GB1578006A - Bowl scraper - Google Patents

Description

(54) BOWL SCRAPER (71) We, CATERPILLAR TRACTOR CO., a corporation organized and existing under the laws of the State of California, United States of America, of 100 N.E.

Adams Street, Peoria, Illinois 61629, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: In our parent British Patent Specification No. 1527015, we describe and claim a self-loading earth-moving bowl scraper of the kind that includes a tractor, a scraper bowl assembly articulately connected to the tractor through a hydraulic cushion hitch assembly and including a scraper bowl, an auger mounted in the bowl, an hydraulic motor for driving the auger, an hydraulic fluid reservoir, first pump means for supplying hydraulic fluid under pressure from the reservoir to the cushion hitch assembly, second pump means for supplying hydraulic fluid under pressure from the reservoir to the auger motor, and control means for directing the output of the second pump means selectively to the motor or to the reservoir, wherein the control means comprises a manually controlled pilot selector valve which has at least first and second positions; an unloading relief valve; a pilot operated normally open auger control valve; a pressure conduit connecting the output of the first pump means to the pilot selector valve; a pilot line from the pilot selector valve to the auger control valve; a drain line from the pilot selector valve to the reservoir; a signal line from the unloading relief valve to the auger control valve; a return line from the auger control valve to the reservoir; unloading conduit means from the second pump means to the unloading relief valve; drain conduit means from the unloading relief valve to the reservoir; and drive conduit means from the second pump means to the auger motor, a first position of the pilot selector valve connecting the pilot line to the drain line, the auger control valve in the first position being open between the signal line and the return line to maintain the unloading relief valve open between the unloading conduit means and the dran conduit means, and manual movement of the pilot selector valve to a second position serving to close the drain line and subject the pilot line to pressure from the pressure conduit so as to close the auger control valve between the signal line and the return line, closing of the signal line serving to close the unloading relief valve between the unloading conduit means and the drain conduit means, whereby hydraulic fluid from the second pump means goes through the drive conduit means to the auger motor.

Preferably, the second pump means comprises two pumps, both of which are connected through the unloading relief valve to the reservoir in the first position of the pilot selector valve, and in which the output of the second of the two pumps passes through the unloading relief valve and joins the output from the first of the two pumps.

We have now appreciated that the hydraulic circuitry of the scraper described and claimed in the parent Application is equally useful when incorporated in a scraper which utilizes a loading assist device in the form of an endless chain elevator instead of an auger.

In order with the present invention, which is a modification of that described and claimed in the parent specification, an endless chain elevator is substituted for the auger of the scraper as claimed in claims 1 and 2 of the parent specification.

An example of a scraper, which has many features in common which that forming the subject of our co-pending Application No.

21310/78 (Serial No. 1578008) and which is constructed in accordance with the present invention is illustrated in the accompanying drawings, in which: - Figure 1 is a side elevation; Figure 2 is an hydraulic circuit- diagram of that portion of the hydraulic circuit of the scraper which relates to operation and control of the elevator and cushion hitch; and, Figure 3 is a schematic hydraulic circuit diagram of the unloading relief valve used in the control circuit.

Figures 2 and 3 are identical in Figure 2 and 3 in the parent specification.

Figure 1 shows a tractor 1 to which a scraper bowl assembly 2 is connected by means of a conventional goose neck 3. The goose neck is connected to the tractor 1 via a cushion hitch 4 incorporating a cushion hitch jack 32 as disclosed in more detail in U.S. Patent Specification No. 3,311,389.

The assembly 2 includes a bowl 6 with a cutting blade 7 horizontally disposed at an open front end of the bowl, a pivotally mounted bowl bottom 8 for facilitating the dumping of a load, and an endless chain elevator 9 having movable flights 10 positioned above the cutting blade 7, to assist in loading material into the bowl, and in dumping the load from the bowl. During dumping, the floor 15 is pivoted rearwardly and upwardly by means of a ram 11, thereby providing an opening in the forward part of the bowl bottom through which the earth is dumped, assisted by the moving elevator flights 10. The flights also assist in moving a load upwardly and rearwardly into the bowl during the loading cycle.

As an alternative to the pivotal bowl bottom 8, the bowl may incorporate a bulldozer type of ejector which is positioned upright near the inner rear end of the bowl and movable forwardly to push earth forwardly out of the bowl as described in the parent Application.

The elevator 9 has a frame 12 mounted on and between brackets 13 which are pivotally connected to the bowl sides to allow the elevator to pivot upwards and ride over any rocks or boulders picked up by the cutting edge 7. The elevator has an endless chain 16 entrained around a lower idler sprocket 17, intermediate idler sprockets 18, and an upper sprocket 19 which is driven by means of an hydraulic motor 23.

Turning now to Figures 2 and 3, the hydraulic operating and control circuit for the hydraulic motor 23 of the elevator includes a hydraulic fluid reservoir 24; a manual pilot selector valve 25 of the kind disclosed in U.S. Patent Specification No.

3,618,984; a large pump 26 having a capacity of 60 gallons per minute and which is coupled with a cushion hitch pump 27 that has a capacity of 8 gallons per minute and is coupled with a 60 gallon per minute scraper pump 29 that is not part of the elevator operating and control system; a relief and unloading valve 30; and a normally open, pilot operated elevator control valve 31; together with the necessary pipes and conduits between the foregoing components, the hydraulic motor 23 and the reservoir 24.

As disclosed in U.S. Patent Specification No. 3,618,984, the manual pilot selector valve 25 is a spool valve which has an operating handle 25a that is movable between the A position shown in Figure 2, a B position, and a C position. In the A position of the pilot selector valve 25 the cushion hitch jack 32 is in a transport mode as disclosed in Patent 3,311,389, and the elevator motor 23 is idle. In the B position, in accordance with the teachings of U.s. Patent Specification 3,618,984, the cushion hitch is deactivated with the cushion hitch locked in a bottom cut position as taight in U.S.

Patent Specification No. 3,311,389 and the motor 23 is still idle. In the C position of valve 25 the cushion hitch is still locked down and the motor 23 is powered from the pumps 26 and 28 to drive the elevator.

The B position of the valve 25 is rarely used, because ordinarily the cushion hitch is lowered and locked only for loading or unloading, and in those situations the motor 23 should be driving. However, there are occasional situations when the operator may want to lock down the cushion hitch when the apparatus is in its transport mode so as to afford the maximum possible control over a loaded vehicle being operated under difficult driving conditions.

A fluid conduit 33 and a branch conduit 34 connect the reservoir 24 with the low pressure sides of the pumps 26, 27, 28 and 29. The high pressure sides of the pumps 26 and 28 connect with the unloading relief valve 30 through respective lines 35 and 36; and as illustrated in Figure 3, the valve 30 is normally open to the reservoir 24 through a manifold 37 and a drain conduit 38. Thus, the output of the pumps 26 and 28 is unloaded to the reservoir in the A position of the manual pilot selector valve 25.

Control of the unloading relief valve 30 is by means of a signal conduit 39 which is joined exteriorly of the valve 30 by a signal conduit 39a so that, in effect, the two signal conduits act as one in the control of the valve 30. The signal line 39 is connected through the normally open control valve 31 to a return line 40 which drains directly to the reservoir 24 through a drain line 41 which aso may receive hydraulic fluid from a conventional leakage drain line 42 connected to the valve 31.

A pilot line 43 for the valve 31 is connected to the manual pilot selector valve 25, and in the A position of the pilot selector valve the pilot line 43 is in communication with a drain line 44 through which hydraulic fluid from the valve 25 returns to the reservoir 24.

Also, in the A position of the pilot selector valve 25 the output of the pump 27 is delivEred through a line 45 to a filter 46 from which the principal flow goes through a line 47 to a normally closed control valve 48 for the cushion hitch cylinder 32. The balance of the flow from the filter 46 goes through a line 49 to the pilot selector valve 25, and from there through a pilot line 50 the pressure from which keeps the normally closed valve 48 open as long as the pilot selector valve 25 is in the A position.

When the pilot selector valve is moved to the B position the fluid from the line 49 is isolated from the pilot line 50 and returns through the drain line 44 to the reservoir 24.

In this position of the pilot selector valve the conditions of the control valve 31 remains unchanged.

When the pilot selector valve 25 is move to the C position, it terminates communication between the pilot line 43 and the drain line 44 and places the line 49 from the cushion hitch pump 27 into communication with the pilot line 43 so as to close the valve 31. This blocks communication between the signal line 39-39a and the return line 40 and drain line 41 and causes the unloading relief valve 30 to break communication between the lines 35 and 36 and the drain line 38. The output from the pump 28 through the line 36 to the valve 30 is shifted within the valve to the line 35, as indicated by the reverse arrows in that line; so that the output from the pump 28 combines with that of the pump 26 and goes through a drive conduit 51 ato the motor 23 from which the fluid returns to the reservoir 24 through several lines which are numbered collectively 52.

For the sake of completeness, the output from the scraper pump 29 goes to a multiple function control valve, indicated generally at 53, which is provided with a scraper bowl elevating or lowering control handle 54, an apron control handle 55, and an ejector control handle 56. A group o conduits, indicated generally at 57, carry hydraulic fluid from the control valve 53 selectively to the ejector ram 11 (figure 1) or to a bowl actuating ram or to an apron ram depending upon the positions of the manual controls 54, 55, and 56.

WHAT WE CLAIM IS: 1. A modification of the self-loading earth-moving bowl scraper as claimed in claim 1 or claim 2 of the parent specification no. 1527015, wherein the auger is replaced by an endless chain elevator.

2. A scraper according to claim 1, substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. valve the pilot line 43 is in communication with a drain line 44 through which hydraulic fluid from the valve 25 returns to the reservoir 24. Also, in the A position of the pilot selector valve 25 the output of the pump 27 is delivEred through a line 45 to a filter 46 from which the principal flow goes through a line 47 to a normally closed control valve 48 for the cushion hitch cylinder 32. The balance of the flow from the filter 46 goes through a line 49 to the pilot selector valve 25, and from there through a pilot line 50 the pressure from which keeps the normally closed valve 48 open as long as the pilot selector valve 25 is in the A position. When the pilot selector valve is moved to the B position the fluid from the line 49 is isolated from the pilot line 50 and returns through the drain line 44 to the reservoir 24. In this position of the pilot selector valve the conditions of the control valve 31 remains unchanged. When the pilot selector valve 25 is move to the C position, it terminates communication between the pilot line 43 and the drain line 44 and places the line 49 from the cushion hitch pump 27 into communication with the pilot line 43 so as to close the valve 31. This blocks communication between the signal line 39-39a and the return line 40 and drain line 41 and causes the unloading relief valve 30 to break communication between the lines 35 and 36 and the drain line 38. The output from the pump 28 through the line 36 to the valve 30 is shifted within the valve to the line 35, as indicated by the reverse arrows in that line; so that the output from the pump 28 combines with that of the pump 26 and goes through a drive conduit 51 ato the motor 23 from which the fluid returns to the reservoir 24 through several lines which are numbered collectively 52. For the sake of completeness, the output from the scraper pump 29 goes to a multiple function control valve, indicated generally at 53, which is provided with a scraper bowl elevating or lowering control handle 54, an apron control handle 55, and an ejector control handle 56. A group o conduits, indicated generally at 57, carry hydraulic fluid from the control valve 53 selectively to the ejector ram 11 (figure 1) or to a bowl actuating ram or to an apron ram depending upon the positions of the manual controls 54, 55, and 56. WHAT WE CLAIM IS:

1. A modification of the self-loading earth-moving bowl scraper as claimed in claim 1 or claim 2 of the parent specification no. 1527015, wherein the auger is replaced by an endless chain elevator.

2. A scraper according to claim 1, substantially as described with reference to the accompanying drawings.