Assessment Brief 3 Student Name/ID Number Course BTEC HNC in General Engineering Unit Number and Title 8: Mechanical Principles Academic Year 2020/21 Unit Tutor Philip Arnold Assignment Title Number...

Assessment Brief 3
    Student Name/ID Numbe
    
    Course
    BTEC HNC in General Engineering
    Unit Number and Title
     8: Mechanical Principles
    Academic Yea
    2020/21
    Unit Tuto
    Philip Arnold
    Assignment Title
    Number 3. Mechanical Power Transmission Systems
    Issue Date
    28th April 2021
    Submission Date
    21st May 2021
    IV Name & Date
    A.Ga
utt 21/4/21
    Allocation of time to complete assignment
    Part 1 & 2 are calculation type questions. Part 2 is to include a written explanation too. Part 3 & 4 is a written explanation of at least 200 words including. Estimated time for completion of work 20 Hours
    Submission Format
    This is a written & problem based assessment.
To evidence that you have met the criteria:
· The written reports must be at least 200 words.
· Must show working out
· Use the co
ect units of measurement
· And use formulas right through.
Remember, answers are only part of the solution. You must show how you got there and be able to document and communicate your problem solving technique.
Some higher criteria questions will draw on you to interpret, compare and draw conclusions of worked solutions.
Format:
Part 1 is a calculation type question. Part 2 Is both calculation and explanation. Parts 3 & 4 are written reports as per the questions
Where references are used, follow Harvard Referencing System including in-text citations.
    
Student declaration
    I certify that the work submitted for this assignment is my own and research sources are fully acknowledged.
Student signature:      XXXXXXXXXXDate:
    Unit Learning Outcomes
    LO3 Investigate elements of simple mechanical power transmission systems
    Assignment Brief and Guidance
    Scenario
You are employed in the R&D dept of an agricultural machine manufacturer. They are planning the design of a new machine. While the performance has been decided before the design can be fixed, the effects and limitations on performance and handling must be identified. Calculate to determine the values at a – b – c -& d
Part 1.
A gea
ox has an input speed of 1300 rpm clockwise and an output speed of 200 rpm anticlockwise. THE Input power is 20kW and the efficiency is 80%
Calculate:
( a ) The Gear Ratio
( b ) The input torque
( c ) The output torque
( d ) The holding torque which is required to securely mount the gea
ox.
Part 2. Screw Jack
A screw Jack with a square cut thread and has an outer diameter of 60mm. It has a pitch od 10mm with a operating lever which has a length of 400mm from one end to the centre of the thread. The machine has an overall co-efficient of friction of 0.3 , It raises a load of 240kg
( a ) Calculate the force require to raise the load.
( b ) The work done raising the load 200mm
( c ) The efficiency
( d ) The mechanical Advantage.
( e ) Explain how Screw jacks can store potential energy, & how this is affected by the factors in its design.
Part 3 Constant Velocity Joints
There are situations where the input drive energy into a shaft is required to be transmitted to a second shaft ( output shaft ) who’s alignment is at an angle, or constantly changing angle such as the drive shafts of a front wheel drive motor vehicle. While this is possible using various couplings they do cause the velocity ratio to change with the change in alignment of the two shafts. In some circumstances this is unacceptable.
You have been tasked to investigate methods of overcoming this change in velocity ratio for a design and write a report which fully explains how your proposed design provides constant velocity ratio. Your report must be written in a manner that both an engineer and a layman can understand and be at least 200 words including plus diagrams / drawings / images / links to videos / to assist in the explanation.
Part 4.
As you will be required to present you findings and designs, you need to be prepared for questions. Its not uncommon to receive awkward and apparently negative questions, such as “ I have heard of cases where transmission systems have failed. How can we be sure your designs will not fail “
So you prepare a documented case study of a Transmission failure and explain the steps you have taken in your design / designs to avoid this by rectifying the design / operating instructions.
Resources
Textbooks
Pearson Higher Nationals in Engineering Core Text Book
John Bird & Carl Ross, Mechanical Engineering Principles, Fourth Edition, Routledge. ISBN XXXXXXXXXX
BOLTON, W XXXXXXXXXXEngineering Science. 5th Ed. London: Routledge.
TOOLEY, M. and DINGLE, L XXXXXXXXXXEngineering Science: For Foundation Degree
and Higher National. London: Routledge.
Journals
International Journal of Engineering Science.
International Journal of Engineering Science and Innovative Technology.
0
00Websites
https:
www.khanacademy.org/ Khan Academy
Physics
(Tutorials)
    Learning Outcomes and Assessment Criteria
    Pass
    Merit
    Distinction
    LO3 Investigate elements of simple mechanical power transmission systems
    D3 Examine the cause of a documented case of mechanical power transmission failure and the steps to co
ect the problem and rectify any design faults
    P6 Determine the velocity ration for compound gear systems and the holding torque required to securely mount a gea
ox
    M3 Examine devices which store mechanical energy in their operation
    
    P7 Calculate the operating efficiency of lead screws and screw jacks
    
    
    P8 Explain the conditions for a constant velocity ratio between two joined shafts
    
    

Part 1.  
A gea
ox has an input speed of 1300 rpm clockwise and an output speed of 200 rpm anticlockwise. THE Input power is 20kW and the efficiency is 80% 
Calculate: 
( a ) The Gear Ratio 
Gear ratio (GR) = = = 6.5
GR = 6.5:1
( b ) The input torque 
Tin = = = 0.14552kNm
( c ) The output torque 
TOUT =
TOUT = = XXXXXXXXXXkNm
( d ) The holding torque which is required to securely mount the gea
ox.  
TOUT – TIN = XXXXXXXXXX – XXXXXXXXXX = 0.611184kNm
 
Part 2. Screw Jack 
A screw Jack with a square cut thread and has an outer diameter of 60mm.  It has a pitch od 10mm with a operating lever which has a length of 400mm from one end to the centre of the thread. The machine has an overall co-efficient of friction of 0.3, It raises a load of 240kg 
( a  )  Calculate the force require to raise the load. 
( b ) The work done raising the load 200mm 
( c ) The efficiency 
( d ) The mechanical Advantage. 
( e ) Explain how Screw jacks can store potential energy, & how this is affected by the factors in its design. 
Due to way we have been taught, I will follow that as its easier to understand and work out the equations.
Velocity Ratio = XXXXXXXXXXVR = = 251.33
Efficiency = η =
α = = = 3.038°
β = = = 16.699°
(c)
η up = = 14.79%
η down = = 21.83%
(d) MA = VR x η = XXXXXXXXXXx 14.79% = 37.17
(a) FE = = = 63.34N
(b) W = Force x displacement = 63.34 x (200 x 10-3) = 12.668J
(e)
Force x Distance equals potential energy, therefore, we can see that Force equals mass x acceleration. This means that if you take the 240kg mass and multiply it by 9.81 (gravitational acceleration), then multiply it by the distance it can go, you'll find that the greater the distance raised, the bigger the potential energy stored. The influence of friction and velocity ratio plays a role in this. If we want to get the most out of the energy transfer, we'll need to change the equation's values for efficiency. However, doing so would affect the MA, which would have an impact on efficiency and velocity ratio.