BASIC TECHNOLOGY LESSON NOTE: Mechanical Transmission System - Drive Mechanism (gears and chain drive) - xpino SCHOLARS

A work tool for teachers and students, but especially for Secondary School Students. Comprehensive lesson notes, with exercises. Past questions in specific subjects for revision and research.

Sunday, March 13, 2016

BASIC TECHNOLOGY LESSON NOTE: Mechanical Transmission System - Drive Mechanism (gears and chain drive)



Drive Mechanism
A drive mechanism is one that takes the power coming from a motor without any reduction. Gears, chains and belts are used to transmit energies.


Gears
Gears
A gear is a rotating machine part having cut teeth, which mesh with another toothed part in other to transmit mechanical energy.
              
The gear system requires friction. The friction in the gear system is extremely high hence lubrication is needed at all times to reduce the friction. The pushing action enables one gear to move another gear – thereby transferring energy to that gear.

Belt drives and Chain drives
Chain and Belt drives
Belts are made of rubber and materials whose length and nature change with temperature. Examples of belts are motor fan belts, grinding machine belts, sewing machines. etc.
Chains are made of metals. Common examples are bicycle and motorcycle chains.

Friction is greatly needed in belt and chain drives. Belts and chains cannot work when friction is absent. Belts and chains are used in pulley mechanisms.

Belt and chain drives are used to:
1.             Transmit energy from one shaft to another when both shafts are separated by a distance greater than that require for gears.
2.             Change the speed of a pulley.
3.             Change the running direction of a pulley.
4.             Carry materials as conveyors from one point to another.

Types of belts and pulleys
     1.      Open belt
     2.      Crossed belt
     3.      V-belt
     4.      Chain belt.

Open belt


Cross Belt

V belt
Chain Belt

Relationship between belts and pulleys
A pulley is the wheel on which a belt runs. The pulley from which power is taken is called the driving pulley or driver. The pulley to which power is carried is called the driven pulley.

Exercises/Research:
     1.      What is a drive mechanism?
     2.      What is a gear?
     3.      How does gear system differ from pulley mechanism?
     4.      What is the main difference between belts and chains?
     5.      What are four uses of belt and chain drives?
     6.      What are the names of four types of belt and pulleys?
     7.      What is the difference between a driving pulley and a driven pulley?
     

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