single toggle jaw crusherponents

difference between single & double toggle jaw crusher

difference between single & double toggle jaw crusher

A double toggle jaw crusher is much larger, heavier, more moving parts and lower throughput than modern single toggle jaw crushers. The lower throughput statement is a bit misleading because its partially attributed to the type of bearings they have versus modern crushers, so if one was to upgrade the bearings, throughput could be closer to that of a modern jaw.

Anyway, double toggle jaw crushes are really more about where the eccentric is located than anything. In a double toggle jaw crusher, the eccentric is located behind the swinging jaw. This has two main effects, it keeps the eccentric out of harms way because there is no shock loading from the rock being crushed being transferred to the eccentric shaft and bearings. The other effect is a limited plane of motion for the swinging jaw which contributes to its lack of productivity. The jaw moves like a swinging door that is hinged at the top and is being pushed open and pulled closed at the bottom. One toggle plate goes from the bottom of the eccentric arm to the bottom of the swinging jaw, the other toggle plate goes from the opposite side of the bottom of the eccentric arm to a fixed point at the very back of the jaw crusher frame.

In contrast, the single toggle jaw crusher has fewer shafts and bearings and only one toggle which goes from the bottom of the swinging jaw to a fixed point at the back of the jaw crusher. The eccentric is located at the top of the swinging jaw and is part of the shaft. The advantage of this is that the jaw has two motions that are happening at the same time. It has the same swinging door motion that the double toggle has, but also has the up and down motion from the eccentric.

The advent of curved jaw crusher wearing plates made an approach other than segmental layout analysis desirable for prediction of capacities. For some time it had been known that the drawing board capacities of crushers using these plates had to be considerably modified by complicated experience factors to achieve agreement with results. Because these apparent capacities could be readily increased severalfold by minor crushing chamber shape changes, it was necessary that the utmost precaution be taken in predicting capacities of jaw plates modified for nonchoking, special wear characteristics, or any other reason.

While this paper is concerned principally with standard type single-toggle crusher capacities, the evaluation of data obtained with these machines is simplified by comparative reduction to the 10 x 7 in. Blake-type equivalents upon which the summary of the preceding paper was made. Convertibility of data from one type of crusher to the other also tends towards confirmation of both. The agreement of these data is sufficient to be considered complimentary. Consequently the feed factors, f, previously reported for Blake crushers are slightly adjusted to an average with the single-toggle crusher results.

d is the apparent density of the broken product in pounds per cubic foot. (If the true specific gravity of the feed is known, 40 pct voids may be assumed and d becomes 37.4 times sp gr). w is the width of crushing chamber in inches. y is the open side setting of the crusher, in inches. In the case of corrugated jaw plates it is measured from the tip of one corrugation to the bottom of the valley opposite. t is the length of jaw stroke in inches at the bottom of the crushing chamber. It is the difference between open and close-side settings. n is rpm, or crushing cycles per minute. a is the nip-angle factor.

To bring the Blake and single-toggle type crusher capacity test results to common terms for evaluation, all data are converted to terms of 10 x 7 in. Blake-type performance at conditions of 100 lb per cu ft, 10 in. chamber width, 250 rpm, 0.65 in. stroke, 3-in. open-side setting, and 18 nip-angle. (The nip-angle of the 107 in. Blake is 18 at 3-in. setting.) The single-toggle crusher performances are also divided by the eccentric throw to bring this effect to unity.

In the Blake-type crusher tests, no capacity variation was noted for materials of different crushabilities, even though a wide range of materials was tested. These feeds had impact strengths ranging from 2.8 to 31 ft lb per in. of thickness as measured by the Bond method, (potash, coke, soft hematite, limestones, traprock, taconites.)

Greater differences in crushability-capacity effect than those just discussed for single-toggle type crushers have been reported by investigators working with small Dodge-type crushers. However, these crushers have rubbing motion between the jaws at the discharge, and in addition have very little jaw stroke at the discharge.

analysis of the single toggle jaw crusher force transmission characteristics

analysis of the single toggle jaw crusher force transmission characteristics

Moses Frank Oduori, David Masinde Munyasi, Stephen Mwenje Mutuli, "Analysis of the Single Toggle Jaw Crusher Force Transmission Characteristics", Journal of Engineering, vol. 2016, Article ID 1578342, 9 pages, 2016. https://doi.org/10.1155/2016/1578342

This paper sets out to perform a static force analysis of the single toggle jaw crusher mechanism and to obtain the force transmission characteristics of the mechanism. In order to obtain force transmission metrics that are characteristic of the structure of the mechanism, such influences as friction, dead weight, and inertia are considered to be extraneous and neglected. Equations are obtained by considering the balance of forces at the moving joints and appropriately relating these to the input torque and the output torque. A mechanical advantage, the corresponding transmitted torque, and the variations thereof, during the cycle of motion of the mechanism, are obtained. The mechanical advantage that characterizes the mechanism is calculated as the mean value over the active crushing stroke of the mechanism. The force transmission characteristics can be used as criteria for the comparison of different jaw crusher mechanism designs in order to select the most suitable design for a given application. The equations obtained can also be used in estimating the forces sustained by the components of the mechanism.

The literature on kinematics and mechanism design identifies three tasks for which linkage mechanisms are commonly designed and used, namely, function generation, motion generation, which is also known as rigid body guidance, and path generation [13]. Way back in 1955, Freudenstein, who is widely regarded as the father of modern Kinematics of Mechanisms and Machines, introduced an analytical method for the design of a four-bar planar mechanism for function generation [4]. Wang et al. presented a study on the synthesis of planar linkage mechanisms for rigid body guidance [5]. An interesting design and application of a planar four-bar mechanism for path generation was reported by Soong and Wu [6]. In general, the use of linkage mechanisms involves the transmission and transformation of motions and forces. In practical applications, linkage mechanisms appear to be more commonly designed and used for the transmission and transformation of motions rather than forces. In such cases, the transmitted forces are quite small.

The jaw crusher happens to be an example of a planar linkage application that is designed and used for the transmission and transformation of motions but also has to transmit, transform, and apply the large forces that are required to crush hard rocks by compression. Therefore it is important to understand the force transmission characteristics of the jaw crusher mechanism and to be able to use them for sound mechanical design of the crusher.

Today, the most commonly used types of jaw crusher are the single toggle and the double toggle designs. The original double toggle jaw crusher was designed by Eli Whitney Blake in the USA in 1857 [7]. The motion of the swing jaw in a double toggle crusher is such that it applies an almost purely compressive force upon the material being crushed. This minimizes wear on the crushing surfaces of the jaws and makes the double toggle jaw crusher suitable for crushing highly abrasive and very hard materials. Even today, the Blake design, with some comparatively minor improvements, can still be found in mines and quarries around the world.

The single toggle design, which was developed between the 1920s and the 1950s, is a simpler, lighter crusher [7]. Its swing jaw has a rolling elliptical motion such that it applies a compressive as well as a rubbing force on the material being crushed. This has a force-feeding effect that improves the throughput of the device, but it also tends to cause rapid wear of the crushing surfaces of the jaws. However, the single toggle jaw crusher has a lower installed cost, as compared to the double toggle design. Improvements in materials and design have made the single toggle jaw crusher more common today as the primary crusher in quarrying operations [8]. According to Carter Russell [9], in 1999 sales of the single toggle jaw crusher exceeded those of the double toggle jaw crusher by a factor of at least nine to one.

This paper performs a static force analysis of the single toggle jaw crusher mechanism. As a result of this analysis, a characteristic force transmission ratio, which may be regarded as a mechanical advantage of the mechanism, is derived. This ratio can be used as a criterion for the comparison of different jaw crusher mechanism designs, with a view to selecting the most suitable design for use in a given application.

Over time, several authors have addressed the static force analysis of the double toggle jaw crusher mechanism. Among the earlier of such efforts is that of Ham et al. [10], who performed a static force analysis of the double toggle jaw crusher mechanism in order to determine the input turning moment that would be required to overcome a known crushing resistance of the material being crushed. They used a graphical method to carry out the analysis.

In discussing linkages, Martin [11] featured the double toggle jaw crusher mechanism as an example of a machine that uses the toggle effect to obtain a large output force that acts through a short distance, but he did not perform a static force analysis of the mechanism.

Erdman and Sandor [1] presented the determination of the mechanical advantage of a double toggle jaw crusher mechanism, as an exercise problem to be solved by(1)the method of instant centres, which is essentially a graphical method;(2)an analytical method that utilized complex number representation of vectors.Norton [2] also discussed the mechanical advantage of linkage mechanisms and explained the toggle effect by the use of a jaw crusher mechanism of the Dodge type [8].

More generally, Lin and Chang [12] addressed the issue of force transmissivity in planar linkage mechanisms. They derived and proposed a force transmissivity index (FTI) that considered the power flow path from the input linkage to the output linkage. They calculated the effective force ratio (EFR) as the ratio of the sum of actual power transmitted at each of the linkage joints in the power flow path to the sum of the maximum possible power that could be transmitted along the same power flow path. They then obtained the FTI as the product of the EFR and the mechanical advantage of the mechanism, thus taking into account the effect of the external load acting on the mechanism. They compared their results to other indices of force transmissivity, such as the Jacobian matrix method [13] and the joint force index (JFI) [14], and found their FTI to be more accurate. Furthermore, the Jacobian matrix method does not consider the effect of the external load while the JFI does not consider the power flow path in the mechanism.

The method used by Lin and Chang [12] involves a static force analysis and the determination of velocities at the joints within the power flow path. Subsequently, Chang et al. [15] extended and applied this method to parallel manipulators, defined, and proposed a mean force transmission index (MFTI). The presentation here will perform a static force analysis and obtain the mechanical advantage of the single toggle jaw crusher mechanism, from first principles.

According to Ham et al. [10], analysis of forces in any machine is based on the fundamental principle which states that the system composed of all external forces and all the inertia forces that act upon any given member of the machine is a system that is in equilibrium.

For a planar mechanism, such as the single toggle jaw crusher, it is customary to treat the forces as if they are coplanar, at least in the initial analysis. The effects of the offsets between the planes of action of the forces can then be revisited at a later stage of analysis and design. The assumption of coplanar forces will be employed in this presentation.

In the static force analysis of a machine, the forces arising due to the accelerations of the machine members are neglected. These forces are taken into account in a dynamic force analysis, which can be done, meaningfully, after the forms and masses of the machine members have been determined. Frictional forces may be taken into account in a static force analysis [16], but in the present case, it shall be assumed that the use of antifriction bearings in the revolute joints reduces frictional forces to negligible levels.

Furthermore, this presentation aims to obtain an indicator of the efficacy of force transmission, in the single toggle jaw crusher, that may be attributed to the structure of the mechanism per se. Therefore, frictional and inertia forces may be regarded as extraneous to this purpose and will not be included in this analysis.

In a planar four-bar mechanism with four revolute joints, which can be denoted by or , the efficacy of force transmission has often been expressed by what is known as the transmission angle [2, 3, 11, 17]. This works well enough if, for instance, the mechanism is a crank-and-rocker, in which the crank is the input link and the rocker is the output link. Then, the transmission angle becomes the acute angle between the rocker and the coupler, and, indeed, its value indicates the efficacy of force transmission in the mechanism.

The single toggle jaw crusher mechanism can be modelled as a planar mechanism, as shown in Figure 1. However, in this mechanism, it is the coupler that is the output link and the transmission angle, as defined in the above cited literature, fails to be a suitable indicator of the efficacy of force transmission. Therefore, a better indicator of the efficacy of force transmission in the single toggle jaw crusher is sought in this paper.

Erdman and Sandor [1], Norton [2], and Shigley and Uicker Jr. [3] presented methods for determining the mechanical advantage of planar mechanisms that make the assumption of 100% mechanical efficiency for the mechanism and find the mechanical advantage of the mechanism to be inversely proportional to the output-to-input angular velocity ratio. The presentation by Shigley and Uicker Jr. [3] defined the mechanical advantage as the ratio of the output torque to the input torque, which led to a slightly different expression for the mechanical advantage, as compared to Erdman and Sandor [1] and Norton [2], who defined mechanical advantage as the ratio of output force to input force.

The methods presented by Erdman and Sandor [1], Norton [2], and Shigley and Uicker Jr. [3] give no indication of the actual forces that are sustained by the members of the mechanism, knowledge of which would be necessary at the design stage.

The method used in this paper includes the following:(i)A static force analysis that neglects the frictional and inertia forces is performed.(ii)All the forces and moments are assumed to be coplanar.(iii)The analysis proceeds by considering the equilibrium of the forces acting at the moving joints of the mechanism and relating them to the input torque as well as the load torque. This may be compared to the method presented by Abhary [18].The method used here is systematic and therefore clear and simple to follow and to use. As a result of the analysis, a characteristic mechanical advantage of the single toggle jaw crusher mechanism is obtained, which may be used as a criterion for selecting such mechanisms.

In the kinematical model of the single toggle jaw crusher, which is illustrated in Figure 1, the eccentric shaft is modelled as a short crank, of length , that continuously rotates about a fixed axis, at . The swing jaw is modelled as the coupler link , of length , which moves with a complex planar motion that has both rotational and translational components. The toggle link is modelled as the rocker , which oscillates about the fixed axis at . The fixed jaw is considered to be an integral part of the frame of the machine.

Oduori et al. [19] analysed the kinematics of the single toggle jaw crusher, as modelled in Figure 1, and found the following expression:Cao et al. [20] used the dimensional data for a PE single toggle jaw crusher, as shown in Table 1.

In the cycle of motion of the single toggle jaw crusher mechanism, two phases, known as the toggle phases, are of particular interest. In each of the toggle phases, the crank and the coupler link fall on a single straight line. Therefore, the toggle phases occur when and when . For the first toggle phase, equation (2) can be reduced to the following:Equation (3) is readily solved to give for the first toggle phase.

In performing the static force analysis it shall be assumed that the masses of the links, as well as friction forces, are negligible. The effects of these forces can be considered at a later stage in the design of the mechanism. In Figure 2, is the driving torque, applied at the crank axis , to drive the crank and the entire crusher mechanism. is the torque, acting about the axis of joint , due to the resistance of the feed material against being crushed. , , and are the forces in links 2, 3, and 4, respectively, and they are all assumed to be compressive. The system of forces and moments is assumed to be in equilibrium in every phase of motion of the mechanism.

Let us start by considering the crank. Static force analysis is based on the assumption that there are no accelerations in the mechanism. Referring to Figures 1, 2, and 3, the equilibrium of moments acting on the crank, about the fixed joint , leads to the following result:Next let us consider the coupler. The equilibrium of forces at joint leads to the following:From equations (5) and (6), it follows thatThe statement in equation (7) is illustrated in Figure 4.

Moreover, it should be evident from Figures 3 and 4 thatNow, in Figure 3, by considering the equilibrium of all the forces acting upon the coupler, the following is obtained:Moreover, in Figure 3, the equilibrium of moments acting on the coupler, about the joint , leads to the following result:From equations (9) and (10), it follows thatA relationship between and can now be obtained from equations (7) and (11), as follows:Equation (12) is in dimensionless form. The left-hand side of this equation can be regarded as a force transmission ratio that compares the nominal transmitted force, , to the nominal input force, . This ratio is an indicator of the theoretical force transmission potential for any given phase of motion of the mechanism.

For a given crusher mechanism, the values of and can be determined from purely kinematical considerations, by the use of (1) along with the dimensional data of the mechanism, and then the value of the right-hand side of (12) will be determined.

Using the dimensional data of the mechanism, given in Table 1, along with given values of , the corresponding values of were computed and then used in (12) to determine the corresponding force transmission ratios, for one and a half cycles of motion of the crank. The results are plotted in Figure 5.

The first spike in Figure 5 indicates the great amplification of the crushing force that occurs at the first toggle position, which corresponds to a crank angle of about . Theoretically, the crushing force amplification should be infinite at this toggle phase. Moreover, there occurs an abrupt reversal of the sign of the force transmission ratio from positive to negative, at this toggle phase. The second spike in Figure 5, which is also accompanied by a reversal in the sign of the force transmission ratio, occurs at a crank angle of about . This spike corresponds to the second toggle phase of the mechanism.

The great amplification of transmitted force, accompanied by the abrupt reversal of the sign of the force transmission ratio, at each of the toggle phases, may be compared with the phenomenon of resonance, in mechanical vibrations, which also features great amplification of the responding motion, accompanied by a reversal of the phase between the forcing and the responding functions.

As the crank rotates from to , the crusher would be on the idle stroke with the swing jaw being retracted and no work being done in crushing the feed material. This is evidenced by the negative values of the force transmission ratio, between these two angular positions of the crank, in Figure 5. Useful work is done as the crank rotates from to , in a succeeding cycle of motion of the crank. Thus, during each cycle of motion of the crank, the useful working stroke of the mechanism lasts for about of rotation of the crank, which is very slightly greater than half the cycle of motion of the crank. On the other hand, during each cycle of motion of the crank, the idle stroke lasts for of rotation of the crank, which is very slightly less than half the cycle of motion of the crank.

Thus, the mechanism has a quick return feature that is hardly noticeable since the crushing stroke lasts for 50.37% of the complete cycle of its motion, while the idle stroke lasts for 49.63% of the complete cycle of the motion of the mechanism.

In the preceding section, we have seen that the crushing stroke lasts for only about 50% of each complete cycle of motion of the single toggle jaw crusher. For the other 50% of the complete cycle of motion, the swing jaw is being retracted in preparation for the next crushing stroke.

Moreover, in Figure 5, it can be seen that the force transmission ratio varies from a very high value, at the beginning of the crushing stroke, that initially falls very rapidly and then levels off to reach a minimum value of less that unity (about 0.6), about halfway through the crushing stroke. The latter half of the crushing stroke appears to be a mirror image of the earlier half, in which the force transmission ratio first rises gradually and then spikes to a very high value at the end of the crushing stroke. Sample values of the force transmission ratio during the useful crushing stroke are given in Table 2.

The fact that the crushing stroke commences with a very high value of the force transmission ratio is advantageous when crushing brittle material, which is often the case. Since brittle materials fracture without undergoing significant deformation, actual crushing of brittle materials in a single toggle jaw crusher would occur soon after commencement of the crushing stroke, where the force transmission ratio is high.

According to Chinese jaw crusher manufacturers data [21], the PE 400 by 600 single toggle jaw crusher has 30kW motor power and an input eccentric shaft speed of 275rpm or 28.7979 radians per second. Assuming that the input speed is constant, the input torque is found to be 1.0417kNm. By using this information, along with the data in Table 1 and (12), the transmitted torque, in kilonewton-metres, can be estimated to be the following:The above calculation assumes a 100% power transmission efficiency. Equation (13) was used to calculate the values of the transmitted torque that are given in Table 3.

The above calculations reveal that the minimum value of the transmitted torque will be about 55 times as big as the input torque, with the theoretical maximum value being infinity. This is why a material that cannot be crushed will lead to breakage of the toggle link.

A force transmission ratio that would characterize the single toggle jaw crusher was calculated as the mean value of the force transmission ratio over a complete useful crushing stroke, which does not include the retraction stroke.

According to the Mean Value Theorem of the integral calculus [22], if a function is continuous on the closed interval , then the mean value of for that interval can be determined as follows:In determining the characteristic mechanical advantage, the mean value of the force transmission ratio was determined as follows:The integral in (15) was evaluated numerically by the use of the composite trapezoidal rule [23]. For , taken at one-degree intervals, the integral was evaluated as follows:For , taken as three unequal intervals, the integral was evaluated as follows:In (16) and (17), , for instance, is the value of for the case where . The total integral was then determined as follows:Thus, the characteristic mechanical advantage was determined as follows:From the preceding analysis, the force transmission characteristics for the PE 400 by 600 single toggle jaw crusher mechanism are summed up in Table 4.

The minimum force transmission ratio occurs at about the midpoint of the active crushing stroke, while the maximum force transmission ratio occurs at the end of the active crushing stroke. However, the force transmission ratio at the beginning of the active crushing stroke is also very highabout 74% of the value at the end of the crushing stroke.

Given a number of different mechanism designs, the characteristics given in Table 4 may be calculated for each candidate mechanism and used, among others, as criterion in the selection of a suitable jaw crusher mechanism for a given application.

A static force analysis of the single toggle jaw crusher mechanism was carried out. The method used is systematic, clear, and simple to follow and to use. As a result of the static force analysis, some force transmission characteristics of the single toggle jaw crusher mechanism were obtained. The analysis can also be used to determine the forces that are sustained by each of the components of the single toggle jaw crusher mechanism, provided that the values of the input torque and load torque are known.

An expression for the force transmission ratio of the single toggle jaw crusher mechanism was derived. By using the dimensional data of the PE 400 by 600 jaw crusher, the maximum value of the force transmission ratio was found to be about 3268, the minimum value of the force transmission ratio was found to be about 0.61, and the mean value of the force transmission ratio was found to be about 10.6. These metrics can be used as criteria in the selection of a suitable mechanism design to be used in a given application, out of different alternatives.

The force transmission ratio was found to be very high at the beginning of the active crushing stroke, dropped off rapidly and then levelled off at about the minimum value, remained at the low value for about two-thirds of the active crushing stroke, and then rose rapidly to a very high value at the end of the active crushing stroke. The fact that the force transmission ratio is very high at the beginning of the active stroke is advantageous in crushing brittle materials which fracture without undergoing appreciable deformation.

Copyright 2016 Moses Frank Oduori et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

jaw crusher working principle

jaw crusher working principle

A sectional view of the single-toggle type of jaw crusher is shown below.In one respect, the working principle and application of this machine are similar to all types of rock crushers, the movable jaw has its maximum movement at the top of the crushing chamber, and minimum movement at the discharge point. The motion is, however, a more complex one than the Dodge motion, being the resultant of the circular motion of the eccentric shaft at the top of the swing jaw. combined with the rocking action of the inclined toggle plate at the bottom of this jaw. The motion at the receiving opening is elliptical; at the discharge opening, it is a thin crescent, whose chord is inclined upwardly toward the stationary jaw. Thus, at all points in the crushing chamber, the motion has both, vertical and horizontal, components.

It will be noted that the motion is a rocking one. When the swing jaw is rising, it is opening, at the top, during the first half of the stroke, and closing during the second half, whereas the bottom of the jaw is closing during the entire up-stroke. A reversal of this motion occurs during the downstroke of the eccentric.

The horizontal component of motion (throw) at the discharge point of the single-toggle jaw crusher is greater than the throw of the Dodge crusher at that point; in fact, it is about three-fourths that of Blake machines of similar short-side receiving-opening dimensions. The combination of favorable crushing angle, and nonchoking jaw plates, used in this machine, promotes a much freer action through the choke zone than that in the Dodge crusher. Capacities compare very favorably with comparable sizes of the Blake machine with non-choking plates, and permissible discharge settings are finer. A table of ratings is given.

The single-toggle type jaw crusher has been developed extensively. Because of its simplicity, lightweight, moderate cost, and good capacity, it has found quite a wide field of application in portable crushing rigs. It also fits into the small, single-stage mining operation much better than the slower Dodge type. Some years since this type was developed with very wide openings for reduction crushing applications, but it was not able to seriously challenge the gyratory in this field, especially when the high-speed modern versions of the latter type were introduced.

Due to the pronounced vertical components of motion in the single-toggle machine, it is obvious that a wiping action takes place during the closing strokes; either, the swing jaw must slip on the material, or the material must slip along the stationary jaw. It is inevitable that such action should result in accelerated wear of the jaw plates; consequently, the single-toggle crusher is not an economical machine for reducing highly abrasive, or very hard, tough rock. Moreover, the large motion at the receiving opening greatly accentuates shocks incidental to handling the latter class of material, and the full impact of these shocks must be absorbed by the bearings in the top of the swing jaw.

The single-toggle machine, like the Dodge type, is capable of making a high ratio-of-reduction, a faculty which enables it to perform a single-stage reduction of hand-loaded, mine run ore to a suitable ball mill, or rod mill, feed.

Within the limits of its capacity, and size of receiving openings, it is admirably suited for such operations. Small gravel plant operations are also suited to this type of crusher, although it should not be used where the gravel deposit contains extremely hard boulders. The crusher is easy to adjust, and, in common with most machines of the jaw type, is a simple crusher to maintain.

As rock particles are compressed between the inclined faces of the mantle and concaves there is a tendency for them to slip upward. Slippage occurs in all crushers, even in ideal conditions. Only the particles weight and the friction between it and the crusher surfaces counteract this tendency. In particular, very hard rock tends to slip upward rather than break. Choke feeding this kind of material can overload the motor, leaving no option but to regulate the feed. Smaller particles, which weigh less, and harder particles, which are more resistant to breakage, will tend to slip more. Anything that reduces friction, such as spray water or feed moisture, will promote slippage.

Leading is a technique for measuring the gap between fixed and moveable jaws. The procedure is performed while the crusher is running empty. A lead plug is lowered on a lanyard to the choke point, then removed and measured to find out how much thickness remains after the crusher has compressed it. This measures the closed side setting. The open side setting is equal to this measurement plus the throw of the mantle. The minimum safe closed side setting depends on:

Blake (Double Toggle) Originally the standard jaw crusher used for primary and secondary crushing of hard, tough abrasive rocks. Also for sticky feeds. Relatively coarse slabby product, with minimum fines.

Overhead Pivot (Double Toggle) Similar applications to Blake. Overhead pivot; reduces rubbing on crusher faces, reduces choking, allows higher speeds and therefore higher capacities. Energy efficiency higher because jaw and charge not lifted during cycle.

Overhead Eccentric (Single Toggle) Originally restricted to sampler sizes by structural limitations. Now in the same size of Blake which it has tended to supersede, because overhead eccentric encourages feed and discharge, allowing higher speeds and capacity, but with higher wear and more attrition breakage and slightly lower energy efficiency. In addition as compared to an equivalent double toggle, they are cheaper and take up less floor space.

Since the jaw crusher was pioneered by Eli Whitney Blake in the 2nd quarter of the 1800s, many have twisted the Patent and come up with other types of jaw crushers in hopes of crushing rocks and stones more effectively. Those other types of jaw crusher inventors having given birth to 3 groups:

Heavy-duty crushing applications of hard-to-break, high Work Index rocks do prefer double-toggle jaw crushers as they are heavier in fabrication. A double-toggle jaw crusher outweighs the single-toggle by a factor of 2X and well as costs more in capital for the same duty. To perform its trade-off evaluation, the engineering and design firm will analyze technical factors such as:

1. Proper selection of the jaws. 2. Proper feed gradation. 3. Controlled feed rate. 4. Sufficient feeder capacity and width. 5. Adequate crusher discharge area. 6. Discharge conveyor sized to convey maximum crusher capacity.

Although the image below is of a single-toggle, it illustrates the shims used to make minor setting changes are made to the crusher by adding or removing them in the small space between the crushers mainframe and the rea toggle block.

The jaw crusher discharge opening is the distance from the valley between corrugations on one jaw to the top of the mating corrugation on the other jaw. The crusher discharge opening governs the size of finished material produced by the crusher.

Crusher must be adjusted when empty and stopped. Never close crusher discharge opening to less than minimum opening. Closing crusher opening to less than recommended will reduce the capacity of crusher and cause premature failure of shaft and bearing assembly.

To compensate for wear on toggle plate, toggle seat, pitman toggle seat, and jaws additional shims must be inserted to maintain the same crusher opening. The setting adjustment system is designed to compensate for jaw plate wear and to change the CSS (closed side setting) of the jaw crusher. The setting adjustment system is built into the back frame end.

Here also the toggle is kept in place by a compression spring. Large CSS adjustments are made to the jaw crusher by modifying the length of the toggle. Again, shims allow for minor gap adjustments as they are inserted between the mainframe and the toggle block.

is done considering the maximum rock-lump or large stone expected to be crushed and also includes the TPH tonnage rate needing to be crushed. In sizing, we not that jaw crushers will only have around 75% availability and extra sizing should permit this downtime.

As a rule, the maximum stone-lump dimension need not exceed 80% of the jaw crushers gape. For intense, a 59 x 79 machine should not see rocks larger than 80 x 59/100 = 47 or 1.2 meters across. Miners being miners, it is a certainty during day-to-day operation, the crusher will see oversized ore but is should be fine and pass-thru if no bridging takes place.

It will be seen that the pitman (226) is suspended from an eccentric on the flywheel shaft and consequently moves up and down as the latter revolves, forcing the toggle plates outwards at each revolution. The seating (234) of the rear toggle plate (239) is fixed to the crusher frame; the bottom of the swing jaw (214) is therefore pushed forward each time the pitman rises, a tension rod (245) fitted with a spring (247) being used to bring it back as the pitman falls. Thus at each revolution of the flywheel the movable jaw crushes any lump of ore once against the stationary jaw (212) allowing it to fall as it swings back on the return half-stroke until eventually the pieces have been broken small enough to drop out. It follows that the size to which the ore is crushed.

The jaw crusher is not so efficient a machine as the gyratory crusher described in the next paragraph, the chief reason for this being that its crushing action is confined to the forward stroke of the jaw only, whereas the gyratory crusher does useful work during the whole of its revolution. In addition, the jaw crusher cannot be choke-fed, as can the other machine, with the result that it is difficult to keep it working at its full capacity that is, at maximum efficiency.

Tables 5 and 6 give particulars of different sizes of jaw crushers. The capacity figures are based on ore weighing 100 lb. per cubic foot; for a heavier ore, the figures should be increased in direct proportion to its weight in pounds per cubic foot.

The JAW crusher and the GYRATORY crusher have similarities that put them into the same class of crusher. They both have the same crushing speed, 100 to 200 R.P.M. They both break the ore by compression force. And lastly, they both are able to crush the same size of ore.

In spite of their similarities, each crusher design has its own limitations and advantages that differ from the other one. A Gyratory crusher can be fed from two sides and is able to handle ore that tends to slab. Its design allows a higher-speed motor with a higher reduction ratio between the motor and the crushing surface. This means a dollar saving in energy costs.

A Jaw crusher on the other hand requires an Ely wheel to store energy. The box frame construction of this type of crusher also allows it to handle tougher ore. This design restricts the feeding of the crusher to one side only.

The ore enters from the top and the swing jaw squeezes it against the stationary jaw until it breaks. The broken ore then falls through the crusher to be taken away by a conveyor that is under the crusher.Although the jaws do the work, the real heart of this crusher is the TOGGLE PLATES, the PITMAN, and the PLY WHEEL.

These jaw crushers are ideal forsmall properties and they are of the high capacity forced feed design.On this first Forced Feed Jaw Crusher, the mainframe and bumper are cast of special alloy iron and the initial cost is low. The frame is ribbed both vertically and horizontally to give maximum strength with minimum weight. The bumper is ruggedly constructed to withstand tremendous shock loads. Steel bumper can be furnished if desired. The side bearings are bronze; the bumper bearings are of the antifriction type.

This bearing arrangement adds both strength and ease of movement. The jaw plates and cheek plates are reversible and are of the best-grade manganese steel. The jaw opening is controlled by the position of an adjustable wedge block. The crusher is usually driven by a V-to-V belt drive, but it can be arranged for either V-to-flat or fiat belt drive. The 8x10 size utilizes a split frame and maybe packed for muleback transportation. Cast steel frames can be furnished to obtain maximum durability.

This second type of forced feed rock crusher is similar in design to the Type H listed above except for having a frame and bumper made of cast steel. This steel construction makes the unit lighter per unit of size and adds considerable strength. The bearings are all of the special design; they are bronze and will stand continuous service without any danger of failure. The jaw and cheek plates are manganese steel; and are completely reversible, thus adding to their wearing life. The jaw opening is controlled by the position of an adjustable wedge block. The crushers are usually driven by V-to-V but can be arranged for V-to-flat and belt drive. The 5x6 size and the 8x10 size can be made with sectionalized frame for muleback transportation. This crusher is ideal for strenuous conditions. Consider a multi jaw crusher.

Some jaw crushers are on-floor, some aboveground, and others underground. This in many countries, and crushing many kinds of ore. The Traylor Bulldog Jaw crusher has enjoyed world wide esteem as a hard-working, profit-producing, full-proof, and trouble-free breaker since the day of its introduction, nearly twenty years ago. To be modern and get the most out of your crushing dollars, youll need the Building breaker. Wed value the privilege of telling you why by letter, through our bulletins, or in person. Write us now today -for a Blake crusher with curved jaw plates that crush finer and step up production.

When a machine has such a reputation for excellence that buyers have confidence in its ability to justify its purchase, IT MUST BE GOOD! Take the Type G Traylor Jaw Crusher, for instance. The engineers and operators of many great mining companies know from satisfying experience that this machine delivers a full measure of service and yields extra profits. So they specify it in full confidence and the purchase is made without the usual reluctance to lay out good money for a new machine.

The success of the Type G Traylor Jaw Crusheris due to several characteristics. It is (1) STRONG almost to superfluity, being built of steel throughout; it is (2) FOOL-PROOF, being provided with our patented Safety Device which prevents breakage due to tramp iron or other causes of jamming; it is (3) ECONOMICAL to operate and maintain, being fitted with our well-known patented Bulldog Pitman and Toggle System, which saves power and wear by minimizing frictionpower that is employed to deliver increased production; it is (4) CONVENIENT to transport and erect in crowded or not easily accessible locations because it is sectionalized to meet highly restrictive conditions.

Whenever mining men need a crusher that is thoroughly reliable and big producer (which is of all time) they almost invariably think first of a Traylor Type G Jaw Crusher. By experience, they know that this machine has built into it the four essentials to satisfaction and profit- strength, foolproofness, economy, and convenience.

Maximum STRENGTH lies in the liberal design and the steel of which crushers parts are made-cast steel frame, Swing Jaw, Pitman Cap and Toggles, steel Shafts and Pitman rods and manganese steel Jaw Plates and Cheek Plates. FOOLPROOFNESS is provided by our patented and time-tested safety Device which prevents breakage due to packing or tramp iron. ECONOMY is assured by our well-known Bulldog Pitman and Toggle System, which saves power and wear by minimizing friction, the power that is used to deliver greater productivity. CONVENIENCE in transportation and erection in crowded or not easily accessible locations is planned for in advance by sectionalisation to meet any restrictive conditions.

Many of the worlds greatest mining companies have standardized upon the Traylor Type G Jaw Crusher. Most of them have reordered, some of them several times. What this crusher is doing for them in the way of earning extra dollars through increased production and lowered costs, it will do for you! Investigate it closely. The more closely you do, the better youll like it.

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