GB/T 24675.2-2024Conservation tillage equipment - Part 2: Subsoiler (English PDF)

1 Scope

The document lays down the product designation, the technical requirements, the inspection rules and the marking, packaging, transport and storage provisions, and describes the matching test methods.

It applies to the manufacture of subsoilers.

3 Terms and definitions

Subsoiler: an implement whose loosening depth goes beyond the plough pan.

Depth of subsoiling: the vertical distance from the bottom of the subsoiling furrow to the ground surface at that point before the operation.

Remote monitoring system for subsoiling operation: a system that monitors the working of the subsoiler automatically and processes the monitored data in real time.

Operation area: the product of the forward working distance of the subsoiling unit in working state and the working width.

4 Product designation

The product designation is drawn up according to JB/T 8574. The designation is built from a category code, in which 1 stands for tillage and land preparation machinery; a class code, in which S stands for subsoiler; the main parameter, which is the working width in centimetres; and an improvement code lettered A, B, C and so on in order.

The example given is a subsoiler of 210 cm working width at its second improvement, whose designation is 1S-210B.

5.1 Safety requirements

The safety guarding of the subsoiler shall comply with GB 10395.1.

The hydraulic pipes and couplings of a folding subsoiler shall have a reliable guard against the spraying of high-pressure fluid.

The safety distances keeping the upper and lower limbs away from danger zones shall comply with clause 4 of GB/T 23821-2022.

Every subsoiler shall carry fixed safety signs complying with GB 10396: a sign on keeping a safe distance between persons and the implement during work; a sign against opening or removing the guards while the implement is running; signs for crushing and shearing hazards, for instance near the hitch lifting system and when the machine is being raised or lowered; on a folding subsoiler, a sign near the folding device on the crushing and shearing hazard and on locking the locking device when the implement is folded; a sign on the hydraulic pipes and couplings of a folding subsoiler against spraying of high-pressure fluid; and, where in any operating or transport position, or when the working parts are folded up or opened out, a working part rises above 4 m, a safety sign and hazard information in a conspicuous position on the machine against entanglement with overhead power lines, the danger warning about contact with power lines being also stated in the instruction handbook.

A subsoiler more than 2.1 m wide shall have contour reflectors fitted, or contour strips made of reflective material.

The instruction handbook shall give the safety points to be watched in operation and maintenance and shall be drawn up according to GB/T 9480.

5.2 Operating performance requirements

The test field shall be level, the vegetation cover above the surface, stubble included, shall be not more than 1 kg per square metre, the stubble height not more than 30 cm, the soil moisture content 15 % to 25 % and the soil firmness not more than 2.0 MPa.

Table 1 fixes the operating performance indices: subsoiling depth not less than 30 cm; subsoiling depth stability not less than 85 %; soil breaking rate, counted on clods no larger than 4 cm within 10 cm of the surface, not less than 35 %; soil looseness 10 % to 40 %; soil disturbance coefficient not less than 50 %; unit slip rate not more than 20 %; entry travel not more than 4 m; and operational reliability, expressed as availability, not less than 95 %.

Table 2 fixes the indices of the remote subsoiling monitoring system: subsoiling depth measurement error not more than 3 cm; subsoiling operation area measurement error not more than 3 %; sampling interval of the implement positioning data not more than 2 s; working speed measurement error not more than 1 %; and interval between reports of operating data by the terminal not more than 10 s.

5.3 General technical requirements

Subsoilers shall be made to drawings and technical documents approved by the prescribed procedure. All parts and assemblies shall have passed inspection, and bought-in and subcontracted parts shall carry an inspection certificate before assembly.

Machined and pressed parts shall be smooth and even, free of burrs and flash, and shall have no cracks or marked wrinkling. Castings and forgings shall be free of visible defects such as blowholes, slag inclusions, shrinkage porosity and sand holes. Welded assemblies shall be firmly welded, with even and clean weld seams and free of defects such as missed welds, oxidation and burning.

A subsoiling unit should have a remote subsoiling monitoring system fitted. The system shall position accurately and shall be able to measure in real time the working parameters of the subsoiler, such as working depth, working speed, working time, missed tillage, operation area and real-time geographical position, and shall be able to take photographs and to transmit data to a server in real time.

The remote monitoring system shall have a memory function: where the network connection is not working normally, the subsoiling monitoring terminal shall be able to store the detected data and make them available for enquiry.

The instruction handbook shall be drawn up according to GB/T 9480.

5.4 Technical requirements for main parts

The type and dimensions of the subsoiler points and shanks shall comply with clauses 3 and 4 of JB/T 9788-2020.

Subsoiler points shall be heat treated to a hardness of 40 HRC to 45 HRC.

Subsoiler points shall be made of 35MnB or 40MnB steel whose mechanical properties are not lower than those given in 6.4 of GB/T 3077-2015.

Medium and heavy subsoiler shanks shall be heat treated to a hardness of not less than 48 HRC, or built up by tungsten carbide surfacing with a surfaced layer hardness greater than 60 HRC; the surfaced layer shall not peel or come away in use.

5.5 Assembly requirements

After the machine is assembled, the difference in vertical height from the point tip of each group of subsoiler points to the underside of the beam shall be not more than 10 mm.

For fasteners at load-bearing positions such as the main beam, the bearing housings and the hitch, bolts and screws shall be of a mechanical property class not lower than 8.8 as given in clause 7 of GB/T 3098.1-2010, and nuts not lower than class 8 as given in clause 7 of GB/T 3098.2-2015; a reliable locking arrangement is required and the tightening torque shall comply with Table 3.

Table 3 gives, for each nominal thread size in millimetres, the minimum and maximum tightening torque in newton metres: 8 mm, 22 to 29; 10 mm, 44 to 58; 12 mm, 76 to 102; 14 mm, 121 to 162; 16 mm, 189 to 252; 18 mm, 260 to 347; 20 mm, 369 to 492; 22 mm, 502 to 669; 24 mm, 638 to 850; 27 mm, 933 to 1244; 30 mm, 1267 to 1689; 36 mm, 2214 to 2952.

After assembly the working depth and the other adjusting mechanisms shall be easy, free and reliable to adjust, rotating parts shall turn freely without jamming or striking, and all lubrication points shall be charged with lubricant.

With the implement set to the transport position, the distance from its lowest point to the ground, that is the transport clearance, shall be not less than 110 mm for a trailed subsoiler and not less than 300 mm for a mounted subsoiler.

5.6 Painting and appearance quality

Rust, oil, welding slag and dirt shall be cleaned off the surface before painting.

Soil-working parts such as subsoiler points need not be primed and may be given only a black top coat.

The painted surface shall be even in colour, flat and smooth and free of bare patches. The machine shall look clean and shall have no defects such as rust or knocks.

The paint thickness shall be not less than 40 µm; three places are checked and at least two shall reach an adhesion of grade II or better as laid down in JB/T 9832.2-1999.

5.7 Classification of subsoilers

After assembly, subsoilers are divided by size according to the type of subsoiler point and the number of points, that number being written as a in Table 4.

Table 4 gives, for the chisel type, large a not less than 8, medium a greater than 4 and less than 8, and small a not more than 4; for the offset shank type, large a not less than 6, medium a greater than 3 and less than 6, and small a not more than 3; for the all-round type, large a not less than 4 and medium a from 2 to 3, with no small class given.

Three notes state that chisel-type points take in chisel points, arrow or duck-foot points and double-wing points; that offset shank points take in curved-face and cambered points; and that the all-round type means the inverted trapezoidal point.

6 Test methods

6.1 The test field shall be level, with vegetation cover including stubble of not more than 1 kg per square metre, stubble height not more than 30 cm, soil moisture content 15 % to 25 % and soil firmness not more than 2.0 MPa. The measured section shall be at least 50 m long, with a run-in and run-out area of at least 10 m at each end, and its width shall be at least ten times the working width. Absolute soil moisture content, soil firmness, vegetation density and ambient temperature are measured according to GB/T 5262 and shall meet 5.2.1. The test machine and its tractor shall be in good technical condition, adjusted and serviced according to the instruction handbook, the tractor shall not be changed at will during the test, operators shall be trained and certificated, and the working speed of the unit shall follow the instruction handbook. Instruments and equipment shall be calibrated before the test and shall be within their verification period.

6.2.1 The test unit works at full width at the maximum, minimum and rated working speeds given in the instruction handbook, each forward speed making one test condition, so that three conditions are tested, and two runs, out and back, are measured for each condition.

6.2.2 Subsoiling depth is measured according to GB/T 5262 at five points on the diagonal of the measured section, with a depth rule or another measuring instrument, and the mean working depth, the coefficient of variation and the coefficient of stability are worked out for each run and for each condition. The symbols named in the equations are the mean subsoiling depth of a run and of a condition in centimetres, the depth value at an individual point in centimetres, the number of measuring points in a run, the number of runs in a condition, the standard deviation of the subsoiling depth in centimetres, and the coefficients of variation and of stability of the subsoiling depth in percent.

6.2.3 Working speed is measured over two runs, out and back, at the rated working speed and the mean is taken. The symbols are the working speed in metres per second, the distance the unit travels during the measured time in metres, and the measured time in seconds.

6.2.4 Soil breaking rate is tested over two runs at the rated working speed, one point being measured on each run and the sample taken along the direction of tillage. Within 10 cm of the surface the clods in an area of 0.5 m by 0.5 m are collected, the mass of the clods whose longest edge is not more than 4 cm and the total mass of the clods are taken, and the mean of the two runs is used. The symbols are the soil breaking rate in percent, the mass of the clods whose longest edge is not more than 4 cm in kilograms, and the total mass of the clods in kilograms.

6.2.5 Soil looseness is tested over two runs, one point on each run. Before and after tillage a profile plotter is used at the same position, perpendicular to the direction of travel, to draw in turn the untilled surface line, the tilled surface line and the subsoiling furrow bottom line; the cross-sectional area from the pre-tillage surface to the theoretical furrow bottom, which is the furrow bottom line cut by the point tip taken as a horizontal plane, and the cross-sectional area from the post-tillage surface to the theoretical furrow bottom are found, and the mean is taken. The symbols are the soil looseness in percent and the two cross-sectional areas in square centimetres.

6.2.6 For the soil disturbance coefficient, once the untilled surface line, the tilled surface line and the furrow bottom line have been measured, the cross-sectional area from the pre-tillage surface to the theoretical furrow bottom and the cross-sectional area from the pre-tillage surface to the actual furrow bottom are found. The symbols are the soil disturbance coefficient in percent and the cross-sectional area from the pre-tillage surface to the actual furrow bottom in square centimetres.

6.2.7 For the slip rate of the unit, the distances travelled by the tractor driving wheels or tracks over the same number of revolutions are measured within the measured section, once running empty and once working. The symbols are the slip rate of the unit in percent, a negative value meaning skidding, and the distances travelled empty and working over n revolutions of the rear driving wheel in metres.

6.3 For the remote monitoring system, the inspector first checks that the terminal is installed as designed, then powers it up, initialises it and runs the remote test according to the instruction handbook to make sure all functions work. The depth measurement error is tested at the same time as 6.2.2 b), with at least five checks and the mean taken; its symbols are the measurement error of the remote monitoring system in centimetres and the mean subsoiling depth measured by the terminal in centimetres. For the operation area measurement error, a rectangular regular plot of at least 2000 square metres is chosen and the unit with the terminal fitted works continuously in straight passes without overlap or missed strips; the area worked is then measured and the check is made three times and the mean taken, the symbols being the operation area measurement error in percent, the operation area metered by the monitoring system in square metres and the area of the test plot in square metres. The working speed error is measured at the same time as 6.2.3 by comparing the speed measured there with the monitoring data. The interval between reports of operating data by the terminal is measured at the same time as 6.2.2 by observing and recording the reporting interval displayed by the terminal.

6.4 The material of the subsoiler points and shanks may be checked by examining the purchase documents and the inspection certificate. Safety, general technical, main part and assembly requirements are checked by visual examination and ordinary measurement. The hardness of points and shanks is checked according to GB/T 230.1. Appearance and paint thickness are checked by eye and with a paint thickness gauge, and paint adhesion is determined according to JB/T 9832.2-1999.

6.5 The reliability test follows Annex A.

7 Inspection rules

7.1 Every subsoiler shall pass inspection by the production inspection department and shall carry a certificate of conformity before it leaves the works. The items of the works inspection follow Table 5, and the manufacturer may add operating performance items according to the quality level of its own product.

7.2 A type test shall be carried out when a new product is approved for production or an old product is transferred to another works; when structure, process or materials change appreciably after regular production has begun in a way that may affect performance; when wear of tooling or dies may affect performance; when production is resumed after a long stoppage; and when the works inspection results differ appreciably from the previous type test.

7.2 Two machines are drawn at random from the products made at the works within the past year; according to the classification of 5.7 the sample base is 2 machines for the large class, 6 for the medium class and not less than 10 for the small class. That restriction does not apply when sampling at users and at sales departments.

7.3.1 Items are divided into class A, class B and class C non-conformities according to how far they affect product quality; the classification is given in Table 5, which lists for each item the corresponding clause and whether it is checked at works inspection, at type test, or at both. Class A holds the safety requirements and the subsoiling depth; class B holds the depth stability, the soil breaking rate, the soil looseness, the soil disturbance coefficient, the operational reliability, the subsoiler points and shanks, and three indices of the monitoring system, namely the depth measurement error, the positioning data sampling interval and the terminal reporting interval; class C holds the slip rate, the entry travel, the operation area measurement error, the quality of pressed, cast, forged and welded parts, the monitoring system requirements, the point mounting height difference, the main fasteners and their tightening torque, the adjusting mechanisms, the transport clearance, the speed measurement error, the painting and appearance quality, the instruction handbook and the nameplate.

7.3.2 The sampling and judgement plan is Table 6, in which AQL is the acceptance quality limit, Ac the acceptance number and Re the rejection number. The table gives 2 sample items for class A, 9 for class B and 13 for class C; inspection level S-1; sample size code letter A; acceptance quality limits of 6.5, 25 and 40 for classes A, B and C; and acceptance and rejection numbers of 0 and 1 for class A, 1 and 2 for class B, and 2 and 3 for class C.

7.3.3 Items are assessed one by one and judged by class. Where the number of non-conforming items is less than or equal to the acceptance number, the product quality is judged conforming; otherwise it is judged non-conforming.

8 Marking, packaging, transport and storage

A product nameplate complying with GB/T 13306 shall be fixed in a conspicuous position and shall carry at least the designation and name; the main technical parameters, such as overall dimensions, matching power, working width, number of subsoiler points and subsoiling depth; the trademark; the works serial number; the date of manufacture; the name, address and telephone number of the manufacturer; and the number of the document.

The packaging shall be such that the subsoiler is not knocked about in normal transport. The technical documents shall be put in a waterproof bag and shall comprise the certificate of quality inspection, the operating and servicing handbook, the packing list and the warranty voucher.

Despatch from the works shall follow the relevant provisions of the transport authorities and shall be such that no part is damaged under normal transport conditions. Subsoilers shall be stored in a dry, ventilated place, and where kept in the open shall be protected against rain and snow.

A Annex A (normative) Reliability test method

A.1 Not less than two machines are drawn at random from the products made within the past year and put through a field reliability test. Operators shall work and service the machines as laid down in the manufacturer's instruction handbook. The testers shall keep a factual record for each subsoiler on the form of Table A.1 and shall summarise and total the records on the form of Table A.2. Table A.1 has heading fields for the name of the implement, the test date, the manufacturer, the test place, the machine number and the working width, and columns for the date of work, the working time in hours, the amount of work in hectares, and, for each fault, the name of the part and the form, cause and remedy of the fault, with a total line, a fault count and a signature. Table A.2 has columns for the machine number, the amount of work before the first fault in hectares, the total working time in hours, the number of faults and the fault clearance time in hours, with a signature.

A.2 The amount of work is calculated from the working width of the subsoiler. The test area is measured each day to a precision of 0.01 ha.

A.3 An event in which the machine or a part loses its prescribed function under the prescribed conditions, or in which its performance index falls outside the conforming range, counts as a fault, and faults are judged according to GB/T 5667. Faults bearing on the intrinsic failure of the machine are relevant faults, such as faults that endanger the safety of the work, cause loss of function or damage parts, and these are counted; faults that merely inconvenience the operator without affecting the work or adjustment of the machine, or that are easily cleared with the tools carried on the machine during routine servicing, are excluded. Faults caused by outside factors are non-relevant and are not counted: faults caused by use outside the range laid down in the instruction handbook or the technical conditions, faults caused by improper use, servicing or mishandling by the operator, and faults brought on by chance outside events. The quantitative truncation of the test is set at 40 ha of work per metre of working width.

A.3.4 Operational reliability, expressed as availability, is calculated from an equation whose symbols are the availability in percent, the working time of the subsoiler during the assessment period in hours, and the fault clearance time of the subsoiler during the assessment period in hours.

A.3.5 Where a major or fatal failure arises during the assessment period, meaning a fault causing personal injury or death, a fault of quality origin that stops the implement working normally, or a fault causing major economic loss, the test is stopped at once and the operational reliability of the implement is judged non-conforming.