US3491906A

US3491906A - Loader apparatus with crowd capability

Info

Publication number: US3491906A
Application number: US665334A
Authority: US
Inventors: Trevor O Davidson
Original assignee: Bucyrus Erie Co
Current assignee: Caterpillar Global Mining LLC
Priority date: 1967-09-05
Filing date: 1967-09-05
Publication date: 1970-01-27
Anticipated expiration: 1987-01-27
Also published as: DE1634735C3; GB1218818A; JPS4823361B1; DE1634735A1; DE1634735B2

Description

Jan. 27, 1970 T. o. DAVIDSON 3,491,906

LOADER APPARATUS WITH CROWD CAPABILITY Filed Sept. 5, 1967 6 Sheets-s l INVENTOR TREVOR o. DAVIDSON ATTORNEY Jan. 27, 1970 T, o. DAVIDSON LOADER APPARATUS WITH CROWD CAPABILITY Filed Sept. 5. 196'? 6 Sheets-Sheet 2 ETn IN VENTCR TREVOR O. DAVIDSON BY A 49% ATTORN EY Jan. 27, 1.970 T, o. DAVIDSON 3,491,906

LOADER APPARATUS WITH CROWD CAPABILITY Filed Sept 5, 1967 e Sheets-Sheet s INVE NTOR REVOR O. DAVIDSON ATTORNEY $1M, no

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Jan. 27, 1970 'r, o. DAVIDSON 3,491,905

LOADER APPARATUS WITH CROWD CAPABILITY Filed Sept. 5, 1967 6 Sheets-Sheet 4 INVEN TOR I TREVOR O. DAVIDSON wzw ATTORNEY Jan. 27, 11970 T, o. DAVIDSON 3,491,906

LOADER APPARATUS WITH CROWD CAPABILITY Filed Sept. 5, 196'? v 6 Sheets-Sheet 5 INVENTOR TREVOR O. DAVIDSON ATTORNEY Jan. 27, 11970 T, o. DAVIDSON BOADER APPARATUS WITH CROWD CAPABILITY Fi'l-ed Sept. 5., 1967 6 Sheets-Sheet 6 INVENTOR TREVOR o. DAVIDSON ATTORNEY United States Patent 3,491,906 LOADER APPARATUS WITH CROWD CAPABILITY Trevor 0. Davidson, Milwaukee, Wis., assignor to Bucyrus-Erie Company, Milwaukee, Wis., a corporation of Delaware Filed Sept. 5, 1967, Ser. No. 665,334 Int. Cl. ROM? 3/ 62, 3/42 US. Cl. 214--77l) 24 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The present invention was created for a front-end loader with a crowd action capability in the operating mechanism for crowding the bucket horizontally without moving the tractor. For years, the front-end loader has consisted essentially of a bucket of some sort mounted on hydraulically actuated arms extending from the chassis of a vehicle, and the movement of the vehicle was relied upon for the horizontal, or crowd, movement of the bucket and the arms provided the lift, or hoist, of the bucket. This type of excavator has begun to supplant the conventional power shovel with its dipper in many applications, and this has given rise to demands for in creasing bucket capacity and decreasing cycling time. The magnification of the machinery necessary to accomplish the increased capacity has made it impractical as well as awkward and slow to move the entire machine. Hence, in many instances the bucket operating mechanism has been modified to provide a crowd or horizontal com ponent to the bucket movement along with the usual hoist or vertical component.

The crowd component is commonly accomplished by pivoting the bucket arm on the end of a crowd arm, which is pivotally mounted on the revolving frame of the machine. A hydraulic cylinder mounted on the revolving frame pivots the crowd arm about its mounting on the revolving frame to propel the bucket outwardly and to retract it. The arrangements for hoisting the bucket, however, have produced a greater variation. Most often, a hydraulic cylinder is end-mounted between the crowd arm and the lift arm. Alternately, the hoist cylinder is mounted between the revolving frame and the lift arm. In at least two instances the cable hoist from the old dipper shovels has been adapted to hoist the bucket. A departure from these more conventional crowd and hoist mechanisms is shown in US. Patent No. 2,795,342 where a pantograph type of movement is employed to crowd the bucket of a loading shovel mounted on a shuttle car.

Summary of the invention The present invention relates to a loader apparatus with crowd capability in which a lift arm having a material handling implement on one end has its opposite end pivotally mounted to move with a swinging quadrilateral that swings in a plane relative to a main supporting frame; the swinging quadrilateral having the anterior member 3,491,906 Patented Jan. 27, 1970 pivoted to the main supporting frame, a posterior men1- ber pivoted to the main supporting frame behind said anterior member, and a floating frame pivotally connected to said anterior and posterior members. Crowd motion of the material handling implement may be provided by a crowd mechanism mounted to swing the anterior and posterior members of the swinging quadrilateral. Hoist motion may be imparted to said material handling implement by a hoist mechanism which pivots said lift arm. A tilt mechanism controls the attitude of the material handling implement.

The structure thus set forth provides maximum crowd reach and hoist for the material handling implement, and is readily adaptable to machines having a broad range of size and capacity. This invention provides the same length of crowd motion for all hoist levels of the material handling implement. These capabilities make possible a large capacity front-end loader that is relatively simple to operate, is highly maneuverable, very versatile and it has short cycling time. Due to the long reach of the front-end loader embodying the present invention at any bucket hoist level, such a front-end loader normally performs digging and dumping operations which hitherto were impossible, or very time consuming and difficult.

Brief description of the drawings FIG. 1 is a side elevation of a first preferred embodiment of the present invention.

FIG. 2 is a side elevation of the embodiment shown in FIG. 1 with the bucket partially extended at ground level.

FIG. 3 is a side elevation of the embodiment shown in FIG. 1 with the bucket extended and hoisted.

FIG. 4 is a side elevation of a second preferred embodiment of the present invention.

FIG. 5 is a side elevation of a third preferred embodiment of the present invention with the bucket in the retracted, ground level position.

FIG. 6 is a side elevation of the third embodiment shown in FIG. 5 with the bucket extended at ground level.

FIG. 7 is a side elevation of the embodiment shown in FIG. 5 with the bucket extended and hoisted.

FIG. 8 is a side elevation of a fourth embodiment of the present invention.

Description of the preferred embodiments All four embodiments are shown in a front-end loader in which a scoop bucket 1 type of material handling implement has a capacity of about 4-8 cubic yards. The main supporting frame in each of the embodiments is a revolving frame 2 which is rotatably mounted by a swing mechanism 3 on a crawler type running gear 4. A cab 5 is mounted on the revolving frame 2 to house the usual machinery, circuitry and controls, which typically consist of an internal combustion engine with associated heat exchangers, mechanical linkages, transmissions and the like, driving hydraulic pumps with their associated reservoirs, conduits and valves, and at the very front is the housing for the operator and his necessary controls.

For the sake of brevity and clarity, it is helpful to describe similar structures of the four embodiments simultaneously. Since the third and fourth embodiments are nearly identical, in this description to follow the same reference numerals will be applied to them, so that three reference numerals for equivalent structures will appear after each element. In each embodiment, the bucket 1 is pivotally mounted on the anterior end of a

lift arm

6, 7 and 8, respectively, and each

lift arm

6, 7 and 8 has its posterior end pivotally connected to the upper anterior corner of a swinging quadrilateral 9, 10 and 11, which swings through a vertical are normal to the revolving frame 2. Crowd motion is imparted to the bucket 1 by a crowd mechanism that is anchored to the revolving frame 2 and that swings the swinging quadrilateral 9, and 11 anteriorly and posteriorly, although a crowd mechanism, such as a hydraulic cylinder mounted diagonally across the swinging quadrilateral 9, 10 and 11 between any two members will operate to the same effect. The vertical movement of the bucket 1 is effected with a hoist mechanism that is anchored to a floating

frame

12, 13 and 14, which provides the top side of the swinging quadrilateral 9, 10 and 11, respectively, and the hoist mechanism actuates the

respective lift arm

6, 7 and 8 to raise and lower it about its pivotal connection to the swinging quadrilateral 9, 10, 11. Finally, a tilt mechanism is provided to control the attitude of the bucket 1 on the end of the

lift arm

6, 7 and 8.

In the first embodiment, as in the other embodiments, the swinging quadrilateral 9 is made up of an anterior member 15 and a posterior member 16 pivotally mounted in tandem on the revolving frame 2 so as to swing in a vertical, fore and aft arc. Hence, the revolving frame 2 provides the third side of the swinging quadrilateral 9 and the floating frame 12 is the fourth side. The anterior member 15 of the swinging quadrilateral 9 is a crowd arm 15 made up of two parallel members mounted on the end of the torque tube 17 on either side of the cab 5, the torque tube 17 being mounted in the front end of the revolving frame 2. The lift arm 6, which has the bucket 1 pivotally mounted on its anterior end, has its posterior end pivotally connected to the top end of the crowd arm 15 at a hinge joint 18. In all the embodiments the lift arm may be pivoted on the floating frame or on the crowd arm near the pivotal connection of the crowd arm to the floating frame.

The floating frame 12 in the first embodiment is a triangular framework of tubular structural members joined at the apexes by corner pieces. A posterior corner piece 19 is pivotally connected to the top end of the guide link 16, and an anterior corner piece 20 is pivotally connected to the top end of the crowd arm 15 at the hinge joint 18 to link together the anterior and posterior members 15 and 16 of the swinging quadrilateral 9. The third apex of the floating frame 12 projects interiorly of the swinging quadrilateral 9, and the interior corner piece 21 forms a mounting to anchor the one end of an hydraulic cylinder 22, which serves as the hoist mechanism in this embodiment. The other end of the hydraulic hoist cylinder 22 is pivotally fastened to the lift arm 6 intermediate its ends. The anterior corner piece 20 forms a bucket tilt lever 23 that projects upwardly from the hinge joint 18, and a tilt link 24 connects the top of the bucket tilt lever 23 to the blind end of a hydraulic tilt cylinder 25, the piston rod end of which is connected to the bucket 1. An L-shaped support arm 26 has one end pivotally mounted on the lift arm 6 and the other end is connected to the junction of the tilt link 24 with the blind end of the hydraulic tilt cylinder 25, completing the tilt mechanism for the bucket 1.

The posterior member, or guide link 16, has bottom ends pivotally mounted on a bracket 27 on the revolving frame 2. Note that in this embodimentas well as in all of the other embodiments disclosed here-the posterior member, or guide link 16 is shorter than the anterior member, or crowd arm 15 of the swinging quadrilateral 9. This relationship of the lengths of the posterior member 16 and the anterior member 15 of the swinging quadrilateral 9 minimizes erratic movements of the bucket 1, as it is crowded forwardly by the action of the swinging quadrilateral 9 so that little or no operator adjustment is required for a level floor cutting operation of the bucket 1.

The crowd mechanism in the first embodiment consists of a hydraulic crowd cylinder 28, in conjunction with its connections to the other structure. The crowd cylinder 28 has one end pivotally mounted to a bracket 29 projecting from the revolving frame 2 and its other end connected to a bracket 30 on the posterior edge of the crowd arm 15. The hydraulic crowd cylinder 28 may be said to be end-mounted between the revolving frame 2 and the crowd arm 15.

FIGS. 1-3 illustrate the first embodiment of the invention in representative position throughout its operating cycle. In FIG. 1 the bucket 1 is at the beginning of its level floor, crowd movement, and the crowd cylinder 28 and the hoist cylinder 22 are completely retracted. To effect a horizontal cut at ground level, the hoist cylinder 22 is retained in its retracted position and the crowd cylinder 28 is extended shoving the bucket 1 forward along the floor level to the position shown in FIG. 2, and the tilt cylinder 25 is retained in the same partially extended condition throughout the horizontal, level floor stroke illustrated in FIGS. 1 and 2. The hoist cylinder 22 is extended to hoist the bucket 1 from the position shown in FIG. 2 to the position shown in FIG. 3, and the tilt cylinder 25 is retracted to tilt the bucket 1 upwardly so as to cut through the bank during the hoist movement toward the position shown in FIG. 3.

In the second embodiment shown in FIG. 4, the swinging quadrilateral 10 has its anterior member 31, or crowd arm 31, pivotally mounted on a bracket 32 on top of the revolving frame 2, and its posterior member 33, or guide link 33, mounted on a pedestal 34 on the revolving frame 2 behind the bracket 32 for the anterior member 31. The floating frame 13 is a solid plate having an anterior corner 35 pivotally mounted on the top of the anterior member 31 of the swinging quadrilateral 10, a posterior comer 36 pivotally connected to the top of the posterior member 33 and a hoist mechanism supporting arm 37 projecting downwardly to the interior of the swinging quadrilateral 10. The lift arm 7 is pivotally connected to the top of the crowd arm 31, and a hoist cylinder 38 is end-mounted between the hoist support arm 37 and a bracket 39 mounted on the underside of the lift arm 7. A hydraulic crowd cylinder 40 is mounted to act between the revolving frame 2 and the crowd arm 31. A hydraulic tilt cylinder 41 is endmounted between a bracket 42 on top of the lift arm 7 and the bucket 1.

The second embodiment difl' ers from the first in that the entire mechanism is mounted somewhat higher being entirely above the revolving frame 2. Also, a diiferent, solid plate type of construction is illustrated for the floating frame 13, as distinguished from the open frame employed in the first embodiment. A different mounting for the blind end of the hydraulic crowd cylinder 40 is illustrated, and the tilt mechanism omits the mechanical linkage that automatically adjusts the bucket 1 in the first embodiment to compensate for the movement of the other members of the mechanism. In the second embodiment, either the operator would have to adjust the attitude of the bucket 1, or some automatic feedback control system would be required to actuate the hydraulic tilt cylinder 41 to adjust the attitude of the bucket 1 to maintain desired bucket attitude at all points in the operating cycle.

The third and fourth embodiments appearing in FIGS. 5-7 and 8, respectively, are identical in all, but one, respect, hence it is convenient to describe the two together. The swinging quadrilateral 11 of the third and fourth embodiments has an arcuate crowd arm 43 :for an anterior member and a straight guide link 44 for a posterior member, the crowd arm 43 and the guide link 44 will be pivotally mounted in tandem on the revolving frame 2 to swing in fore and aft vertical arcs. The floating frame 14 is an open framework having a flat base 45, the ends of which are pivotally mounted, respectively, to the top of the crowd arm 43 and the guide link 44. A hoist lever 46 projects perpendicularly upward from the flat base 45 at its connection to the top of the crowd arm 43, and an arched top piece 47 joins the top of the hoist lever 46 and the posterior end of the base 45. The lift arm 8 has the shape of an inverted, wide V, one leg of which is horizontal and has its posterior end pivotally fastened on the end of the crowd arm 43. The other end of the horizontal leg 48 meets another leg 49 of the lift arm 8 at a knee 50, this other leg 49 being generally vertical, and the lower end of the leg 49 terminates in a foot 51 on which the scoop bucket 1 is pivotally mounted. A hydraulic hoist cylinder 52 is end-mounted between the top of the hoist lever 46 of the floating frame 14 and a bracket 53 on the top of the knee 49 of the lift arm 8. A bucket tilt cylinder 54 has its piston rod connected to the bucket 1 and its blind end suspended from a suspension arm 55 hanging from the horizontal leg 48 of the lift arm 8, and a tilt link 56 connects the blind end of the bucket tilt cylinder 54 to the top member 47 of the floating frame 14 so that the bucket tilt cylinder 54 is also anchored against the floating frame 14 in its action on the bucket 1. In the third embodiment, a hydraulic crowd cylinder 57 has its blind end anchored at the pivotal mounting of the guide link 44 on the revolving frame 2 and its piston rod connected to the crowd arm 43, but in the fourth embodiment, a hydraulic crowd cylinder 58 has its blind end pivotally mounted to the revolving frame 2 behind the guide link 44 and its piston rod connected to the guide link 44. Hence, in the third embodiment, as in the previous embodiments, the hydraulic crowd cylinder 57 swings the swinging quadrilateral 11 by pivoting the crowd arm 43 about its mounting on the revolving frame 2, but in the fourth embodiment, the hydraulic crowd cylinder 58 acts directly on the guide link 44, and by pivoting the guide link 44 it swings the swinging quadn'lateral 11.

In the third and fourth embodiments, the swinging quadrilateral 11 is kept behind the operators compartment of the cab 5 by means of the arcuate shape of the crowd arm 43. The angled lift arm 8 with its extended horizontal leg 48 keeps the lift arm 8 above and in front of the operators compartment. The inverted floating frame 14 with its hoist mechanism anchoring attachment projecting upwardly on the end of the hoist lever 46 raises the hoist mechanism above the operators compartment. Only the bucket tilt mechanism crosses the operators compartment, but it does not detrimentally obstruct the operators vision. Obviously, the bucket tilt mechanism could also be moved to the front of the vertical leg 49 of the lift arm 8 by employing a system similar to that shown in the second embodiment.

FIGS. 5, 6 and 7 illustrate the operating positions for the third and fourth embodiments corresponding to the operating positions of the first embodiment as shown in FIGS. 1, 2 and 3, except that in FIG. 7 the bucket is shown tilted for high digging or partial dumping while in FIG. 3 the bucket is shown in its carry position. FIG. 5 shows the swinging quadrilateral 11 swung to its extreme posterior position by the crowd cylinder 57. Thus, in FIG. 5 the bucket 1 is retracted to its posterior position, and since the hoist cylinder 52 and the tilt cylinder 54 are extended, the bucket 1 is at ground level and opening forwardly. When the crowd cylinder 57 is extended, the hoist cylinder 52 and the tilt cylinder 54 remaining the same, the bucket 1 is crowded horizontally forward to cut a level floor to the position shown in FIG. 6. By retracting the hoist cylinder 52, the bucket is raised to the position shown in FIG. 7.

If all of the possible positions of the bucket 1 were plotted in any one of the embodiments shown, an area would be defined having the shape of a distorted parallelogram with two sides curved. The posterior arcuate limit of the distorted parallelogram would be described by pass ing the bucket 1 through its entire hoist range with the

crowd cylinder

28, 40, 57 and 58 completely retracted, and the anterior arcuate limit would be described by hoisting the bucket 1 with the

crowd cylinder

28, 40, 57 and 58 fully extended. The top and bottom of the distorted parallelogram would be of equal length and defined by the reach of the bucket 1 achieved by crowding the swinging quadrilateral 9, 10 and 11. The bucket 1 can be placed anywhere within that arcuate area, and therefore it can dig a level floor at any height within its hoist range and can be retracted or thrust forward at its maximum height for dumping. Such flexibility, maneuverability and range of movement is made available in front-end loaders for the first time by the present invention.

The four embodiments described above illustrate different ways in which the present invention may be ap plied, either to achieve slightly different results in some respects or to employ different types of structural materials. However, the invention is not confined to these four embodiments or any other embodiments not shown here but rather is set forth in the claims that follow. Also, while the invention has been described in relation to its use with a bucket it can be effectively employed for providing crowd capability to other material handling implements such as a fork lift.

Iclaim:

1. A loader apparatus comprising the combination of a main supporting frame;

a swinging quadrilateral having four members including said main supporting frame, an anterior member having one end pivotally mounted on said main supporting frame, a posterior member having one end pivotally mounted on said main supporting frame behind said anterior member and a floating frame joining said anterior and posterior members spaced from said main supporting frame;

a lift arm having a material handling implement mounted on its anterior end and having its posterior end pivotally mounted to said swinging quadrilateral;

a crowd mechanism acting between at least two members of said swinging quadrilateral to cause said posterior and anterior members to pivot about their pivotal mountings on the main supporting frame; and

a hoist mechanism mounted between said floating frame and said lift arm to pivot said lift arm about its connection to said swinging quadrilateral.

2. A loader apparatus as set forth in claim 1 wherein said swinging quadrilateral projects generally normal to said revolving frame, and said floating frame has a depending projection; and

said hoist mechanism is a hydraulic cylinder mounted between said depending projection on said floating frame and said lift arm.

3. A loader apparatus as set forth in claim 2 wherein said floating frame is an open framework having three corners.

4. A loader apparatus as set forth in claim 2 wherein said floating frame is a solid plate member.

5. A loader apparatus as set forth in claim 1 wherein said crowd mechanism is a hydraulic cylinder mounted between said main supporting frame and said anterior member of said swinging quadrilateral.

6. A loader apparatus as set forth in claim 1 wherein said crowd mechanism is a hydraulic cylinder mounted between said main supporting frame and said posterior member of said swinging quadrilateral.

7. A loader apparatus as set forth in claim 1 wherein said lift arm is an angled member having one leg adjacent its posterior end and another leg adjacent its anterior end, said legs converging together to be joined at a knee.

8. A loader apparatus as set forth in claim 7 wherein said floating frame has an upwardly projecting hoist lever; and

this said hoist mechanism is a hydraulic cylinder mounted between a top end of said hoist lever and said knee on said lift arm.

9. A loader apparatus as set forth in claim 8 wherein said anterior member of said swinging quadrilateral is an arcuate shaped crowd arm.

10. A loader apparatus comprising the combination of a main supporting frame;

a swinging quadrilateral supported on and including said main supporting frame as one of its four members to swing through an are generally normal to said main supporting frame and having an anterior member with one end pivotally mounted on said main supporting frame, a posterior member having one end pivotally mounted on said main supporting frame in tandem with said anterior member, said posterior member being shorter than said anterior member, and a floating frame as a top member of said swinging quadrilateral and being pivotally connected to said anterior member and to said posterior member;

a lift arm being pivotally connected to said swinging quadrilateral and suporting a material handling implement on its end;

a hoist mechanism including a hydraulic cylinder mounted between said floating frame and said lift arm for pivoting said lift arm about its pivotal connection to said swinging quadrilateral; and

a crowd mechanism acting between at least two of said four members of said swinging quadrilateral to cause said posterior and anterior members to pivot about their mountings on said main supporting frame.

11. A loader apparatus as set forth in claim 10 wherein said crowd mechanism is a hydraulic cylinder mounted between said main supporting frame and said anterior member of said swinging quadrilateral.

12. A loader apparatus as set forth in claim 10 wherein said crowd .mechanism is a hydraulic cylinder mounted between said main supporting frame and said posterior member of said swinging quadrilateral.

13. A loader apparatus as set forth in claim 10 wherein said material handling implement is pivotally supported on the end of said lift arm; and

a tilt mechanism is connected to said material handling implement to control the attitude of said material handling implement about its pivotal connection to said lift arm.

14. A loader apparatus as set forth in claim 13 wherein said tilt mechanism includes a hydraulic cylinder connected between said lift arm and said material handling implement.

15. A loader apparatus as set forth in claim 13 wherein said tilt mechanism includes a hydraulic cylinder connected between said floating frame and said material handling implement to control the attitude of said materialhandling implement.

16. A loading apparatus with crowd action capability comprising the combination of a main supporting frame;

a crowd arm having a lower end pivotally mounted and said crowd arm to swing in unison about their respective pivotal mountings;

a hydraulic crowd actuator anchored to said supporting frame and connected to swing said crowd arm and said guide link about their pivotal mountings; and

a hydraulic hoist actuator connected between said floating frame and said lift arm to pivot said lift arm about its pivotal mounting on said upper end of said crowd arm.

17. A loader apparatus as set forth in claim 16 wherein said guide link is shorter than said crowd arm to guide said scoop bucket in a substantially horizontal path when said hydraulic crowd actuator swings said crowd arm and said guide link.

18. A loader apparatus as set forth in claim 16 wherein a bucket tilt .mechanism is connected between said floating frame and said bucket to automatically control the attitude of said bucket when said lift arm is pivoted by said hydraulic hoist actuator to maintain a preset attitude of said bucket.

19. A loader apparatus as set forth in claim 16 wherein said bucket tilt mechanism includes a hydraulic cylinder connected to said bucket for operator adjustment of said bucket attitude.

20. A loader apparatus as set forth in claim 16 wherein said hydraulic crowd actuator is a hydraulic cylinder end-mounted between said main frame and said crowd arm.

21. A loader apparatus as set forth in claim 16 wherein said floating frame has a projection extending downwardly intermediate its ends; and

said hydraulic hoist actuator is a hydraulic cylinder end-mounted between said projection on said floating frame and an underside of said lift arm.

22. A loader apparatus as set forth in claim 16 wherein said floating frame has a hoist lever projecting upwardly from its anterior end; and

said hydraulic hoist actuator is a hydraulic cylinder end-mounted between said hoist lever on said floating frame and said lift arm.

23. A loader apparatus as set forth in claim 16 wherein said floating frame is a solid plate structure having at least three corners, two of said corners being said ends pivotally fastened to said guide link and said crowd arm, respectively.

24. A loader apparatus as set forth in claim 16 wherein said main supporting frame is a revolving frame rotatably supported by a swing mechanism on a crawler type running gear and supporting a cab for housing an operator and a power source for said apparatus.

References Cited UNITED STATES PATENTS 2,795,342 6/1957 Steele 21478 3,024,933 3/1962 Albert et a1. 21477O X 3,197,049 7/1965 SchWing 214138 HUGO O. SCHULZ, Primary Examiner US. Cl. X.R. 214141