Single-ridge double-seedling-belt front profiling depth limiting, staggered ditching and independent pressing device
By adjusting the spacing between the discs and rollers of the single-ridge double-seedling belt with pre-positioned contour-guided depth limit, staggered furrowing, and independent pressing device, the problem of inaccurate sowing in existing technologies has been solved, achieving precise sowing and high emergence rate.
Patent Information
- Application Number
- CN202423076877.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-11-18
- Estimated Expiration
- 2034-12-13
AI Technical Summary
The existing single-ridge double-seedling belt contouring and pressing device is prone to inaccurate contouring and pressing when the ridge height is uneven, the soil is hard, or there are many soil clods, which affects the sowing depth and germination rate.
The system employs a single-ridge double-seedling belt with pre-positioned contour-following depth control, staggered furrowing, and independent compaction device. By adjusting the number of disc adjustment shims and compaction wheel adjustment shims, the spacing between the double disc furrow opener and the V-shaped compaction wheel is adjusted to ensure consistent walking trajectory and achieve precise sowing and soil covering.
It enables adjustment of the double seedling strip distance within a range of 120-160 mm to meet different planting needs, improves sowing accuracy and germination rate, and reduces the risk of seeds being exposed to the ground.
Smart Images

Figure CN223553746U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of agricultural machinery, especially to a single-ridge double-sowing-belt front-located profiling depth-limiting, staggered ditching and independent compacting device. BACKGROUND
[0002] In the prior art, single-ridge double-sowing-belt profiling depth-limiting and compacting generally adopt two structures. One is to use an integral wheel at the rear end of a seeding unit to profile and limit the depth of the double-sowing belt and compact it together through a screw rod integral wheel. The disadvantage is that the position of the integral wheel is fixed after adjustment, and the profiling and compacting are obviously affected by the effect of land leveling. When the ridge height is uneven, the seeding depth is not uniform, the soil is hard or contains many clods, the seeds are not exposed to the ground surface. The other structure is to install a profiling depth-limiting wheel outside two pairs of disc ditchers and install two groups of four V-shaped compacting wheels at the rear end. Since the spacing between the double-sowing belts is limited to 120-160mm by the structure, the profiling depth-limiting wheels on the two sides are wide, and one side of the profiling wheel often exceeds the range of the ridge during work. In severe cases, both wheels run under the ridge, and the rear V-shaped compacting wheels deviate from the position of the sowing belt, reducing the seedling rate and affecting the later intertillage and fertilization. SUMMARY
[0003] In view of the above-mentioned problems of the existing single-ridge double-sowing-belt profiling depth-limiting and compacting, the purpose of the utility model is to provide a single-ridge double-sowing-belt front-located profiling depth-limiting, staggered ditching and independent compacting device.
[0004] To achieve the above-mentioned purpose, the utility model adopts the technical scheme that:
[0005] A single-ridge double-sowing-belt front-located profiling depth-limiting, staggered ditching and independent compacting device, comprising:
[0006] a single-unit main beam 4 and a lifting device mounting frame, the lifting device mounting frame being connected to the front end of the single-unit main beam 4;
[0007] a lifting device mounted in the lifting device mounting frame;
[0008] a profiling depth-limiting wheel 1 and a depth-limiting wheel mounting frame, the depth-limiting wheel mounting frame being mounted at the lower end of the lifting device, and the profiling depth-limiting wheel 1 being rotatably mounted on the depth-limiting wheel mounting frame;
[0009] a V-shaped compacting wheel 6 and a compacting wheel mounting frame, two compacting wheel mounting frames being symmetrically mounted at the rear end of the single-unit main beam 4, and each V-shaped compacting wheel 6 being rotatably mounted on a compacting wheel mounting frame;
[0010] a double-disc ditcher 3 and a ditcher mounting frame, two ditcher mounting frames being respectively mounted at the two sides of the single-unit main beam 4, and each double-disc ditcher 3 being mounted on a ditcher mounting frame.
[0011] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein the lifting device comprises a rotating driving mechanism, a lead screw 2, a lead screw mounting nut, a first rectangular steel pipe and a second rectangular steel pipe, the first rectangular steel pipe is installed in the lifting device mounting frame, the lead screw mounting nut is installed in the first rectangular steel pipe and located at the top end of the first rectangular steel pipe, the lead screw 2 is assembled on the lead screw mounting nut and the lower part thereof is located in the first rectangular steel pipe, the second rectangular steel pipe is slidingly installed in the first rectangular steel pipe, the bottom end of the second rectangular steel pipe is connected with the depth-limiting wheel mounting frame, and the top end of the second rectangular steel pipe is rotationally connected with the lower end of the lead screw 2.
[0012] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein the rotating driving mechanism is a handle, the handle is installed at the upper end of the lead screw 2, and rotating the first handle can realize the rotation of the lead screw 2 around its own axis.
[0013] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein the rotating driving mechanism is a driving motor, the driving motor is installed on the lifting device mounting frame, and the driving motor is used to drive the rotation of the lead screw 2.
[0014] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein the two double-disc ditchers 3 are staggered.
[0015] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein the distance between the vertical planes where the two double-disc ditchers 3 are located ranges from 120 mm to 160 mm, and the distance between the vertical planes where the two V-shaped compacting wheels 6 are located ranges from 120 mm to 160 mm.
[0016] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein it further comprises disc adjusting shims 7, at least one disc adjusting shim 7 is assembled between each ditcher mounting frame and the monomer main beam 4 to adjust the distance between the vertical planes where the two double-disc ditchers 3 are located.
[0017] The single-ridge double-sowing-belt pre-imitation depth-limiting, staggered ditching and independent compacting device, wherein it further comprises compacting wheel adjusting shims 8, at least one compacting wheel adjusting shim 8 is assembled between each compacting wheel mounting frame and the monomer main beam 4 to adjust the distance between the vertical planes where the two V-shaped compacting wheels 6 are located.
[0018] The single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device, wherein the compacting wheel mounting frame comprises a compacting wheel mounting frame body and a tension spring mechanism, one end of the compacting wheel mounting frame body is rotationally connected with the rear end of the single main beam 4, and a V-shaped compacting wheel 6 is rotationally mounted at the other end of the compacting wheel mounting frame body; one end of the tension spring mechanism is rotationally connected with the rear end of the single main beam 4, and the other end of the tension spring mechanism is rotationally connected with the other end of the compacting wheel mounting frame body.
[0019] The single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device, wherein the tension spring mechanism comprises a compacting tension spring 5, an adjusting bolt and an adjusting nut seat, one end of the compacting tension spring 5 is rotationally connected with the rear end of the single main beam 4, the other end of the compacting tension spring 5 is connected with the adjusting nut seat, the adjusting nut seat is assembled on the adjusting bolt, the nut of the adjusting bolt is rotationally connected with the other end of the compacting wheel mounting frame body, and the tension amount of the compacting tension spring 5 is adjusted by rotating the adjusting bolt.
[0020] The single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device, wherein the tension spring mechanism comprises a compacting tension spring 5, an adjusting bolt and an adjusting nut seat, one end of the compacting tension spring 5 is rotationally connected with the rear end of the single main beam 4, the other end of the compacting tension spring 5 is connected with the adjusting nut seat, the adjusting nut seat is assembled on the adjusting bolt, the nut of the adjusting bolt is rotationally connected with the other end of the compacting wheel mounting frame body, and the tension amount of the compacting tension spring 5 is adjusted by rotating the adjusting bolt.
[0021] (1) The number of disc adjusting shims between the two pairs of double-disc ditchers and the single main beam is increased or decreased to adjust the spacing of the two pairs of double-disc ditchers, and the number of compacting wheel adjusting shims between the two groups of V-shaped compacting wheels and the single main beam is increased or decreased to adjust the spacing of the two groups of V-shaped compacting wheels, so that the double-sowing-belt distance can be adjusted between 120-160mm to meet different planting requirements.
[0022] (2) In the utility model, the spacing of the two groups of V-shaped compacting wheels needs to be consistent with the spacing of the two pairs of double-disc ditchers by increasing or decreasing the disc adjusting shims and the compacting wheel adjusting shims, so that the walking track of the V-shaped compacting wheel can be consistent with the walking track of the double-disc ditcher located in front of the V-shaped compacting wheel. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 It is a front view of a single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device.
[0024] Figure 2 It is a front view of a single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device.
[0025] Figure 3 It is a front view of a double-disc ditcher of a single-ridge double-sowing-belt front-imitation depth-limiting, staggered ditching and independent compacting device.
[0026] Figure 4It is a top view of the double-disc furrower of the single-ridge double-mulch-belt front-imitation-depth-limiting, staggered furrowing and independent compacting device according to the utility model.
[0027] Figure 5 It is a front view of the compacting wheel frame of the single-ridge double-mulch-belt front-imitation-depth-limiting, staggered furrowing and independent compacting device according to the utility model.
[0028] Figure 6 It is a top view of the compacting wheel frame of the single-ridge double-mulch-belt front-imitation-depth-limiting, staggered furrowing and independent compacting device according to the utility model. DETAILED DESCRIPTION
[0029] The utility model will be further described in connection with the drawings and specific embodiments, but not as the limitation of the utility model.
[0030] Please refer to Figures 1 to 6 It shows a single-ridge double-mulch-belt front-imitation-depth-limiting, staggered furrowing and independent compacting device, wherein, including:
[0031] The monomer main beam 4 and the lifting device mounting frame are connected with the front end of the monomer main beam 4.
[0032] The lifting device is installed in the lifting device mounting frame.
[0033] The imitation depth-limiting wheel 1 and the depth-limiting wheel mounting frame are installed at the lower end of the lifting device, and the imitation depth-limiting wheel 1 is rotatably installed on the depth-limiting wheel mounting frame.
[0034] The V-shaped compacting wheel 6 and the compacting wheel mounting frame are symmetrically installed at the rear end of the monomer main beam 4, and each V-shaped compacting wheel 6 is rotatably installed on one compacting wheel mounting frame.
[0035] The double-disc furrower 3 and the furrower mounting frame are installed on both sides of the monomer main beam 4, and each double-disc furrower 3 is installed on one furrower mounting frame.
[0036] Further, in a preferred embodiment, the lifting device comprises a rotary driving mechanism, a lead screw 2, a lead screw mounting nut, a first rectangular steel pipe and a second rectangular steel pipe, the first rectangular steel pipe is installed in the lifting device mounting frame, the lead screw mounting nut is installed in the first rectangular steel pipe and located at the top end of the first rectangular steel pipe, the lead screw 2 is assembled on the lead screw mounting nut and the lower part thereof is located in the first rectangular steel pipe, the second rectangular steel pipe is slidably installed in the first rectangular steel pipe, the bottom end of the second rectangular steel pipe is connected with the depth-limiting wheel mounting frame, the top end of the second rectangular steel pipe is rotatably connected with the lower end of the lead screw 2, and the rotary driving mechanism drives the lead screw 2 to rotate around the axis thereof.
[0037] Further, in a preferred embodiment, the rotating driving mechanism is a handle, the handle is installed on the upper end of the lead screw 2, and rotating the first handle can realize the rotation of the lead screw 2 around the axis thereof.
[0038] Further, in a preferred embodiment, the rotating driving mechanism is a driving motor, the driving motor is installed on the lifting device mounting frame, and the driving motor is used for driving the rotation of the lead screw 2.
[0039] Further, in a preferred embodiment, the two double-disc furrowers 3 are staggered.
[0040] Further, in a preferred embodiment, the distance between the vertical planes where the two double-disc furrowers 3 are located ranges from 120 mm to 160 mm, and the distance between the vertical planes where the two V-shaped packers 6 are located ranges from 120 mm to 160 mm.
[0041] Further, in a preferred embodiment, the vertical planes where the two double-disc furrowers 3 are located are adjusted by at least one disc adjusting gasket 7 arranged between each furrower mounting frame and the monomer main beam 4.
[0042] Further, in a preferred embodiment, the vertical planes where the two V-shaped packers 6 are located are adjusted by at least one packer adjusting gasket 8 arranged between each packer mounting frame and the monomer main beam 4.
[0043] Further, in a preferred embodiment, the packer mounting frame comprises a packer mounting frame body and a tension spring mechanism, one end of the packer mounting frame body is rotationally connected to the rear end of the monomer main beam 4, and the V-shaped packer 6 is rotationally installed on the other end of the packer mounting frame body; one end of the tension spring mechanism is rotationally connected to the rear end of the monomer main beam 4, and the other end of the tension spring mechanism is rotationally connected to the other end of the packer mounting frame body.
[0044] Further, in a preferred embodiment, the tension spring mechanism comprises a packer tension spring 5, an adjusting bolt and an adjusting nut seat, one end of the packer tension spring 5 is rotationally connected to the rear end of the monomer main beam 4, the other end of the packer tension spring 5 is connected to the adjusting nut seat, the adjusting nut seat is arranged on the adjusting bolt, the nut of the adjusting bolt is rotationally connected to the other end of the packer mounting frame body, and the tension of the packer tension spring 5 is adjusted by rotating the adjusting bolt.
[0045] The above is only a preferred embodiment of the utility model, and does not limit the implementation mode and protection scope of the utility model.
[0046] The utility model further has the following implementation modes on the basis of the above:
[0047] The further embodiment of the utility model discloses still include: baffle, two baffles all install on single main beam 4, and every baffle is located in the front of a double disc furrower 3, play the function of shielding thrown soil and fertilizer.
[0048] The further embodiment of the utility model discloses still include: inner scraper and outer scraper, two inner scrapers and two outer scrapers all install on single main beam 4, and every inner scraper and an outer scraper are used to carry out the scraping work of rotating double disc furrower 3, guarantee double disc furrower 3 stable work.
[0049] The further embodiment of the utility model discloses, profiling depth limiting wheel 1 is installed in the front of two pairs of staggered arrangement and is used to sow double disc furrower 3, and through the rotation of lead screw 2 drive profiling depth limiting wheel 1 moves up and down and adjusts the height position of profiling depth limiting wheel 1, in order to realize the function of sowing depth limiting and flattening ridge. Two pairs of double disc furrower 3 are installed to the both sides of single main beam 4, and the rear end of single main beam 4 installs two groups V type press wheel 6 to the seed trench after sowing and carries out extrusion and compaction function.
[0050] The further embodiment of the utility model discloses, through the number of disc adjusting gasket 7 between two pairs of double disc furrower 3 and single main beam 4 is increased or reduced to adjust the spacing of two pairs of double disc furrower 3, through the number of press wheel adjusting gasket 8 between two groups V type press wheel 6 and single main beam 4 is increased or reduced to adjust the spacing of two groups V type press wheel 6, can adjust double seedling zone distance between 120-160 millimeters, satisfy different planting demand, through the disc adjusting gasket 7 and press wheel adjusting gasket 8 of increasing or reducing, the spacing of two groups V type press wheel 6 needs with the spacing of two pairs of double disc furrower 3 keep consistent, guarantee the walking track of V type press wheel 6 can keep consistent with the walking track of double disc furrower 3 located in its front side.
[0051] The further embodiment of the utility model discloses, double disc furrower 3 is used to set up seed trench and carries out sowing, and V type press wheel 6 is used to extrude the seed trench after sowing and compaction.
[0052] In the further embodiment of the utility model, the profiled depth limiting wheel 1 walks on the road surface, the height of the profiled depth limiting wheel 1 can be adjusted through rotating the lead screw 2, the lead screw 2 is perpendicular to the monomer main beam 4, two double-disc furrow openers 3 are fixedly installed on the monomer main beam 4, the two double-disc furrow openers 3 are used for opening seed furrows on the road surface, the depth of furrowing, fertilizing and seeding of the two double-disc furrow openers 3 can be adjusted by adjusting the height of the profiled depth limiting wheel 1, the seed furrows after seeding are extruded and compacted by two groups of V-shaped compacting wheels 6 with the same walking track as the two double-disc furrow openers 3, the spacing of the two groups of double-disc furrow openers 3 is adjusted by increasing or decreasing the number of disc adjusting shims 7 between the two groups of double-disc furrow openers 3 and the monomer main beam 4, the spacing of the two groups of V-shaped compacting wheels 6 is adjusted by increasing or decreasing the number of compacting wheel adjusting shims 8 between the two groups of V-shaped compacting wheels 6 and the monomer main beam 4, the function of adjusting the double seedling belt distance is realized, and the consistency of the walking track is ensured.
[0053] In the further embodiment of the utility model, the first rectangular steel pipe is installed in the lifting device mounting frame, the second rectangular steel pipe is slidingly installed in the first rectangular steel pipe, the bottom end of the second rectangular steel pipe is connected with the depth limiting wheel mounting frame, and the overall turning of the compacting device can be realized by driving the turning of the lifting device mounting frame.
[0054] In the further embodiment of the utility model, the lifting device mounting frame and the monomer main beam 4 are each provided with a connecting part for being connected with other agricultural machines, and the agricultural machines include seed boxes, fertilizer boxes, walking devices and the like.
[0055] In the further embodiment of the utility model, the specific structure and function of the double-disc furrow opener 3 are as follows: the seeding disc 31 and the disc hub 35 are fastened into an integral whole by screws, and they are installed on the furrow opener frame 32 by bearings; when the seeding disc 31 works, the lower end penetrates into the soil, and the seeding disc 31 rotates around the shaft on the furrow opener frame 32 when advancing and receiving the resistance of the soil, thereby completing the furrowing function; the furrowing sliding cutter 34 is inserted into the bottom end of the furrow opener frame 32 and connected by an elastic pin, is located between the two seeding discs 31, separates the soil at the gap between the two seeding discs 31, and guarantees the furrowing quality; the middle part of the seed guiding pipe 33 is inserted into the middle part of the furrow opener frame 32, and the upper end is fixed in position with the furrow opener frame 32 by bolts; the seeds discharged by the seed metering device pass through the internal passage of the seed guiding pipe 33 and are smoothly put into the seed furrow cleaned by the seeding disc 31 and the furrowing sliding cutter 34, thereby completing the seeding.
[0056] In the further embodiment of the utility model, the specific structure and function of V-shaped roller 6: bolt is used to fix roller 64 on both sides of roller frame 61, and the distance between two rollers 64 is ensured according to requirements. Hang roller tension spring 5 on pressure adjusting plate 63, then hinge pressure adjusting plate 63 on the rear end of roller frame 61. The other end of roller tension spring 5 is hung to the end of single main beam 4. Handle 62 is bolted to the upper end of pressure adjusting plate 63, hold handle 62 to move pressure adjusting plate 63, and put it into different grooves on the back plate of roller frame 61, then change the working length of roller tension spring 5, adjust the pressure of roller 64 on the ground, and complete the roller pressing of sowed seeds.
[0057] The above is only the preferred embodiment of the utility model, and does not limit the implementation and protection scope of the utility model. For those skilled in the art, it should be realized that the equivalent replacement and obvious changes made by using the utility model specification and drawing contents should be included in the protection scope of the utility model.
Claims
1. A single ridge double seedling strip pre-imitation depth limiting, staggered ditching and independent compacting device, characterized in that, It comprises: a single main beam (4) and a lifting device mounting frame, the lifting device mounting frame being connected with the front end of the single main beam (4); a lifting device, the lifting device being mounted in the lifting device mounting frame; a profiling depth wheel (1) and a depth wheel mounting frame, the depth wheel mounting frame being mounted at the lower end of the lifting device, and the profiling depth wheel (1) being rotatably mounted on the depth wheel mounting frame; two V-shaped press wheels (6) and press wheel mounting frames, the two press wheel mounting frames being symmetrically mounted at the rear end of the single main beam (4), and each V-shaped press wheel (6) being rotatably mounted on a press wheel mounting frame; two double-disc furrow openers (3) and furrow opener mounting frames, the two furrow opener mounting frames being respectively mounted on the two sides of the single main beam (4), and each double-disc furrow opener (3) being mounted on a furrow opener mounting frame.
2. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 1, characterized in that, The lifting device comprises: a rotating driving mechanism, a lead screw (2), a lead screw mounting nut, a first rectangular steel tube and a second rectangular steel tube, the first rectangular steel tube being mounted in the lifting device mounting frame, the lead screw mounting nut being mounted in the first rectangular steel tube and located at the top end of the first rectangular steel tube, the lead screw (2) being assembled on the lead screw mounting nut and having a lower part located in the first rectangular steel tube, the second rectangular steel tube being slidably mounted in the first rectangular steel tube, the bottom end of the second rectangular steel tube being connected with the depth wheel mounting frame, and the top end of the second rectangular steel tube being rotatably connected with the lower end of the lead screw (2), the rotating driving mechanism being used to drive the lead screw (2) to rotate around its own axis.
3. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 2, characterized in that, The rotating driving mechanism is a handle, the handle being mounted on the upper end of the lead screw (2), and the lead screw (2) can be rotated around its own axis by rotating the first handle.
4. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 2, characterized in that, The rotating driving mechanism is a driving motor, the driving motor being mounted on the lifting device mounting frame, and the driving motor being used to drive the lead screw (2) to rotate.
5. The device according to claim 1, characterized in that, The two double-disc furrow openers (3) are arranged in a staggered manner.
6. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 1, characterized in that, The distance between the vertical planes in which the two double-disc furrow openers (3) are located ranges from 120 mm to 160 mm, and the distance between the vertical planes in which the two V-shaped press wheels (6) are located ranges from 120 mm to 160 mm.
7. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 6, characterized in that, It further comprises: a disc adjusting gasket (7), at least one disc adjusting gasket (7) being assembled between each furrow opener mounting frame and the single main beam (4) to adjust the distance between the vertical planes in which the two double-disc furrow openers (3) are located.
8. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 6, characterized in that, It further comprises: a press wheel adjusting gasket (8), at least one press wheel adjusting gasket (8) being assembled between each press wheel mounting frame and the single main beam (4) to adjust the distance between the vertical planes in which the two V-shaped press wheels (6) are located.
9. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 1, characterized in that, The press wheel mounting frame comprises: a press wheel mounting frame body and a tension spring mechanism, one end of the press wheel mounting frame body being rotatably connected with the rear end of the single main beam (4), and the V-shaped press wheel (6) being rotatably mounted on the other end of the press wheel mounting frame body; one end of the tension spring mechanism being rotatably connected with the rear end of the single main beam (4), and the other end of the tension spring mechanism being rotatably connected with the other end of the press wheel mounting frame body.
10. The single ridge double seedling strip pre-imitation depth-limiting, staggered ditching and independent compacting device according to claim 9, characterized in that, The tension spring mechanism comprises a pressing tension spring (5), an adjusting bolt and an adjusting nut seat, one end of the pressing tension spring (5) is rotatably connected with the rear end of the single main beam (4), the other end of the pressing tension spring (5) is connected with the adjusting nut seat, the adjusting nut seat is assembled on the adjusting bolt, the nut of the adjusting bolt is rotatably connected with the other end of the pressing wheel mounting frame body, and the tension of the pressing tension spring (5) is adjusted by rotating the adjusting bolt.