POWER TRANSMISSION
SYSTEMS
• Mechanical power can be transmitted from one
shaft to another by using four methods
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–
–
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Belt drive
Rope drive
Chain drive
Gear drive
• The shaft from which power is transmitted is
called driver shaft and the shaft to which power
is transmitted is called driven shaft
BELT DRIVE
1. A belt is a looped strip of flexible material, used to
mechanically link two or more rotating shafts.
2. They may be used as a source of motion, to efficiently
transmit power, or to track relative movement. Belts are
looped over pulleys.
3. In a two pulley system, the belt can either drive the pulleys in
the same direction, or the belt may be crossed, so that the
direction of the shafts is opposite.
TYPES OF BELTS
OPEN BELT DRIVE
• It is used with shafts arranged in parallel and
to be rotated in same direction.
• The driver pulley pulls the belt from one side
and delivers the same to the other side.
• Side where tension is more is called tight side
and the other side is called slack side
CROSS BELT DRIVE
• It used with shafts arranged in parallel and to
be rotated in opposite direction.
• At the point where belts crosses, it rubs
against itself and wears.
• Shafts are placed at a minimum distance of
20b to minimize the wear.
Length of belt
CHAIN DRIVE
• It consists of an endless chain running over
toothed wheel. Toothed wheel is called
sprocket.
• The smaller sprocket is called pinion and the bigger one is
called wheel.
CLASSIFICATION OF CHAINS
• Based on application we can classify chains as
1) Power transmission chains
2) Pulling chains
Used in elevators
3) Hoisting chains
Used in lifting loads
TYPES OF POWER TRANSMITTING
CHAINS
1. ROLLER CHAIN
2. SILENT OR INVERTED TOOTH CHAIN
1
2
3
4
5
Outer plate
Inner plate
Pin
Bushing
Roller
ROLLER CHAIN
• It consists of rollers, bushes, pins, inner plates
and outer plates.
• The pin passes centrally through the bush and
the roller surrounds the bush.
• The bush moves freely on the roller and the
roller moves freely on the bush.
• Bushes are held together by outer plates.
• Rollers are held together by inner plates.
• To prevent the lateral movement of the outer
plates the pin ends are hammered in the
shape of a rivet head.
Inverted tooth chain
• It is employed when heavier loads are to be
transmitted and maximum quietness is
desired
GEAR DRIVE
• Gear is a term used to generally denote toothed
wheels.
• For transmitting power one gear will be mounted
on driving shaft and the other will be mounted on
driven shaft.
• The teeth's of the gears will be meshed with each
other
• The distance between the shafts must be
sufficient to enable meshing of the gear tooth.
Gear materials
• For heavy duty – cast steel and alloy steel
• For corrosive environment – Non ferrous
materials
(phosphor bronze, nickel,
manganese)
• The cheapest material – Grey iron
SPUR GEAR
In this the teeth will be cut parallel to the shaft
Used to transmit power between parallel shafts