US3021022A

US3021022A - Material handling machine

Info

Publication number: US3021022A
Application number: US66882A
Authority: US
Inventors: Daniel M Schwartz
Original assignee: Eimco Corp
Current assignee: Eimco Corp
Priority date: 1960-11-02
Filing date: 1960-11-02
Publication date: 1962-02-13
Anticipated expiration: 1979-02-13

Description

Feb. 13, 1962 D. M. scHwAR-rz 3,021,022

MATERIAL HANDLING MACHINE Filed Nov. 2, 1960 6 Sheets-Sheet 1 INVENTOR DAN/EL M SCHWARTZ ATTORNEY Feb. 13, 1962 D. M. SCHWARTZ 3,021,022

MATERIAL HANDLING MACHINE Filed Nov. 2, 1960 6 Sheets-Sheet 2 1N VENTOR DAN/El. M. SCHWARTZ.

BY www. M

ATTORNEY Feb. 13, 1962 D` M. SCHWARTZ 3,021,022

MATERIAL HANDLING MACHINE Filed Nov. 2. 1960 e sheets-sheet s INVENTOR DAN/El. M. SCHWARTZ ATTORNEY Feb. 13, 1962 D. M. scHwAR-rz 3,021,022

MATERIAL HANDLING MACHINE Filed Nov. 2, 19Go e sheets-sheet 4 O INVENTOR DANIEL M. SCHWARTZ ATTORNEYS.

Feb. 13, 1962 D. M. SCHWARTZ 3,021,022

MATERIAL HANDLING MACHINE Filed Nov. 2, 1960 6 Sheets-Sheet 5 HomzoNTAl.

INVENTOR Y" DANIEL M. SCHWARTZ ATTORNEYS D. M. SCHWARTZ MATERIAL HANDLING MACHINE 6 Sheets-Sheet 6 Filed Nov. 2, 1960 INVENTOR- Daniel M. schwanz BY 5M #WJ/. JW

ATTORNEYS 3,921,022 Patented Feb. 13, 1962 tic 3,021,022 MATERIAL HANDUNG MACHINE Daniel M. Schwartz, Sait isake City, Utah, assigner to The Eirnco Corporation, Salt Lake City, Utah, a corporation of Deiaware Filed Nov. 2, 196i), Ser. No. 66,852 4 Claims. (Cl. 214-131) This invention relates to a material handling structure for an overhead material handling machine and in particular to material handling structures wherein a bucket or other material handling device is attached to paired rocker arms adapted for rolling engagement on rails carried by a mobile or immobile material handling machine.

Material handling machines of the overhead rocker bucket type generally include a vehicle mounted for travel on rails or upon individual crawler tracks. The bed of the machine is provided with paired rails upon which rocker arms having curved surfaces are adapted to roll. To the rocker arm-s is secured a material handling device such as a muck bucket and the rocker arms are connected by flexible draft means to a pulling device such as a motor driven pulley whereby upon rotation of the pulley the rocker arms are caused to traverse the paired rails carried upon the main frame of the machine to actuate the shovel bucket from a low forward digging position to a rearward elevated dumping position.

It is a principal object of the present invention to provide novel rocker arms tor such a machine wherein the rocker arms are shaped to provide maximum discharge of the mucked material from the bucket into a truck or car positioned behind the loader.

A further object of the present invention is to provide rocker arms having substantially improved material discharge along with good roll back characteristics whereby the rocker arms and attached bucket will return to the digging position by gravity without the application of a positive power return system.

A further object is to provide improved rocker arms wherein sliding movement between the bumper pistons and bumper plate means may be maintained effectively low.

These and other objects and advantages Vare provided by the material handling structure of the present invention for an overhead material handling machine for use on horizontal or incline surfaces which generally comprises paired rocker arms, a shovel bucket supported by and extending from said rocker arms, cooperating bumper means on the rocker arms and the material handling machine, said rocker arms having curved surfaces adapted for rolling engagement with trackways on the material handling machine from a low forward material digging position to an elevated rearward material discharge position of the bucket to provide a diggingdischarge cycle,

a portion of said curved surfaces of said rocker arms being i shaped to bring the trace of the geometrical center of the t bucket through a substantially rectilinear path generally parallel to the ground and normal to the line connecting said geometrical center and the point of instantaneous rolling contact between the curved surface and the trackways when the rocker arms are adjacent the point of initial contact between the cooperating bumper means to provide maximum discharge rearwardly of the machine of the mucked material from the bucket.

The invention will be more particularly described with reference to the acompanying drawings wherein:

FIG. l is an elevational view in partial section oi a material handling machine incorporating the new and im l proved rocker arms of the invention;

FIG. 2 is a diagram-matic view of a variable torque shovel bucket at the low forward digging position and at its most rearward elevated discharge position;

FIG, 3 is a diagrammatic view of one of the rocker arms shown in FlG. l at the point of contact of its bumper piston with the bumper stop;

FIG. 4 is a diagrammatic view similar to that shown in FIG. 3 with the bumper piston in the compressed position;

FIG. 5 is a diagrammatic view of a rocker arm similar to that shown in FIG. 3 with a portion of the curved surface thereof modified to provide yminimum piston wipe;

FIG. 6 is a diagrammatic view of one of a pair of arms of a modified form of the rocker arm structure of the present invention adapted for use in loading on inclines; and

FIG. 7 is a diagrammatic View illustrating a method of locating the center of gravity ofthe load of a fully loaded bucket.

Referring to the drawings and in particular to FIGS. l through 4, the material handling machine 10 for use on generally level ground comprises a main frame or body l2 mounted on crawler or endless track units 14 driven by a motor i6 through a suitable gear train, not shown in the drawings.

The main frame l2 carries the material handling overhead bucket assembly l. The superstructure of the material handling machine includes side frames 20 secured to the main frame 12 and a bumper bar on plate 22 which extends between the side frames 2t) at the rearward end of the machine.

Secured to the main frame 12 along the longitudinal sides thereof is a pair of tracks or rails 24, only one of which is shown .in the drawings. Each of the pair of parallel rails 24 provides a trackway for its rocker arm 26. Each of the rocker arms 26 has a curved surface 28 for rolling engagement with its trackway 24.

Each of the rocker arms 26 is also provided, in the Wide section thereof, with a spring loaded bumper assembly 30 which includes a bumper cylinder 32 and a bumper piston 34. The extended ends 34 of the pistons 34 are adapted to contact the bumper plate 22 of the loader at the beginning of the discharge portion of the digging-discharge cycle of the machine, and the high discharge momentum of the rocker arms and the rocker bucket is absorbed as the pistons 34 are telescoped into their cylinders 32 against the tension of internal springs maintained `is secured to a reel 42 driven through a suitable gear train and motor arrangement, and the cable 4G passes over anv idler pulley tf-i during a substantial portion of the travel of the curved rocker surfaces 28 or the rocker arms 26.

ln operation of overhead rocker arm type material handling machines the material handling bucket 36 is loaded from a muck pile or the like when the bucket is in the low forward position as shown in FlG. 1 of the drawings. The loading is accomplished by forcing the bucket into the muck pile by application of power to the crawler tracks le while at the same time the bucket reel 42 is rotated to reel in the ilexible draft means 40 which causes the rocker arms to begin the digging portion of the digging-discharge cycle. As the bucket is lifted through the muck pile the bucket 36 is filled and continued application of power to the reel 42 raises the bucket substantially as shown in' dotted lines at H. Upon continued application of power to the reel the raised'bucket is transported to thevrear vof the machine E as the rocker arms continue to roll on the trackways 24.-. Adjacent the rearwardmost portion of the rocker arms and bucket travel the extended ends of the pistons 34 contact the bumper plate 22 to begin the discharge portion of the digging-discharge cycle.

As soon as the extended ends 3-5 of the pistons 34 strike the bumper plate 22 the speed of the rocker arms rearward movement is progressively decreased and the tremendous discharge momentum of the rocker arms, and the bucket is absorbed through the long stroke of the pistons. During this portion of the digging-discharge cycle it is desirable to obtain maximum throw of the material contained in the bucket to insure that the mucked material is deposited in a waiting vehicle positioned at the rearward end of the material handling machine.

It has been found that the maximum discharge distance of the mucked material is obtained, for a predetermined discharge speed when the loader is operating on generally level ground, if the mucked material is discharged from the bucket when the center of mass of the mucked material therein is at least instantaneously travelling in a substantially straight horizontal path when the extended ends 34' of the pistons strike the bumper plate 22 and the velocity of the rocker arms and the attached bucket is decelcrated. The trajectory of the bucket load is primarily determined at this point as the material in the bucket disengages itself from the bucket and continues at substantially its original high velocity even though the bucket itself is decelerated and finally brought to a stop at the end of the stroke of the pistons 34.

As to be more fully described hereinafter, where the material handling machine is operating on inclined ground, the discharge path of the center of mass of the mucked material would also be parallel with the surface of the ground to obtain maixmum discharge.

On prior art machines it was the common practice to increase the discharge velocity of the bucket and its load during discharge by sharply rotating the rocker arms in a downward direction. While this downward movement increased the velocity of discharge the trajectory of the bucket load has been found to be shorter than for discharge parallel to the ground and cars and trucks placed behind the machine could not be loaded as full.

Referring particularly to FIG. 2 of the application drawings, there is shown a diagrammatic View of one of a pair of the rocker arm structures of the invention wherein the supporting tracks are parallel to the base level of the machine. ri`he curved surface 28 of the illustrated rocker arm has rolling Contact with its track 24, shown diagrammatically as line x-y. For the purposes of this example, curved surface 23 comprises two separate curved portions A-B and B-C The curved portion A-B may comprise a single arc or a plurality of arcuate portions to provide low speed high torque conditions at the beginning of the digging portion of the diggingdischarge cycle and relatively high speed during the transport portion of the digging-discharge cycle after the bucket has been elevated out of the muck pile and the torque demands of the loader are reduced. The curvilinear portion A-B of the curved surface 28 contacts the rolling path along the rail line .r--y between points A', B. The second portion B-C of the curvilinear surface 2S contacts the rail line x-y between points B', C while the trace of the path of the center of mass E of the bucket load moves between points F and G. At the instantaneous point B-B of rolling contact between the curved surface of the rocker arm and its rail the extended end 34' of the piston is almost in contact with the bumper plate 22. In order to insure that the instantaneous path of the center of gravity E of the bucket mass is horizontal and parallel to the ground during discharge, it is essential that the trace of the path of the center of mass of the bucket load is tangent to curve DMF from point F to the point where the bucket and rocker arm has decelcrated and the material in the bucket is disengaged from the bucket. 'Ihc length of this path would depend upon the mass of the individual particles comprising the bucket load and the rate at which the bumper piston decelerates the rocker arm and bucket. ln FIG. 2 of the drawings, the path of the trace of the center of mass of the bucket load is illustrated as being horizontal and parallel to the ground from point F throughout the entire movement of the illustrated piston 34. Thus this portion B-C of the curvilinear surface 28 is an are about the center of gravity of the bucket load whereby the point E travels on a horizontal path parallel with the line x--y as indicated at F-G in FIG. 2.

The larger radius of curvature of the portion B-C of the illustrated rocker arm also insures that the center of gravity of the rocker arm and the bucket generally indicated at O is maintained forward of the point ol instantaneous contact of the curvilinear surface 28 with its rail 24 whereby the rocker arm and bucket will automatically return to the low forward digging position after the material in the bucket has been discharged.

The length of the arc B-C which provides a horizontal trace of the center of gravity of the bucket mass may be varied substantially and still provide the novel eects of the invention. However, it has been found that very satisfactory operation is provided when the length of the arc B-C is such that at the time the point B of the arc engages in rolling contact with its rail 24 the face 34 of the shock absorbing piston 34 is about to contact the bumper plate 22 whereby throughout the entire deceleration of the bucket and rocker arm, when the material loaded in the bucket is being thrown therefrom the center of gravity of the bucket load is travelling in a horizontal path.

Referring particularly to FIGS. 3 and 4 of the drawings, a further advantage in providing the substantially large radius of curvature B-C on the rocker arms is that the angular change a of the extended face 34 of each bumper 34 relative to the bumper plate 22 is effectively reduced. Angle a is the angular change between the line J-K, the center line of the illustrated piston 3ft at the point the piston strikes the bumper plate 22 and line I-L, the center line of the piston, when the piston is fully compressed. `Reducing the angular change a reduces the amount of piston wipe of the spring pressed bumper pistons 34 against the face of the bumper plate 22 thus decreasing the wear on these parts. The most effective reduction in piston wipe is brought about when the portion of the curved surface of each rocker arm having rolling contact with its rail throughout the piston stroke is a circular are about the center point K of its piston. Under these conditions, the piston faces 34 merely pivot about points on the bumper plate Z2 eliminating substantially all piston wipe.

In FIG. 3 it is shown that a portion of each curved surface 2S comprises two arcs; one of the arcs B, D" has a radius R about the point E, the center of mass of the bucket load; and the other arc D", C has a radius of curvature R2 about the point S in the area of contact between the cooperating bumper means when the rocker arm is at the most rearward position. With this form of construction, the piston wipe comprises the angle a, the angular change between the line I-K, the center line of the illustrated piston 34 at the point the piston strikes the bumper plate 22 and the line J-L, FIG. 4, the center line of the piston when the piston is fully compressed.

Referring to FIG. 5, a further form of rocker arm construction for use on generally level ground is illustrated. For the purposes of this example, the curved surface 28 of the illustrated arm comprises three separate curved portions L-M, M--N and N O, which have rolling contact with its track diagrammatically illustrated as line X-Y. Each curved portion L M may comprise a -single arc or a plurality of arcuate portions to provide spannen low speed high torque conditions at the beginning of the digging portion of the digging-discharge cycle and relatively high speed during the transport portion of the digging-discharge cycle after the bucket has been elevated out of the muck pile and the torque demands ofthe loader are reduced. The curvilinear portion M-N of the curved surface 28 contacts the rolling path along its rail line X-Y between points LM. The second portion M-N of the curvilinear surface 28 of each arm contacts its rail line XY' between points M-N. The radius of curvature of each curvilinear surface M-N is struck about the point E', the center of mass of the bucket load for the bucket 36. At the instantaneous points M of rolling contact between the curved surfaces of the rocker arms and their rails, the extended ends 34 of the pistons are almost in contact with the bumper plate 22. In order to insure that the instantaneous path of the center of gravity E of the bucket load is horizontal during discharge, each arc about point E continues to the instantaneous point N of rolling contact between the curved surface of each rocker arm and its rail.

The third portion of each curved surface 2S' comprises the arc N-O and has a radius of curvature R3 on line ll-Kl about the point K", the center point of its piston at the time the piston face 34 contacts the bumper plate 22', substantially eliminating all piston wipe.

From the foregoing discussion of the principles of the present invention, it will be appreciated by those skilled in the art that the shape of the rocker arms will vary with buckets of differing shape and capacityas the curvilinear portions B--C of the curve surfaces 28 of the arms are determined by the point of the center of mass of the load of the bucket under normal operating conditions. It will further be appreciated that on overhead material handling machines adapted for slope loading special slope loading rocker structures would be employed.

In FIG. 6 of the drawings a special slope loading rocker arm structure 50 is illustrated. A pair of rocker arms Sti, each of which has a curved surface 52, support at the opposite end from the curved surfaces a shovel bucket generally designated 54. Each of the rocker arms 50 for the slope loading machine is provided with a springloaded bumper assembly 56 including a bumper cylinder 58 and a bumper piston il. The extended end 61 of each piston 60 is adapted to contact, at the beginning of the discharge portion of the digging-discharge cycle of the overhead rocker type shovel, a bumper plate means 62 secured to the rearward end of a loading machine. The high discharge momentum of the rocker arm assembly and the rocker bucket is absorbed as the pistons 60 are telescoped into the cylinders 58 against the tension of internal springs maintained therein. The curved surface 52 of each of the rocker arms Si) has rolling contact with a track carried by a material handling machine of the type illustrated in FIG. l and shown diagrammatically in FIG. 6 as line X-Y". For the purposes of this example, each rail line X"-Y" represents the relative position of the rails of a loading machine having rails parallel with the ground when operating on slopes. The curvilinear surface 52 of each rocker arm Si) comprise two separate curved portions P-Q and Q-V. The curved portion P-Q of each arm is shaped to provide the low speed high torque conditions at the beginning of the digging portion of the digging-discharge cycle and relatively high speed during the transport portion of the digging-discharge cycle after the bucket has been elevated out of the muck pile and the torque demands of the loader are reduced. rl`he curvilinear portion P-Q of each curved surface 52 contacts the rolling path along its rail line X"-Y" between points P-Q.

The second portion Q-V of each curvilinear surface 52 contacts its rail line X"-Y" between points Q-V while the trace of the path of the center of mass E" of the bucket load moves between the points 64 and 64'. At the instantaneous points Q" of rolling contact between the curved surfaces of the rocker arms and their rails, the extended ends of the pistons 60 are almost in contact with the cooperating bumper plate 62. In order to insure that the instantaneous path of the center of gravity E" of the load of the bucket is parallel to the ground line during its discharge, the curve Q-V of each arm is an arc about point E to provide the substantially rectilinear path 64E-64' which is parallel to the ground for the trace of the center of mass of the bucket load throughout the entire movement of the pistons 60. With the line 64-64 parallel to the ground any particle at E would be discharged parallel to the ground. When the bucket 54 is in the position shown in full lines, line E"Q must be at 90 to the line 64-64'. y

Throughout the specification, the points E, E and E" which have been defined as the point of center of mass of the bucket load is also the center of the projected side area of the bucket. In the normal operation of overhead material handling machines, the muck bucket is substantially completely full of material so that the outline of the bucket load is substantially the same as the outline of the bucket side. Accordingly, for the purposes of this invention, the curved surfaces of the rocker arms are constructed for a bucket design when completed loaded for it is at such time that the greatest torque demands are required of the prime mover of the vehicle which in turn reduces the available speed during the discharge portion of the digging-discharge cycle. v

To determine the center of the projected side Iarea of the shovel bucket whic-h in turn establishes the center of -mass of the bucket load as employed hereinand in the claims appended hereto, an estimate is made of the load outline when the bucket is lled as illustrated by the `dash line designated $2 in FIG. 7 of the drawings. For purposes of computation, this irregular outline is replaced with an assumed line 84 so that the bucket shape and its load can be divided into regular geometric figures. Having establis-hed the assumed load line 84 for the bucket 80, the sides of the bucket including the assumed load line 8d is divided into triangles Al-Dl--Eb B1--C1-F1, and E1-F1-G1 and rectangle C1--D1-E1-G1. The center of gravity of the bucket load is calculated by establishing convenient X-X and Y-Y axes and from these considering the area and distance of individual centers of gravity from each axis.

The center of gravity of triangle Al-Dl--El is established at point CG1; the center of gravity of triangle B1-C1F1 is established at point CG3; the center of gravity of triangle El-Fl-Gl is established at point CG4; and the center of gravity of `the rectangle C1-D1- .E1-G1 is established at point CG2. Then the center of gravity of each of the triangles and the rectangle from the X-X axis and the areas of the triangles B1-C1--F1,

El-Fl-Gb Al-Dl-El and of the rectangle C1-D1-` El-Gl are determined. From these determinations the distance from the X-X axis to the center of gravity of the entire area is determined thus:

Therefore, Y1=the distance from X-X axis to center The distance X1 from the Y-Y axis to the center of gravity of the entire area is found in the sarne manner and the center of gravity point E is thus determined.

Whereas various details of construction have been presented in the drawings and set forth in the above description, it is to be understood that various modifications may be resorted to without departing from the essence of the invention as defined in the following claims.

This application is a continuaticn-in-part of my application Serial No. 826,100, filed July 9, 1959.

I claim:

1. A material handling structure of an overhead material handling machine comprising paired rocker arms, a shovel bucket supported by and extending from said rocker arms, cooperating bumper means on the rocker arms and the material handling machine, said rocker arms having curved surfaces adapted for rolling engagement with trackways on the material handling machine from a low forward material digging position to an elevated rearward material discharge position of the bucket to provide a digging-discharge cycle, a portion of the curved surfaces of said rocker arms being shaped to bring the trace of the geometrical center of the bucket through a substantially rectilinear path generally parallel to the ground and normal to the line connecting said geometrical center and the point of instantaneous rolling contact between the curved surface and the trackways when the rocker arms are adjacent the point of initial contact between the cooperating bumper means to provide maximum discharge rearwardly of the machine of the mucllcd material from the bucket.

2. A material handling structure of an overhead material handling machine comprising paired rocked arms, a shovel bucket supported by and extending from said rocker arms, cooperating bumper means on the rocker arms and the material handling machine, said rocker arms having curved surfaces adapted for rolling engagement with trackways on the material handling machine from a low forward material digging position to an elevated rearward material discharge position of the bucket to provide a digging-discharge cycle, a portion of the curved surfaces of said rocker arms being shaped to bring the trace of the geometrical center of the bucket through a substantially horizontal rectilinear path substantially normal to the line connecting said geometrical center and the point of instantaneous rolling Contact between the curved surface and the trackways when the rocker arms are adjacent the point of initial contact between the cooperating bumper means to provide maximum discharge rearwardly of the machine of the niucked material from the bucket.

3. The invention defined in claim 2 wherein said portion of the curved surfaces is followed by a circular arc about a point in the center of Contact between the cooperating bumper means.

4. The invention dened in claim 2 wherein said portion of the curved surfaces is followed by a circular arc about a point in the area of contact between the cooperating bumper means at the most rearward position of the rocker arms.

No references cited,