8: Mechanical Principles (L4) 1
Assignment Title Unit Code Assignment No
Mechanical Power Transmission Systems F/615/1482 3 of 4
Submission Format
Please append your answers to the end of this brief. Include ALL pages of this brief in your submission.
Do not submit separate documents.
All text elements of your submission should be word processed, analytical elements can be hand written
(neatly) and scanned into your document: –
Structurally, you should submit a report with the following sections: –
Cover page – This should feature your name and assignment title – perhaps a nice graphic, if you like (no
page number on this sheet).
Contents page – Lists each section in the document and the page number where that section begins (these
pages are numbered i, ii, iii etc).
Tasks – Tasks 1, 2, 3 ——- etc. This is the main body of your submission.
Bibliography – Lists all the sources you used when researching your assignment but you have not
referenced.
References – List of all the sources that you have referred to in completing the tasks, you can use either the
Harvard or Vancouver referencing system. Do not use Wikipedia as a source.
Note
Recommended word-count : Not applicable
Relevant Learning Outcomes and Assessment Criteria
Pass Merit Distinction
LO3 Investigate elements of simple mechanical power transmission
systems
LO3
P6
Determine the velocity ratio
for compound gear systems
and the holding torque
required to securely mount a
gearbox.
M3
Examine devices which
function to store mechanical
energy in their operation.
D3
Examine the cause of a
documented case of
mechanical power
transmission failure and the
steps taken to correct the
problem and rectify any
design faults.
P7
Calculate the operating
efficiency of lead screws and
screw jacks.
P8
Explain the conditions
required for a constant
velocity ratio between two
joined shafts.
Unit Learning Outcomes
LO3: Investigate elements of simple mechanical power transmission systems
Assignment Brief and Guidance
Scenario:
As a new Junior Engineer in an agricultural machinery supplier, you have responsibility for overseeing and
managing after sales activities and dealing with warranty issues.
Activity 1
Agricultural machinery generally comprises of an array of mechanical mechanisms. As you have responsibility
for after sales care and warranty issues your CEO needs to have confidence in your technical abilities and has
asked you to complete Task 1, 2 & 3 to demonstrate your technical competence.
Task 1:
a) A gear box has an input speed of 2000 rpm clockwise and an output speed of 300 rpm anti-clockwise.
The input power is 30 kW and the efficiency is 65%. Determine the following;
i. The velocity ratio (gear ratio)
ii. The Input Torque
iii. The Output Power
iv. The Output Torque
v. The Holding Torque.
b) A lead screw-jack is being used to support the axle of a van, the load on it being 3.2 kN. The screw jack
has an effort of effective radius 300 mm and a single-start square thread, having a lead of 6 mm. Determine the efficiency of the jack if an effort of 50 N is required to raise the van axle.
c) Excluding a screw jack, briefly explain with the aid of sketches two applications of a lead screw mechanism.
Task 2:
In a short report, explain the method whereby torque can be transmitted between two non-axial shafts.
The report needs to identify the basic problem with a simple universal coupling arrangement and how this
problem can be solved. Finally, you need to detail the arrangement where universal couplings can provide
constant velocity between two joined, non-axial shafts.
Activity 2
Some agricultural machinery utilises mechanical energy storage devices to improve operating performance.
To aid your personal development it has been suggested by your line manager that you investigate the
principles and applications of energy storage devices, which would be achieved by completing Task 3.
Task 3:
Research and discuss two devices (one mechanical) which store energy.
Your discussion will need to focus on the storage principle, application and operating method.
Activity 3
In your role dealing with warranty claims, you have identified that a relatively high number of claims are
being made regarding gear box failures on a newly introduced piece of machinery. Although the cause of the
failures are being investigated by the manufacturer, your line manager has suggested that you expand your
knowledge of drive train failure by completing Task 4.
Task 4:
By conducting your own research, or by relating your personal experience, describe a documented case
of mechanical transmission failure. You will need to describe the mechanism involved in the failure, the
consequences of the failure, what steps were taken to correct the problem or defect, and if design
modification was required.
Your line manager has asked you to aim for a word count in the region of 1200 words for Task 4.