The general concept and layout of a torque increasing pulley system has progressed to the stage where the
detailed design of parts of it can now be undertaken.
In this assignment you will be responsible for detailing the following elements such that they can be fully
manufactured by an external fabricator using custom and existing hardware:
1. Horizontal driveshaft (custom)
2. Bearings to support shaft (commodity)
3. Pulleys (commodity)
4. Electric motor (commodity component specified below)
5. Supporting structure (custom)
The electric motor is a 3-phase, 4-pole (per phase) induction motor supplied with 400V
and 50 Hz AC. You should select a motor from the WEG catalogue such that the system can
transmit a power of at least 6+3(X+Y) kW where X and Y are the last digits in the student numbers
of partners 1 and 2 respectively. The motor is started direct on line. Truncated data for this motor is
available on the attached sheet – further details may be found in WEG Motor Catalogue available online
and on the blackboard.
The shaft will run in one direction only and is used for a total of 12 hours per day. It is started and stopped
seven times a day and runs for 6 days a week, for 50 weeks per year. The shaft should run at 460 rpm ±
3% when the motor is running at its rated speed. Wedge belts (not Vee belts) are to be selected from
AS2784 (i.e. from belt section sizes A, B, C, or D). Pulley pitch diameters are to be selected from the
recommended sizes listed in the catalogue data provided in the design workshop.
The bearings on the drive shaft should achieve a life of 40,000 hours with 95% reliability. Selection is to
be made of deep groove ball bearings selected from the Timken catalogue available on the blackboard
(the design procedure presented in lectures should be applied, in preference to the procedure provided by
the bearing manufacturer). Appropriate plummer blocks should be identified by you from an online source
(please clearly reference your source, note that downloaded CAD data is not acceptable, your drawings
must be your own).
You will define a simple supporting structure that will ground the plummer blocks and “foot mounted”
electric motor, while allowing assembly and tensioning of belts. Schematic design of appropriate guarding
should be provided according to AS 4024 “Safety of machinery”. In this work it is important that correct
assembly dimensions be maintained, however, structural design should be completed “by eye”, i.e. the
dimensions and supporting structures should be plausible for the expected load, but their integrity does
not need to be directly assessed.
Belts: All belts are to be designed to AS2784.
Work to be submitted.
This assignment is worth 25% of the subject’s marks for MIET 2420 Mechanical Design 1. Students are
to work in pairs and submit a joint set of documentation. Students will be awarded an average mark unless
a request for individual marks is clearly indicated. If marked individually, the marks will be awarded
according to areas of responsibility as indicated in the margin by P1 (partner 1) and P2 (partner 2).
During the design workshop on week 6 students are to describe to the tutors: their preliminary belt and
pulley selection (preferably in a design table), hub load calculations and the reaction forces at the
bearings, as described in (b) (i) and (ii) below.
Final submission of documentation is, by 5PM Friday September 7. Further details on submission
procedure to follow. Documentation is to include a neat set of confirming calculations which deal with the
P1 and P2 Belt / pulley selection, including selection process and justification, plus hub
loads when static and running at design power.
P1 and P2 The reaction forces at the bearings (static and dynamic)
P1 Selection of the bearing near the pulley (static and dynamic)
P2 Selection of the bearing near the coupling (static and dynamic)
P1 and P2 Bending Moment Diagrams in two planes for the shaft and a Torque Diagram.
These should be completed for the peak loading condition.
P1 and P2 Sizing of the shaft at a critical location-as per Australian Standard 1403-2004
“Design of rotating steel shafts” to resist fatigue. This sizing should be based on
the peak shaft load.
P1 Overall external drawings of the motor – belts – guards – shaft system including
motor mounting arrangements. The drawings are to give principal dimensions,
showing at least two views of the system.
P2 Detailed sectioned dimensioned drawing of the horizontal drive shaft assembly
excluding the flexible coupling, (i.e. showing the pulley; the shaft and the
associated: bearings, housings, and seals; in position.).
P1 and P2 Schematic design of appropriate guarding according to AS 4024.
Where P1 is the lowest student number and P2 is the larger student number. Calculations should be clear
and logical and incorporate free body diagrams where appropriate. Data drawn from tables and graphs in
texts or catalogues must have their source identified, and the reasons for a particular value being chosen
must be clearly stated.
Required drawing may be done by hand or using CAD and is to be submitted on paper as an appendix to
the report. Any submitted CAD work must be original work produced solely by the student pair.
Use of example models supplied by the course staff or models obtained from online catalogues will not
attract any marks. Minor modifications of example models will not considered as original work. Any
plagiarism will be dealt with according to the University Policy.
Presentation is to be of a professional report standard, including (in this order) an executive summary,
systematic and comprehensive analysis, bibliography and appendices.
The names of P1and P2 and the associated student numbers must be clearly identified on the
assignment cover. A request for individual marks needs to be clearly indicated along with
identification of who is P1 and P2.