NZ337892A - Ground working equipment to cut channels for subsequent sowing of seed - Google Patents

Abstract

There is provided a method of operating a ground cutting blade characterised by the steps of: a) imparting to the blade a substantially vertical motion and b) deliberately imparting to the blade a sideways motion. Preferably, the cutting blade is a disk coulter such as those used in agricultural ground working machinery. Referring to Figure 1 there is provided ground working apparatus generally illustrated by arrow 1 which can operate a blade 2 as indicated above. A drag arm 3 depends from a ground working unit (not shown). A shaft 4 extends from the drag arm 3. The longitudinal axis of the shaft 4 is at approximately right angles to the direction of travel of the drag arm 3. Bearings 8 enable the shaft 4 to rotate with respect to the drag arm 3. At the end of the shaft 4 closest to the blade 2 is an off-set portion 6. The off-set portion 6 is connected to a hub 7 onto which the blade 2 is mounted. The shape of the off-set portion 6 and its relationship to the shaft 4 and the hub 7 is such that the central longitudinal axis of the hub 7 is not aligned with the central longitudinal axis of the shaft 4. Further, the off-set portion 6 causes the hub 7 to tilt with respect to the vertical. This relationship is shown in exaggerated form in Figure 1A.

Description

GROUND WORKING EQUIPMENT Technical Field This invention relates to ground working equipment.

In particular, the present invention relates to such ground working 5 equipment as cutting blades that are used to cut channels, cultivating implements (herein after referred to as boots) used to open out those channels for subsequent sowing of seed and seed sowing equipment.

It should be appreciated however that the principles of the present invention can relate to other ground working apparatus.

BACKGROUND ART Typical ground working apparatus used for sowing seed consists of a number of ground working units which are towed by a vehicle over the ground to be worked.

Typically, a unit includes a cutting blade which cuts a line in the 15 ground. There is also included a boot which opens up the ground cut by the disk to form a channel or bed suitable for sowing seed in.

In addition, the unit often includes a seed tube through which seed or sometimes fertiliser is fed into the seed bed as well as a press wheel which acts to close the cut over the seed bed once it has been sown.

Examples of these units can be seen in New Zealand Patent Nos. 215589, 219869/220332 and 157041. 1 Printed from Mimosa Unfortunately, there are a number of problems associated with these units.

One problem is that considerable horsepower and weight must be applied to the cutting blade. This requirement increases if the ground 5 being worked is heavy soil.

Not only is the provision of extra weight and horsepower expensive, but this can lead to: (1) the ground being churned by the action of the vehicle towing the ground working apparatus, and (2) excessive ground compaction which can impair plant growth and reduce yield.

Another problem is that the blade itself must of heavy construction. This leads to a wider blade being required and thus wider channels being cut.

The wide channels formed by the heavy blade can also be undesirable. In some circumstances as wide channels do not retain moisture desirable for seed growth to the same extent as narrow channels.

Yet another problem with conventional ground working apparatus is that a condition known as "hairpinning" can occur. Hairpinning is the 20 pushing of organic matter known as "trash" into the channel by the cutting blade. This organic matter can decompose causing a toxic environment for the seeds sown there. The trash within the channel can also prevent the formation of a friable seed bed or even result in seeds or other material fed into the channel being forced out of the Printed from Mimosa channel or not being placed at the optimum depth within the channel.

Another problem with trash is that it can build up on the ground working apparatus blocking its operation.

Still another problem with existing ground working apparatus is that 5 the blade may smear the sides of the channel thus preventing the production of a friable seed bed ideal for seed growth.

Yet a further problem is that boots tend to catch on rocks, roots, pipes and the like thus impeding the seed sowing operation. This also causes considerable wear and damage to the boot.

There are also problems associated with the seed tube. Dirt and/or trash can be forced or driven up the seed tubes and cause blockages preventing the seed from emerging.

Another problem with the seed tubes is that often both fertiliser and seed are delivered through the same tube. Unfortunately the 15 placement of these two items in the channel formed by the ground working apparatus so close that the seed is burnt by the high concentration of fertiliser in close proximity.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. 3 Printed from Mimosa WO 98/42175 PCT/NZ98/00043 DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a method of operating a ground cutting blade characterised by the step of a) imparting to the blade a substantially vertical motion.

In preferred embodiments of the present the cutting blade is a disk coulter such as those used in agricultural ground working machinery. It should be appreciated however that the principles of the present invention can be applied to blades of different configurations and used in non-agricultural situations.

It should be remembered that typically a cutting blade rotates as a consequence of being pulled along the ground and therefore in normal use the blade in total has a rotational and horizontal motion.

Imparting a substantially vertical motion to a blade in addition to the other motions overcomes a number of the problems in the prior art.

The vertical motion assists the blade in cutting the soil and trash. Particularly, it is the trash which prevents the efficient operation of the conventional ground working apparatus. The vertical motion of the blade cuts the trash thus making it easier to also cut the ground.

As the blade cuts better as a consequence of its up and down motion, 20 the machinery associated with the blade requires less horsepower and weight. This is more economical than previous machinery and further the machinery is less likely to churn and compact the ground. 4 Printed from Mimosa As less horsepower and weight are required to be used, the blade itself need not be as strongly constructed and can be narrower in width giving rise to narrow channels. Narrow channels retain moisture better and provide a more conducive environment for growing seed.

The vertical action of the blade also helps avoid hairpinning as instead of trash being pushed into the channel by the blade, the action of the blade serves to cut the trash instead.

In preferred embodiments of the present invention there is also imparted a sideways movement to the blade. A sideways movement is 10 defined as is in a plane at approximately right angles to the forward motion of the blade and at approximately right angles to the substantial vertical motion.

In preferred embodiments of the present invention the blade has a fast vibrating surface as a consequence of this additional motion.

This sideways motion can assist in the preparation of the soil by the cutting blade.

Sideways motion can help loosen the soil making it more friable.

It is common for blades to "smear" curtain types of soils as a consequence of presenting a continuous surface to the side of the 20 channel being formed. The imparting of a sideways movement reduces the chance of smear happening as a continuous surface is not presented but a fast vibrating surface instead.

The sideways movement can also assist in the clearing of trash in that it can push trash sideways rather than encouraging the entry of trash Printed from Mimosa into a channel.

Reference throughout this specification shall be made to the blade as having both a substantially vertical and substantially sideways movement as described. It should be appreciated however that some 5 embodiments of the present invention may not have the sideways movement.

In some embodiments of the present invention the blade may be directly driven to produce the vertical and sideways movements. For example, hydraulics or a suitably converted cam may be used to 10 achieve this.

However, in other embodiments of the present invention the blade is not directly driven, but moves as an indirect consequence of the motion of the apparatus towing the ground cutting blade during its operation.

In one embodiment the vertical movement may be imparted to the 15 blade as a consequence of the center of the blade not being aligned with the central axis of the shaft on which the blade rotates. It can be seen that this is a simple and effective way of imparting vertical movement.

To provide the substantially sideways movement, the blade may be 20 tilted or inclined from the plane perpendicular to the axis on which the blade rotates. Again it can be seen that this simple positioning of the blade obviates the needs for complicated machinery. A slight tilt in combination with a fast rotation of the blade provides the motion required. 6 Printed from Mimosa In some embodiments of the present invention the blade has a substantially vertical and a substantially sideways movement which is given by the blade being positioned so that its center is offset from the shaft on which the blade turns and the blade is also inclined from the 5 plane perpendicular to the axis on which the blade rotates.

An alternative means for imparting the required motion to the blade may be by the use of an eccentric sleeve which receives the shaft on which the blade turns.

For example, the blade may be centrally mounted on a shaft as with 10 conventional ground working apparatus. However, the shaft may be attached to the ground working apparatus via an eccentric sleeve, the configuration of which causes the shaft to move the blade so that it has a substantially sideways and a substantially vertical movement.

In a preferred embodiment of the present invention there is provided 15 an eccentric sleeve situated within the plane of the blade and capable of interacting with bearings which enable rotation of the blade.

For example, a standard drive shaft may pass from the agricultural equipment and be fixed inside the sleeve. The inside of the sleeve may be free to rotate between inner bearings situated between the inner 20 walls of the sleeve and the drive axle. The outside of the sleeve may bear against outer bearings situated in between the outer walls of the sleeve and the cutting blade.

Preferably the eccentric sleeve is manufactured to be of varying thickness and/or skewed with respect to the drive shaft. 7 Printed from Mimosa If the drive shaft is turned, say by a hydraulic motor then this may impart motion directly to the eccentric sleeve. As the sleeve turns it presses against the outer bearings to which the disk is fixed.

The varying thickness of the eccentric sleeve or "offset" gives a vertical 5 movement to the blade via the outer bearings.

The skew of the eccentric sleeve against the outer bearings with respect to the shaft provides a sideways movement to the blade.

The applicant has found that the use of an eccentric sleeve as described above can lead to the cutting of narrower rows than by having a shaft 10 offset as previously described.

The applicant has also found that the operation of the apparatus is enhanced by bleeding of oil from the hydraulic motor to lubricate the shaft.

It is an unusual consequence of the construction of the present 15 invention that the action of the blade rotation provides additional benefits. When the blade is off the ground, the blade rotates in the same direction as the motor. This direction is opposite to the direction the blade would be inclined to turn if not driven and pulled through the ground.

Once the blade hits the ground, the blade will stop spinning and then change its direction of rotation. Even though not coupled directly to a drive system, the blade has a form of torque. The blade appears to want to drive itself forward, that is in the direction that the vehicle is moving. 8 Printed from Mimosa There may be provided other means of imparting the required motion of the blade. For example, there may be provided a loosely controlled suspension allowing the blade to effectively wobble in the required directions. Other systems are also envisaged.

According to a further aspect of the present invention there is provided a method of working ground with a blade that has a substantial vertical motion characterised by the step of a) placing the blade in close proximity to a boot also working the ground.

In preferred embodiments of the present invention the blade has a substantially vertical and sideways movement as previously described.

In preferred embodiments the boot is configured to accommodate the close proximity of the blade. For example, the boot may have a curved face of substantially the same curvature as the blade.

The proximity of the boot and blade to each other can vary according to their relative sizes and situations in which the ground working apparatus is to be used.

In most embodiments of the present invention the tolerance between the blade and the boot will be in the order of 0.001 to 3 millimeters. 20 Tolerance in this order ensures that the movement of the blade in relation to the boot provides a guillotine effect which can cut any trash which is brought down by the blade.

This tight fit and an increasing gradient between the blade and boot allows little room for trash to build up. As the trash is cut by the 9 Printed from Mimosa guillotine action it can be forced away to the sides by the vibrating action and curved sides of the boot. Thus, this embodiment of the present invention further avoids the "hairpinning" problem.

According to a further aspect of the present invention there is provided 5 a boot for ground working which is configured to operate in close proximity to a blade for ground working.

One problem with boots in general (whether used in combination with a vibrating blade such as in the present invention or with a standard blade) is caused by excessive volumes of trash. Often, trash builds up 10 between the seed tube and the boot is a consequence of the trash wrapping round the boot.

In a preferred embodiment of the present invention the boot includes an angled portion near the top of the boot which is angled between the horizontal and the vertical. This prevents trash riding up or sliding 15 around the boot.

A known problem of dirt blocking the seed tube could be avoided by having a curved seed tube. However, a curved seed tube can lead to problems in that the travel of seed down the tube can be impeded.

In preferred embodiments of the present invention a straight seed tube 20 is provided which forms part of a boot. In this situation the boot can be used with a vibrating blade as described earlier with the vibration assisting to prevent blockage of the seed tube by continually shaking the trash and dirt downwards.

If the base of the boot is below the bottom of the seed tube, dirt or 25 seeds are less likely to become blocked in the seed tube. This Printed from Mimosa PCT /NZ98/00043 embodiment of a boot can also be used with a non-vibrating blade.

A general problem with boots and seed tubes in general is that it is often desired to deposit seed and fertiliser at the same time in the trench created by the boot. The close placement of fertiliser to the seed 5 can cause burning of the seed.

According to one aspect of the present invention there is provided a boot which incorporates at least two guides, one guide capable of directing seed into a trench created by the boot, and the other guide capable of directing fertiliser into the trench created by the boot characterised in that the guides ensure that the seed and the fertiliser are placed in separate positions from each other.

The guides in the boot may come in various forms but in preferred embodiments the guides are in the form of internal tubes. A first internal tube may at the rear of the boot situated higher than an internal tube immediately in front of the first tube. The rear tube in this embodiment may deliver seed behind and above fertiliser 20 delivered by the front tube.

The heights of the base of the tubes may be determined by having the outlet seed tube at an angle to create a space between the outlet of the tube and seed bed so that the seed can fall between the base of the boot into the soil bed created by the boot. 11 Printed from Mimosa According to another aspect of the present invention there is provided a boot for ground working characterised in that the toe of the boot sits higher than the cutting edge of the ground working blade with which the boot operates.

By having the toe higher, the boot can readily ride over rocks, roots, pipes and the like which would otherwise be caught by the boot if the toe was brought to a point level with the base of the boot. This is also the point of highest wear and a toe so designed reduces the degree of damage. This is believed to be a significant advantage over the design 10 of previous boots.

If a boot is used in combination with a vibrating blade as described previously, the width of the boot may be narrower than other boots. This also reduces the chance of "smearing" as described previously and reduces the chance of moisture loss as there is minimum disturbance of 15 the soil.

Brief Description of drawings Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side view of a method of operating a blade in accordance with one embodiment of the present invention, and Figure 2 is a diagrammatic cross-sectional view of an alternate method of operating a blade in accordance with one 25 embodiment of the present invention, and 12 Printed from Mimosa wo 98/42175 pct/nz98/00043 Figure 3 is a diagrammatic side view of a boot in accordance with one embodiment of the present invention, and Figure 4 is a diagrammatic end view of the boot illustrated in Figure 3, and Figure 5 is a diagrammatic view showing how the distance between the boot and blade can be adjusted.

Best Modes for Carrying out the Invention Referring to Figure 1 there is provided ground working apparatus generally illustrated by arrow 1 which can operate a blade 2 in 10 accordance with one embodiment of the present invention.

A drag arm 3 depends from a ground working unit (not shown). A shaft 4 extends from the drag arm 3. The longitudinal axis of the shaft 4 is at approximately right angles to the direction of travel of the drag arm 3. Bearings 8 enable the shaft 4 to rotate with respect to the drag 15 arm 3.

At the end of the shaft 4 closest to the blade 2 is an off-set portion 6. The ofF-set portion 6 is connected to a hub 7 onto which the blade 2 is mounted.

The shape of the off-set portion 6 and its relationship to the shaft 4 and 20 the hub 7 is such that the central longitudinal axis of the hub 7 is not aligned with the central longitudinal axis of the shaft 4. Further, the off-set portion 6 causes the hub 7 to tilt with respect to the vertical. This relationship is shown in exaggerated form in Figure 1A. 13 Printed from Mimosa The hub 7 is journalled for free rotation on the off-set portion- 6 by the use of suitable bearings (not shown) such as for example taper roller bearings. The hub 7 is held into place on the ofF-set portion 6 by a nut 8.

The blade 2 is fixed with respect to the hub 7.

A hydraulic motor (not shown) is directly coupled to the shaft 4 via a flexible universal coupling (not shown) which may accommodate slight irregularities in alignment.

Drive mechanisms other than hydraulic motors may of course be used -10 for example electric motors, belts or counter shaft mechanisms.

If the shaft 4 is driven by the motor with the blade 2 not touching the ground, the blade 2 naturally rotates in the same direction as the shaft 4. However, in preferred embodiments the direction of rotation of the shaft 4 is counter to the direction in which the blade 2 would rotate 15 with no drive applied and being pulled through the ground by the ground working apparatus.

As a consequence of the center of the hub 7 being ofF-set with respect to the center of the shaft 4, a substantially vertical oscillation is imparted to the blade 2.

As a consequence of the blade 2 being inclined from the vertical (this is a result of the ofF-set portion 6) a sideways movement is imparted to the blade.

The substantially vertical vibrations and sideways vibrations still occur when the blade 2 is in the ground and being towed by the ground 14 Printed from Mimosa working apparatus.

As discussed previously, a cleanly cut channel is formed in the ground with the cut being greater than the cross-sectional thickness of the blade 2. A consequence of the sideways movement of the blade is that 5 the edge of the blade moves more than the center. This leads to a seed bed that is wide at the bottom and narrower at the top. This means there is minimum exposure of the seed bed to the air and minimum surface disturbance to the soil.

In a preferred embodiment of the present invention the center of the 10 hub 7 at point X is approximately 2 millimetres out of alignment from the central axis of the shaft 4. Through the rotation of the hub 7, this provides a 4 millimeter movement to the blade in the vertical direction.

In preferred embodiments where the blade is 45 cm in diameter the degree a between the central axes is 0.25°. The offset will of course 15 vary with blade sizes. It can be seen that this slight off-set can give a very fine sideways vibrational movement to the blade 2.

Figure 2 illustrates an alternative embodiment of the present invention in which a similar movement can be imparted to a blade 9.

In the embodiment illustrated in Figure 2, there is provided an 20 eccentric sleeve 10 situated within the plane of the blade 9.

The eccentric sleeve 10 is milled so that it has a varying wall thickness and is skewed with respect to a drive shaft 11. In this embodiment, the drive shaft 11 is driven by a hydraulic motor 12.

Printed from Mimosa The sleeve 10 may be fixed directly to the drive shaft 11 by grub screws 12A.

There may be provided inner bearings 13 between the sleeve 10 and the blade axle 14. The inner bearings 13 allow ready rotation of the 5 sleeve 10.

Outer bearings 15 are positioned between the outer walls of the sleeve 10 and the blade 9.

In operation, the hydraulic motor 12 causes the shaft 11 to rotate which in turn rotates the eccentric sleeve 10 affixed to same. The 10 eccentric sleeve 10 turns between the inner bearings 13 and the outer bearings 15. The rotation of the sleeve 10 pushing against the outer bearings 15 imparts the required motion to the blade 9. It is the varying thickness of the eccentric sleeve 10 that gives a vertical movement to the blade 9. The skew of the eccentric sleeve 10 provides 15 a sideways movement to the blade 9.

Figure 3 illustrates a boot which can be used with a vibrating blade in accordance with the present invention or with a standard blade.

The boot generally indicated by arrow 16 comprises a toe 17, a first leading face 18, a second face 19, a seed tube generally indicated by 20 arrow 20 and a base 21.

An end view of the boot 16 is illustrated in Figure 4.

The face 18 has a curvature which is similar to that of the blade (not shown) with which it is to co-operate. In preferred embodiments of the present invention the face 18 is positioned in the order of 0.001 to 3 16 Printed from Mimosa millimetres from the blade.

If the blade has a movement substantially the same as that described previously with respect to the present invention, then the co-operation of the blade with the face 18 may cause a guillotining action. This can 5 act to cut trash thereby improving the performance of the ground working apparatus.

The face 19 is angled to prevent trash riding up or sliding around the boot 16. This also prevents trash becoming stuck between the seed tube 20 and other parts of the ground working unit (not shown).

The seed tube 20 is divided into two tubes or guides 21 and 22. The outlet of the seed tube 20 generally indicated by arrow 23 is angled with respect to the base 21 of the boot 16.

If fertiliser is fed down tube 22 and seed is fed down tube 21, the angling of the outlet 23 ensures that the seed is deposited behind and 15 above the fertiliser delivered through the tube 22. This ensures that the placement of the seed and the fertiliser is not so close so as to cause the seed to be burnt by the fertiliser.

In preferred embodiments the seed tube 20 extends out from the sides of the main portion of the boot 16 (see Figure 4). This assists in 20 clearing trash away from the channel opened out by the boot 16.

The toe 17 of the boot 16 sits higher than the base 21 of the boot 16 and also higher than the cutting edge of the blade with which the boot is to co-operate. By having the toe 17 higher, the boot 16 can readily ride over rocks, roots, pipes and the like with would otherwise be 25 caught by the boot 16 if the toe 17 was brought to a point level with the 17 Printed from Mimosa base 21 of the boot 16.

Figure 5 illustrates how the clearance between the blade 2 and the boot 23 can be adjusted. It is important that clearance be adjustable to account for differing amounts of trash on the ground and for wear on 5 the blade or boot.

This can be achieved by loosening bolt B so that it still supports the seed tube 20. Then, nut C is loosened. Bolt B and the eccentric bush A are then rotated to give the required clearance. Finally, the nut C and the bolt B are tightened.

Loosening both the bolt B and the nut C also allows raising and lowering of the seed tube 20.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope 15 thereof as defined in the appended claims. 18 Printed from Mimosa

Claims (1)

1. PCT/NZ98/00043 WH/ T WE CLAIM IS: % % $ Q ^ £, w W ® A method of operating a ground cutting blade characterised by the steps of: (a) deliberately imparting to the blade a substantially vertical motion, and (b) deliberately imparting to the blade a substantially sideways motion, -wherein the blade is not directly driven and moves as an indirect consequence of the motion of an apparatus that tows the ground cutting blade during its operation. A method as claimed in claim 1 characterised by the further step of directly driving the blade to produce the vertical and sideways movements, A method as claimed in claim 3 characterised in that the vertical movement is imparted to the blade as a consequence of the centre of the blade not being aligned with the central axis of the shaft on which the blade rotates. A method as claimed in claim 3 characterised in that the substantially sideways movement is imparted to the blade as a consequence of the blade being tilted or inclined from the plane perpendicular to the axis on which the blade rotates. A method as claimed in any one of claims 3 to 5 characterised by the step of imparting the required motion to the blade by an eccentric sleeve which receives the shaft on which the blade turns. A method as claimed in claim 6 wherein there is provided an eccentric sleeve situated within the plane of the blade and capable of interacting with bearings that enable rotation of the blade. ■! OTr? Oc N.I. 1 - r":-> '-."fi i » ! . . ,i • ..! 19 PCT/NZ98/00043 # 8 9 10 11 12 13 A method as claimed in claim 7 wherein the outside of the eccentric sleeve bears against outer bearings situated in between the outer walls of the sleeve and the cutting blade. A method as claimed anyone of claims 6 to 8 characterised in that the eccentric sleeve is manufactured to be of varying thickness. A method as claimed in any one of claims 6 to 9 wherein the eccentric sleeve is manufactured to be skewed with respect to the drive shaft. A method as claimed in any one of claims 1 to 10 characterised by the further step of bleeding oil from a hydraulic motor associated with a ground working apparatus operating the blade to lubricate the shaft on which the blade turns. A method of working ground with a blade that has a substantially vertical and substantially sideways motion characterised by the step of (a) placing the blade in close proximity to a boot also working the ground. A method of operating a ground cutting blade as claimed in any one of claims 1-10 further characterised by an initial preliminary step of placing the ground cutting blade in close proximity to a boot also adapted to work ground. A method as claimed in claim 13 characterised in that the boot has a curved face of substantially the same curvature as the blade. A boot for ground working which is configured to operate in close proximity to a ground working blade operated as claimed in any previous claim, said boot including a first curved leading face, said curve being a concave curve which faces towards the blade which the boot is configured to operate in close proximity to, and 20 PCT/NZ98/00043 3378 § a second angled face near the top of the boot which is angled between horizontal and the vertical, wherein the concave curve of the first leading edge has a curvature substantially the same as the blade with which it works in close proximity to, and said first curved face is configured to co-operate with the blade to cut material which passes between the boot and the blade. 15 A boot as claimed in claim 15 wherein the toe of the boot sits higher than the cutting edge of the ground working blade with which the boot operates. 16 A boot as claimed in any one of claims 15 or 16 wherein the boot incorporates at least two guides, one guide capable of directing a seed into a trench created by the boot, and the other guide capable of directing fertiliser into the trench created by the boot characterised in that the guides ensure that the seed and the fertiliser are placed in separate positions from each other. 17 A boot as claimed in claim 17 wherein the guides are in the form of internal tubes. 18 A boot as claimed in claim 18 wherein one internal tube is positioned at the rear of the boot higher than an internal tube positioned immediately in front of the first internal tube. C.'.'iG. i\i.~ 1 3 F- ™ 21 PCT/NZ98/00043 19 A ground working unit which is configured to operate in accordance with the methods as claimed in claims 1 to 14. 20 A ground working unit which includes apparatus as claimed in any one of claims 15 to 20. 21 A method substantially as herein described with reference to and as illustrated by the accompanying drawings. 22 Apparatus substantially as herein described with reference to and as illustrated by the accompanying drawings. •; c . -• 1 3 F71 ji ^ r? r' ""7' ; n ij 22