ass3 unit 8, is something i've started if the expert wants to use it, ive added it also
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 3. Mechanical Power Transmission Systems Issue Date 28th April 2021 Submission Date 21st May 2021 IV Name & Date A.Garbutt 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 correct 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: Date: 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 gearbox 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 gearbox. 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 978-0-367-25324-0 BOLTON, W. (2006) Engineering Science. 5th Ed. London: Routledge. TOOLEY, M. and DINGLE, L. (2012) Engineering 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 correct 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 gearbox 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 gearbox 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 = = 0.756704 kNm ( d ) The holding torque which is required to securely mount the gearbox. TOUT – TIN = 0.756704 – 0.14552 = 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 = VR = = 251.33 Efficiency = η = α = = = 3.038° β = = = 16.699° (c) η up = = 14.79% η down = = 21.83% (d) MA = VR x η = 251.33 x 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.