RU2396394C1 - Stripping aggregate - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention refers to mining and can be implemented at open development of mineral deposits by non-transport system in complicated mining and geological conditions. The stripping aggregate consists of face and dumping non-rotary carrier platforms with masts interconnected with two running cables, and of a double-sided bucket with a bottom of V-shape coupled with each mast by means of a lift-and-drag cable enveloping a corresponding block installed between the running cables. The block of the face non-rotary platform is rigidly tied with the first running cable and is connected to the second running cable; it travels along this cable relative to the block of the non-rotary dumping carrier platform together with the second running cable. The block of the dumping non-rotary platform is rigidly tied with the second running cable and is connected to the first running cable; it travels along this cable relative to the block of the non-rotary face carrier platform together with the first running cable.

EFFECT: raised efficiency of stripping aggregate and reduced wear of cables.

10 dwg

Description

The invention relates to the mining industry and can be used in open pit mining of minerals through a transport-free system in difficult mining and geological conditions.

The problem of using overburden aggregates is as follows.

The effectiveness of such units depends on the bucket suspension system. Two suspension systems are known.

The first provides for a rigid connection of the bucket with the supporting or traction-bearing rope [USSR copyright certificate No. 840246, class. E02F 3/48, published June 23, 81. Bulletin No. 23; Rzhevsky V.V. "Open cast mining." Part 1. Production processes. M .: Nedra, 1985, 509 p., Pp. 370-371, fig. 17.12, b; Skurikhin Yu.G., Gordeev Yu.K., Dorofeev V.A. "The results of studies of the stripping unit." Coal Magazine, 1996, No. 6, pp. 34-36; patent of the Russian Federation for copyright certificate No. 225181, cl. E02F 3/54, published June 27, 2005; USSR certificate of authorship No. 132568, class E02F 3/46, E02F 3/54, published 01.01.1960 in the bulletin of inventions No. 19]. In this case, the bucket is lowered to the place of scooping associated with the supporting or traction-bearing rope. As a result, unit performance is reduced and rope wear is increased.

Productivity is reduced due to the increase in the duration of the working cycle due to the implementation of additional auxiliary work, the use of single-acting buckets, as well as double-acting with moving elements, etc.

The reason for the increased wear of the rope is its friction against the rock with an increase in the distance from the overburden to the upper edge of the ledge with a decrease in mining or an increase in the width of the overburden. A decrease in mining leads to an increase in the width of the safety platform and an increase in the distance between the equipment and the upper edge of the ledge. This reduces the distance between the rope and the upper edge of the ledge up to its elimination and cutting the rope into the rock. In this case, the rope wears out intensively. In addition, in the area of the upper edge of the ledge of the dumping blade, the bucket is moved by drawing along the rock. AT

As a result, the bucket moving speed decreases several times, the cycle time increases and the unit's performance decreases. In the development of coal deposits, the width of the overburden is 80-100 m with a traditional width of 40-60 m, which increases the distance between the overburden and the upper edge of the overburden ledge and the dump dump.

The second bucket suspension system is characterized by controlling the distance between the bucket and the towing rope [patent of the Russian Federation for copyright certificate No. 2034114, cl. E02F 3/54, published April 30, 1995, Bulletin No. 12]. This increases the performance of the stripping unit through the use of a double-acting bucket and reduces the wear of the ropes when rubbing them against the rock.

However, the performance of such units is reduced as a result of unproductive time expenditures when performing bucket moving elements during the working cycle. The increased wear of the ropes occurs due to the friction between the hoisting ropes.

Thus, the problem of using a stripping unit is to increase its productivity and reduce rope wear.

A well-known machine for the development of soil, consisting of two running platforms equipped with arrows, which are connected by a traction rope to move a double-sided bucket [USSR copyright certificate No. 840246, class. E02F 3/48, published June 23, 1981, Bulletin No. 23].

Common features of the well-known soil development machine with the claimed invention are: fixed running platforms, traction ropes and a double-sided bucket.

The disadvantages of this machine are:

- low productivity due to the heavy weight of running platforms on which booms of equal length are mounted, tilted to the side opposite from the operational trench, as well as the presence of articulated buckets with a traction rope, which cannot be used to scoop and unload rock anywhere in the way of its transportation, to produce a frill of the slope of the ledge; scooping the rock with such buckets is associated with increased sticking and freezing of the rock mass, while scooping the rock is accompanied by a low filling factor of the bucket and an increase in the duration of the working cycle;

- increased wear of the traction rope when rubbing it against the rock as a result of an increase in the width of the safety platform, with a decrease in mining or an increase in the width of the overburden.

A tower excavator is known, consisting of a tail and a head running platforms equipped with towers interconnected by a supporting rope, a bucket connected to the corresponding towers by pulling ropes and a trolley moving along the supporting rope. [Rzhevsky V.V. Open cast mining. Part 1. Production processes. M .: Nedra, 1985, 509 p., Pp. 370-371, Fig. 17. 12, b].

Common signs of a well-known tower excavator with the claimed invention are: fixed running platforms, a carrying rope and a bucket.

The disadvantages of the famous tower excavator are:

- low productivity due to the rigid connection of the bucket of the excavator with the support rope and the use of a single-acting bucket, as well as scooping the bucket in the direction opposite to its movement to the place of unloading at the dump. This increases the time of formation of dump tiers, stripping of the roof of a mineral deposit, excavation of rock ridges between aisles of a bucket, elimination of freezing of rock massifs, etc. At the same time, an additional volume of rocks is excavated, resulting from its movement in front of the loaded bucket in the so-called "drawing prism" and the distance of transportation of rocks to the dump increases;

- increased rope wear occurs due to its friction against the rock when the distance between the tower excavator and the upper edge of the ledge increases due to the increase in the width of the safety platform with a decrease in mining or an increase in the width of the entry.

Known overburden unit, consisting of a downhole fixed chassis with an arrow and a dump fixed chassis with a mast. The boom and the mast are interconnected by a traction-bearing rope with a block to which a bucket is connected, connected by a traction rope to a downhole non-rotating running platform [Skurikhin Yu.G., Gordeev Yu.K., Dorofeev V.A. "The results of studies of the stripping unit." Coal Magazine, 1996, No. 6, pp. 34-36].

Common features of the known stripping unit with the claimed invention are: fixed bottomhole running platform, fixed rotary dumping platform with a mast connecting the fixed running platforms traction-carrying rope and bucket.

The disadvantages of the known stripping unit are:

- low productivity due to the rigid connection of the bucket with the traction rope and the use of a single-acting bucket. This increases the time of formation of dumping tiers, cleaning the roof of a mineral deposit, excavating ridges between aisles of a bucket, eliminating freezing of loosened rocks, slope frills, cleaning of rocks in the area of the lower edge of the ledge, increasing the working cycle time when moving a bucket filled with rock by the "drawing" method in the region of the upper edge of the dumped dumping entry with a decrease in mining operations, etc .;

- increased rope wear as a result of tight connection of the overburden aggregate bucket with the supporting rope occurs due to the friction of the ropes against the rock with an increase in the distance between the overburden and the upper edge of the ledge or dump entry as a result of an increase in the width of the overburden entry or the width of the safety platform while lowering mining operations.

A well-known tower excavator, consisting of a machine and tail towers, interconnected by two load-bearing and two traction ropes, as well as two buckets with runners connected with trolleys moving on load-bearing ropes [patent of the Russian Federation for copyright certificate No. 225181, cl. E02F 3/54, published June 27, 2005].

Common features of a well-known tower excavator with the claimed invention are ropes and a bucket.

The disadvantages of the famous tower excavator are:

- low productivity due to the movement of buckets in the soil due to a decrease in its speed by several times; increasing the time of filling the bucket when cleaning the lower edge of the ledge, when loading vehicles and when forming a dumping tier;

- increased wear of the rope as a result of its friction against the rock with an increase in the distance between the tower excavator and the upper edge of the overburden ledge or the dumped dump approach as a result of an increase in the width of the safety platform with a decrease in mining or an increase in the width of the overburden.

Known cable-tower excavator, including downhole and dump fixed rotary platforms with masts interconnected by a bearing rope, and a double-sided bucket [USSR copyright certificate No. 1322568, class. E02F 3/46, E02F 3/54, published 01.01.1960 in the bulletin of inventions No. 19].

Common features of the well-known cable-tower installation with the claimed invention are downhole and dump fixed rotary platforms with masts interconnected by a rope, a double-sided bucket connected with corresponding masts by ropes.

The disadvantages of the known cable-tower installation are:

- low productivity due to the use of a double-sided bucket, consisting of two ladles interconnected by a chain, and their rigid connection with the support rope. When storing rocks unilaterally relative to the trench, only one of the two buckets will be in operation. The second bucket will prevent the first bucket from filling. A rigid connection of each bucket with a supporting rope increases the time of formation of dump tiers, cleaning the roof of a mineral deposit, cleaning ridges between aisles of a bucket, eliminating loosened loosened rocks, fringing slopes of ledges, cleaning rocks in the area of the lower edge of the ledge, and the working cycle by moving the filled rock of the bucket by the method of "drawing" in the region of the upper edge of the dumped dumping entry while lowering mining operations, etc .;

- increased wear of the rope as a result of the rigid connection of the double-sided bucket with the bearing rope occurs due to the friction of the ropes against the rock with increasing distance between the cable-tower installation and the upper edge of the ledge or the dumped dumping entry due to the increase in the width of the safety platform while reducing mining or overburden width .

A unit for a transportless development system according to a patent of the Russian Federation for invention No. 2034114, class. E02F 3/54, published 04/30/1995, as the closest in technical essence and its functions.

A unit for a developmentless transport system consists of a bottomhole and dump fixed turret with masts connected by a traction-carrying rope, and a two-sided bucket with a V-shaped bottom connected to the masts by hoisting-and-pulling ropes enveloping the corresponding unit fixed to the traction support rope.

Common features of the known unit for a transportless development system with the claimed invention are:

- bottomhole and dump fixed rotary platforms with masts interconnected by a towing rope;

- a bucket with a V-shaped bottom, connected to the masts by hoisting ropes, enveloping the corresponding unit, mounted on a hoisting rope.

The disadvantages of the known unit for a transportless development system are:

- low productivity as a result of non-productive operations during the work cycle. So, when moving the bucket after unloading from the dump non-rotating running platform to the digging site towards the downhole non-rotating running platform, the hoisting-and-pulling ropes in the section between the bucket and the block are parallel and in a vertical position, in which the bucket is lowered to the surface of the rock for scooping.

To move the bucket during scooping towards the dump platform, the traction-bearing ropes in the area between the bucket and the block are tilted towards the dump platform and set at an angle that ensures filling of the bucket when moving it. After filling the bucket with rock, the hoisting ropes are returned to their original vertical position to detach it from the place of scooping and transporting the bucket to the dump platform. Tearing the bucket from the place of scooping, it is set in position to move to the dump platform for unloading. When transporting a loaded bucket, the hoisting ropes in the section between the bucket and the block occupy a parallel vertical position.

During the tilt of the hoisting ropes to the scooping position and returning them after scooping to the original transport position, the bucket is stationary and does not perform any work.

As a result, the duration of the working cycle increases by the amount of time the slope of the hoisting ropes in the section between the bucket and the block for scooping and returning them to their original vertical position for transporting the bucket to the place of unloading. So when conducting mining operations at a depth of 70.0 m, the average duration of the duty cycle is 95.0 s. The time of tilting the hoisting ropes to the position for scooping and returning them to the position for transporting the bucket to the unloading point is 18.0 s or 19.0% of the working cycle, is unproductive and reduces the performance of the overburden unit.

- increased wear of the ropes occurs as a result of the friction of the hoisting ropes against each other in the area between the bucket and the block when they sag during scooping.

The disadvantage of the prototype is the lack of technical solutions aimed at:

- reducing unproductive time for the transfer of hoisting ropes in the area between the bucket and the unit from the transport position to the position for scooping with the bucket, and after scooping and detaching the bucket from the place of scooping, back to the position for transporting the loaded bucket to the unloading place;

- reduction of rope wear.

The invention is aimed at solving problems of increasing the performance of the stripping unit and reducing wear of the ropes.

The technical result of the claimed invention is to increase the performance of the stripping unit and reduce wear of the ropes due to changes in the suspension system of the bucket.

The technical result is achieved by the fact that the overburden unit, consisting of a bottomhole and dump fixed rotary platforms with masts connected by a traction-carrying rope, and a double-sided bucket with a V-shaped bottom connected to the masts by lifting and traction ropes enveloping the corresponding unit fixed to traction rope, equipped according to the claimed invention with an additional traction rope connecting the masts of the bottomhole and dump fixed slewing platforms, while the blocks of the bottomhole and dump fixed rotating platforms are placed between the towing ropes and are connected with them with the possibility of moving relative to each other together with the towing ropes, and the block of the downhole fixed rotating platform is rigidly connected with one traction-bearing rope, and the block of the dump fixed rotating platform is connected to another traction rope.

The connection of the masts of the bottomhole and dump non-rotating running platforms with an additional traction-carrying rope provides the ability to move blocks of hoisting-and-ropes relative to each other together with traction-carrying ropes. This allows you to change the distance between the blocks and adjust the angle of inclination of the ropes during the execution of the work cycle.

Placing the blocks between the traction-bearing ropes creates the places of attachment of the hoisting-ropes to the bucket in the plane coinciding with the vertical plane passing through the middle of the bucket width and ensuring its balance. This is aimed at achieving a technical result, including ensuring the balance of the bucket in conjunction with two traction-bearing ropes.

The connection of the blocks with the traction-bearing ropes creates the structural strength of the bucket suspension system.

Providing the ability to move blocks relative to each other together with traction-carrying ropes involves changing the distance between the blocks of hoisting ropes during the execution of the working cycle of the overburden, reduce the time to change the angle of inclination of the hoisting ropes when moving them from the transport position to the position for scooping bucket and vice versa. This reduces the duration of the working cycle of the stripping unit and increases its productivity, providing a technical result.

Rigid fastening of a block of a downhole non-revolving running platform to one traction-carrying rope and rigid fastening of a block of a dumping non-revolving running platform to another traction-carrying rope allows you to move the blocks by changing the distance between them, ensuring the position of the bucket necessary to perform workflow elements and reduce the cycle time .

As a result of the expansion of the blocks, the distance between the hoisting ropes increases, which reduces their wear by reducing friction against each other when they sag. This ensures the achievement of a technical result.

The invention is illustrated by drawings (Fig.1-10), where Fig.1 shows a stripping unit in operation; figure 2 presents the connection diagram of the blocks downhole and dump fixed rotary platforms with traction-bearing ropes in the plan; figure 3 - connection diagram of the block dump rotary running platform with traction-bearing ropes in cross section; figure 4 - connection diagram of the block downhole fixed running platform with traction-bearing ropes in cross section; figure 5 is a diagram of the position of blocks of fixed running platforms after they are moved to fixed running platforms (arrows indicate the direction of movement, dotted lines show the initial position of the blocks); Fig.6 is a diagram of the position of blocks of fixed running platforms after their movement from fixed platforms (arrows indicate the direction of movement, dotted lines show the initial position of the blocks); figure 7 - moving the bucket after unloading; on Fig - scooping rock with a bucket; figure 9 is the position of the bucket after scooping; figure 10 - fringe slope ledge bucket.

The overburden unit (Fig. 1) consists of a bottomhole 1 and dump 2 fixed turret platforms with masts 3 and 4 of these platforms, which are located on the sides of the operational trench a, b, c, d, etc. Mast 3 of the downhole platform 1 is connected to the mast 4 dump platform 2 with two traction-bearing ropes 5 and 6 with blocks 7, 8, 9 and 10 attached to them (in Figs. 1, 7, 8, 9, 10, rope 6 is not visible, but shown in Figs. 2, 3 , 4, 5, 6. Block 9 in Figs. 1, 7, 8, 9, 10 is not visible, but is shown in Figs. 2, 4, 5, 6.) On one side, the bucket 11 is connected to the mast 3 of the downhole fixed platform 1 hoisting rope 12 downhole fixed platform 1 (figure 1), the envelope of block 7. Block 7 is connected with the traction-bearing ropes 5 and 6 of the axis of rotation 13 and block 9 (shown in figure 2, 4, 5, 6). On the other hand, the bucket 11 is connected to the mast 4 of the dump non-rotary running platform 2 (Fig. 1) by a lifting and pulling rope 14 of the dump moving platform 2, enveloping the block 8. Block 8 is connected to the traction-carrying ropes 5 and 6 by the axis of rotation 15 and block 10 (see figure 2, 3, 5, 6).

Block 7 of the hoisting rope 12 of the downhole non-rotating running platform 1 is located between the traction-bearing ropes 5 and 6 and is rigidly connected by the axis of rotation 13 of this block 7 with the traction-bearing rope 5 and the block 9 mounted for movement along the traction-bearing rope 6 (figure 2, 4, 5, 6). Block 8 of the hoisting rope 14 of the dump non-rotatable running platform 2 is located between the traction-bearing ropes 5 and 6 and is rigidly connected by the axis of rotation 15 of this block 8 with the traction-bearing rope 6 and the block 10 mounted for movement along the traction-bearing rope 5 (see figure 2, 3, 5, 6).

In this case, schematically in FIG. 1, the elements of the trench are indicated by the following positions: 16 — overburden ledge; 17 - internal dump; 18 - blasted rock; a, e, g - the contour of the dumped internal dump.

The overburden unit works as follows.

The downhole non-rotating running platform 1 is installed on the overburden ledge 16 at a distance from the upper edge of this ledge, excluding the collapse of the ledge under the influence of the load from the downhole non-rotating running platform 1. The dump non-rotating running platform 2 is installed on the internal dump 17 at a distance from the upper edge of this dump, excluding collapse of the blade under the influence of the load from the dump fixed rotary platform 2. Downhole fixed rotary platform 1 moves along the overburden ledge 16. The total non-rotating running platform 2 moves along the upper edge of the internal dump 17. At the same time, the blasted rock 18 is excavated, moves and is stored in the internal dump within the boundaries of the a-e-g circuit.

A study of the operation of a double-sided bucket with a V-shaped bottom showed that the stability of the bucket 11 is ensured when the inclination angles of the lifting and traction ropes 12 and 14 are equal in the sections between the bucket 11 and blocks 7 and 8 of the bottomhole 1 and dump 2 non-rotary running platforms. If the angle of inclination of the hoisting rope 12 in the section between the bucket 11 and the block 7 is less than the angle of inclination of the hoisting rope 14 in the section between the bucket 11 and the block 8, then the bucket tilts its teeth down towards the hoisting rope 7 with a smaller angle of inclination. The dragline bucket also works according to this scheme, the balance of which is created by the presence of a balancing rope. When the angle of inclination of the traction rope is less than the angle of inclination of the hoisting rope and the absence of a balancing rope, the bucket lowers its teeth down towards the traction rope.

The suspension scheme of the bucket 11 is tested on the model design installation.

When unloading the bucket 11 on the upper platform of the dump dump approach along the contour a-e-g, the hoisting ropes 12 and 14 in the sections between the bucket 11 and blocks 7, 8 of the bottomhole 1 and dump 2 of non-rotating running platforms respectively occupy a vertical position that provides the closest the location of the unloaded rock to the dump fixed rotary platform 2.

To move the bucket 11 in the process of scooping the rock toward the dump non-rotary running platform 1, the bucket 11 is transported in the direction of the downhole non-rotary running platform 1 by a traction-bearing rope 5 with blocks 7, 9 and a hoisting-and-traction rope 12, a traction-carrying rope 6 with blocks 8 10 and the hoisting rope 14, ensuring the vertical position of the hoisting rope 12 in the section between the bucket 11 and the block 7, and the inclined rope of the hoisting rope 14 in the section between the bucket 11 and the block 8. The bucket 11 is tilted down and lower the pr and its movement in the direction of the downhole non-revolving running platform 1. Block 8 of the lifting and pulling rope 14 of the dump non-rotating platform 2 is stopped above the upper edge of the dumped dumping entry within the contour a-e-f, and the block 7 of the lifting and traction rope 12 of the downhole non-rotating running platform 1 - above the place of scooping (see Fig.7).

By loosening the hoisting rope 12 of the downhole non-rotating running platform 1, the bucket 11 is lowered and pulling the hoisting-and-pulling rope 14 of the dump non-rotating running platform 2 move the bucket 11 in the process of scooping the rock towards the dump rotary running platform 2. The angle of introduction is regulated by the hoisting and pulling rope 12 of the downhole fixed chassis 1 (see Fig.8).

Before the separation of the bucket 11 filled with rock from the place of scooping and its transfer to the transport position, the angle of inclination of the hoisting and pulling rope 14 in the area between the bucket 11 and the block 8 of the dump non-rotating running platform 2 is increased and the angle of inclination of the lifting and hoisting rope 12 in the area between the bucket 11 is reduced and block 7 downhole non-rotating running platform 1 until they are equal to each other by tensioning the traction-bearing rope 6 with blocks 8, 10 and traction-bearing rope 5 with blocks 7, 8 towards the downhole non-rotating running platform 2 ( see figures 1, 9).

By the action of the traction-bearing ropes 5, 6 and hoisting-and-trailing 12, 14, the bucket 11 filled with the rock is torn off from the place of digging and if the inclination angles of the hoisting-and-hoisting ropes 12, 14 are equal in the sections between the bucket 11 and blocks 7, 8, respectively, and are moved to the side internal dump 17 to the place of unloading.

To move the bucket 11 in the process of scooping the rock towards the downhole non-rotating running platform 1, the bucket 11 is transported after unloading it to the bottom hole platform 1 by the traction-carrying rope 5 with blocks 7, 9 and a hoisting-rope rope 12, a traction-bearing rope 6 and a lifting - traction rope 14, ensuring the vertical position of the hoisting and traction rope 12 in the area between the bucket 11 and the block 7, and inclined - hoisting and traction rope 14. In this case, the teeth of the bucket 11 are tilted down, lowering it to the point of digging when moving towards the bottom hole platform s 1. Block 7 lifting and pulling rope 12 is stopped above the upper Brovko overburden ledge 16, lifting-unit 8 of the traction rope 14 - digging over the place.

By loosening the hoisting rope 14 of the dump non-rotating running platform 2, lower the bucket 11 to the place of scooping and pulling the lifting and hauling rope 12 of the downhole non-rotating running platform 1 move the bucket 11 in the process of scooping towards the downhole non-rotating running platform 1. The introduction angle is regulated by the lifting and hauling rope 14 dump fixed turntable 2.

Before tearing the bucket 11 filled with rock from the place of scooping and transferring it to the transport position, reduce the angle of inclination of the hoisting rope 14 in the area between the bucket 11 and block 8 and increase the angle of inclination of the hoisting rope 12 in the area between the bucket 11 and block 7 to equality these angles to each other by tensioning the traction-bearing rope 6 with blocks 8, 10 and the traction-bearing rope 5 with blocks 7, 9 towards the dump fixed rotary undercarriage 2.

After filling the bucket 11 with rock by the action of the traction-bearing ropes 5, 7, of the hoisting-traction ropes 12, 14, the loaded bucket 11 is torn off from the place of digging and if the inclination angles of the hoisting ropes 12, 14 are equal in the sections between the bucket 11 and blocks 7, 8 respectively move towards the internal dump to the place of unloading.

The change in the angle of inclination of the hoisting ropes 12, 14 in the area between the bucket 11 and the blocks 7, 8, respectively, is combined in time with the movement of the bucket 11 from the place of its unloading to the place of scooping. Therefore, unproductive operations are not performed, and time is not spent on this. Changing the angle of inclination of these ropes before breaking the bucket 11 filled with rock from the place of scooping and preparing it for transportation to the place of unloading is an unproductive operation, as this is done with the bucket 11 stationary. However, the angle of inclination of the hoisting ropes is half that of the prototype, which corresponds to a decrease in unproductive time by half.

When loading vehicles, cleaning the roof of the mineral layer and its lower edge, the frill of the slope of the ledge (see figure 10), the processes of changing the tilt angles of the hoisting ropes and transporting the bucket from the unloading place to the place of scooping are fully combined in time, and after filling bucket breed or minerals unproductive time spent on preparing the bucket for separation from the site of digging and transportation, is reduced by half. This reduces the working cycle time as a result of reducing the duration of unproductive operations.

Claims (1)

An overburden unit, including a downhole and dump non-rotating running platforms with masts connected by a traction-carrying rope, a double-sided bucket with a V-shaped bottom connected to each mast by means of a hoisting-and-trailing rope, enveloping the corresponding block, fixed on the traction-bearing rope, different the fact that it further comprises a towing rope connecting the bottomhole and dump fixed rotary platforms, while the blocks of downhole and dump fixed rotary platforms are located between the traction uschimi ropes and connected with them to move relative to one another in conjunction with trailer-bearing rope, wherein the downhole unit chassis platform pivot is rigidly associated with one towing rope carrier, and the block moldboard pivot platform suspension - with another trailer bearing rope.

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