.(10 marks)
Let the examiner inspect your work and disconnect the circuit.

1. correct layout of components 1/x6=3marks
2. Battery polarity (_ve to the ignition switch) 1mark
3. coil polarity (-ve to the distributor terminal)
4. wires and cables connected in the correct positions 1/2x10 =5marks
   total 10marks

STATION 7
Instructions
The single cylinder engine provided has a clearance volume of 48cm3.

1. Measure the bore……..mm
2. Measure the stroke……mm
   Calculate
3. the cubic capacity of the engine
4. The compression ratio of the engine
5. The amount of fuel the engine consumes in 10 minutes if its air fuel ratio is 15:1 and the engine is running at 1200 has a volumetric R.P.M and efficiency of 80%.
   Correct bore measurement 1mark
   Correct stroke measurement 1mark
   Correct calculation for the cubic capacity 2marks
   Correct calculation for compression ratio 3marks
   Correct calculation of the engine fuel consumption 3marks
   Total 10 marks              

STATION 8
Instructions:  
Identify the components numbered 1 to 10 and complete the table given below. (10 marks)
Name of component               one use

1. camshaft           -        opens the valves
2. terminal nut- Terminal for connection of H.T.L                                                                                                                                    
3. push rod –pushes against rocker arm to open valves
4. condenser -prevents arcing at C.B points
5. tappet - pushes against push rod to open valves
6. retainer- holds the spring in position around valve stem
7. deflector directs air to the cooling fins
8. rod dipper for oil distribution
9. connecting rod lock –prevents rod bolts from working loose
10. piston pin-connects piston and con- rod

STATION 9
Instructions
The engine provided has faults in its basic system indicated below. Identify the faults and state the effect of each on the performance of the engine.(10 marks)

SYSTEM                     FAULTS           EFFECTS

1. Fuel     - no tank       - engine will stall due to lack of fuel.
2. Ignition -loose high tension lead   -engine fails to fire due to lack of sparks.
3. Lubrication - no oil in the sump   -possible wear and knocking of the engine
4. Cooling - air deflector missing   -engine will overheat
5. Exhaust - silencer -missing - exhaust noise.

STATION 10
Instructions

1. On the gas welding equipment provided: a) identify the parts labelled A to F correct identification of part of the welding bit:
   A   -acetylene cylinder.
   B   -oxygen cylinder
   C   -oxygen pressure regulator.
   D  - Acetylene pressure regulator.
   E   - blow pipe
   F -Nozzle.
2. Light the equipment and set the torch to a carburizing flame.
   (NOTE: The regulator pressures are already set). Correct demonstration of procedure for lighting.
3. Open the cylinder valves 1
4. Set the working pressures 1
   Light the frame ½
5. Open the oxygen blow pipe valve ½
6. Adjust the blow pipe valves until desired flame is obtained 1mark
   Let the examiner check your work. (10 marks)