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1.

KNOWLEDGE & UNDERSTANDING QUESTIONS

1. Classify belt drives based on the geometry of belts. 2. List some of basic advantages, disadvantages, and applications for using belt drives. 3. Show the advantages and disadvantages for using v-belts over than flat belts. 4. Discuss what is meant by:

a) Length correction factor. b) Angle of contact correction factor. c) Slipping action. d) Slack side. e) Design power. f) Nominal power. g) Rated power. h) Pitch line. i) Wedge angle. j) Simple and compound belt drives.

5. Give a name for three popular belt body materials. 6. Specify the V-belt cross section basic terminologies (a-e) as dedicated in the figure

below.

SHEET3: BELT DRIVE SYSTEMS

BENHA UNIVERSITY M471 MACHINE DESIGN BANHA FACULTY OF ENGINEERING 4TH YEAR MECHANICAL ENGINEERING MECHANICAL ENGINEERING DEPARTMENT DR. AL-ASSAL | ENG. AMRO | ENG. ABDALLA

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2.

KINEMATICS

Specify the belt and pulleys motion’s directions, the tight and slack sides with indicating the drive and driven pulley in each case in the figure below (a-d):

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3.

DESIGN PROBLEMS

Solve the following problems, assume any missing data, and use the tables for selecting standard V-belt dimensions (according to DIN standards): 1. V belt drive is to be selected to deliver engine power to the wheel-drive transmission of

a riding tractor. A 5-hp single cylinder-engine is used. The required reduction ratio is 0.25. The center distance should be as close to a 92-in as possible. The engine speed is governor-controlled to a maximum of 3100 rev/min. Select a satisfactory belt, sheave sizes, and number of belts.

2. A single V belt is used in a drive composed of a 140 mm driving sheave, rotating at 1200 rev/min, and a 400 mm driven sheave. If the tension in the tight side of the belt is 1 KN, find the power capacity of the drive based on a service factor of 1.25, and select standard V belt.

3. A 60-hp four-cylinder internal combustion engine is used to drive a brick-making machine under a schedule of two shifts per day. The drive consists of two 450 mm sheaves spaced about 2 m apart, with a sheave speed of 400 rev/min. Select a V-belt arrangement.

4. A 2-hp electric motor running at 1720 rev/min is to drive a blower at a speed of 240 rev/min. Select standard V belts, and sheave sizes for this application. The motor size limits the center distance to at least 22 in.

4.

ANALYTICAL PROBLEMS

1. Five v-belts are used to transmit power from a motor rotates at 2000 rpm in a lathe

machine, where the diameter of the drive pulley is 140 mm and the reduction ratio

is 7. Select which profile of V-belts is acceptable to transmit a nominal power of 32

kW.

2. Deduce the belt length equation which is used in simple belt drives.

3. Derive a mathematical formula for determining the belt length for a belt drive

system consists of three different size pulleys in an arrangement like the figure

shown below.

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