INTRODUCTION

This invention relates to a method and apparatus for constructing a mound from earth and, more particularly, to a method and apparatus for constructing a mound on which to plant tree seedlings.

BACKGROUND OF THE INVENTION

Reforestation is desirable for many reasons and is generally reguired by statute following the logging of forested areas. Such reforestation requires that seedlings be planted to provide forest regrowth for environmental and economic reasons.

The survival and subsequent growth rate of planted seedlings, however, is heavily dependent on the conditions under which such seedlings are planted and nurtured. If a reforestation site has poor drainage and cool soil temperatures, it is beneficial to provide the seedlings with better growing conditions such as enhanced drainage, warmer soil temperatures, increased access to nutrients and decreased competition from surrounding vegetation.

The use of mounds in which to plant seedlings is known to increase their growth rate. The method of construction of such mounds, however, is important. For example, it may be desirable to invert the "duff cover" which comprises the nitrogen rich litter, fermentation and humus soil layers of the forest floor so as to make the duff cover accessible for the sensitive seedling roots. The duff cover will be buried under the mineral soil covering which forms the top of the mound. The mineral

soil will facilitate warming by the sun and generally lead to increased soil temperatures in the mound. If the depth of the mineral soil is sufficient, it also assists in controlling the growth of competing vegetation surrounding the seedling. The elevated planting position is beneficial on wet sites. A mineral soil mound, without inverted "duff cover", may be desirable on some sites, and can be created by removing the duff cover before mounding.

Previously, mounds have been machine constructed in a process called "spot mounding" using apparatuses called "spot mounders" but some such techniques have often been less than satisfactory. In one machine used for site preparation, for example, two sets of scarifying wheels are used which continuously rotate and which are attached to a frame pivotally attached to and towed behind a prime mover such as a tractor or crawler. A braking system slows the rotation of the scarifying wheels when it is desired to form the mounds used for seedling planting. While the device operates satisfactorily in some soil conditions, it does not operate well in all soil conditions. This is so because the scarifying wheels are not driven into the ground nor is the towed frame heavy enough to give the required depth to the digging elements in heavy compacted soil or thick duff layer conditions.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a spot mounder apparatus comprising a digging blade frame, a digging blade pivotably connected to said digging blade frame, connection means operatively connected between said digging blade frame and a support frame for raising and lowering said digging blade frame and means to rotate said digging blade relative to said digging blade frame.

According to a further aspect of the invention, there is provided a method of constructing mounds from earth comprising the steps of inserting the teeth of a digging blade assembly connected to a digging blade frame in a first position into the ground at a predetermined time and location, applying downwards force to said digging blade frame while maintaining said digging blade in a fixed position relative to said digging blade frame, releasing and rotating said digging blade to a second position relative to said digging blade frame while raising said digging blade frame and rotating said digging blade from said second to said first position.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A specific embodiment of the invention will now be disclosed, by way of example only, with the use of drawings in which:

Figure 1A is a side view of a crawler with the spot mounder apparatus according to the invention connected to the back end of the crawler in a lowered position;

Figure IB is a rear view of the crawler and spot mounder apparatus of Figure 1A;

Figure 1C is a plan view of the crawler and spot mounder apparatus of Figure 1A;

Figure 2A is an enlarged partial section side view of the digging blade and digging blade frame of the spot mounder apparatus;

Figure 2B is a rear view of the digging blade and digging blade frame of Figure 2A;

Figures 3A - 3J are side views illustrating diagrammatically the sequential operation of the spot mounder apparatus;

Figure 4 is a schematic of the hydraulic circuit according to the invention;

Figure 5 illustrates the time actuation chart for various of the operating cylinder elements of the hydraulic circuit;

Figure 6A is a diagrammatic side view of a further embodiment of the hydraulic system and spot mounder;

Figure 6B is a diagrammatic rear view of the spot mounder of Figure 6A; and

Figure 6C is a view similar to Figure 6A but illustrating the spot mounder connected to the rear of the crawler.

DESCRIPTION OF SPECIFIC EMBODIMENT

Reference is now made to the drawings and, in particular, to Figure 1 where a spot mounder apparatus is generally illustrated at 10 as being attached to the rearward end of a prime mover such as a crawler tractor generally illustrated at 11. The spot mounder 10 includes two digging blade assemblies generally illustrated at 12. As seen in Figure IB, two digging blade assemblies 12 are connected to the spot mounder 10 which is connected to the back end of the crawler tractor 11. The digging blade assemblies 12 are connected together with a transverse cross beam 42, the assembly being generally referred to as the ripper assembly generally illustrated at 15. For the

purpose of the subsequent description, only one digging blade assembly 12 will be described, it being understood that the oppositely located digging blade assembly 12 of the ripper assembly 15 is a mirror image and will operate in a virtually identical manner.

The digging blade assembly 12 comprises a digging blade 19 operatively and rotatably connected to a digging blade frame 13. A connection in the form of a four bar linkage 14 extends between the ripper assembly 15 and a back or support frame 20 which is rigidly connected to the rearward end of the crawler tractor 11. Mechanical stops 16 are connected to the back support frame 20 and are adapted to contact the ripper assembly 15 when the ripper assembly is in its lowermost and uppermost positions so as to restrain further movement beyond these two positions.

With reference to Figures 2A and 2B, the digging blade 19 has a concave forward surface 22 and is pivotably mounted about axis 18 on digging blade frame 13. The shape of the concave surface 22 of the digging blade 19 is important to properly form the mounds. Reference is made to Figure 2A where the centre 17 of the radius of curvature is given. A radius of approximately 24" for the curvature of the digging blade 19 has been found satisfactory. A hydraulic or flip cylinder 23 is pivotably connected between the digging blade 19 and the digging blade frame 13. It extends to pivotably join an arm 24 which is rigidly connected to the digging blade 12.

Two latch pins 30 are retained in a latch pin arm 31 which extends from and is pivotably mounted to the digging blade frame 13 at axis 34. Complementary recesses 32 in recess arms 33 are adapted to mate with the ends of the latch pins 30 when the digging blade 19 is in its

initial non rotated position as described in more detail hereafter and as illustrated in Figure 2A. The latch pin arm 31 is rotated about axis 34 with hydraulic or latch cylinder 40 also as described in more detail hereafter.

A mudflap 25 to protect the working mechanisms inside the digging blade assembly 12 when it is in the rotated position is connected between the digging blade frame 13 and the digging blade 19 by pins 26, 27, 28 which are mounted in plastic self-lubricating bushings. A rear mudguard 35 for a similar function at the back of the digging blade 19 is connected between the digging blade frame 13 and a pin 36 located on the bottom of the digging blade 19.

With reference again to Figure 1A, two hydraulic ripper cylinders 41 are connected between the four bar linkage 14 of the ripper assembly 15 and the back or support frame 20. Hydraulic ripper cylinders 41 are used to lift and lower the ripper assembly 15 and the two attached digging blade assemblies 12 relative to the back support frame 20 and the crawler 11, between the two positions illustrated in Figure 1A, the upper position of the ripper assembly 15 being the retracted position of the spot mounder 10 and the lower position being the operating position of the spot mounder 10. It will be understood cylinders 41 can apply substantial downward force to the ripper assembly 15 so as to force the assembly 15 and its associated digging blade assemblies 12 into even hard and compacted soil.

Two side plates 45 are mounted to the forward edge of the digging blade 19. The sideplates 45 act to retain the soil which is removed by the action of the digging blade 19. The sideplate 45 rotates with the digging blade 19 when in operation.

The spot mounder apparatus 10 is self-powered by an engine 48 mounted in the upper portion of the spot mounder 10. A hydraulic circuit is used to provide power to the operating components of the spot mounder 10 and includes an accumulator 46 and a hydraulic fluid reservoir 47 mounted adjacent engine 48. The hydraulic circuit operation is initiated by computer control which allows the operator to determine the operation commencement time.

A schematic of the hydraulic circuit is seen in

Figure 4. The principle elements include a control valve 55 which initiates the operating sequence of the flip, latch and ripper cylinders 23, 40, 41, respectively, as seen in Figure 5. The upper, middle and bottom bar graphs illustrate the operating sequence of the flip, latch and ripper cylinders 23, 40, 41, respectively, and the operation of the cylinders will be described in greater detail hereafter.

OPERATION

In operation, it will be assumed that the crawler 11 is moving forwardly or to the right as viewed in Figure 1A and that the ripper assembly 15 with its connected digging blade assemblies 12 is in the raised or lifted position illustrated in phantom in Figure 1A. The engine 48 will be operating and the accumulator 46 in the hydraulic system will have been brought to the correct pressure.

The operation is initiated by the operator engaging the computer controlled electrical system (not illustrated) which initiates operation of the hydraulically activated circuitries (Figure 5) by a timer. The timer will initiate the operating sequence of the ripper, latch and flip cylinders 41, 40, 23,

respectively, according to the sequence illustrated in Figure 5. Initially, as viewed in Figure 5, the ripper cylinders 41 will lower the digging blade assemblies 12 and the digging blades 19 and, in so doing, the "duff layer 43" and the mineral soil layer 44 of the soil are penetrated as illustrated in Figure 3 until the proper operating depth or lowermost position is reached for the digging blade assemblies 12 as viewed in Figure 1A. The side plates 45 (Figure 2A) are lowered with the digging blades 19 and keep a substantial portion of the soil displaced forward of the digging blade 19 as the ground is entered. The mudflap 25 will be in the position as illustrated in Figure 2A at this time. The latch cylinders 40 will maintain the digging blade 19 in position and are required to counteract the large force applied on the digging blade 19 which tends to rotate the blade 19 in a clockwise position about axis 18.

As the digging blade 19 enters the soil, the duff layer 43 initially and the mineral soil layer 44 thereafter, will move upwardly on the concave forward surface 22 of the digging blade 19 as seen in Figures 3B and 3C until the soil is turned over as best seen in Figures 3D and 3E and a mound 50 is formed from the soil with the duff layer 43 on the bottom and the mineral soil layer 44 on the top of the mound 50.

In accordance with the sequence chart of Figure 5, and as the soil moves upwardly on the concave forward surface 22 of the digging blade 19, the automatic control system will initiate withdrawal of the ripper assembly 15 and digging blade assemblies 12 by activating the ripper cylinders 41. As the ripper assembly 15 is withdrawn from the ground, the latch cylinders 40 will be activated to rotate the latch pin arm 31 counter clockwise as viewed in

Figure 2A and to therefore remove the pins 30 from the complimentary recesses 32 on the recess arms 33.

When the latch pin arm 31 is rotated to an extent such that the pins 30 are removed from recesses 32 and the digging blade 19 is therefore unlatched, the flip cylinder 23 will extend and rotate the digging blade 19 clockwise as seen in Figure 2A about pivot axis 18 as seen in Figures 3D-3F. The movement of the flip cylinder 23 will assist in forming the mound 50. When the mound 50 is fully formed, the digging blade 19 will have assumed the position illustrated in Figures 3E and 3F.

As the crawler 11 continues to move to the left as viewed in Figure 3, the rotation of the digging blade 19 under the influence of hydraulic flip cylinder 23 will continue until the digging blade 19 clears the mound 50 as illustrated in Figure 3G. Thereafter, the digging blade 19 is rotated clockwise under the influence of hydraulic flip cylinder 23 until the initial condition of the blade 19 is assumed as illustrated in Figure 31. The latch cylinder 40 reinsert the pins 30 in their recesses 32 whereupon the spot mounder 10 is then ready for a further operating sequence.

When the digging blade 19 is rotated under the influence of flip cylinder 23, the mudflap 25 will rotate with the digging blade 19 about pins 26, 27, 28 relative to the digging blade frame 13. The extended area of the mudflap 25 will close the side area of the digging blade assembly 12 as seen in Figure 3F which is otherwise open to dirt and other contaminants. As well, the lateral or frontal area 29 of the mudflap 25 will close the frontal area of the digging blade assembly 12 for the same purpose.

The use of the latch pins 30 in association with the recess 32 on recess arm 33 have been found advantageous as described above. When the digging blade 19 initially contacts the ground surface, there is a tendency for the blade 19 to rotate due to the large ^• longitudinal drag forces on the digging blade 19 in the ground. The use of the latch pins 30 on latch pin arm 31 which is under the control of hydraulic cylinder 40 tends to counteract such forces and to stabilize the digging blade 19 in the ground until rotation of the digging blade 19 by the automatic control system commences as illustrated in Figure 3C and as earlier described.

In operations to date, it has been found that a timed sequence of operations from the position of the digging blade 19 and digging blade frame 13 illustrated in Figure 3A to the position of the digging blade 19 and digging blade frame 13 illustrated in Figure 3J will satisfactorily be 5.0 seconds as indicated in Figure 5 with a speed of the crawler 11 being 1.8 m.p.h. The engine of the crawler 11 at such a speed will typically have a speed of 2000 r.p.m.

A duff layer 43 typically has a thickness of 3" to 5" as seen in Figures 3B and 3C. In the fully lowered position as viewed in Figure 1A, the digging blade 19 is intended to be fully 25" below the ground surface. When the digging blade 19 is rotated as seen in Figure 3G, the distance from the uppermost concave surface 22 to the ground surface is contemplated to be 24". At the end of the sequence as seen in Figure 31, the digging blade 19 is located approximately 20" above the surface of the ground.

Other dimensions which are of interest are shown in Figure 3 . As seen, the distance for one cycle from the point of ground penetration by the digging blade 19 to

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the commencement- of a new cycle where ground penetration is again imminent is approximately 10*. A mound 50 is formed which is typically 14" high and which has a width of approximately 30".

A further embodiment of the spot mounder apparatus is illustrated in Figure 6. In this embodiment, the hydraulic system of Figure 4 is replaced with the hydraulic circuit generally illustrated at 50 in Figure 6A and the ripper assembly 15 of Figure 1 is replaced with the ripper assembly generally illustrated at 51.

In this embodiment, there exists only three cylinders, namely one arm cylinder 52 and one scoop cylinder 53 for each digging blade 54. The latch cylinder 40 of the embodiment of Figure 1 is eliminated. Similarly, the four bar linkage 14 is replaced by a link 70 which rotates about axis 71 under the influence of arm cylinder 52. It has also been found that replaceable teeth 72 (Figure 6B) on the leading edge of each digging blade 54 are advantageous to reduce the force necessary to insert the digging blade 54 into the ground. Likewise, by the appropriate use of accumulator 60 in hydraulic circuit 50, it is intended to reduce the power requirements and, therefore, to eliminate the need for the independent engine 48 of the Figure 1 embodiment or, at least, to reduce the power required from the independent engine 48, with the hydraulic pump 61 being driven from the engine of the crawler 62.

As seen in Figure 6A, the scoop cylinder control valve 63 and the arm cylinder control valve 64 are solenoid controlled and under the influence of an automatic control system similar to the automatic control system of the Figure 1 embodiment. In operation, the control valves 63, 64 are activated under the influence of

a programmable computer which allows the operator to adapt the spot mounder apparatus to a variety of soil and site conditions as in the case with the embodiment of Figures 1 - 5. In accordance, therewith, the raising and lowering of the digging blade frame and the rotation of the digging blade 54 relative to the digging blade frame are programmed in the same way as the programming described and illustrated in connection with the Figure 1 embodiment.

While the sequence of operations illustrated in Figure 3 has been described as being time activated, the functions could also be sequenced from the power take off assembly on the prime mover or crawler 11.

Many further modifications will occur beyond those described and contemplated to those skilled in the art, which modifications will fall within the scope of the invention. The embodiments described, therefore, should be considered as illustrative of the invention only and not as limiting its scope as defined in accordance with the accompanying claims.