Cork Institute of Technology
Bachelor of Engineering in Building Services Engineering -Stage 2
(EBSEN_7_Y2)
Autumn 2008
Drawing & Design – Mechanical Design
(Time: 3 Hours)
Instructions
Answer FIVE questions.
All questions carry equal marks.
Examiners: Mr. T. A. Farrell
Mr. D. Leonard
Dr. M. Smyth
Q1 (a) Explain carefully, with the aid of sketches, the following terms in connection with belt
drives:
(i) Belt pitch length.
(ii) Pulley pitch diameter.
(iii) Belt contact angle.
(iv) Belt static tension. (8 marks)
(b) A compressor in a refrigeration plant is driven by a 10kW AC squirrel cage electric motor,
running at 1450 RPM. The compressor runs for 24 hrs. per day, and the required compressor
speed is 800 RPM approximately.
Design a suitable drive consisting of classical V-belts and sheaves. The design should
include:
(i) The pulley diameters, and actual centre distance. (3 marks)
(ii) Belt cross-section, and pitch length. (3 marks)
(iii) The required number of belts. (3 marks)
(iv) The actual compressor speed. (3 marks)
Assume an initial centre distance estimate of C = D + 1.5d, where D and d are the diameters
of the large and small sheaves respectively.
