Jaw crusher

Jaw Crusher Modified

1. The first stage of size reduction of hard and large lumps of ore is to crush and reduce their size
because of this fact crushers are used for breaking of large pieces of solid materials into small
lumps.
Crushers
Crushers employ compression, slow speed machines hired for coarse reduction of large quantities
of solid. A primary crusher is the one which crushes the feed to yield a product 150-250mm in size
whereas, secondary crusher is the one which takes the product of a primary crusher and reduces it
to particles of about 6mm. The main types of crushers are given as;
 Jaw Crusher
 Smooth Roll Crusher
 Gyratory Crusher
Jaw Crusher
Jaw crusher consist of a set of vertical jaws, one jaw being fixed and the other being moved back
and forth relative to it by a pitman mechanism. The jaws are farther apart at the top than at the
bottom, forming a tapered force so that the material is crushed progressively smaller and smaller
as it travels downward until it is small enough to escape from the bottom opening. The compressive
strength of jaw crushers is 320 mega Pascal and the Rpm of jaw crusher is between 200- 400. The
jaw crusher is used for crushing trash, making it easy for transportation from one to another
location. This is very important because the crushed materials are always easier for transportation,
loading and dumping. This machine is heavily used on construction sites where a large amount of
hard materials need to be crushed on a daily basis, including stones, rocks, concrete, and other
form of debris.

Figure 1 Jaw Crusher
Design of Jaw Crusher
As jaw crusher is designed to impart an impact on the solid particles placed between a fixed and a
moving plate. The faces of the plate is made up of harden steel, both plates could be flat or the
fixed plate and the moving plate convex. The surfaces of both plates could be plain or corrugated.

2. The moving plate applies the force of impact on the particles held again the stationary plate, plates
are bolted on to a heavy block. The moving plate is pivoted at the top end (Blake) or at the bottom
end (Dodge) type crusher. In universal crusher the plates are pivoted in the middle so that both the
top and the bottom ends can be moved.

Figure 2 Jaw Crusher

Mode of Operation
Jaw crusher is equipped with one fixed and one moveable crushing jaw (wear parts) forming a
wedged shaped crushing area. The side walls of crushing area are made of replaceable wearing
sheets. Crushing is carried out between two crushing jaws. The moving jaw of the single toggle
jaw crusher moves elliptically. A pendulum motion is being carried out by double toggle jaw
crusher. The crushing force is produced by an eccentric shaft, then it is transferred to the crushing
area by a toggle plate system and supported by the rear of the housing of the machine. Spring
pulley rods keep the whole system in a condition of non-positive connection. Centrifugal masses
of the eccentric shaft serve as compensation of heavy loads. A flywheel is provided in the form of
pulley. The favorable angle of dip between the crushing jaws has a positive impact on the intake
conditions of the feed material. The final grain size distribution is influenced by both the adjustable
gap as well as the appropriately selected tooth shape of the crushing plates. One important thing
that needs to be closely considered when choosing which jaw crusher to be used, is the size and
the length of the crushing chamber. The crushing chamber should be large enough to allow the
materials to easily enter inside. As a general rule, a jaw crusher with larger crushing chamber has
more crushing power. Long crushing chambers are suitable for hard materials that demand more
strength.
Parts of Jaw Crusher
The parts of a jaw crusher are given as;
 Frame
 Fixed Jaw
 Moveable Jaw
 Flywheel
 Grooved Wheel
 Spring System
 Toggle Plate

3.  Toggle Seat
 Gap
 Size of set
 Crushing cavity
 Pivot
 Check Plates
 Adjusting Screw
Working Principle of Jaw Crusher

Types of Jaw Crusher
Jaw crusher are divided into two types, both uses compressive force for size reduction;
 Blake Jaw Crusher
 Dodge Jaw Crusher


Figure 3 Types of Jaw Crusher
Blake Jaw Crusher
Blake jaw crusher is a type of crusher in which the swing jaw is pivoted at upper position, the
amount of motion is at the bottom which means less choking. Blake jaw crusher has a fixed feed
area and a variable discharge area. Greatest amount of motion is at the bottom of “V” which means
that it have a little tendency to chock. The swinging jaw reciprocates in a horizontal plane usually
make an angle of 20-30° with the fixed jaw.

4. Figure 4 Blake Jaw Crusher
Dodge Jaw Crusher
Dodge jaw crusher is a type of crusher in which the the swing jaw is pivoted at bottom position, it
has a greater tendency to choke. The amount of motion is greatest at the top of “V”. The Dodge
jaw crusher has a variable feed area and a fixed discharge area which leads to choking of the
crusher hence, it is used only for laboratory purposes and not for heavy duty operations.


Figure 5 Dodge Jaw Crusher

Double Toggle Jaw Crusher
Double Toggle Jaw Crusher is preferred for crushing unusually hard, abrasive rocks and other
materials like ferroalloys and glass. In double there is no rotary motion in the crushing cycle and
all crushing is done by compression of the feed material between two massive jaws plates. The
moving jaw compresses the material against the stationary jaw. Jaw plates can be either smooth or
corrugated.

5. Figure 6 Double Toggle Jaw Crusher
Double Toggle Jaw Crusher have one jaw fixed, while the other pivots about a top hinge. There is
no rubbing or grinding. Only compression, which produces a generally cubical product with
minimum fines. The moving jaw is very well balanced, so 95% of the drive motor power is used
for crushing while 5% of the power is needed to move the jaw itself. As a result of this high
mechanical efficiency, double toggle jaw crushers require smaller size motors, keeping power cost
down.
There are several major advantages to this arrangement;

 The horsepower requirement is substantially reduced and only one small diameter flywheel
is used.
 The eccentric, toggle plates, and shaft bearings run in an oil bath and are protected from
dust and other contaminants.
 The tramp-iron release mechanism is mounted on the much smaller flywheel and is easily
reset.
 The swing motion is in a straight line rather than elliptical and the manganese wear plates
last longer.

6. Figure 7 Labelled Diagram of Double Toggled Jaw Crusher

7. Single Toggle Jaw Crusher
In a single toggle jaw crusher a pitman mounted on an eccentric shaft at the top. At the bottom of
the assembly, the pitman is held in position by a toggle plate. The combination of eccentric motion
at the top and rocking motion at the bottom provides a positive downward thrust throughout the
crushing chamber. Single toggle jaw crushers have better feed acceptance capability than the
corresponding double toggle crushers. Jaw crushers are reliable, robust machines, offering a 6:1
reduction ratio in most applications, and will accommodate hard, abrasive materials. Or
The single-toggle crusher is the simplest and the lightest of the jaw crushers but is suitable only
for producing low crushing forces and therefore used for soft rocks.


Figure 8 Single & Double Toggle Jaw Crusher

Jaw Crusher Protection
Jaw crusher can be kept safe by keeping some points in mind;
 Be sure that the crushing chamber is clear.
 Be sure that all guards and other safety devices are correctly installed and tightly secured
before starting the crusher.
 Do not allow personnel to be on or near the crusher during operation. Stay clear of feed
and discharge areas to prevent being injured or killed by flying or falling rock.
 Never attempt to clear jammed material from the crushing chamber while the crusher is
operating.
 Serious injury or death could result if you are pulled into, or fall inside, the crushing
chamber.
 Never attempt to adjust the discharge setting during crusher operation. Always wait until
the crusher is completely stopped before making any adjustments.

8.  Always stop the crusher immediately if any gauges show abnormal readings, or if there is
a sudden obvious change in operation. Be alert for noises that might indicate trouble.
Industrial Application of Jaw Crusher
The industrial applications of Jaw crusher are given as;
 Building stones- water construction- construction industry mobile crushing plant
 Mining industry- coal industry- rotary dryer
 Chemical Industry
 Concrete Recycling
 Jaw Crusher in Quarry
Building stones- water construction- construction industry mobile crushing
plant
Building stones- water construction- construction industry mobile crushing plant.
Since the found of New China, the water conservancy construction develop rapidly, but the water
conservancy project that has been built has much low scale, project quality is poor; jaw crusher
can be used in the process of water infrastructure.
Mining industry- coal industry- rotary dryer
Jaw crusher is the most important mining machinery, the mining of ore production, crushing
equipment and grinding machine are all can’t do without the crusher machine or spiral ore washing
machine. Thus building strong and have competitive machinery industry contributes to China
achieve to modernization, revitalization and development of machinery industrialization and our
country gradually become the economic powers are inseparable.
Chemical Industry
At present our country’s crusher device continuous develops and update, develop the crusher
equipment to meet the needs of different users. Industry crushing equipment can be used in the
cement, chemical, power, metallurgical and other industries to crushing the hard material, such as
limestone, slag, coke, coal and other materials.
Concrete Recycling
Jaw crushers can be used in concrete recycling. Jaws compress the concrete between a stationary
and moveable plate. Concrete is reduced in size as it travels down the length of the wedge between
the two plates. Jaws are used as primary crushers and typically produce a 4" to 8" minus product
usually used as fill.
Jaw Crusher in Quarry
The primary crushing of the stones is normally carried out by the jaw crushers. Jaw crushers are
used on the large scale in this field.

Advantages of Jaw Crusher
The advantages of Jaw crusher are given as;

9. Following are the different advantages of the jaw crushers:

 Simple structure
 Low cost
 Maintenance are convenient
 Reliable work
 Small machine body
 Easy to use


Disadvantages of Jaw Crusher
The disadvantages of Jaw Crusher are given as;
 Lower productivity
 Lower power Consumption
 Bigger vibration
 Small crushing Ratio
 Uneven particle size
 Can’t crowd feeding ore