The aim of this assignment is for the student to use the information, data and analysis techniques presented during lectures to design a belt drive transmission for a ventilation fan.
Objectives: By the end of this assignment the student should be able to:
• Know and understand the use of standard analytical techniques to prove a design.
• Create and synthesise solutions to mechanical engineering problems.
• Apply modelling and drawing techniques using CAD.
• Locate information on and select materials and preparatory parts for particular purposes including bearings, ‘v' belts, pulleys, etc.
An ‘axial fan' is required to move air for ventilation purposes within an industrial building. The requirements for this fan are that the electric motor cannot be connected directly to the fan drive shaft but must sit outside the cowling and drive the fan by means of Wedge Drive Belts. Due to the operating requirements for adequate ventilation, the fan itself is Φ0.788m diameter and 0.147m long. To the central hub of the fan, a fan shaft can be attached as is deemed appropriate. It has already been established that, for the type of fan being used and its operating capacities, it will rotate at 750 rev/min and at a power requirement of 0.91kW. The cowling, support for the fan shaft, drive system, motor selection and motor mounting have yet to be decided and/or designed.
The cowling is to be a round tube, sufficient to house the fan and its support and secure the motor on its outside surface. The cowling should also have a flange at each end so that it can be connected up to ventilation ducting. The method of securing the whole assembly in its place of operation is not considered here and need not be designed for.
The air temperature varies from 10oC in winter to 35oC in summer with little humidity but carrying a substantial amount of dust and light debris.
The ventilation system is to operate all day and every day, 365 days a year, without maintenance except for checking and changing belts, pulleys, motor, etc, at their required service period. Any planned maintenance should result in as little ‘down-time' as possible.
It has already been decided that the transmission will consist of; an AC Electric Motor and ‘V' Belt drive. The actual motor, belts, pulleys, etc, have yet to be chosen and decided. 3 Phase 50Hz electric supply is available.