US3785156A

US3785156A - Hydraulic control for self-loading scraper with three-speed elevator drive

Info

Publication number: US3785156A
Application number: US00212136A
Authority: US
Inventors: J Junck; J Kokaly
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1971-12-27
Filing date: 1971-12-27
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15

Abstract

A hydraulic control system for a self-loading scraper elevator drive having a plurality of pumps for combined control of the scraper bowl, ejector, and elevator drives, the flow from the pumps being selectively combinable under the control of an operator to vary the speed of the elevator drive to accommodate different conditions of machine operation. The system permits more efficient utilization of the available engine torque which must be used for propelling the vehicle and driving the scraper bowl, ejector and elevator.

Description

United States Patent Junck et al.

[ Jan. 15, 1974 HYDRAULIC CONTROL FOR SELF-LOADING SCRAPER WITH THREE-SPEED ELEVATOR DRIVE Inventors: John A. Junck, Joliet, 111.; Joseph Kokaly, Buckeye, Ariz.

Assignee: Caterpillar Tractor Co., Peoria, 111.

Filed: Dec. 27, 1971 Appl. No.: 212,136

U.S. Cl 60/421, 60/471, 91/414 Int. Cl. F1611 39/48 Field of Search 60/52 HE, 375, 421,

References Cited UNITED STATES PATENTS 12/1937 Henry 60/421 X 3/1942 Vosseler et a1 60/53 R UX 2,879,612 3/1959 Schultz at al 611/52 Hli X 3,258,926 7/1966 Junck et a1..., 60/52 HE X 3,443,380 5/1969 Karazija 60/52 HE Primary Examiner-Edgar W. Geoghegan Attorney-Leonard Phillips [57] ABSTRACT 3 Claims, 1 Drawing Figure 3 RESERV O HYDRAULIC CONTROL FOR SELF-LOADING SCRAPER WITH THREE-SPEED ELEVATOR DRIVE BACKGROUND OF THE INVENTION In recent years elevating self-loading scrapers have been developed into production tools which are required to handle a variety of materials from rock and relatively undisturbed soils to more'easily handled materials such as sand and windrows. As a result the de mands on the drive mechanism of these self-loading scrapers have resulted in the advent of electric and hydraulic drives for more rugged and dependable operation as well as greater flexibility and simplicity in providing the correct elevator speeds.

As the use of the self-loading scraper has been extended to a considerable variety of materials, the torque requirements for propelling the vehicle and for driving the elevator varies with each material encountered. For example, when loading extremely strong undisturbed materials, a considerable amount of torque is required to propel the machine along the ground in view of the resistance to movement of the scraper cutting edge through the material being loaded. This dictates that a large portion of the available torque be directed to the tractor wheels to maintain movement of the vehicle.

When loading rocks it is necessary that the resistor be driven rather slowly such that the impact of the flights on the rocks will not result in forces damaging or destroying the elevator construction. When the scraper is used for the loading of average or light materials the torque requirement for propelling the vehicle is less severe. Therefore, more of the torque may be used to drive the elevator with the result that a higher speed drive and thus increased loading efficiency may be achieved.

When the scraper is used for loading sand, windrows, and other easily handled materials, a substantial portion of the available torque may be used for driving the elevator, thus permitting it to be operated at a substantially higher speed to increase the rate of loading. Therefore it is desirable that an elevator drive be provided which will permit the operator to select the elevator speed most compatible with the conditions under which the scraper is being operated.

SUMMARY OF THE INVENTION The present invention relates to an improved hydraulic control system for self-loading scrapers of the elevating type, and more particularly to a combined control system wherein three pumps are used for supply of fluid to the circuit to control the scraper bowl and ejector drives as well as to provide three speeds of elevator drive.

In the accomplishment of the foregoing and other advantages and features, the control system of the present invention generally includes a control valve for selectively channeling the flow of fluid from a pump to the scraper bowl and ejector drives to effect bowl lift and ejector operations, and for selectively combining and channeling the fluid flows from such pump and two additional pumps to the elevator drive to effect selectable speed control of the elevator.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a schematic fluid circuit diagram of a hydraulic control system in accordance with the present invention, a control valve of the system being shown in elevation with portions broken away.

DETAILED DESCRIPTION OF THE INVENTION Considering now the invention in detail and referring to the illustrated form thereof in the drawing, there will be seen to be provided a hydraulic control system for selectively controlling the operations of the bowl, ejector, and elevator drives of an elevating self-loading scraper.

The bowl drive includes the usual pair of bowl lift jacks 11 for raising or lowering the: bowl in accordance with the direction of fluid flow to and from the opposite ends of the jack cylinders. The ejector drive comprises an ejector jack 12 for operating or retracting the ejector depending upon the direction of fluid flow to and from the ends of the jack cylinder in a conventional manner. The elevator drive comprises a hydraulic motor 13 coupled to the elevator to drive same at a speed determined by the volume of fluid flow through the motor.

The control system basically includes a plurality of

pumps

14, 16 and 17 and a three-spool control valve 18, or equivalent means for selectively channeling the flow of output fluid from the pumps to the bowl jacks ll, ejector jack 12, and elevator drive motor 13. More particularly, the valve comprises a body 19 having three

parallel bores

21, 22 and 23 for reciprocably housing bowl, ejector and elevator

speed control spools

24, 26 and 27. The vlave body is provided with

inlet ports

28, 29 and 31, a fluid return port 32, and control ports 33, 34 and 36.

The pump 14 is adapted to draw fluid from reservoir 37 for supply through a conduit 38 to inlet port 28, and the return port 32 is connected via conduit 39 to the reservoir. Pumps 16 and 17 are likewise adapted to draw fluid from reservoir 37 for supply through

conduits

41 and 42 to inlet ports 29 and 31.

Inlet port 28 is communicated with a central portion 43 of bore 21, in turn communicated with a central portion 44 of bore 22 by means of a bifurcated passage 46. A bifurcated passage 47 communicates the central portion 44 of bore 22 with a central portion 48 of bore 23, and central portion 48 communicates with return port 32 via a passage 49.

First end portions 51, 52 and 53 of

bores

21, 22 and 23 are commonly communicated with return passage 49 by means of an interconnecting passage 54, and a passage 56 commonly communicates second

opposite end portions

57, 58 and 59 with passage 49.

Inlet port 29 is communicated with an intermediate portion 61 of bore 23 disposed between central portion 48 and the second end portion 59 thereof. Inlet port 31 is communicated with an intermediate portion 62 of bore 23 disposed between the first end portion 53 and central portion 48 thereof.

Bore 21 is similarly provided with portions 63 and 64 respectively intermediate central portion 43 and opposite end portions 51 and 57, and bore 22 is provided with portions 66 and 67 respectively intermediate central portion 44 and

opposite end portions

52 and 58. Intermediate bore portions 64 and 67 are commonly communicated with control port 33 via an interconnecting passage 68. Intermediate bore portions 63 and 66 are respectively communicated with control ports 34 and 36.

Control port 33 is then commonly connected by means of conduit 69 to one end of the cylinders of bowl jacks 11 and one end of the cylinder of ejector jack 12. Control port 34 is connected via conduit 71 to the second ends of the cylinders of the bowl jacks, and control port 36 is connected via conduit 72 to the second end of the cylinder of the ejector jack.

With regard to the connections of the elevator drive motor 13 to the hydraulic control system, it is to be noted that the supply conduit 41 from pump 16 is connected to the inlet port of the motor by means of a conduit 73 and check valve 74. The inlet port of the motor 13 is also connected via conduit 76 to the supply conduit 42 of pump 17. The outlet port of the motor is connected via conduit 77 to the reservoir 37. A releif valve 78 is paralleled with the motor and a relief valve 79 is paralleled with pump 14 to limit maximum pressure in the elevator drive circuit and in the bowl and ejector control portion of the circuit.

Considering now the

control spools

24, 26 and 27 in more detail, it is to be noted that same are appropriately configured to control the flow of fluid from the

pumps

14, 16 and 17 through the valve 18 to the elevator motor 13 and bowl and ejector jacks 11 and 12 in accordance with the positions of the spools in the

bores

21, 22 and 23.

More particularly, bowl control spool 24 is of such a configuration that in a neutral position (N) thereof, as shown in the drawing, communication is permitted between inlet port 28 and central portion 43 of bore 21, as well as between such central portion and passage 46 leading to central portion 44 of bore 22. At the same time, communication is blocked between central portion 43 and intermediate portions 63 and 64, as well as between the intermediate portions 63 and 64 and respective end portions 51 and 57.

Ejector spool 26 is similarly configured such that in a neutral position (N) thereof, as shown in the drawing, communication is permitted between passage 46 and central portion 44 of bore 22, and between central portion 44 and passage 47. At this time communication is blocked between central portion 44 and intermediate portions 66 and 67 of bore 22, as well as between such intermediate portions and

end portions

52 and 58.

Elevator spool 27 is of a configuration such that in a neutral position (N) thereof, as shown in the drawing, communication is permitted between central porition 48 of bore 23 and passages 47 and 49. Communication is simultaneously blocked between central portion 48 and intermediate portions 61 and 62. However, communication is permitted between intermediate portion 61 and end portion 59 and between intermediate portion 62 and end portion 53.

It will be thus appreciated that with all of the

spools

24, 26 and 27 in neutral position, pump 14 returns fluid to reservoir 37 via a path including inlet port 28, central portion 43 of bore 21, passage 46, central portion 44 of bore 22, passage 47, central portion 48 of bore 23, passage 49, return port 32, and conduit 39. Pump 16 returns fluid to reservoir 37 via a path comprising inlet port 29, intermediate and end portions 61 and 59 of bore 23, passage 49, return port 32 and conduit 39. Pump 17 returns fluid to reservoir 37 via a path comprising inlet port 31, intermediate and end portions 62 and 53, passage 49, return port 32 and conduit 39. Consequently, the valve 18 diverts the output flows from

pumps

14, 16 and 17 directly to reservoir 37 and away from the hydraulic drives for the bowl, ejector, and elevator, when the spools are in their neutral positions.

The configuration of the bowl control spool 24 is further arranged such that in a raise position (R) thereof shifted to the right from the position depicted in the drawing, communication is blocked between inlet port 28 and central portion 43 of bore 21, while communication is established between such port and intermediate portion 63. Communication is still blocked between intermediate portion 63 and end portion 51, but communication is established between intermediate portion 64 and end portion 57.

With the

spools

26 and 27 in their neutral positions, flow is at this time effected from pump 14 to the appropriate ends of bowl lift jacks 11 to produce raising of the bowl, while flow is effected from the opposite ends of the jacks to the reservoir 37.

More particularly, the output supply of fluid from pump 14 flows via a path including conduit 38, inlet port 28, intermediate portion 63 of bore 21, control port 34, and conduit 71 to the lower ends of the jacks 11. The upper ends of the jacks are communicated with the reservoir 37 via a path comprising conduit 69, control port 33, intermediate portion 67 of bore 22, passage 68, intermediate and end portions 64 and 57 of bore 21, passages 56 and 49, return port 32 and conduit 39.

When the control spool 24 is moved to a lower posi tion (L) shifted to the left from the position depicted in the drawing, communication is blocked between inlet port 28 and central portion 43, while communication is established between the inlet port and intermediate portion 64. Communication is blocked between intermediate portion 64 and end portion 57, while communication is established between intermediate portion 63 and end portion 51. As a result, flow is established from pump 14 to the upper ends or lift jacks 11, while flow is established from the lower ends thereof to the reservoir 37 to thereby effect lowering of the bowl.

In this regard, the output supply of fluid from pump 14 flows via a path including conduit 38, inlet port 28, intermediate portion 64 of bore 21, passage 68, intermediate portion 67 of bore 22, control port 33, and conduit 69 to the upper ends of the jacks 11. The lower ends of the jacks are communicated with the reservoir 37 via a path comprising conduit 71, control port 34, intermediate and end portions 63 and 51 of bore 21, passages 54 and 49, return port 32 and conduit 39.

The configuration of ejector spool 26 is also arranged such that in the retract position (R) shifted to the right from the position depicted in the drawing, communication is blocked between passage 46 and central portion 44 of bore 22. Communication is at this time established between passage 46 and intermediate portion 66 of bore 22, while communication is blocked between passage 46 and intermediate portion 67. Communication is blocked between intermediate and end portions 66 and 52, and established between intermediate and end portions 67 and 58.

Thus, in the retract position of spool 26, spools 24 and 27 being in their neutral positions, the output supply of fluid from pump 14 flows via a path comprising conduit 38, inlet port 28, central portion 43 of bore 21, passage 46, intermediate portion 66 of bore 22, control port 36, and conduit 72 to a first end of ejectorjack 12. At the same time, the second end ofjack 12 is communicated with reservoir 37 via a path comprising conduit 69, control port 33, intermediate and end portions 67 and 58 of bore 22, passages 56 and 49, return port 32, and conduit 39. As a result, the jack 12 retracts the ejector.

In response to movement of the spool 26 to an eject position (E) shifted to the left from the position depicted in the drawing, communication is blocked between passage 46 and central portion 44 of bore 22. Communication is established between passage 46 and intermediate portion 67 of bore 22, while communication is blocked between passage 46 and intermediate portion 66. Communication is established between intermediate and end portions 66 and 52, while communication is blocked between intermediate and end portions 67 and 58. Consequently, the output supply of fluid from pump 14 flows via a path defined by conduit 38, inlet port 28, central portion 43 of bore 21, passage 46, intermediate portion 67 of bore 22, control port 33, and conduit 69 to the second end of jack 12. The first end of jack 12 is communicated with reservoir 37 via a path comprising control port 36, intermediate and end portions 66 and 52 of bore 22, passages 54 and 49, return port 32, and conduit 39. The flow conditions are thus such as to effect an eject stroke of the ejector.

[t is to be noted that the elevator spool 27 is arranged to provide three speeds of the elevator motor 13 responsive to the spool being respectively in low (L), medium (M), and high (H) speed positions. When the spool is in the low speed position, communication is permitted between central portion 48 of bore 23 and passages 47 and 49. Communication is blocked between intermediate portion 62 and passage 47 and end portion 53. Communication is blocked between intermediate portion 61 and passage 47, while communication is established between intermediate portion 61 and end portion 59.

With the bowl and ejector spools 24 and 26 in neutral position, the output supply of fluid from pump 14 is returned to reservoir 37 via a path defined by conduit 38, inlet port 28, central portion 43 of bore 21, passage 46, central portion 44 of bore 22, passage 47, central portion 48 of bore 23, passage 49, return port 32, and conduit 39. The output supply of fluid from pump 16 is returned to reservoir 37 via a path comprising conduit 41, inlet port 29, intermediate and end portions 61 and 59 of bore 23, passage 49, return port 32 and conduit 39.

However, at the same time, communication between pump 17 and reservoir 37 is interrupted by virtue of spool 27 blocking portion 62 of bore 23 from portion 53. Under these conditions, the output of pump 17 is redirected through conduits 76 and 73 from where it flows through motor 13, effecting relatively slow speed drive of the elevator, and is discharged from the motor through conduit 77 to reservoir 37. This results in a minimum of the available torque being used to drive the elevator such that sufficient torque is available to the tractor wheels for propelling the vehicle. Such distribution of torque is desirable when loading relatively strong materials and/or rocks where considerable torque is required for propelling the vehicle, or when relatively high flight speed might result in damage to the elevator.

The medium speed position of spool 27 establishes flow conditions which are particularly appropriate when the scraper is used for the loading of average soils and the torque requirements for driving the elevator and propelling the machine permit the use of a somewhat higher elevator speed to achieve the maximum loading rate.

More particularly, when the spool 27 is in the medium speed position, communication is still blocked between intermediate and end portions 62 and 53, and communication is still permitted between central portion 48 and passages 47 and 49. However, communication is now blocked between intermediate and end portions 61 and 59. Thus, as in the case of the low speed position of the spool, the output of pump 17 is redirected through motor 13, while the output of pump 14 is returned to the reservoir 37 via the same flow path previously described. However, in addition, the output of pump 16 is now blocked from the reservoir and is redirected through check valve 74 and conduit 73 where it is combined with the discharge volume of pump 17 to effect medium speed drive of elevator motor 13.

When the scraper is used for loading sand, windrows, or other easy to load materials, the torque requirements of propelling the vehicle are relatively low such that the speed of the elevator may be increased. The high speed position of spool 27 establishes flow conditions to the foregoing ends. In this regard, when the spool is in the high speed position, it maintains the conditions hereinbefore described for medium speed and in addition blocks communication between passage 47 and central portion 48 of bore 23 and establishes communication between passage 47 and intermediate portion 61 of bore 23. Under these conditions the discharge volume from pump 14 flows via the path previously described as far as passage 47 whereat it is diverted via bore portion 61 to port 29 and conduit 41 for combination with the output volume of pump 16. These combined volumes flow through check valve 74 to conduit 73 where they are combined with the output of pump 17 with the total volume of all three pumps being directed through motor 13 to effect high speed drive of the elevator.

Under the conditions just described, should either of

spools

24 or 26 be actuated to one of the operative positions to divert the volume of pump 14 to the bowl lift jacks 11 or ejector jack 12, the fluid returning from the opposite ends of the actuated jacks is returned to reservoir 37 by way of one or the other of

passages

54 or 56, passage 49, return port 32 and conduit 39.

This results in the speed of motor 13 being reduced to that provided by the combined volumes of pumps 16 and 17, or, in other words, the same speed as that provided with spool 27 in the previously described medium speed position. It should be noted that when spool 27 is in either of the medium or low speed positions, actuation of

spools

24 and 26 does not affect the speed at which motor 13, and hence the elevator, is driven.

Although the invention has been hereinbefore described and illustrated in the accompanying drawing with respect to a single preferred embodiment, it will be appreciated that various modifications and changes may be made therein without departing from the true spirit and scope of the invention, and thus it is not intended to limit the invention except by the terms of the appended claims.

I claim:

1. A multiple speed hydraulic drive for an elevating self-loading scraper comprising a. hydraulic elevator drive motor, a fluid reservoir, at least three pumps communicating with said reservoir and having outlet sides communicably coupled to a first side of said motor, means communicably coupling a second side of said motor to said reservoir, and valve means coupled between said outlet sides of said pumps and said reservoir and operable by movement of a single valving element thereof to selectively divert the fluid flows thereof from said first side of said motor to said reservoir whereby flow from one pump may be selectively supplied to said motor to drive said motor at one speed, flow from another pump may be selectively supplied to said motor in addition to said flow from said one pump to drive said motor at another, higher speed, and flow from the other pump may be selectively supplied to said motor in addition to said flows from said one and said another pumps to drive said motor at another, still higher speed.

2. A hydraulic control for an elevating self-loading scraper comprising bowl lift hydraulic jacks having first and second ends for inlet or outlet of fluid, an ejector hydraulic jack having first and second ends for inlet or outlet of fluid, an elevator hydraulic drive motor having first and second sides respectively for inlet and outlet of fluid, a fluid reservoir, means communicating said second side of said motor with said reservoir, first, second, and third pumps having inlet sides communicated with said reservoir and having outlet sides, means communicably connecting said outlet sides of said second and third pumps to said first side of said motor, and a spool control valve including bowl, ejector, and elevator speed control spools and having first, second, and third inlet ports, a fluid return port, and first, second, and third control ports, said bowl lift spool having se lectable neutral, raise, and lower positions, said ejector spool having selectable neutral, eject, and retract positions, said elevator spool having selectable neutral, low, medium, and high speed positions, said outlet sides of said first, second, and third pumps respectively communicably connected to said first, second, and third inlet ports, said return port communicably connected to said reservoir, said first control port communicably connected to said first ends of said bowl lift jacks, said second control port communicably connected to said first end of said ejector jack, said third control port communicably connected to said second ends of bowl lift jacks and to said second end of said ejector jack, said valve being arranged to communicate said first, second, and third inlet ports with said return port responsive to said bowl, ejector, and elevator spools being in said neutral positions thereof, said valve being arranged to communicate said first inlet port with said first control port and communicate said third control port with said return port responsive to said bowl spool being in said raise position thereof, said valve being arranged to communicate said first inlet port with said third control port and communicate said first control port with said return port responsive to said bowl spool being in said lower position thereof, said valve being arranged to communicate said first inlet port with said second control port and communicate said third control port with said return port responsive to said ejector spool being in said eject position thereof while said bowl spool is in said neutral position thereof, said valve being arranged to communicate said first inlet port with said third control port and communicate said second control port with said return port responsive to said ejector spool being in said retract position thereof while said bowl spool is in said neutral position thereof, said valve being arranged to communicate said second inlet port with said return port and block communication between said third inlet port and said return port while communicating said first inlet port with said return port responsive to said elevator spool being in said low speed position thereof while said bowl and ejector spools are in said neutral positions thereof, said valve being arranged to block communication between said second and third inlet ports and said return port while communicating said first inlet port with said return port responsive to said elevator spool being in said medium speed position thereof while said bowl and ejector jacks are in said neutral positions thereof, said valve being arranged to block communication between said second and third inlet ports and said return port while establishing communication between said first inlet port and said second inlet port responsive to said elevator spool being in said high speed position thereof while said bowl and ejector spools are in said neutral positions thereof.

3. A hydraulic control according to claim 2, further defined by said valve having a body including said inlet, return, and control ports, said body having a first bore housing said bowl spool for reciprocation therein between said neutral, raise and lower positions thereof, said body having a second bore housing said ejector spool for reciprocation therein between said neutral, eject, and retract positions thereof, said body having a third bore housing said elevator spool for reciprocation therein between said neutral, low, medium, and high speed positions thereof, said first, second, and third bores respectively having central portions, first and second opposite end portions, and first and second intermediate portions between said central portion and said first and second end portions, said first inlet port communicated with said central portion of said first bore, said second and third inlet ports respectively communicated with said first and second intermediate portions of said third bore, said first and second control ports respectively communicated with said second intermediate portions of said first and second bores, said third control port communicated with said first intermediate portion of said second bore, said body having a passage communicating said central portions of said first and second bores, a second passage communicating said central portions of said second and third bores, a third passage communicating said central portion of said third bore with said return port, a fourth passage communicably connecting said first end portions of said first, second and third bores to said third passage, a fifth passage communicably connecting said second end portions of said first, second and third bores to said third passage, and a sixth passage communicably connecting said first intermediate portions of said first and second bores, said bowl spool being configured to block communication between said central portion and first and second intermediate portions of said first bore, block communication between said first and second intermediate portions and first and second end portions of said first bore, and permit communication between said central portion of said first bore and said first passage in said neutral position thereof, block communica tion between said first inlet port and said central portion of said first bore, block communication between said first inlet'port and said first intermediate portion of said first bore, block communication between said central portion and first intermediate portion of said first bore, block communication between said second intermediate and end portions of said first bore, establish communication between said first inlet port and second intermediate portion of said first bore, and establish communication between said first intermediate and end portions of said first bore in said raise position thereof, and block communication between said first inlet port and said central portion of said first bore, block communication between said first inlet port and said second intermediate portion of said first bore, block communication between said central portion and second intermediate portion of said first bore, block communication between said first intermediate and end portions of said first bore, establish communication between said first inlet port and first intermediate portion of said first bore, and establish communication between said second intermediate and end portions of said first bore in said lower position thereof, said ejector spool being configured to permit communication between said central portion of said second bore and said first and second passages, block communication between said central and first and second intermediate portions of said second bore, and block communication between said first and second intermediate portions and first and second end portions of said second bore in said neutral position thereof, block communication between said central portion of said second bore and said first passage, block communication between said central and first and second intermediate portions of said second bore, block communication between said first intermediate and end portions of said second bore, establish communication between said first passage and said first intermediate portion of said second bore, and establish communication between said second intermediate and end portions of said second bore in said eject position thereof, and block communication between said central portion of said second bore and said first passage, block communication between said central and first and second intermediate portions of said second bore, block communication between said second intermediate and end portions of said second bore, cs

tablish communication between said first passage and said second intermediate portion of said second bore, and establish communication between said first intermediate and end portions of said second bore in said retract position thereof, said elevator spool being configured to permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, establish communication between said first intermediate and end portions of said third bore, and establish communication between said second intermediate and end portions of said third bore in said neutral position thereof, permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, permit communication between said first intermediate and end portions of said third bore, and block communication between said second intermediate and end portions of said third bore in said low speed position thereof, permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, block communication between said first intermediate and end portions of said third bore, and block communication between said second intermediate and end portions of said third bore in said medium speed position thereof, and block communication between said central portion of said third bore and said second passage, block communication between said central and first and second intermediate portions of said third bore, block communication between said first intermediate and end portions of said third bore, block communication between said second intermediate and end portions of said third bore, and establish communication between said second passage and said first intermediate portion of said third bore in said high speed position thereof.

Claims

1. A multiple speed hydraulic drive for an elevating selfloading scraper comprising a hydraulic elevator drive motor, a fluid reservoir, at least three pumps communicating with said reservoir and having outlet sides communicably coupled to a first side of said motor, means communicably coupling a second side of said motor to said reservoir, and valve means coupled between said outlet sides of said pumps and said reservoir and operable by movement of a single valving element thereof to selectively divert the fluid flows thereof from said first side of said motor to said reservoir whereby flow from one pump may be selectively supplied to said motor to drive said motor at one speed, flow from another pump may be selectively supplied to said motor in addition to said flow from said one pump to drive said motor at another, higher speed, and flow from the other pump may be selectively supplied to said motor in addition to said flows from said one and said another pumps to drive said motor at another, still higher speed.

2. A hydraulic control for an elevating self-loading scraper comprising bowl lift hydraulic jacks having first and second ends for inlet or outlet of fluid, an ejector hydraulic jack having first and second ends for inlet or outlet of fluid, an elevator hydraulic drive motor having first and second sides respectively for inlet and outlet of fluid, a fluid reservoir, means communicating said second side of said motor with said reservoir, first, second, and third pumps having inlet sides communicated with said reservoir and having outlet sides, means communicably connecting said outlet sides of said second and third pumps to said first side of said motor, and a spool control valve including bowl, ejector, and elevator speed control spools and having first, second, and third inlet ports, a fluid return port, and first, second, and third control ports, said bowl lift spool having selectable neutral, raise, and lower positions, said ejector spool having selectable neutral, eject, and retract positions, said elevator spool having selectable neutral, low, medium, and high speed positions, said outlet sides of said first, second, and third pumps respectively communicably connected to said first, second, and third inlet ports, said return port communicably connected to said reservoir, said first control port communicably connected to said first ends of said bowl lift jacks, said second control port communicably connected to said first end of said ejector jack, said third control port communicably connected to said second ends of bowl lift jacks and to said second end of said ejector jack, said valve being arranged to communicate said first, second, and third inlet ports with said return port responsive to said bowl, ejector, and elevator spools being in said neutral positions thereof, said valve being arrangEd to communicate said first inlet port with said first control port and communicate said third control port with said return port responsive to said bowl spool being in said raise position thereof, said valve being arranged to communicate said first inlet port with said third control port and communicate said first control port with said return port responsive to said bowl spool being in said lower position thereof, said valve being arranged to communicate said first inlet port with said second control port and communicate said third control port with said return port responsive to said ejector spool being in said eject position thereof while said bowl spool is in said neutral position thereof, said valve being arranged to communicate said first inlet port with said third control port and communicate said second control port with said return port responsive to said ejector spool being in said retract position thereof while said bowl spool is in said neutral position thereof, said valve being arranged to communicate said second inlet port with said return port and block communication between said third inlet port and said return port while communicating said first inlet port with said return port responsive to said elevator spool being in said low speed position thereof while said bowl and ejector spools are in said neutral positions thereof, said valve being arranged to block communication between said second and third inlet ports and said return port while communicating said first inlet port with said return port responsive to said elevator spool being in said medium speed position thereof while said bowl and ejector jacks are in said neutral positions thereof, said valve being arranged to block communication between said second and third inlet ports and said return port while establishing communication between said first inlet port and said second inlet port responsive to said elevator spool being in said high speed position thereof while said bowl and ejector spools are in said neutral positions thereof.

3. A hydraulic control according to claim 2, further defined by said valve having a body including said inlet, return, and control ports, said body having a first bore housing said bowl spool for reciprocation therein between said neutral, raise and lower positions thereof, said body having a second bore housing said ejector spool for reciprocation therein between said neutral, eject, and retract positions thereof, said body having a third bore housing said elevator spool for reciprocation therein between said neutral, low, medium, and high speed positions thereof, said first, second, and third bores respectively having central portions, first and second opposite end portions, and first and second intermediate portions between said central portion and said first and second end portions, said first inlet port communicated with said central portion of said first bore, said second and third inlet ports respectively communicated with said first and second intermediate portions of said third bore, said first and second control ports respectively communicated with said second intermediate portions of said first and second bores, said third control port communicated with said first intermediate portion of said second bore, said body having a passage communicating said central portions of said first and second bores, a second passage communicating said central portions of said second and third bores, a third passage communicating said central portion of said third bore with said return port, a fourth passage communicably connecting said first end portions of said first, second and third bores to said third passage, a fifth passage communicably connecting said second end portions of said first, second and third bores to said third passage, and a sixth passage communicably connecting said first intermediate portions of said first and second bores, said bowl spool being configured to block communication between said central portion and first and second intermediate portions of said firSt bore, block communication between said first and second intermediate portions and first and second end portions of said first bore, and permit communication between said central portion of said first bore and said first passage in said neutral position thereof, block communication between said first inlet port and said central portion of said first bore, block communication between said first inlet port and said first intermediate portion of said first bore, block communication between said central portion and first intermediate portion of said first bore, block communication between said second intermediate and end portions of said first bore, establish communication between said first inlet port and second intermediate portion of said first bore, and establish communication between said first intermediate and end portions of said first bore in said raise position thereof, and block communication between said first inlet port and said central portion of said first bore, block communication between said first inlet port and said second intermediate portion of said first bore, block communication between said central portion and second intermediate portion of said first bore, block communication between said first intermediate and end portions of said first bore, establish communication between said first inlet port and first intermediate portion of said first bore, and establish communication between said second intermediate and end portions of said first bore in said lower position thereof, said ejector spool being configured to permit communication between said central portion of said second bore and said first and second passages, block communication between said central and first and second intermediate portions of said second bore, and block communication between said first and second intermediate portions and first and second end portions of said second bore in said neutral position thereof, block communication between said central portion of said second bore and said first passage, block communication between said central and first and second intermediate portions of said second bore, block communication between said first intermediate and end portions of said second bore, establish communication between said first passage and said first intermediate portion of said second bore, and establish communication between said second intermediate and end portions of said second bore in said eject position thereof, and block communication between said central portion of said second bore and said first passage, block communication between said central and first and second intermediate portions of said second bore, block communication between said second intermediate and end portions of said second bore, establish communication between said first passage and said second intermediate portion of said second bore, and establish communication between said first intermediate and end portions of said second bore in said retract position thereof, said elevator spool being configured to permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, establish communication between said first intermediate and end portions of said third bore, and establish communication between said second intermediate and end portions of said third bore in said neutral position thereof, permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, permit communication between said first intermediate and end portions of said third bore, and block communication between said second intermediate and end portions of said third bore in said low speed position thereof, permit communication between said central portion of said third bore and said second and third passages, block communication between said central and first and second intermediate portions of said third bore, block communication between said first intermediate and end portions of said third bore, and block communication between said second intermediate and end portions of said third bore in said medium speed position thereof, and block communication between said central portion of said third bore and said second passage, block communication between said central and first and second intermediate portions of said third bore, block communication between said first intermediate and end portions of said third bore, block communication between said second intermediate and end portions of said third bore, and establish communication between said second passage and said first intermediate portion of said third bore in said high speed position thereof.