US2700482A - Mine skip car - Google Patents

Description

Jan. 25, 1955 c. ERICKSON MINE SKIP CAR 8 Sheets-Sheet l INVENTOR.

C. Ewe/(sew Original Filed May 2, 1951 Jan. 25, 1955 c. ERICKSON 2,700,482

MINE SKIP CAR Original Filed May 2, 1951 8 Sheets-Sheet 2 INVENTOR. Laws C fb/cxsoxv Jan. 25, 1955 c. ERICKSON MINE SKIP CAR 8 Sheets-Sheet 3 Original Filed May 2, 1951 JNVENTOR. LEW/s C EIQ/oKso/v- FIG. 7

Jan. 25, 1955 L... c. ERICKSON MINE SKIP CAR 8 Sheets-Sheet 4 Original Filed May 2 1951 INVENTOR. LEW/s C. ER/c'KsoN BY M z a Jan. 25, 1955 L. c. ERICKSON MINE SKIP CAR Original Filed May 2, 1951 8 Sheets-Sheet 5 LEW/s G Ema/ ON 1 Jan. 25, 1955 L. C. ERICKSON MINE SKIP CAR Original Filed May 2, 1951 2 dim 8 Sheets-Sheet 6 INVENTOR. LEW/s C fi7=wcKsoN Jan. 25, 1955 L. C. ERICKSON MINE SKIP CAR 8 Sheets-Sheet 7 Original Filed May 2, 1951 MK M N@ a up m WE L G [I n 9 1 a pm 4 n 4 3 5 4 4 Jan. 25, 1955 L; c. ERICKSON 2,700,482

MINE SKIP CAR Original Filed May 2, 1951 8 Sheets-Sheet 8 49 iimmlii INVENTOR. LEW/S C EQ/C'KSON BY W W I United States Patent lVIINE SKIP CAR Lewis C. Erickson, Duluth, Minn., assignor to National Iron Qompany, Duluth, Minn., a corporation of Delaware Original application May 2, 1951, Serial No. 224,226, new Patent No. 2,659,502, dated November 17, 1953. Divided and this application August 20, 1953, Serial No. 375,453

7 Claims. or. 214-103 This application is a division of application No. 224,226 filed May 2, 1951, and now Patent No. 2,659,502.

This invention relates to new and useful improvements in mine skips, generally, and particularly to a novel mechanism for automatically imparting a positive loaddumping action to the skip body when it reaches a predetermined location in its travel, as, for example, over a receiving hopper.

Various types of equipment have in the past been used for transporting material out of open pits or mines, including motorized trucks, and trains of dump cars, usually propelled by locomotives. The use of such equipment for removing strippings, ore, and other bulk materials from deep pits or mines is fast losing favor with many mine operators for various reasons, for example, because of the inability of such equipment to negotiate relatively steep inclines or grades, thereby requiring long, winding road-beds which comprise benches left around the pit walls, thus making less ore available for excavation from a given area, and also because of the continual expense incurred in the maintenance of adequate roadways and trackage for such rolling equip ment. In addition, the cost of maintaining a fleet of vehicles, such as motorized trucks, and other equipment necessary in the operation thereof, usually runs extremely high. The use of other forms of material handling equipment have therefore been resorted to, such as cable-operated skips, but to the best of my knowledge from wide experience in the field, none of these have proven entirely satisfactory.

The present invention is directed to the latter type of apparatus, and preferably comprises "two skips'mounted for alternate up-and-down traveling movement between a loading station, which may be located at the bottom of an open pit or mine, and an unloading station, usually located exteriorly of the pit or mine.

An object of the present invention, therefore, is to provide an improved mine skip adapted for traveling movement between a loading point at the bottom of an open pit or mine, and an unloading station located at a higher elevation and laterally spaced from the loading point, usually exteriorly of the pit or mine, and means being provided at the unloading station for automatically imparting a positive load-dumping or rocking movement to the skip body upon its supporting chassis, whereby the load dumping movement of the skip body is progressive and constant throughout the cycle, including the return movement of the skip to loadreceiving position, thereby greatly minimizing shocks and severe strains in the cables and other equpment, and thus protecting them against damage from such shocks and vibration, even when handling material which may contain large heavy chunks or particles, which frequently have a damaging elfect upon equipment when a load is suddenly dumped into a hopper or other receiving means.

A further object is to provide a skip comprising a suitable frame or chassis provided at its front and rear ends with suitable carrying Wheels adapted for traveling movement upon suitable rails, a skip body pivotally carried by said frame, and a cam mechanism located at the' upper end of the track adapted to be engaged by means carried on the skip body, thereby to impart a rocking motion to the skip body to dump its contents into a suitable receiving means when the skip reaches a predetermined position in its upward travel.

2,700,482 Patented Jan. 25, 1955 A further object resides in the novel construction of the skip, per se, which includes a supporting frame or chassis provided at its forward end with suitable guides for movably and resiliently supporting a pair of journals which rotatably support an axle having a pair of flanged wheels secured thereto for traveling movement upon suitable rails, and a rocker or evener being pivotally mounted in the rear end of the supporting frame of the skip adapted for rocking movement about an axis disposed lengthwise of said frame, the opposed ends of said rocker engaging a pair of spring elements, having their lower ends seated on journals mounted for vertical movement in suitable guides provided in the rear end portion of the skip frame, and an axle being mounted in said rear journals and having similar flanged wheels secured thereto, said rocker cooperating with the carrying Wheels at the front end of the frame to provide a threepoint suspension for the skip frame on its supporting rails, and the resilient mounting of the axle supporting journals functioning to assist in absorbing load shocks and cooperating with the evener to compensate for irregularities in the rails of the track over which the skip travels.

Other objects of the invention reside in the unique mounting and construction of the load-carrying body of the skip, the walls of which may be of box-like cross-section, whereby they may be made of boiler plate intimately welded together to provide, in effect, an integral structure having great strength and ruggedness, with a minimum of weight, and whereby said walls provide a certain degree of resiliency which cooperates with the spring mounting of the skip body upon its supporting chassis to absorb severe load impacts and shocks; in the unique construction of the bottom wall of the skip body whereby a plurality of closely spaced ducts are provided therebeneath through which a suitable heating medium may be circulated, if desired, to permit operation of the apparatus in freezing temperatures; in the novel construction of the cable attaching means for detachably securing the ends of the pull-cables to the wheeled frames of the skips, whereby the cable ends may readily and quickly be secured thereto without damaging the cable, and also whereby cable slack may readily be taken up in a comparatively short space of time, if necessary, and whereby the ends of the pullcables are attached to their respective skips at an elevation close to the rails, thereby to minimize whip in the cables, and also whereby should the operating mechanism for the pull-cables fail when a skip reaches its load-dumping position, the skip may pass completely over the head sheaves without seriously damaging said sheaves or the supporting structure.

A further object of my invention is to provide, as a safety factor, means to lock the skip body in its loadcarrying position during its loading and load-carrying periods, and to unlock same immediately before the dumping operation begins.

These and other objects of the invention and the means for their attainment will be more apparent from the following description taken in connection with the accompanying drawings.

In the accompanying drawings there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawings:

Figure 1 is a diagrammatic view illustrating a typical installation such as utilized in open pit mines, wherein one of the skips is shown in load-receiving position at the bottom of the pit, while the other skip is in loaddumping position above the pit;

Figure 2 is a View showing a loaded skip approaching the unloading station above the ground level;

Figure 3 is a view partly in section showing the cam Figure is a view similar to Figure 4 showing in full lines the skip body in its full load-dumping position;

Figure 6 is an enlarged detail sectional view on the line 66 of Figure 8, showing one of the cam engaging rollers on the skip body engaged in a cam groove;

Figure 7 is an enlarged detail sectional view on the line 77 of Figure 9, showing one of the control cams of the skip engaged with its respective guide roller;

Figure 8 is a fragmentary view showing in full lines the position of one of the cam rollers when the skip body initially begins its tilting or load-dumping movement, and showing in dotted lines the position of the cam roller on the skip when entering the depression or gap in the bottom of the cam plate, with the triangular cam element thereof about to enter the upwardly and forwardly extending portion of the cam groove;

Figure 9 is a view similar to Figure 8, but showing the cam roller of the skip in the position assumed when the skip approaches its full dumping position, illustrated in Figure 5;

Figure 10 is a diagrammatic view illustrating in full and dotted lines various positions assumed by the skip car during its load-dumping movement;

Figure 11 is an enlarged detail sectional view substantially on the line 11--11 of Figure Figure 12 is a detail sectional view on the line 1212 of Figure 11;

Figure 13 is an enlarged detail sectional view on the line 1313 of Figure 11;

Figure 14 is a diagrammatic plan view showing the preferred arrangement of the two sets of tracks adjacent to the unloading station, and also showing the location of the cam plates relative to the rails of the tracks;

Figure 15 is an enlarged plan view of a skip with its load-dumping body in normal load-carrying position;

Figure 16 is a rear end View of a skip with its loadcarrying body in the position shown in Figure 15 Figure 17 is a longitudinal sectional view on the line 17--17 of Figure 19, showing the box-like construction of the walls of the skip body;

Figure 18 is a side elevation of Figure 17;

Figure 19 is a cross-sectional view on the line 19-19 of Figure 18, showing the trunnions at the opposite sides of the skip body;

Figure 20 is a bottom view of Figure 18; and

Figure 21 is a rear view of the skip body.

Loading station and unloading station In the selected embodiment of the invention herein disclosed, there is diagrammatically illustrated in Figure 1 a mine skip installation comprising a pair of inclined tracks 2 which extend downwardly into an open pit or mine 3 to a loading platform 4, onto which a conventional dump truck 5 may be driven to dump its load into a skip 6, shown positioned adjacent thereto. The loading platform 4 is of simple inexpensive construction, whereby it may readily be moved as the loading point follows operations to deeper levels. The tracks 2 continue upwardly above the ground level and are herein shown terminating in a head frame 7, which supports the operating mechanisms for actuating the skips, including supporting sheaves 8 which have running connections with the pull-cables of the two skips. The power means for operating the cables is of conventional construction, and therefore need not be illustrated in the drawings.

An important feature of the invention resides in the relationship between the upper ends of the rails 2 and the sheaves 8, whereby should one of the skips accidentally excessively overrun its unloading position, shown in full lines in Figure 1, it could without causing serious damage to the sheaves 8 and the control tower, pass completely over the sheaves 8 onto the ground below the tower. Such an incident could rarely occur because the trackage is extended a considerable distance beyond the receiving station 62 to take care of most abnormal over-runs, as illustrated in Figure 1.

Skip and supporting chassis Another important feature of the invention resides in the specific construction of the skip which, as best illustrated in Figures 2 to 4, inclusive, and 15 and 16, comprises a load-carrying body 9 having oppositely disposed trunnions 10 secured thereto and mounted for rocking or tilting movement in suitable bearings or journals 11 provided on the side beams or members of a carrying frame or chassis 12, whereby the skip body 9 is mounted for pivotal movement on an axis disposed transversely of the chassis 12, as will be understood by reference to the drawings. Journals 11 are provided with split sleeves or bushings 49, the lower halves of which are spherical in configuration whereby when supported in the journal boxes 11, shown in Figures 2 and 3, the bushings are made self-aligning to compensate for variations or irregularities in the mounting of the body on the chassis frame, and also whereby any this-alignment or distortion of the chassis frame will have no effect upon the pivotal action of the skip body thereon. The upper faces of journal boxes 11 are preferably disposed at an angle to the upper edges of the side members of the chassis frame, and are open to form saddle-like supports adapted to detachably receive the split bushings 49 which rotatably support the skip trunnions 10 in the journal boxes 11. By this arrangement, should the skip body accidentally become damaged, another one may readily be substituted therefor by simply lifting the damaged skip body from its supporting chassis with a suitable crane.

The frame or chassis 12 comprises front and rear cross members 13 and 14, respectively, and side members 15, all of which are shown constructed of hightensile steel plate, whereby said frame members are boxshaped in construction, cross-sectionally, thereby to provide the utmost in strength and ruggedness with minimum of weight. Light weight is an important factor in an apparatus of this general type, as it makes it possible to relatively increase the pay load carried on the ski 5.

he forward end of chassis 12 is provided at each side with vertically disposed guides 16 adapted to slidably receive a pair of journal blocks 17 which rotatably carry an axle 18 to which are secured a pair of flanged wheels 19 adapted to travel on the rails 21 of the tracks 2, as will be understood by reference to Figures 2, 3, 15 and 16. Suitable means not shown is provided for retaining the journals 17 in the guides 16. Spring elements 22 are shown interposed between the upper ends of journals 17 and the bottoms of the inverted guides 16 to resiliently support the forward end of the chassis frame upon the front axle 18, as will be understood.

Three point suspension Another important feature of the invention resides in the meansprovided at the rear end portion of the chassis frame to provide a three-point suspension for the chassis frame on its supporting wheels. Such means is shown comprising a rocker or evener 23, mounted for rocking movement upon a pivot pin 24 preferably having its ends fixed in the walls of the rear cross member 14 of the chassis. The opposed ends of the rocker 23 are received in the bottoms of vertical guides 25 provided at the rear corners of the chassis frame, and engage the upper ends of suitable spring elements 26, similar to springs 22 at the forward end of the frame. The lower ends of springs 26 are seated on the upper ends of a pair of journal blocks 27, movably supported in the guides 25, and which cooperate to rotatably support a rear axle 28 in a manner similar to the journal blocks 17 at the forward end of the chassis, as will be understood by reference to Figure 16.

The above construction, as hereinbefore stated, is important in that the rocker cooperates with the front wheels to provide a three-point suspension for the chassis frame on its supporting wheels, whereby irregularities or variations in the rails 21 will not have any ill eifects upon the operation of the skips as they travel back and forth on the rails 21 of the tracks 2. The provision of the spring elements 22 and 26 at the front and rear of the chassis is also extremely important in that they sufliciently cushion the impact of loads dumped into the skip body at the loading station to greatly minimize damage to the skips.

In a skip installation such as herein disclosed, each skip is usually designed to carry a load which, in actual practice, is substantially equal to the load of a truck body, whereby an entire truck load may be dumped into an empty skip body stationed at the loading station, as shown in Figure 1. Such dumping of the material into the skip body results in extremely heavy load impacts on the skip which, in the present instance, the spring elements 22 and 26 of the skip chassis assist in absorbing.

The severe load impacts imposed on the skips when being loaded, will be more fully realized when it is understood that the tail end of a loaded truck stationed on the loading platform in the bottom of the pit may be between fifteen and twenty or more feet above the bottom of the empty skip body, and the skips herein disclosed have therefore been carefully designed and constructed to readily withstand such severe load impacts over long periods without damage.

Another feature of the invention, therefore, resides in the novel construction of the skip body, per se, which, as best shown in Figures 17 to 21, inclusive, is constructed entirely of metal, such as high-tensile steel plate, welded together to form box-like side walls, the outer walls 29 thereof being here shown as having openings 33 therein to provide means whereby the vertical and horizontal members 31 which space the inner walls 32 from the walls 29 may be securely welded in place to form the box-like double wall construction here shown. The rear wall of the skip body is similarly constructed to provide an outer wall 34 having openings 36 and 37 therein and similar members 31 welded between the wall 34 and the inner wall 35. The box-like, double wall construction of the skip body provides for extreme strength because of the intimately welded association of the inner and outer walls with the spacer members 3131 secured between same at substantially right angles to provide a plurality of adjacent relatively small box elements which provide great strength and reinforcement with least possible weight.

The bottom 41 of the skip body is similarly of boxlike construction, as best illustrated in Figure 19, and comprises inner and outer plate elements 42 and 43 spaced apart by upright metallic spacer and strengthening elements 44, all of which are intimately welded together to provide the required strength in the same manner as the side and rear walls.

The skip body is also provided with strength and reinforcement in its general construction; that is, the skip body is so formed as to have substantially U-shaped yokes to support and sustain its load and stresses. These yokes are clearly illustrated in Figures and 19. In Figure 15, it can be readily seen that the skip body is open in front, as at 39, and has a U-shaped side and rear 7 wall contour, with the trunnion 10 extending from the yokes side walls 29-29. The longitudinal yoke embraces the load of the skip body as the cables pull the skip upwardly, of course.

In addition, there is a yoke transversely of the skip body. As seen in Figure 19, the cross section of the skip is of U-shape and the trunnions 10 are secured to the side walls 29-29 thereof whereby the weight of the load is adequately supported between the trunnions 10.

An abutment member 38 is provided on the rear wall 34 of the skip and is adapted to engage the upper surface of the rear cross member 14 of the chassis frame when the skip body is in its normal load-carrying position, as seen in Figure 2, to support the rear end of the skip body and prevent its being tipped rearwardly on its pivotal mountings 10. The position of the trunnions 10 relative to the skip body is preferably slightly forwardly of the normal center of gravity of the skip body, both when loaded and empty. This positioning of the trunnions is to insure that the skip body is biased rearwardly and remains in its normal load-carrying position during its operation except when it is intentionally caused to be tipped at the unloading station, as will become apparent. It is deemed apparent that the load of the skip body is supported between the trunnions 1010 and the abutment member 38 which rests on the rear transverse frame member, and that these parts, and their relation to each other, serve as means to hold the skip body against pivotal movement when traveling, especially when carrying a load, thus preventing loss of material at undesired points along the skip-travel-path.

A wear plate 45 constitutes the effective bottom surface of the skip body, and is shown supported upon a plurality of closely spaced fluid-circulating passages 47 provided in the bottom wall of the skip body. The angle irons are disposed adjacent each other lengthwise of the skip body, as shown in Figure 19. Should it be found necessary to operate the apparatus in freezing temperatures, a heating medium may be circulated through the passages 47 in the skip bottom, and, of course, the heating medium may be directed into the 6 spaces between the side and back walls as well to keep material from sticking or freezing to the inner walls of the body.

A guard plate 52 is provided at the front end of the chassis frame, as best shown in Figure 4, and provides a partial front wall for the skip body when the latter is in its normal load-carrying position, shown in Figures 2 and 3. The guard plate 52 also extends forwardly and upwardly over the front cross member 13 of the chassis frame to prevent material from spilling forwardly into contact with the cable attaching means.

Cable attaching means Another important feature resides in the means provided for attaching the ends of the pull cable 20 to the chassis frames of the two skip cars, it being understood that the two skip cars are preferably utilized in the installationwhich are so arranged that when a loaded skip is ascending from the mine pit, an empty skip is descending to the loading station to receive another load.

The cable-attaching means is best illustrated in Figures 10 to 13, inclusive, and comprises a semi-circular member 53 having a peripheral groove 54 for receiving the pull-cable 20. The free end portion of the cable is wrapped around a wedge-like element 55, indicated in dotted lines in Figure 11, with the bight in the cable around the larger end of the member 55 and facing the direction of pull on the cable. Said Wedge-like element with the cable thus wrapped about it is then inserted into a socket member 56 provided on the upper portion of member 53, as shown at 57, the socket member being disposed above the member 53 and preferably forwardly of the vertically center line of the member 53. The angles of the opposed sides of wedge element 55 are such that when said element is forced into the. socket member 56, as shown in Figure 12, and the cable 20 is placed under tension, a force is constantly exerted on the wedge element 55 to firmly secure it and the cable in the socket member 56 without damaging the cable, and positively preventing the cable from accidentally becoming detached from the skip chassis.

The cable-attaching means includes the upright semicircular member 53 which is a fiat plate-like piece having its cable receiving, peripheral groove therein, as shown, and the socket member 56 attached thereto, as by welding, for example. The member 53 is removably secured to the front end of the skip frame, whereby the member 53 may be very conveniently removed and mounted on the cable with comparative ease once the mounting point has been established, as there will be no diflicult maneuvering of the unwieldly cable through slots or other small openings in confined spaces. It is desirable that a cable clamp, suggested at 89, be installed adjacent the lower end of the cable anchor plate 53, as shown, to hold the cable securelly in its mounting. With the plate 53 thus mounted on the cable, the plate and cable can be conveniently remounted on the skip frame, as shown.

The member 53 is secured to the frame of the skip by means of angle brackets 58 adjacent the upper end thereof, which are welded to the opposed vertical faces of the member 53, the brackets being bolted to the outer face of the downwardly projecting portion of the frame member 13, as seen in Figure 11, it being noted that the said outer portion of the member 13 is amply supported and braced by brackets to carry thev member 53. In addition, the member 53 is fastened to the transversely disposed anchor tie plate 91 as by angle members 92 disposed on each side of the member 53, the tie plate having a slot 97 therein to receive the member 53 and the members 92 being, preferably, welded to the tie plate on each side of the slot and having bolts 93 extending through the upwardly facing flange of the members 92 and the plate 53, as shown, whereby the cable anchorage is secure.

The tie plate 91 has an upwardly turned flange 94 on its outer edge, as shown, and has its inner edge welded to the lower edge of the skip body closure portion 52 of the member 13, whereby the tie plate has a girder effect and reinforces the frame of the skip as well as serving as a portion of the cable anchorage. Obviously, the cutting of the slot 97 into the plate 91 weakens same; however, I have provided a heavy bar of metal 98 to extend across the slot and to be bolted to the flange 94 of the tie plate on each side of the slot, thereby restoring, the girder effect of the tie plate and further securing the cable anchorage.

To further provide adequate cable anchorage and to distribute the pulling stress as equally as possible to the skip frame, one end of a girder or stress distributing member 96 is firmly fixed to each end of the portion 52 of the member 13 adjacent the lower end thereof where the plate 91 meets the member 13. The opposite end of each of the girders 96 is secured to the side members 15 of the skip frame, preferably adjacent the trunnions 10, as shown in Figure 15. Thus it may be seen that there is a U-shaped yoke (girders 9696 and tie plate 91), which carries the cable pull on the skip, making for more even disribution of stresses.

By attaching the cable to the chassis frame as above described, and as shown in the drawings, the cable is located close to the surface plane of rails 21, whereby whipping of the cable is reduced to a minimum. Such construction also makes it possible to readily vary the length of the cable at any time if necessary and also whereby excessive slack which may develop in the cable may readily be taken up without damaging the cable. if desired, the excess cable 59 may be supported upon the upper front frame member 13 beneath the forwardly extending guard member 52, said frame member 13 serving as a deck upon which to plate the excess cable.

Skip body operating mechanism Another important feature of the present invention resides in the novel means provided for operating or tilting the skip body from its normal load-carrying position, shown in Figure 2, to its full load-dumping position, indicated at A in Figure 10, and back to its horizontal loadcarrying position, indicated at B. This operation is extremely important in the operation of the skip body, as it assures a smooth rocking motion without ony abrupt changes of direction, and the unloading of the material may be targeted to a restricted area, such as the wall 61 of the receiving hopper 62 in the control tower. Such controlled discharging of the load from the skip is accomplished regardless of the skip speed, and minimizes spilling of material from the skip and damage to the equipment.

Cam plates The operating mechanism is best illustrated in Figures 2 to 9, inclusive, and comprises a pair of cam plates 63, shown secured to supporting beams 64 which may constitute a portion of the supporting structure of the receiving station, as shown in Figure l. The beams also provide the main support for the upper ends of the tracks 2 and the operating mechanism for the skips.

In Figure 14 it will be noted the installation herein disclosed comprises two tracks 22. The cam plates 63 are best illustrated in Figure 5. Two such cam plates are utilized for each skip, and are located adjacent to each pair of rails 21, at the inner sides thereof, as clearly illustrated in Figures 14 and 15. Each cam plate 63 has a longitudinally extending cam groove 65, which may be formed by welding to one side surface of the plate a pair of spaced bars 66 and 67, which extend forwardly and downwardly to a recess or gap 68.

Similar cam bars 69 and 71 are secured to the other end portion of each cam plate 63 and cooperate with the bars 66 and 67 to complete the formation of the longitudinal cam groove 65, as will be understood by reference to Figure 5. The adjacent faces of cam bars 66 and 67 and cam bars 69 and 71 are provided with high carbon steel facings 72 which cooperate to provide wearing surfaces for a pair of cam rollers 73, mounted on brackets 74 secured to depending portions or structural brackets 75 provided at the lower front corners of each skip car, as best illustrated in Figures 3, 5, l7, 18, and 21.

The cam grooves 65 and rollers 73 of the skips constitute a very important feature of the present invention in that this mechanism positively controls the dumping actions of the skid bodies, as each skip passes over the receiving hopper 61. As hereinbefore stated, the dumping movement of each skip body is progressive and gradual from the time the skip body initiates its dumping movement until it has completely discharged its load and is returned to its normal load-receiving position, preparatory to returning to the pit for reloading. Such movement is important because it assures a gradual discharge of the material from the skip body as it is tilted to its full dumping position, clearly indicated in Figures 1 and 10, which greatly minimizes shocks and vibration.

The positive-but gradual dumping or tilting action of the skip body is, of course, controlled by the relative formation or contour of the cam grooves 65 with respect to the line of travel of the trunnions 10, and the location of the cam or dump rollers 73 with respect to the trunnions. By referring to Figure 10 of the drawing, it will be seen that the gradual dumping of the skip body results because of the progressively varying distances between the cam grooves and the line of travel a-a of the skip trunnions 10, it being understood that the distance between the skip trunnions 10 and the cam rollers 73 always remains constant. Therefore, for each forward increment of travel of the skip body, the degree of tilt or dump of the skip body can be accurately predetermined and controlled by the formation of the cam grooves.

In the instant disclosure, the initial tilt per increment of travel is but slight so that there will be least possible stress to the cable and other mechanism required to overcome the inherent inertia of the skip body which resists tilting. Once this inertia is overcome, however, the degree of tilt per increment of travel may be gradually increased without undue stresses to the equipment.

In the same manner, the dumping of the skip can be targeted to a particular point of discharge irrespective of which of the said increments of travel the skip happens to be in at a given time. This is a very desirable feature, as different types of material handled by the skips dumps in different manners; in other words, some leaves the skip body relatively earlier than others, yet all materials engage substantially the same target point in the hopper 62. This makes it possible to design receiving stations in a manner to sustain the load-dumping shocks most eificiently, of course.

Because the skip frame travels in a continuously straight line, and only the skip body tilts, the cam grooves cannot, of course, be designed to extend farther from the trunnions 10 than the cam rollers 73 extend. Therefore, I have provided means for making it possible to use relatively flat cam grooves to tilt the skip body more than as shown, to insure complete emptying of the skip each time it is dumped. This means includes V-shaped cam elements 76 fixed to the roller supporting brackets 74 inwardly of the cam rollers 73, the elements 76 being adapted to engage a pair of rollers 77, rotatably mounted on trunnions 78 of a pair of brackets 79, shown secured to the cam plates 63 at a point intermediate the cam bars 66 and 69. See Figures 6 and 7. The rollers 77 are spaced inwardly from the cam plates 63, and are aligned with the cam elements 76 or the skip body so that said cam elements engage the rollers 77 when the cam rollers 73 approach the downwardly open gap 68 in the bottom of the cam grooves between the cam bars 67 and 71, as shown in Figure 3.

As is deemed apparent from the drawings, especially Figures 7, 8, and 9, the V-shaped cam elements take over from the cam rollers 73 as the latter move into the point Where cam bars 66 and 69 meet; that is, the upper side of the cam elements 76 engage the rollers 77 and guide the cam rollers 73 downwardly into the gap 68 and the said upper side of the cam passes beyond the roller, as shown, as the skip moves forward. As the skip continues forward, the front corners of the skip are restrained from forward movement momentarily until the trunnions 10 pass over the center of the gap 67 to the position shown at G in Figures 5 and 10. As the skip frame continues forward, the skip body moves therewith, of course, causing the rollers 73 and cam elements 76 to move upwardly out of the gap 68. Now, because of the V-shape of the cam elements 76, the other side thereof engages the rollers 77 and they guide the dump or cam rollers 73 into the cam groove area B defined by the bars 69 and 71 and the skip body moves into the position D, as shown, until the skip reaches its full loaddumping position A, attained when the cam rollers 73 enter the straight portions F of the cam grooves. Of course, this action takes place relatively fast and the travel of the skip frame and body is uniformly smooth so that no jarring or jolting takes place.

This cam-dumping arrangement, as described, serves to make the dumping operation less critical in speed of dump and in the final stopping place of the skip when dumped, whereby cable length does not have to be critically adjusted to permit loading of the down-skip.

Safety latch for securing skipfiodyjin load-carrying position As a safety factor, means is provided for locking the skip body against tilting or; rocking movement :upon its trunnions duringthe traveling movement thereof between the receiving station and the bottom ofthe pit,'thereby to prevent any possibility of the skip, body ,tilting-forwardly and interruptingits travel shouldthe center of gravity of its load be located forwardly of-;its,trunnions 10. Because of the construction heretofore-described,

this is not likely to occur; however, in the construction and operation of heavy equipment, it is goodpractice to include safety features To lock theskip body against. tilting movement, a pair of latches, generally designated by the numeral 81, are pivotallymounted on the for-. ward end of the chassis frame, as shown at 82 in Figures 2,3, 4, and 15.

Each latch is providedatits upperend with. .a pin. 83 adapted to engage in seats or. notches ,84 providedin the lower ends of a pair of latch-engagingmembers 85 secured to the forward end of the. skip body in' laterally spaced relation, as clearly illustrated in Figures 3 andlS. Rollers 86 are also mounted .on the lower ends of the latch arms and are laterally offsetinlan outward direction from the upper rollers 83, as illustrated -.in Fig.-.,

ure 15. Rollers 36 are adapted ,to engagestationary cam bars 87 disposed in spaced parallel relation to the rails,

21 or track 2, when thelskipapproaches its load-dump. ing position in the control tower.. Cam bars 87 extend from the lower ends ofthe cam .plates'63f to a .point well beyond the upper ends; of the cam. pl ates,, whereby the latches are retained in unlatching positionthroughout.

73' when the skip approaches its load-dumpinggposition:-

Assoon as cam rollers 73 have fully entered cam grooves 65, the cam grooves take-over complete controlof. the

dumping action of the skip body and provide-a positive vaction whereby the skipbody is progressivelyutilted in a forward direction from its load-carrying position,

shown in Figure 2, to its full load-dumpingyosrtion;

shown in full lines in Figure 1,- assisted; as stated; by

the V-shaped cam elements 76"and' rollers- 77'. The return movement ofthe skip body from, the full lines position, shown in Figure -1,' to its load-receiving-"position,

controlled by the cams in amannenv similar to the actionimparted thereto when dumpingits load.

In Figure 14, it will be-noted thatonly three latchoperating cams '87 are-utilized,- whereas..zeachl.,sk ip car comprises two latches- The center-latch cam; 87-thus serves the. two skips,-and-toavoid interference'between the adjacent latches ofthe two skips the tracks 2 gradually diverge from the receiving--station;:in an outward direction sufficiently -to permit ample clearance between the two skip bodies at"[hBlzPOiHlffllHblhfiil travel where they pass eachother in their up and down movements on the.,tracks 2. The converging-of-thetracks at-the-receiving station permits-the --receiv-ingstation to beef less width, and obviously, reduces the bulk and cost of the receiving station proportionately.

Operation In the operation of the novel skip car installation herein disclosed, the skips, after having been operatively secured to the pull cable 20, may be set into motion by an hoist operator located in any convenient location. The operators station, however, is preferably, and may well be, arranged so that the operator may clearly view the loading operation at the bottom of the pit and the unloading operation in the tower. A suitable communication system may be provided between the operator in his control station, not shown, and the observer at the loading station, whereby the loading observer may signal or apprize the control operator each time a skip has been loaded and is ready to ascend to the receiving station. The apparatus is then set into motion whereby the loaded skip ascends to the unloading station, over the hopper 61, and simultaneously the empty skip descends to the loading station.

. station.

anism over the hopper 61, the cam'rolle'rs 73 of the skip enter the camgrooves- 65"at C in Figure -10; and simul-'- taneously or immediately thereafter-the latch rollers 86, engage the inclined surfaces 88 of the fixed fcams 87, whereby the 'upper' rollers--83 of the latches are moved out of locking engagement with the elements 85 to thereby release the skip bodyso that it may proceed' As the skip passes with its load-dumping movement. between cam plates 63, its cam rollers 73 enter and follow said cam grooves The V-shaped cam elements 76 prevent cam rollers 73 from passing over cam recesses 68 and into the lower portions E of the upper portions of cam grooves 63 before the skip is properly tilted, because the upper surface of the cam elements 76 remain'in engagement with the peripheries of rollers 77 until rollers 73 have entered cam recesses or gaps 68; as will be understood by reference to Figure 4. As the advancing skip body'tilts from positionG to position DJ in Figure 10, the opposite face of the V-cams engages; the rollers 77 to guide the cam rollers 73' upwardly into cam section E, as indicated.

This action, as hereinbefore stated, is extremely important in that it imparts to each skip car a positive dumping action which is gradual and uniform throughout its full cycle, and is not dependent upon nor can it be Elf? fected by'gravity. The cam mechanism also compensates for any variation in the distance between the pathofvtravel aa of the skip .trunnions-IO and the support-:- ing rails 21' of, the tracks 2 as a result of the resilient' mounting of the skip body upon its supporting chassis.

In actual practice, the novel cam mechanism herein dis-1 closed :has been-found to function positively and efficiently, and with the assurance that each load as it is graduallydischarged from a skip: body is directed onto azpredetermined area substantially without shock to the skipmechan-ism, which .is an extremely important factor 1 in 'apparatusof this general type where the load particles may. greatly vary in size and weight.

The unique mounting-of the skip body on its supporte ingchassis isalsoimportant-in that it makes it possible to quickly remove-a damaged skipbody fromits supporting chassis and substitute another therefor without requiring the removal of any. bolts or other fastening elements.-

Apparatus of this generaltype isusually subjected-to extremely rough treatment'because of the nature of the material. to be handled-thereby. It :frequently contains large, heavy chunks which maybe extremely heavy,

whereby they may contact the skip bottoms with severe impacts; when dumped thereinto at the loading station.

Theparticular 'constructionof' the skip body, the re-' silient mounting of theskip bodies upon theirsupporting chassis, and the. inclination atwhich the'skipis normally carried .when loading and running protect the skips against damage fromsuch severe load shocks. The three-point suspension of'the chassisuponthe rails is also instrumental -zin,minimizingwexcessive strains which may be impartedtothe skips as: a result of irregularities in the rails.

lt is to-be noted that onelof-the features of my invention is thatit is designed foruse in open pit mining wherein .the.tracks lie: on .the wall of the pit the walls of the pit,

of course; being at aninclination which the material being minedinherently maintains That.is,.the .walls of the pitassume the natural angle of repose of the material being mined and the tracks are laid at this inclination.

The upper edge of the skip body and the skip bottom lie substantially parallel with the track, as is readily apparent from the drawings; thereby, when the skip is loaded from a truck or the like, the material assumes its natural angle of repose and the skip cannot be overloaded to the point that spillage will occur along the track as the skips ascend, as all spillage will occur at the loading In this manner also, the skip load can be accurately predetermined, and it cannot be overloaded to put excess strains on the equipment, thereby providing for longer life and durability of the entire assembly.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

Having thus described my invention, what I claim is:

1. A skip comprising a wheeled frame and a load-carrying body mounted for pivotal movement thereon, abut- When the loaded skip approaches the control mech- 35 ment means on the rear wall of the skip body engageable with means on the Wheeled frame to retain the body in load-carrying position, latch means carried by the wheeled frame for locking the body, said skip body being open at its forward end, each of the upright walls of the skip body and also the body wall of the skip body comprising an inner and an outer plate member spaced apart to receive therebetween a plurality of metallic reinforcing elements, all of which are intimately welded together and to said inner and outer plate members to provide hollow box-like walls, and all of said upright box-like walls being intimately welded to one another and to said hollow box-like bottom wall thereby to provide, in effect, an integral unitary body structure whose walls and bottom are inherently resilient to minimize load shocks and impacts.

2. A skip comprising a frame having a pair of downwardly directed guides at its forward end, a journal block movably supportedin each guide and rotatably supporting an axle having track-engaging wheels secured thereto, resilient elements interposed between said journal blocks and the upper walls of said guides for absorbing load shocks and vibration at the forward end of the skip, said frame having a rear cross member provided at its ends with guides for movably supporting a pair of journal blocks, having a rear axle mounted therein and provided with rear track engaging wheels, a rocker having its intermediate portion pivotally connected to the spaced walls of the rear frame member and having its opposed terminals received in said rear guides above the journal blocks mounted therein, and spring elements interposed between said journal blocks and the ends of said rocker adapted to cooperate with the spring elements at the forward end of the skip frame to provide a three-point resilient suspension for said frame on its carrying wheels.

3. A skip comprising: a frame having a pair of guides at its forward end, an axle movably supported in each guide and having a wheel at each end thereof, resilient elements interposed between said axle and the frame for absorbing load shocks and vibration at the forward end of the skip, guides at the rear of said frame on each side thereof for movably supporting a pair of journal blocks, an axle carried between said blocks and having wheels at each end thereof, a rocker having its intermediate portion pivotally connected to the rear of the frame and having its opposed terminals received in said rear guides above the journal blocks mounted therein, spring elements interposed between said journal blocks and the ends of said rocker to provide a three-point resilient suspension for said frame on its wheels.

4. A skip comprising: a frame, a load carrying body, means pivotally mounting said body on said frame with the axis of rotation of said body transverse said body and substantially centrally between the front and rear ends thereof, means on said body engageable with said frame to retain the body in load carrying position, said skip body being open at its forward end, and means mounting said frame in a three-point suspension for travel comprising a rear axle extending transversely of the rear portion of said frame and being provided with wheels, a journal block mounting said axle at each end thereof, guides movably carrying said journal blocks, a rocker having its intermediate portion pivotally connected with said frame and having its opposed terminals received in said guides above said axles, spring elements interposed between the ends of said rocker and said axle, a front axle extending transversely ,of the forward end of said frame, and spring means supporting the front end of said frame on each end of said front axle.

5. In a skip having a frame, a load carrying body pivotally mounted on said frame with the axis of rotation of said body transverse said body and substantially centrally between the front and rear ends thereof, and means on said body engageable with said frame to retain the body in load carrying position; means mounting said frame in a resilient three-point suspension for travel comprising a rear axle extending transversely of the rear portion of said frame and being provided with wheels, a journal block mounting said axle at each end thereof, guides in said frame movably carrying said journal blocks, a rocker having its intermediate portion pivotally connected with said frame and having its opposed terminals received in said guides above said axles, spring elements interposed between the ends of said rocker and said journal blocks, a front axle extending transversely of the forward end of said frame, a spring means supporting the front end of said frame on each end of said front axle.

6. A skip comprising a wheeled frame and a loadcarrying body mounted for pivotal movement thereon, means on said body engageable with said frame to retain the body in low carrying position, said skip body being open at its forward end, said skip body having each of its upright walls and its bottom wall composed of inner and outer plate members, a plurality of longitudinally and transversely disposed metallic reinforcing elements fixed to and between said spaced plate members and forming a network of box-like compartments between said spaced walls, the longitudinally disposed reinforcing elements being in substantial alinement with each other throughout said skip body forming an integral reinforcing unit of substantially U-shape extending around the side and rear walls of said body, said transversely disposed reinforcing elements being united in end-to-end relationship to form a plurality of substantially U-shaped reinforcing elements between said side and bottom walls, said transversely disposed elements being intersected and secured to said longitudinal elements whereby a unitary body structure is provided Whose walls are inherently strong and resilient to dminimize load shocks and impacts imparted to said bo y.

7. The structure as set forth in claim 6 and said outer plate member having openings therethrough into said box-like compartments to permit the welding of said outer plate to the edges of the reinforcing elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,499,675 McDougal July 1, 1924 1,712,495 Farrell May 14, 1929 1,942,207 Ferwerda I an. 2, 1934 2,386,410 Taggart Oct. 9, 1945 2,595,028 Vutz Apr. 29, 1952. 2,639,186 Sewelin May 19, 1953 2,659,502 Erickson Nov. 17, 1953 FOREIGN PATENTS 451,404 France Feb. 12, 1913 1876/26 Australia May 17, 1926

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