US 3738031 A
A drive for an elevator in an earthmoving machine which includes an hydraulic motor, flywheel and reduction gear train mounted in a separate housing which is pivoted for rocking movement about the elevator drive shaft and which includes a spring between the housing and the frame of the vehicle to permit limited rocking in the face of reaction torque when shock loads are encountered by the elevator.
Description (OCR text may contain errors)
United States Patent 1 Lott [ RESILIENTLY MOUNTED ELEVATOR DRIVE HOUSING  inventor: Walter E. Lott, Washingtomlll.
 Assignee: Westinghouse Air Brake Company,
 Filed: Jan. 21, 1971  Appl. N0.: 108,307
 U.S. Cl. 37/8, 37/89, 37/192,
 Int. Cl A011) 5/06, 865g 65/06  Field of Search 37/8, 89, 192;
 I References Cited UNITED STATES PATENTS 3,526,978 9/1970 Jordan 37/8 2,753,969 7/1956 Chung 74/411 June 12, 1973 3,460,405 8/1969 Simmons 74/410 3,557,473 1/1971 Grossklaus i 37/8 3,559,312 2/1971 Fox et al 37/8 2,844,048 7/1958 Bennett et al. 74/41 1 FOREIGN PATENTS OR APPLICATIONS 694,594 7/1940 Germany 198/203 Primary ExaminerWi1liam B. Penn Assistant Examiner-C. W. Hanor Attorney-Wolfe, Hubbard, Leydig, Voit & Osann  ABSTRACT A drive for an elevator in an earthmoving machine which includes an hydraulic motor, flywheel and reduction gearrtrain mounted in a separate housing which is pivoted for rocking movement about the elevator drive shaft and which includes a spring between the housing and the frame of the vehicle to permit limited rocking in the face of reaction torque when shock loads are encountered by the elevator.
1 Claim, 4 Drawing Figures PAIENIEDmzm: 3.738.031
FLYWHEEL c 53 l GEAR TRAIN CONVEYOR I- lmvsuron WALTER E. Lorr RESILIENTLY MOUNTED ELEVATOR DRIVE HOUSING In a scraper type of earthmoving machine dirt tends to pile up in front of the scraper blade which interferes with its scraping efficiency as well as increasing the load on the draft frame. Consequently an inclined elevator is employed just ahead of the blade having flights which act on the underside of the elevator, to raise the loosened earth including rock structure out of the way of the blade for depositing in the bowl behind the blade. Because of the difficulties in providing a direct mechanical drive from the tractor the tendency has been to use an hydraulic motor closely coupled to the elevator drive shaft via reduction gearing. To make up for the lack of inertial mass in the hydraulic motor needed to carry through peak loads, it has been proposed to use a flywheel on the motor shaft. It has been found, however, that when a flywheel is used the life of the gearing is reduced and breakage is experienced, particularly when working in rocky soil.
It is accordingly an object of the present invention to provide a drive for an elevator associated with a scraper blade or the like, and having a motor, flywheel and gear train, which is capable of operating in conditions of severe shock loading but which avoids the setting up of transient peak forces in the gears thereby to avoid undue wear and breakage and enabling the gears to operate for long periods without maintenance or replacement. It is a related object to provide a drive for an elevator which, for a given amount of average transmitted power, protects the gears so effectively against transient forces that there is no need to resort to heavy cumbersome gearing, shafting or supporting structure.
It is another object of the invention to provide a drive for an elevator in an earthmoving machine which enables the elevator to momentarily slow down upon encountering a rock or other obstruction so that high transient peak forces are not only avoided in the reduction gears but also in the elements of the elevator itself adding to the life of the elevator.
It is a more detailed object of the invention to provide an elevator drive which includes a spring effectively connected in series with the load which not only prevents development of peak forces but which acts as an energy storage element to absorb energy at one point in the cycle and to efficiently restore it to the system at a subsequent point. Thus it is an object to provide a drive which is highly efficient and which tends to minimize the energy dissipated by impact with rocks or the like.
Other objects and advantages of the present invention will become apparent when the following detailed description is read in conjunction with the attached drawing, in which:
FIG. I is an elevational view of a self-loading scraping machine which is equipped with an elevator drive mechanism that is mounted in accordance with the present invention;
FIG. 2 is a fragmentary, enlarged elevational view of the elevator drive portion of the scraping machine shown in FIG. 1;
FIG. 3 is a sectional view taken along the line 3-3 in FIG. 2 to further illustrate the elevator drive mechanism and mounting;
FIG. 4 is a block diagram of the power train.
While the invention will be described hereinafter in connection with a single illustrated embodiment, it is to be understood that the intent is not to limit it to that embodiment. On the contrary, the intent is to cover all modifications, alternatives and equivalents falling within the spirit and scope of the invention as defined by the appended claims.
Turning now to the drawings, and particularly to FIG. 1, it will be seen that the articulated earth moving machine shown is a self loading scraper comprising a powered tractor 11 which is pivotally connected by a gooseneck and draft frame unit 12 to a bowl assembly 13, the tractor 11 and the bowl assembly 13 being supported by respective sets of ground engaging wheels 14 and 15.
At the forward lower edge of the bowl assembly 13 there is a transversely extending scraper blade 16, which typically comprises a plurality of spaced, heavy duty cutting teeth. For adjusting the vertical position of the scraper blade 16, there is an hydraulic ram 17 (only one can be seen) at either side of the bowl assembly 13. Suitably, the rams 17 are pivotally connected, as shown between the forward part of the bowl assembly 13 and the draft frame and gooseneck unit 12, so that they can be actuated to rock the bowl assembly 13 forwardly for lowering the scraper blade 16 into any one of a series of ground scraping positions or rearwardly for raising the scraper blade 16 to a travel position.
Disposed at the front of the bowl assembly 13 there is an elevator mechanism, indicated generally at 18 in FIG. 2, for carrying the loosened dirt or other material away from the vicinity of the scraper blade 16and depositing it in a bin or chamber provided bythe bowl assembly 13. As here shown, the elevator mechanism 18 extends upwardly and rearwardly from a lower and positioned immediately above the scraper blade 16 to an upper end positioned above the bin. The bin or chamber is conventionally defined by a pair of opposed side walls 21 (again only one can be seen), a rear wall 22, and a floor 23. As is known, for convenient and efficient emptying of the bin, the floor 23 may comprise an hydraulically powered movable portion 24 and a fixed portion 25, and the rear wall 22 may be defined by an hydraulically powered ejector blade. With this construction, the bin can be emptied by opening portion 24 and actuating the ejector blade 22 to push the material in the bin forwardly toward the opening. Generally, it is emptied at a desired dump site while the machine is in motion so that the ejected material is substantially evenly distributed over the dump site area.
The illustrated elevator mechanism 18 is of more or less conventional construction. Referring additionally to FIGS. 2 and 3, it includes a pair of transversely spaced longitudinal frame members 31 (only one of which can be seen), which are rigidly interconnected by longitudinally spaced transverse members (not shown). Extending between and journalled on the upper and lower ends of the frame members and extending outwardly therefrom there are respective shafts, including a drive shaft 32 at the upper end. Sprocket wheels 33 are fixed to the ends of the shaft 32 outwardly of the conveyor frame members 31. The portion of the shaft 32 that is between the conveyor frame members 31 is housed within a sleeve 34, which aids in protecting the bearings (not shown) from contamination by dirt, dust and other debris.
For transporting the loosened material from the area of the scraper blade 16 and depositing it in the bin provided by the bowl assembly 13, the elevator mechanism 18 includes a plurality of longitudinally spaced transverse flights 36. The flights 36 are pinned at their ends as at 37 between a pair of endless chains 38 which, in turn are trained around respective sets of upper sprockets and lower idler wheels 33. The endless chains 38 are further trained over intermediate idler wheels 39 journalled on brackets 41 (only one of which can be seen) which are fixed to the respective conveyor frame members 31. The elevator sprockets and idlers rotate counterclockwise with the dirt being lifted along the underside.
The elevator mechanism 18 is preferably mounted on the bowl assembly 13 so that its forward lower end is normally biased to dig deeply into the loosened material, but nevertheless free to swing upwardly to clear any unloosened material or exceptionally large rocks that may be encountered. Such mounting may be entirely conventional and forms no part of the present invention. It is, therefore, not shown in detail, with the exception that the upper end of one conveyor frame 31 can be seen in FIG. 3 as being fixed to a bracket 42 which, in turn, is pivotally connected at 43 to a frame member 44 of the bowl assembly 13.
To transmit power between the tractor 11 and the bowl assembly 13 while permitting the operation of the entire scraper to be controlled from an operators position or seat 46 on the tractor l1, fluid powered drives are used for the various functions of the bowl assembly 13. Such drive requires nothing other than flexible hose couplings 47 between the tractor 11 and the bowl assembly 13. For control of the various fluid drives, control levers 48 for manual operation of suitable control valves (not shown) are mounted within convenient reach of the operators seat 46.
In accordance with the present invention a motor is provided having an associated flywheel and speed reduction gearing for driving the conveyor drive shaft with the motor, flywheel and gearing being mounted in a housing which is rockable about the drive shaft and which is resiliently restrained with respect to the frame of the vehicle to permit limited rocking movement to prevent buildup of destructive transient forces. Thus I provide a drive unit generally indicated at 50 having a housing 51 enclosing a hydraulic motor 52, flywheel 53 and reduction gear train 54, the output of which is directly coupled to the elevator drive shaft 32. The end of the drive shaft extends directly into the housing 51 through a collar 55 formed in the wall of the housing. The housing, it will be noted, has no direct connection with the frame and is thus free to rock bodily about the shaft. To restrain the rocking movement resulting from the reaction force from the elevator drive shaft under operating conditions, a resilient restraint is provided in the form of a coil spring 56. The coil spring is connected at one end by a pin 57 to an arm 58 bolted or otherwise secured to the housing 51. The other end of the spring is anchored by a pin 59 to the upper end of a bracket 61 which is mounted upon the bracket 42 connected, as previously noted, to the frame of the bowl assembly.
In operation the scraper is lowered so that the blade 16 bites into the surface loosening soil and rock structure which piles up ahead of the elevator and into which the elevator moves as the vehicle proceeds forwardly. Rotation of the motor 52 drives the flywheel and input of the gear train at high speed. This produces rotation of the elevator drive shaft at an appropriate speed to drive the elevator flights at a speed which may be on the order of 220 feet per minute. Upward and rearward movement of the flights on the underside causes the loosened earth and rocks to be propelled upwardly for depositing in the scraper bin.
The spring 56 acts to resist the reaction torque imposed by the elevator drive shaft 32. The spring is sufficiently stiff so that relatively little rocking movement of the housing need occur when the scraper operates in soil of even and loose consistency. However where there are rocks or pieces of concrete or other foreign material having appreciable size and weight the impact with the elevator flights tends to produce a shock upon the entire drive train. In the case of a loose rock of large size, the rapid acceleration of the rock in elevator velocity is accompanied by a correspondingly high accelerating force concentrated against the elevator flight. The force is further increased when the obstruction is not loose but imbedded in clay or the like and must be forcibly torn free. The flywheel, which is included in the system to carry through peak loads, tends to be suddenly decelerated by the relative blockage of the elevator flight. Such sudden deceleration tends to be accompanied by peak values of torque in the drive system. The gear train is, so to speak, trapped between the elevator which is suddenly decelerated and the flywheel whose reaction to sudden deceleration is to produce a large torque. Indeed where the rate of deceleration is infinite, force tends to be infinite. In the present construction, incorporating the spring 56, reaction torque which is effective between the drive shaft and the housing 51 acts to compress the spring 56 accompanied by clockwise yielding movement of the housing. Thus instead of a sudden application of peak torque to the gears upon striking a rock or other obstruction, the torque is limited to that amount which may be exerted by the spring in its stressed state. Thus the peak torque becomes more a matter of design than of accident. The gears, not being subjected to repeated shock loads, exhibit a much longer life and there is no need to resort to large cumbersome gears and shaft sections to meet the peak loading.
The spring rate of the spring 56 is a matter of design well within the capability of one skilled in the art. The spring rate is made sufficiently low so that yielding may occur even upon striking of relatively small rocks or obstructions and yet sufficiently high so that bottoming of the spring convolutions will not occur even when relatively large rocks are encountered by the conveyor flights. The length of the spring, also, is a matter of design judgment and where a longer spring is desired the spring may be arranged generally longitudinally of the conveyor rather than transversely, accompanied by corresponding rotation of the equilibrium position of the arm 58. If desired the spring may be of the type known as variable rate in which the convolutions are more closely spaced at one end of the spring than at the other to achieve progressive bottoming of the convolutions under a heavy load. While the spring is used in its compression mode, it will be apparent that the spring may be mounted so that it elongates when an obstruction is engaged, for example, by mounting it at from the position shown.
Where the present invention is employed the elevator flights and other components are protected in addition to the protection afforded the gear train. The reason for this is that as a flight moves into contact with a large rock, for example, the rock resists acceleration, producing a reaction force which is proportional to the acceleration in accordance with Newtons well-known law. This reaction force is immediately reflected as additional torque loading on the elevator drive, causing immediate additional compression of spring 56 and movement of the arm 58 connected to the gear housing which in turn produces a momentary decrease in the speed of the conveyor drive shaft 32. Thus the conveyor flight is momentarily slowed and the reaction force of the rock against the flight is less than it would be otherwise, thereby reducing the likelihood that the flight will be bent by the impact and reducing the chance that the shaft 32 and the other force transmitting elements in the elevator will be strained or broken.
After the rock has been accelerated in the direction of movement of the flight, with the peak forceproducing condition successfully overcome, the reaction torque applied to the shaft 32 decreases permitting the spring 56 to expand slightly to a new, temporary equilibrium condition. Expansion of the spring is accompanied by momentary speed-up at the elevator flights. The free capability of the spring to compress and expand means that energy is conserved. Energy which is stored in the spring upon striking an obstruction is, a moment later, given up and acts momentarily to augment the speed of the motor and flywheel. Thus the invention is to be distinguished from the use of slipping clutches or the like where the protective slippage results in a wastage of energy.
The term elevator drive shaft as used herein refers to any drive shaft exiting from the gear housing for the purpose of powering the conveyor.
While the invention has been described in connection with an hydraulic motor 52 the invention contemplates that an electric motor may be substituted therefor; hence the term motor" used in the claims is inrial.
I claim as my invention: 1. In an earthmoving machine of the type having: 1. a wheeled bowl assembly having an open end and defining an earth receiving receptacle,
2. a scraper blade mounted on said assembly adjacent the open end of said receptacle,
3. an elevator mounted on said assembly including a end thereof;
and further having a power transmission system for driving said elevator, said system including:
a housing floatably mounted for. rocking movement at one end of said drive shaft,
5. an hydraulic motor mounted on said housing,
tended to cover any self contained source of driving energy. While the invention has been described using spring 56 as the resilient element, it will be apparent that other means may be used, within the scope of the invention, to provide resilient restraint such as an elastic body of gas or a body of rubber or rubber-like mate- 5a. said motor having a motor shaft, and
a reduction gear train mounted in said housing having an input shaft and an output shaft, said input shaft being connected to said motor shaft and said output shaft being connected to said elevator drive shaft; the combination with said power transmission system of:
A. a flywheel mounted on said motor shaft having sufficient inertia to produce high values of torque in said power transmission system in response to deceleration resulting from engagement of one or more of said elevator flights with rocks and similar foreign material obstructions, thereby to overcome such obstructions while reducing variations in torque-loading applied to said motor; and,
B. an energy storing spring interposed between said housing and said bowl assembly for limiting the value of torque imposed on said gear train by said flywheel to the value exerted by said spring in its