Design and Testing of Agricultural Machines: Belt, Pulley, Sprocket, Chain, Gear Drives Flashcards
the most simple method of transmitting power in agricultural machines and widely adopted in driving various production and postproduction parts of agricultural machines.
Belt-and-pulley drive
The cost of transmitting power is very much lower
compared with sprocket-and-chain and gear drives.
Belt-and-pulley drive
a flexible material which is banded on two or more
pulleys where power is transmitted from the driver to the driven pulley. Power transmission primarily depends on the friction between the belt and the pulley surfaces.
Flat Belt
is a transmission system that consists of an endless
flexible belt that transmits power by contacting and gripping the sheaves which are keyed to the shaft of the driving and the driven machine.
V Belt
TRUE/FALSE
Flat Belt and Pulley Drives are suitable for high-speed drives, adaptable to the dusty and abrasive environment, and transmits power on a long-distance shaft.
TRUE
TRUE/FALSE
Flat Belt and Pulley Drives have longer life span, high efficiency, low cost, and low maintenance. Also applicable for the short-distance drive using pivoted or spring-actuated motor bases. Requires tension to minimize slip below 2 percent. High bearing load due to high tension requirement for the belt.
TRUE
TRUE/FALSE
V-Belt and Sheave Drives are suitable for short-center-distance driving and the ability to transfer heavy tensile load.
Usually used to transmit power between parallel shafts and used for non-parallel drives applicable for single or in multiple sheaves.
FALSE (long-centered)
Prone to elongation because of wear and operation; hence,
there is a need of mechanism to maintain the proper tension to take up the belt slacks.
V-Belt and
Sheave Drive
They rotate with slip and creep conditions’ therefore, the angular velocity between the two shafts is neither constant nor exactly equal to the ratio of the sheave pitch diameter. Power losses caused by slip and creep ranged from 3 to 5 % for most belt
drives.
V-Belt and
Sheave Drives
– is used to transmit rotary motion and power
between two shafts which lie flat on the face of the
corresponding pulley.
Flat Belt
– is a belt with trapezoidal cross-section to
transmit rotary motion to parallel shafts.
Narrow V-Belt
– is a V-belt with inverted V on top making it
more suitable for multiple-sheaves drive arrangement.
Double V- Belt
– is a V-belt with teeth design for a special kind
of sheave to provide more gripping action to obtain higher
efficiency hence minimizing belt slip.
Cogged Belt
– combines the features of a flat belt and a
V-belt. It operates very efficiently and can run at a very high
speed.
V-Ribbed Belt
– is most common where there is a
large center distance between shafts or where drive ratio
goes beyond the commonly supplied drive.
Variable-Speed Belt
It can carry significant load of up to 500hp and
can provide long service life. However, it is costly and
requires to be cleaned and dressed at all times. It is also
prone to stretch and shrink. Also, it is normally limited to low
or moderate speed.
Leather
This is a combination of both
fabric and cord reinforcement that provides the strength of
chord reinforcement and the abrasion resistance of the
fabric.
Rubberized fabric or cord
This kind of belt material is the least
costly of all. For the same width and thickness, this type
transmits less power and has a shorter life than leather.
Rubberized Fabric
This is only available as endless belt and
not designed to be spliced. It carries 50% more power that
fabric reinforced belt.
Rubberized Chord
This has a nylon member
covered by rubber or plastic. Its capacities ranged from
fractional horsepower to 100hp per inch of width. It is capable
of operating at 40,000 fpm.
Reinforced Rubber or Plastic
It is made either of plain or with chemical or
rubberized coatings. It has the ability to tract uniformly
Fabric
ordered according to the material, width and
number of plies. Example, canvas-type flat belt 4in. wide, 4
plies.
Flat belts
ordered according to brand, type, (A, B, C, D, E,
etc.) and length. Example, Mitsubishi B-52 belt means type B
with circumferential length of 52 inches.
V-belts
are used to transmit the power from the belt to the shaft. Generally made of cast iron. However, there are steel pulleys that are also available and are made in various sizes
and combinations. And should be carefully selected to fit the need and requirement of the drive
Pulleys and sheaves
are grooved sheaves or flat pulleys which do not serve to
transmit power. Instead they are used to tighten belt when it is
not possible to move either shaft for belt installation and take-up
Idlers
Pulley shafts are parallel with each other
Pulleys have the same direction
Shorter belt length
Smaller arc of contact of belt on two pulleys
Suitable for v-belt and flat belt drives
Open-Belt Drive
• Pulley shafts are perpendicular with each other
• Requires longer belt than open-belt drive
• Relatively higher arc of contact between belt and
pulley
• Suitable for flat belt or special type of v-belt
Quarter-Turn Drive
- Pulley shafts are parallel with each other
- Pulleys direction are opposite
- Requires longer belt length
- Higher arc of contact of belt on pulleys
- Suitable for flat belt drive or special type of v-belt
Cross-Belt Drive
Pulley Speed and Diameters Formula
N1 D1 = N2 D2
Speed Ratio Formula
Speed Ratio – It is the ratio of the angular speed of
two pulleys making no allowance for slip and creep.
Nr = N1 / N2
Belt Velocity Formula
Belt Velocity – is the linear speed of the belt.
Vb = 0.262 x D x N
Belt Length (Open Drive) Formula
Belt Length – is the stretched-out length of the belt.
L = 2C + 1.57 (D + d) + [D – d]^2 / 4C
Belt Length (Crossed Drive) Formula
L = 2C + 1.57 (D + d) + [D + d]^2 / 4C
Belt Length (Quarter Turn Drive Formula
L = 1.57 (D + d) + √(C^2 + D^2) + √(C^2 + d^2)
Length of Arc Formula
Length of Arc – is the length of belt that is linked on pulley or
pulleys.
La = D x A / 115
Arc of Contact of Smaller Pulley
Arc of Contact – is the angle by which the belt is in contact
with the pulley.
Arc = 180 - [ 57.3 ( D – d ) / C ]
Design Power for V-Belt Drive Formula
DP = NPR x SF
V-Belt Power Rating Formula
Power Rating = Table Rating + Additional power for Speed Ratio
V-Belt Corrected Power Rating Formula
Corrected Power Rating= Power Rating x Arc of Contact Factor x Belt Length Correction Factor
Number of V-Belts Formula
Number of Belts = Power Capacity / Corrected Power Rating
What formula is this?
Wb = ( H x S ) / ( K x C )
Width of Flat Belt
What formula is this?
Wp = Wb +Allowance
Width of Pulley
An engine is to be used to drive
a hammer mill to run at 3,000rpm
speed. How would you couple the
hammer mill to the engine?
By connecting the engine to the
mill using belt and pulley drive to
reduce its speed while running the
mill at 3000 rpm.
If two shafts are perpendicular
with each other, what type of drive
system would you recommend?
Flat belt
When one pulley is to be driven
horizontally and the other pulley is
to be driven vertically, what drive
system would you recommend?
Quarter-turn drive
If two parallel flat pulleys are to
be driven in opposite direction,
what drive would you recommend?
Cross drive
Drive used to run perpendicular
shafts.
Drive used to run perpendicular
shafts.
Machine element used to drive
flat belts.
Pulley
Pulley that is used to tighten
the belt of a drive system.
Idler pulley
Flat pulleys are usually
provided with crown to ____.
prevent the belt from slipping
Flat pulleys are crowned by
making the center diameter larger
than the edge diameter by ___.
1/8 in. per foot of the pulley
diameter
If the driver pulley diameter is
increased, the speed of the driven
pulley will ____.
Increase
Commonly used belt drive for
engine-driven multi-pass rice mills.
Flat belt
Type of flat belt that has the advantage of high-tensile strength to hold metal fasteners satisfactorily and has high resistance to deterioration due to moisture.
Reinforced-nylon chord belt
basically consists of an endless chain whose links
engage the teeth of sprocket keyed to the shaft of the driving and the driven mechanisms.
chain drive
used to transmit power and to synchronize
motion or maintain a fixed-speed ratio between rotating shafts and commonly used in the construction of transmission boxes for power and puddling type floating tillers in the Philippines.
chain drive
TRUE/FALSE
The chain drive shaft distances are unrestricted, i.e. the drive is well suited for long and short center distances.
They do not creep or slip but maintain a positive speed ratio
between the driver and the driven shafts.
TRUE
TRUE/FALSE
They are physically not more compact than belt drives and require less accurate alignment of the shaft and the
sprockets. Arc of contact is bigger for chains than for belts.
They are more practical for mild speed.
FALLSE (more compact, more accurate, smaller for chains, low speed)
is one of the oldest styles chains that are still in use today
Detachable Chain
• They are used for slightly higher speed (up to about 450
fpm) and heavier loads.
• They are made of individual cast links having full round
barrel end with offset sidebars.
Pintle Chain
• They are high-speed chains used predominantly for prime
mover power take-off drive.
Inverted-Tooth or Silent Chain
• They are used for manually-controlled or slow-speed drives.
Bead or Slider Chain
a type of roller chain made of basic components called link plates, rollers, bushings and pins. The chain can be either single- or multi-strand and comes in various sizes with different tensile strengths.
Engineering Steel Chain
• This is the most important type for agricultural use. It is
available either single- or multiple-strand type.
• Roller chain composed of roller, links, and pin links,
alternately spaced throughout the length of the chain. The
roller link consists of two sets of rollers and bushing, and
two link plates, and the pin links consists of two pins and
two link plates.
Roller Chain
Types of Sprockets • A - • B - • C - • D -
- A - plain plate
- B - with hub on one side only
- C - with hub on both sides
- D - detachable hub
Materials of Sprockets
• Cast iron – for large sprockets
• Steel - small sprockets
• Stainless steel or bronze – for corrosion resistant
application
• Formica, nylon, and special purpose plastic – for special
condition
• Cast iron – for large sprockets
• Steel - small sprockets
• Stainless steel or bronze – for corrosion resistant
application
• Formica, nylon, and special purpose plastic – for special
condition
It is the distance between adjacent joint members.
Chain Pitch –
It is the diameter of the pitch circle that passes
through the center of the link pins as the chain wrapped on the
sprocket.
Pitch Diameter
TRUE/FALSE
The size of chain-and-sprocket drive is designated as RC
Number. The higher the chain number, the larger is the loading
capacity of the drive.
TRUE
What is this formula?
Nr Tr = Nn Tn
Sprocket Speed
What is this formula?
R = Nr/Nn
Speed Ratio
What is this formula?
V = [ p x T x N] / 376
Chain Velocity
What is this formula?
L = 2 C + [(Tl – Ts)/2] + [(Tl-Ts)/ 4 π^2 C]
Length of Chain
Sprocket Pitch Diameter Formula
PD = P / [ sin (180/T)]
Chain Forces Formula
Cp = 1000 P / V
Design Power = Power to be transmitted x service factor /
Multiple strand factor
Power Rating
Power Rating Required = Design Power x Design Life /
15,000
Power Rating Required
– Oil is supplied periodically with
brush or spout can once every 8 hours of operation.
Manual Lubrication
– Oil drops are directed between the link
plate edges from a drip lubricator.
Drip Lubrication
– The lower strand of chain runs
through a sump of oil in the drive housing
Bath or Disc Lubrication
– The lubricant is usually supplied
by a circulating pump capable of supplying each chain
drive with a continuous stream of oil.
Oil-Stream Lubrication
A drive system consisting of an endless chain whose links engage the teeth of sprocket keyed to the shaft of the driving and of the driven mechanism that is commonly used for power tiller transmission boxes.
By connecting the engine to the
mill using belt and pulley drive to
reduce its speed while running the
mill at 3000 rpm
A drive system consisting of an endless chain whose links engage the teeth of sprocket keyed to the shaft of the driving and of the driven mechanism that is commonly used for power tiller transmission boxes.
Roller chain drive
Chain size is usually specified
in terms of ____.
roller chain number
RC-50 chain is stronger than
____.
RC-40
Minimum size of chain for the
transmission box of a walking-type
hand tractor.
ANSI chain number 50
Length of chains is usually
expressed in ____.
pitches
If roller chain number 40 is to
be replaced with no. 60, the
strength of the chain will ____.
increase
For slow-speed operation, the
recommended number of teeth for
driver sprocket is ____.
16 teeth
Recommended minimum
number of sprocket teeth for highspeed
operation.
18 - 24 teeth
The slack strand for chain with
horizontal center should be located
at the ____.
lower side
Which of the following is not a part of the roller chain construction? a. Rollers b. Pins c. Outside link plates d. Inside link plates e. None of the above
e. None of the above
Connecting link assembly for easy and rapid replacement of parts of chain drive. a. Pin link b. Link plate c. Retainer d. All of the above
All of the above
Profiled wheel with teeth that
meshes with a chain, track or other
perforated or indented material.
Sprocket
Drive in which shafts are
operating on a counterclockwise
direction.
Gears
Gears are used for agricultural
machinery because ____.
they transmit high power and
efficiency and with long service life
Most common type of gear used
in agricultural machinery with
straight and parallel teeth to the
shaft axis.
Spur gear
The projecting part of a gear that
comes in contact with the other
gear resulting in an opposite
direction rotation.
Gear tooth
Spacing of gear teeth which is
measured along the pitch circle.
Circular pitch
Type of gear commonly used for
gear reducers or gear motors.
Worm gear
Type of gear used for powertake-
off drive.
Spline shaft gear
Smallest gear that is meshing
together.
Pinion
Service factors used in calculating the design power for gears include \_\_\_\_. a. type of load b. type of lubrication c. All of the above
All of the above
A gear is rotating at 800 rpm and
is driven by another gear at 400 rpm.
What is the speed ratio of the gear
drives?
2
AGMA stands for ____.
American Gear Manufacturers
Association
Type of gear used to transmit
rotational motion and power between
parallel shafts.
Helical gear
Type of gear used for
intersecting shaft usually at right
angles.
Bevel gear
Type of gear used to transmit
rotational motion and power
between intersecting shafts.
Bevel gear
Type of gear used to connect
an implement shaft to the tractor
PTO shaft.
Spline shaft gear
When buying gear box,
which of the following important
parameters need to be
specified?
Speed ratio & power rating
The larger part of the
meshing gear is called
Gear
The larger part of the
meshing gear is called
pinion gear
Which of the following belongs to parallel shaft gears? a. Spur gears b. Helical gear c. Internal gear d. All of the above e. Two of the above
All of the above
Parallel shaft gears with
straight tooth line.
Spur gear
Parallel shaft gear with
winding tooth line.
Helical gear
Parallel shaft gear that can
transmit high load and higher
speed applications.
Helical gear
A straight rod that mesh with
pinion used to convert rotational
motion to linear motion
Gear Rack
Which of the following belongs to non-parallel shaft gears? a. Bevel gear b. Worm gear c. Miter gear d. All of the above e. None of the above
All of the above
are tooth wheels used to transmit power and motion
at a constant ratio from one rotating shaft to another by
means of a positive contact of successively engaging teeth.
Gears
TRUE/FALSE
Compared with V-belts and chain drives, gear drives are
more compact and can operate at a higher speed. Gear
drive also provides precise timing of motion.
TRUE
TRUE/FALSE
In agricultural machinery, gears are commonly used in
loading drives for tractors, self-propelled combines,
power tiller, and many others.
FALSE (transmission)
refers to the pitch circle or pitch diameter of the
gear.
Gear size
is the height of the gear tooth beyond the pitch
circle.
Addendum
is the depth of the tooth below the pitch circle.
Dedendum
is the spacing of the gear teeth measured
along the pitch circle.
Circular Pitch
is the ratio of the number of teeth to the
pitch diameter in inches.
Diametral Pitch
is the sum of addendum and dedendum
Gear Depth
is equal to the sum
of the addendum.
Work Depth or Depth of Engagement
is equal to the sum
of the addendum.
Work Depth or Depth of Engagement
is the line connecting the center of gear
rotation
Line of Centers
is a curve formed that unwrapped around a
cylinder.
Involute
is a curve generated from the involute
Base Circle
is a line through the point of tangency
and tangent to the base circle.
Pressure Angle
It is the most common type of gear identified as simple, low cost, and easy to maintain. The teeth are straight and parallel to the shaft axis.
Spur Gear
It can carry more load than the equivalent size spur gear. Operates more smoothly and quietly however it is more costly than spur gears.
Helical Gear
It is a quiet and smooth action that provides a maximum reduction ratio for a given center distance used only for speed reduction.
Worm Gear
Cannot back-drive at ratios greater than 20:1.
The contact area is large hence load capacity is high and shafts are almost always at right angles.
Worm gear
This is the simplest type of gear for intersecting shaft.
It is commonly used for shaft intersecting at right angle but
can also be used for shaft mating at any angle.
Straight Bevel Gear
Gears are designed in pairs thus are not always
interchangeable. The supporting shaft and bearings must be rigid to maintain
proper tooth contact.
Straight Bevel Gear
Similar to spiral-bevel gears except that the shafts do not
intersect. Operates more smoothly and more quietly and is
stronger for a given ratio also permits a very high drive ratios and shaft angles usually 90 deg, but other angles are
possible.
Hypoid Gear
Module = Circular Pitch / π
Module = Pitch Diameter / Number of Teeth
Pitch Diameter = Number of Teeth x Module
Number of Teeth = Pitch Diameter / Module
Tooth thickness on the Pitch Line = 1.5708 x Module
Formula for Spur Gear
Outside Diameter = 2 Addendum plus pitch diameter
Addendum = Module
Dedendum = 1.25 x module
Clearance = Whole depth – 2 dedendum
Min Whole Depth = 2.35 x Module
Center Distance = Module (t1 + t2) / 2
Formula for Spur Gear
It is the ratio between the number of teeth of the driver and
the driven gear.
Gear Ratio
What is this formula?
Ft = T / [D/2] or = 19.1 x 10^6 kW / [ D x N ] where: Ft - transmitted load, N D - pitch diameter, mm kW - power, kW N - speed of shaft, rpm
Gear Tooth Load
This is a required power which is a function of the type of
load and of lubrication. Identified as Power to be Transmitted multiply with the Service Factor
Design Power
