US2591639A

US2591639A - Jaw type crusher

Info

Publication number: US2591639A
Application number: US20943A
Authority: US
Inventors: Jr Samuel W Traylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-04-14
Filing date: 1948-04-14
Publication date: 1952-04-01
Anticipated expiration: 1969-04-01

Description

S. W. TRAYLOR, JR

April 1, 1952 JAW TYPE CRUSHER 6 Sheets-Sheet 1 Filed April 14, 1948 h U m a April 1, 1952 s. w. TRAYLOR, JR

JAW TYPE CRUSHER 6 Sheets-Sheet 2 Filed April 14, 1943 Iwerfior Same! WTmyIon/k Aprir 1, l 52 S. W. TRAYI OR, JR

JAW TYPE CRUSHER 6 Sheets-Sheet :5

Filed April 14, 1948 m a 3 OI I 5 M m .m@ j s a m April 1, 1952 s. w. TRAYLOR, JR

JAW TYPE CRUSHER 6 Sheets-Sheet 4 Filed April 14, 1948 v V a 4 by his flfiomegs A ril 1, 1952 s. w. TRAYLOR, JR

JAW TYPE CRUSHER 6 Sheets-Sheet 5 Filed April 14, 1948 Z31; 711$ Affamegs April 1, 1952 s. w. TRAYLOR, JR 2,591,539

JAW TYPE CRUSHER Filed April 14. 194.8 6 Sheets-Sheet 6 Patented Apr. 1, 1952 UNITED STATES PATENT OFFICE JAW TYPE CRUSHER Samuel W. Traylor, J r., Alentown, Pa. Application April 14, 1948, Serial No. 20,943

6 Claims.

This invention relates to new and useful improvements in crushers, and more particularly to crushers of the jaw type.

Jaw type crushers generally comprise a relatively fixed jaw and a movable jaw which is actuated toward and away from the fixed jaw to produce a predetermined crushing force on material passing through the crushing chamber between the jaws. For many years prior to the present invention it has been the accepted practice in jaw type crushers to actuate the movable jaw relative to the fixed jaw by means of a toggle or like mechanism. Toggle actuating mechanisms can develop crushing pressures far in excess of the pressures needed for crushing rock or other desired materials and hence crushers employing actuating means of this nature necessarily are required to be constructed to stand up under the maximum crushing pressures developed in the crusher. It follows, therefore, that such machines not only are very heavy, bulky and cumbersome, but likewise are expensive to manufacture. Furthermore, jaw type crushers heretofore available have a characteristic limited discharge area from the crushing chamber between the jaws, and hence the material being crushed usually cannot be reduced to the desired fineness of size in a single crushing operation so that for finer sizes of crushed products the general practice in the art has been to subject the material to multistage crushing operations.

With the foregoing in mind, the principal object of the present invention is to provide a jaw type crusher embodying novel features of construction and operation which eliminate the aforesaid disadvantages of prior jaw'type crushers and provide certain positive structural and operational advantages thereover.

Another object of the present invention is to provide a novel jaw type crusher which employs no toggle or similar actuating mechanism and wherein novel and improved means is provided for effecting actuation of the crushing jaws relative to one another.

Another object of the invention is to provide a jaw type crusher having a novel jaw construction and arrangement which provides a crushing chamber that is operable effectively at lower crushing pressures than prior conventional jaw type crushers due to the substantially larger discharge area provided and the resulting elimination of any tendency for the material to pack in the crusher.

A further object of the invention is to provide a jaw type crusher embodying the structural features and advantages set forth wherein a novel mechanism and arrangement is employed for the relief of the relatively fixed jaw member under excessive crushing pressures and for discharging automatically tramp iron and other uncrushable objects which find their way into the crusher.

Still a further object of the present invention is to provide a jaw type crusher as set forth which embodies a novel crushing chamber having a discharge area several times greater than in prior jaw type crushers of comparable size, whereby a substantially finer setting of the crusher jaws may be obtained and the number of stages or crushing operations required to produce a fine product is substantially reduced.

A still further object of the present invention is -;to provide a novel jaw type crusher embodying the foregoing features and advantages which is of comparatively simplified construction, materially lighter in weight and smaller in bulk, and substantially less expensive to manufacture, than prior conventional jaw type crushers of comparable size. V

These and other objects of the invention and the various features and details of the construction and operation thereof are hereinafter fully set forth, described and claimed with reference to the accompanying drawings, in which:

Fig. l is a side elevational view of a jaw type crusher made according to the present invention;

Fig. 2 is a top plan view of the in Fig. 1;

crusher shown Fig. 3 is an end elevational view (with portions cutaway) as viewed from line 3-3. Fig. 1;

Fig. 4 is an end elevational view taken on line 4-4, Fig. 1;

Fig. 5 is an enlarged vertical sectional view taken longitudinally on line 5-5, Fig. 2;

Fig. 6 is a sectional view taken on line 66, Fig. 5;

Fig. '7 is a sectional view taken on line l'l, Fig. 5;

Fig. 8 is a sectional view taken on line 8-8, Fig. 5;

Fig. 9 is an enlarged sectional view taken on line 9-9, Fig. 1;

Fig. 10 is a detached view in perspective showing the contour and relative arrangement of the crushing surfaces of .the relatively fixed and movable jaw members of the device;

Fig. 11 is a schematic study drawing illustrating certain operating characteristics of the crusher;

Fig. 12 is a sectional view on line i2-l2, Fig. 11; and

Fig. 13 is a side elevational view of a simplified form of jaw crusher embodying important features of the invention.

Referring now more particularly to the drawings, the illustrated embodiment of a jaw type crusher made according to the present invention comprises a main frame generally designated by reference numeral 2 which usually is mounted upon base standards I of concrete or other suitable material. The main fram structure 2 comprises an upper open frame portion 3 of rectangular configuration from opposite sides of which the leg portion 4 depend. As shown, the depending leg portions 4 of the main frame stencture 2 seat upon and are secured to the upper faces of the standards I, and these legs 4 are of the generally triangular shape indicated so as to support the rectangular open frame portion 3 in a position angularly inclined to the horizontal.

Mounted within the rectangular open portion 3 of the main frame 2 for limited pivotal movement with respect thereto under predetermined operating conditions hereinafter set forth, is a sub-frame structure generally designated 5. The sub-frame structure 5 is generally J-shaped in side elevation and includes a sleeve bearing portion 6 which is rotatably mounted upon a supporting shaft 1 that has its opposite end portions tapered and suitably mounted in bushings 8 secured in opposite sides of the portion 3 of the main frame structure 2.

The lower portion of the sub-frame 5 is suspended between the supporting leg portions 4 of the frame structure 2 and between the upper portions of the base I. Formed on opposite sides of the lower central portion of the sub-frame 5 are lugs or abutments which engage against the adjacent faces if of the frame le portions 4 at opposite sides of the crusher. The subframe is heavily unbalanced at the left hand side of the shaft I (Fig. 5) so that it would tend to rotate in the counterclockwise direction about said shaft 1 but for the lugs 10 which predeterminedly position the sub-frame 5 with respect to its supporting frame structure 2 and preclude relative rotation of the sub-frame structure 5 in the counterclockwise direction with respect to said frame structure 2. This is the normal working position of the sub-frame 5 during operation of the crusher. The sub-frame 5 of the crusher constitutes, in effect, the relatively fixed jaw of the device, and to this end a surface of the lower portion of the sub-frame is inclined as indicated at l2 and configurated both longitudinally and transversely to receive the upper jaw crushing plates hereinafter described.

Disposed for cooperation with the relatively fixed jaw just described is a movable jaw generally designated 16 which underlies the fixed jaw, and is configurated both longitudinally and transversely to receive the lower jaw crushing plates which are described in detail hereinafter. The jaw member It has one end thereof pivotally mounted within the rectangular portion 3 of the main frame 2 upon a transversely extending shaft 48 which has its opposite ends mounted in the sides of the said rectangular frame portion 3.

At its other end the movable jaw I6 is provided with relatively laterally spaced outwardly projecting lug portions I9 which engage upon and are secured to support pads or the like 20 having split bearing portions journalled upon the ends of a transversely extending shaft 2|. Also journalled on the shaft 21 intermediate the pads 20 is the radial bearing portion 22 of a crank or pitman 23 which has its main bearing 24 rotationally mounted upon the slightly eccentric central portion 25 of a drive shaft 26. The shaft 26 has its opposite ends rotatably mounted in journals 2'! provided in the rearwardly extending relatively spaced leg portions 28 of the sub-frame structure 5. With this construction and arrangement it will be noted that upon rotation of the shaft 26 the slightly eccentric mid-portion thereof will operate through the crank and pitman 23 to cause the lower jaw Hi to oscillate about its shaft 48 toward and away from the fixed jaw portion of the sub-frame 5. The desired setting or adjustment of the crusher to perform a given crushing operation and also readjustment of the crusher in compensation for wear may be accomplished by inserting between the lugs IQ of the lower jaw l6 and the pads 20 carried by the shaft 2| shims or the like I921. of the required thickness.

In the illustrated embodiment of the invention, one end of the drive shaft 26 extends laterally beyond the adjacent sub-frame leg 28 and has a drive pulley 29 mounted thereon which is driven by a belt 38 from an electric motor 3| that is mounted upon a platform portion 32 of the subframe 5 which lies above its pivot shaft 1. By mounting the drive motor 3| as well as the pulley 29 upon the sub-frame 5 as described, it will be apparent that pivotal movement of the subframe about the shaft 7 can take place, under certain operating conditions hereinafter set forth, without interrupting or interfering in any way with the drive of the eccentric shaft 26. Hence oscillation of the lower jaw 15 can continue regardless of pivotal movement of the sub-frame 5 and the relatively fixed jaw.

A feature of the present invention resides in the construction and arrangement of the crushing plates associated with both the fixed and movable jaws. According to the present invention, each of the fixed and movable jaws comprise complementary primary and secondary crushing surfaces. As shown in Fig. 10 of the drawings, the primary crushing

plates

35 and 36 of the fixed and movable jaws, respectively, reside intermediate oppositely disposed secondary crushing

plates

31 and 38 which extend along opposite sides of the primary crushing plates. In accordance with the present invention the primary crushing

plates

35 and 36 of each jaw gradually decrease in width longitudinally of the jaw from a maximum width at the intake ends of the plates to a minimum width at the discharge ends thereof.

Conversely, the laterally adjacent secondary crushing plates 3'! and 38 of the two jaws gradually increase in width from a minimum at the intake ends of the crushing chamber to a maximum width at the discharge ends thereof. In addition, as shown in Figs. 6 and '7 of the drawings, the primary crushing

plates

35 and 36 of the jaws are relatively flat and at any given point longitudinally thereof are parallel to each other. On the other hand, and as more particularly shown in Figs. 7 and 8 of the drawings, the secondary crushing

plates

31 and 38 of the fixed and movable jaws are angularly disposed so that their crushing surfaces decline laterally from the crushing surfaces of the intermediate primary crushing

plates

35 and 36. Furthermore, as shown in the drawings, the primary crushing plate 35 of the fixed jaw is convex longitudinally in the direction of fiow of material through the crushing chamber so that the spacing between the two primary crushing

plates

35 and 36 diminishes gradually from a maximum at the intake end of the crushing chamber to substantially a minimum at the discharge end thereof. At the intake end, the sides of the crushing chamber are defined by vertical plates 39 secured interiorly of the main frame legs 4.

In the operation of a crusher having fixed and movable jaws constructed and arranged as described, it will be apparent that when material to be crushed first enters the crushing chamber it is subjected to a maximum crushing force provided solely by the primary crushing

plates

35 and 36. Following this initial crushing action produced by the primary crushing plates 35 and 36 a, portion of the material has been crushed sufi'iciently for secondary crushing so that the maximum primary crushing surface area is no longer needed and, as passage of the material progresses longitudinally through the crushing chamber, the need for primary crushing surface area continues to decrease. Thus, as the material travels longitudinally through the crushing chamber, a gradually increasing portion of the material is crushed to sufiicient fineness with the result that it passes laterally outward between the gradually increasing areas of the secondary crushing

plates

31 and 38 from which it is discharged when orushed to the fineness for which the jaws have been set. In this manner and by causing the crushed material to be discharged laterally from between the jaws as passage through the crushing chamber takes place, it will be observed that the crushed material is not retained between the crushing surfaces of the jaws and hence any tendency for the material to pack is substantially eliminated.

According to the present invention, the subframe structure 5 which carries the relatively fixed

jaw plates

35 and 3! is urged or biased to its normal operating position, with the lugs l abutting the supporting legs 4 of the main frame structure 2, by means of a plurality of relatively stiff coil springs 40 which are interposed and reactbetween relatively spaced apart

portions

41 and 42 of the said main frame structure 2 and the subframe 5 respectively. As previously described, during the operation of the crusher the movable jaw I6 is given an oscillatory movement about its shaft l8 by the crank or pitman 23 with the result that the jaw plates 36 and33 carried by the movable jaw are caused to approach toward and retreat from the corresponding crushing

plates

35 and 37 of the relatively fixed jaw carried by the sub-frame structure 5.

With reference to Fig. 11 of the drawings, it is to be noted particularly that the arrangement and spacing of the several pivots or shafts 1, l8 and 26 with respect to one another is such that the leverage from the crank or pitman 23 to the lower jaw pivot I8 is substantially greater than the leverage from the crankshaft 26 to the subframe pivot 1. Accordingly, at the point X which lies directly beneath the axis of shaft 7 and may be termed the neutral point, the crushing force A applied at that point is neutralized by the force B exerted by the crank or pitman 23. Both the force B and the force of the springs 40 act on the relatively fixed jaw and tend to rotate it and the sub-frame 5 about the shaft 1 in the counterclockwise direction, but the lugs l0 which are engaged against the legs 4 of the main frame structure 2 preclude counterclockwise rotation of the sub-frame 5 from its normal working position. On the other hand, the crushing force A, exerted by the movable jaw It tends to rotate the relatively fixed jaw and the sub-frame 5 in the clockwise direction about its shaft 1 against the force of the springs but at the neutral point Xthe moment of force A is equal and opposite to the moment of force B so that no movement of the relatively fixed jaw takes place.

On the other hand, at anypoint below the neutral point X previously described, the moment of the crushing force A will exceed the moment of the crushing force B, with the result that if it were not for the springs 40 the upper jaw and sub-frame structure 5 would be rotated in the clockwise direction. The springs 40 are suificiently strong to maintain the sub-frame 5 in the normal operating position of the upper jaw with the lugs l0 engaged against the legs 4 of the main frame structure 2 so long as rock or other crushable materials pass through the crushing chamber. However, in the event that non-crushable objects such as tramp iron or the like of greater size than the minimum opening between the jaws finds its way between the crushing plates, excessive crushing strains are generated which normally would be transmitted from the lower jaw to the upper jaw and, in accordance with the present invention, these strains are relieved by the yielding of the springs 40 which permit limited clockwise rotation of the upper jaw and the sub-frame 5 about its shaft 1.

In order to facilitate the passage of. noncrushable material between the crushing surfaces, suitable mechanism is provided at opposite sides of the crusher for retarding the return of the sub-frame and upper jaw to the normal working position of the latter. With reference now more particularly to Figs. 1 and 9 of the drawings, rods 42 having eye portions 43 are anchored by means of bolts 44 in a suitable recess 45 provided in the aforesaid stop lugs 10. The rodsliz extend laterally from the stop lugs 10 through openings 46 in the web portions 4a of the main frame legs 4 and endwise into hydraulic cylinders 48. Each of the cylinders 48 is pivotally anchored at its other end by means of a bolt 50 to an upstanding lug portion 5| formed on the base of the main frame legs 4.

, Secured upon the end of each rod 42 within the ell) cylinders 48 is a piston 52 which is slidablydis posed within the chamber of the cylinder.

'As shown in Fig. 9 the pistons 52 are provided with passages 55 therethrough of substantial area arranged laterally adjacent the rods 42.

These openings 55 normally are closed against the passage of oil from one side of the pistons to the other by means of valve rings 56 disposed endwise of the pistons and normally retained in closing relation with respect to the passages 55 by means of coil springs or the like 51 which act between the valve plates 56 and retaining nuts on the extremity of stems 42a. that are secured endwise of the connecting rods 42. The

valve plates 56 are each provided with a bleedv opening 58 disposed in register with one of the relatively large passages 55 and operative to permit oil or other liquid to bleed therethrough from the right hand side of the piston 52 to the left hand side thereof under certain operating conditions of the piston.

The operation of the crusher, in the event that non-crushable objects such as tramp iron or the like finds its way between the crushing plates, is graphically illustrated in Figs. 11 and 12 of the drawings wherein the relative positions of the jaws in the normal operating position of the upper jaw member is shown in solid lines and the relative position of the jaws in the maximum yield position of the upper jaw is shown in broken lines. In this connection it should be noted that in the relieved position of the upper jaw member there occurs a longitudinal shifting of the upper and lower crushing plates with respect to each other as well as a definite retraction or raising of the upper jaw.

Suppose now that a piece of tramp iron finds its way into the chamber, the upper jaw and sub-frame will be actuated in the clockwise direction about the shaft I against the force of the springs in the manner previously described. This upward movement of the subframe 5 causes the rods 42 and pistons 52 to move to the left with respect to Fig. 9 of the drawings within the cylinders 48. If the pistons 52 move to the left, oil or other liquid which is contained in the cylinder chamber is displaced through the large passages 55 with sufiicient force to open the valve plates 56 against their springs 51 and thereby cause a relatively free and rapid fiow of liquid from the left hand side of the pistons 52 to the right hand side thereof. However, when the sub-frame 5 and its relatively fixed jaw are free to be returned by the springs 40 to the normal operating position thereof, movement of the pistons 52 to the right within the cylinders 48 is retarded by the oil therein and, since the valve plates 56 will be moved into closing relation with the large piston passages 55by virtue of the springs 51 and the pressure of the oil in the cylinder, the only passage of oil that can take place from the right hand side of the pistons 52 to the left hand thereof is through the small bleed ports 58 that are provided in the valve plates 56.

From the foregoing it will be apparent that return movement of pistons 52 and rods 42 is materially retarded with the result that the return of the sub-frame 5 and movable jaw to the normal operating position thereof likewise is correspondingly retarded. This delayed return of the fixed jaw to its normal operating position is a particularly important factor in accomplishing the discharge from the crushing chamber of tramp iron or other uncrushable objects which find their way into the crusher. Thus, as the movable jaw member periodically backs away from the normally fixed jaw in the course of its oscillatory movement toward and away from the fixed jaw, it will be apparent that the delayed return of the fixed jaw to its normal operating position after it has been displaced against the force of the springs 40, will provide, intermittently, suflicient additional clearance between the crushing surfaces of the jaws to allow the tramp iron or other uncrushable object to work its way step-bystep laterally outward between the crushing surfaces until ultimately it is discharged.

Operation of the crusher in this manner continues until the tramp iron or other uncrushable object has worked its way laterally outward from between the crushing plates whereupon the springs 40 operate to return the sub-frame structure 5 and upper jaw to the normal working position thereof shown in solid lines in Fig. 11, with the lugs ID of the sub-frame engaged against the legs 4 of the main frame structure 2 as previously described.

A simplified form of jaw crusher embodying important features of the present invention is shown in Fig. 13 of the drawings. In this elementary form of crusher, the upper jaw 60 is fixed to a transversely extending frame structure 6i which is in turn fixedly supported upon a suitable base, standard or the like 62. Disposed for cooperation with the fixed jaw 60 is a movable jaw, generally designated 63, which underlies the fixed jaw.

The movable jaw 63 has one end thereof pivotally mounted intermediate relatively spaced side portions of the frame 6! upon a transversely extending shaft 64 which has its opposite ends mounted in the sides of the said frame, and the other end of the movable jaw 63 is provided with laterally spaced outwardly projecting lug portions which engage upon pads or the like 66 having split bearing portions journaled upon the ends of a transversely extending shaft 61.

Also journaled on the shaft 61 is the radial bearing portion of a crank or pitman 88 which has its main bearing rotationally mounted upon the slightly eccentric portion 69 of a drive shaft 10. The shaft 10 has its opposite ends rotatably mounted in laterally spaced portions of the fixed frame structure 6|. One end of the shaft 10 extends outwardly beyond the frame structure 6! and has a drive pulley H secured thereon which may be rotationally driven in any suitable manner to rotate the shaft it and cause the crank or pitman 88 to oscillate the lower jaw 63 about its shaft 64 toward and away from the fixed jaw portion of the frame.

As in the case of the crusher shown in Figs. 1 to 12, inclusive, each of the fixed and movable jaws 60 and 63, respectively, of the crusher shown in Fig. 13, comprises complementary primary and secondary crushing plates arranged as shown in the drawings and operable in the manner previously described herein. The desired setting or adjustment of the crusher to perform a given crushing operation and also readjustment of the crusher in compensation for Wear may be accomplished by inserting between the lugs 65 of the lower jaw l6 and the pads 86 carried by the shaft 2! shims or the like 650. of the required thickness.

From the foregoing description it will be ap parent that the present invention provides a novel jaw type crusher which embodies novel and improved means for efiecting actuation of the crushing jaws relative to one another. The invention also provides a jaw type crusher having a crushing chamber of novel design that is operable efiectively at relatively low crushing pressures due to the substantially larger discharge area provided and the resulting elimination of any tendency for the material to pack. In addition, the present invention provides a jaw type crusher which embodies an entirely novel and improved construction and arrangement of the crushing surfaces of both the relatively fixed and movable jaws of the device. The invention further provides a jaw type crusher which in one embodiment embodies a novel construction and arrangement of parts for the relief of the relatively fixed jaw member under excessive crushing pressures together with means for re tarding return of the relatively fixed jaw members to its normal working position to effect discharge of tramp iron or other uncrushable objects which find their way into the crusher.

While a particular embodiment of the present invention has been illustrated and described herein it is not intended to limit the invention to such disclosure and it is contemplated that changes and modifications may be made therein and thereto Within the scope of the following claims.

I claim:

1. In a jaw type crusher, a stationary frame structure, a normally fixed jaw mounted in said frame for limited pivotal movement relative thereto, oscillating mechanism comprising an eccentrically driven member carried by said normally fixed jaw and having its axis spaced laterally at one side of the pivotal axis of the normally fixed jaw, a normally movable jaw pivotally mounted in said frame with its pivot axis spaced laterally at the opposite side of the fixed jaw pivot from said eccentric drive member, said normally movable jaw being disposed for cooperation with said fixed jaw and defining therebetween a longitudinally extending crushing chamber between the pivotal axis of said movable jaw and the eccentric drive member, the pivotal axes of said fixed and movable jaws being relatively spaced and arranged with respect to each other and the axis of said .eccentric drive member to provide longitudinally of the crushing chamber in the vertical plane containing the fixed jaw axis a neutral point at which the force moment exerted by the movable jaw drive means about the pivot of the fixed jaw is equal and opposite to the moment of the crushing force exerted upon said fixed jaw by the movable jaw.

2. A jaw type crusher as claimed in claim 1 wherein the pivot axes of the jaws and the axis of the movable jaw drive mean are relatively spaced and arranged with respect to one another so that at any point in the crushing chamber ahead of the neutral point therein the moment of the crushing force exerted upon the fixed jaw by the movable jaw is less than the force moment exerted by the movable jaw drive means about the fixed jaw pivot.

3. A jaw type crusher as claimed in claim 1 wherein the pivot axes of the jaws and the axis of the drive means are relatively spaced and arranged with respect to one another so that at any point in the crushing chamber below of the neutral point therein the moment of the crushing force exerted upon the fixed jaw by the movable jaw is greater than the force moment exerted by the movable jaw drive means about the fixed jaw pivot.

4. In a jaw type crusher, a stationary frame structure, a normally fixed jaw mounted in said frame for limited pivotal movement relative thereto, a normally movable jaw disposed for cooperation with said fixed jaw and pivotally mounted in said frame for movement toward and away from the fixed jaw, spring means tending to pivot said normally fixed jaw toward the movable jaw, intercooperating means on said fixed jaw and frame structure operable to prevent pivotal movement of the fixed jaw toward said movable jaw and thereby predeterminedly position said fixed jaw in normal working position, an eccentric shaft carried by said normally fixed jaw, a drive connection between said eccentric shaft and the movable jaw operable to impart oscillatory movement to the latter and move the same relative to'the fixed jaw, power means for rotationally driving said eccentric shaft also carried by said normally fixed jaw so that limited pivotal movement of the latter does not interfere with operation of the movable jaw, said springs being yieldable under predetermined crushing stresses exerted on the normally fixed jaw to permit limited pivotal movement thereof in the other direction, and piston means operable upon pivotal movement of the normally fixed jaw to retard the return thereof to said normal working position, the pivot axis of said movable jaw being spaced at the opposite side of the fixed jaw pivot from said eccentric shaft and providing longitudinally between said jaws underlying the fixed jaw pivot a neutral point where the force moment exerted by the eccentric shaft and drive connection about the pivot of the normally fixed jaw is equal and opposite to the moment of the crushing force exerted upon said normally fixed jaw by the movable jaw.

5. A jaw type crusher as claimed in claim 4 wherein the pivot axes of the jaws and the axis of the movable jaw drive means are relatively spaced and arranged with respect to one another so that at any point in the crushing chamber ahead of the neutral point therein the moment of the crushing force exerted upon the fixed jaw by the movable jaw is less than the force moment exerted by the movable jaw drive means about the fixed jaw pivot.

6. A jaw type crusher as claimed in claim 4 wherein the pivot axes of the jaws and the axis of the drive means are relatively spaced and arranged with respect to one another so that at any point in the crushing chamber below the neutral point therein the moment of the crushing force exerted upon the fixed jaw by the movable jaw is greater than the force moment exerted by the movable jaw drive means about the fixed jaw pivot.

SAMUEL W. TRAYLOR, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 127,574 Comly June 4, 1872 364,480 Christy et al. June 7, 1887 419,460 Krom Jan. 14, 1890 450,890 Morris Apr. 21, 1891 581,756 Morris May 4, 1897 1,014,532 Stacks Jan. 9, 1912 1,972,930 Green Sept. 11, 1934 2,264,915 Meister Dec. 2, 1941 2,302,723 Symons Nov. 24, 1942