How to choose a chock. Wheel chocks - general information

Introduction

Wheel chocks are effective insurance against arbitrary movement of the vehicle on uneven surfaces. Taking into account the requirements of European legislation, using the test results of the most authoritative German automobile club ADAC, AL-KO manufactures and supplies to Ukraine wheel chocks designed for all classes and types of vehicles, from a light boat trailer to heavy special equipment and trucks.

According to the vehicle release regulations, the vehicle must be equipped with at least 2 wheel chocks of suitable radius and sufficient efficiency. They should be located in easily accessible places on the frame of the trailer or on the body of the car (for cars it is allowed to store stops in the luggage compartment) in brackets-holders to prevent their loss or turning into a source of noise.

Types of wheel chocks

AL-KO wheel chocks are available in two form factors:

• , resembling the usual car "shoe";
• - ergonomic and discreet even in a small trunk.

Each form factor can be made from either high quality . The buyer himself can choose which material suits him best.

Features of the use of wheel chocks

As already mentioned, the main task of the wheel chock is to prevent the spontaneous movement of the vehicle, whether it be a trailer or a truck, for example, on a slope, in an uneven parking lot, or when changing tires from winter to summer. The shape of the wheel chock is made in such a way that it completely repeats the shape and radius of the wheel, so spontaneous movement becomes impossible; the tensile strength of each model has a specific coefficient of 1.35, which means that the stop will withstand a load of 1.35 times more than the wheel itself, under which it is placed.

Application in special vehicles and in the transport of dangerous goods - DIN76051

Due to the high quality of workmanship and proven reliability, AL-KO wheel chocks are approved by Ukrainian legislation for use in the transportation of dangerous and especially dangerous goods. The special DIN76051 marking on the face of the stop indicates that it has passed special safety tests and is accepted by the local traffic control authorities.

However, when choosing a wheel chock, additional safety regulations must be taken into account. So, for example, when transporting explosive goods, trailer and vehicle must be equipped with plastic wheel chocks, as the use of metal wheel chocks can spark when in contact with metal or asphalt.

On the other hand, when transporting bulk goods, such as sand, metal stops should be used, since the ingress of small homogeneous particles under the plastic bearing surface can reduce the drag coefficient of the stop.

Selecting the right wheel chock

When choosing a wheel chock, you should pay attention to a number of fundamental factors:

In order to securely fasten the wheel chock to the vehicle body or trailer frame, special ones are used. Depending on the material of the stop, the holders can also be made of steel or plastic, and depending on the model, they can have different sizes, the principle of fastening and the method of fixing the stop.

The wheel chock is an indispensable device in the operation of trucks. Another name in the language of car owners is the "shoe", as their shape resembles it: a right-angled triangle with a bend. When stopping, the driver usually puts the car on the handbrake, but in some cases one handbrake may not be enough.

For example, when stopping on the slope of a mountain, a hill, an additional safety measure is required - a wheel chock, which ensures that the car is held when the roadway is sloped. It is able to withstand high loads, so it can be suitable for both cars and trucks.

The wheel chock for trucks must comply with certain quality standards and have a certificate. With their help, it is easy to prevent unexpected movement of the machine. At the moment, emphasis should be mandatory for all car owners.

The design of the chocks

Vehicle operating rules oblige owners to always have wheel chocks for trucks. The requirements for them are as follows: they must have a design that meets all standards, and also withstand high loads. In this case, the driver must comply with certain conditions:

• The stops must be of the correct diameter for the wheel.
• Stop location.
• Location in the trunk of a car (for trucks, they must be on the body or in the trailer).

Ignoring these conditions threatens with punishment - a large fine

There are 2 types of wheel chock design: triangular of the usual type and folding in the form of a wedge stop. There are also two materials from which the wheel chock for trucks is made. Firstly, it is a very durable, high quality reinforced plastic. Secondly, it is galvanized steel. For the first instance, the degree of load starts from 800 kg and ends at around 6500 kg. For the second instance, the minimum withstand load is 1750 kg and the maximum is 6500 kg.

It would seem that the advantage of a steel stop is obvious, but there is a limitation. When transporting combustible, flammable liquids, materials, only plastic stops are allowed for fire safety. If the truck transports bulk materials, such as sand, then it is preferable to use a steel stop, since there is a possibility of small elements of the transported cargo falling into the gap between the stop and the road, which, in the case of plastic ones, can lead to the car rolling back due to the reduced stop resistance coefficient and roadbed.

plastic stops

The most common mistake when buying a wheel chock for trucks is made by beginners who do not have experience. They buy hard but fragile plastic products. These stops break quickly when hitting them with a wheel. There is also a situation in which the driver forgets to remove them before continuing the movement, then in the case of plastic ones, only small pieces remain from them.

Plastic stops are very fragile, short-lived, so it is not recommended to purchase them if you plan to use them in extreme conditions in the future.

Rubber

More durable than plastic is the rubber wheel chock for trucks.

The description of the product, according to many buyers, coincides with reality. Rubber stops are a very good option to buy, they are made of durable hard rubber, if you run over them they will not break, unlike plastic ones. There are many different brands of rubber products, but the quality is about the same for all - good.

metal

The most durable of the presented models is the metal chock for trucks. Metal has both a number of advantages and a number of disadvantages compared to plastic and rubber counterparts. First, the main advantage of metal stops is their strength. It is many times more durable than rubber or plastic. Secondly, it is possible to reliably use the folding version, which is much more practical than its counterparts from other materials; the folding version will take up very little space in the trunk compared to the usual one.

The main disadvantage, which is sometimes the key when choosing, is corrosion instability, that is, if the storage rules are violated, the product will become covered with rust and lose its reliability and strength. It will then be unsafe to use the wheel chock for trucks.

Requirements

According to known rules, wheel chocks must meet the following requirements:

1. The maximum load that the stops must withstand is half the gross vehicle weight.
2. A tight fit under the wheels must be ensured.
3. Any possible slippage on the roadway of the stop must be excluded.
4. Must have a signal color: red, orange or yellow.

The conditions below must be observed when wheel chocks for commercial vehicles are used. The traffic regulations for them are as follows:

1. In vehicles weighing more than 3.5 tons (for trucks) and 5 tons (for buses), at least two stops must be used.
2. The complete set of trucks weighing more than 3.5 tons and buses weighing more than 5 tons must provide for the presence of at least two stops.
3. They must be in an easily accessible place, but must be firmly installed to prevent their loss.
4. For the design should assume a workable brake device and wheel chocks.

Conclusion

If all of the above requirements are met, then the wheel chocks are allowed to operate. In addition, before being sent for sale, they must pass strength tests. Therefore, in the store, the choice of the buyer should fall on a quality product that can serve him for a long time.

GOST 28307-2013

INTERSTATE STANDARD

TRAILERS AND SEMI-TRAILERS

Test Methods

Tractor-drawn trailers and semi-trailers. Methods of testing

MKS 65.060.10

Introduction date 2014-07-01

Foreword

The goals, basic principles and basic procedure for carrying out work on interstate standardization are established in GOST 1.0-92 "Interstate standardization system. Basic provisions" and GOST 1.2-2009 "Interstate standardization system. Interstate standards, rules, recommendations for interstate standardization. Rules for the development, adoption , updates and cancellations"

About the standard

1 DEVELOPED by the Russian Association of Agricultural Machinery Manufacturers (Rosagromash Association)

2 INTRODUCED by the Federal Agency for Technical Regulation and Metrology (Rosstandart)

3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes N 58-P dated August 28, 2013)

Voted for the adoption of the standard:

4 By order of the Federal Agency for Technical Regulation and Metrology dated November 22, 2013 N 1590-st, the interstate standard GOST 28307-2013 was put into effect as the national standard of the Russian Federation from July 01, 2014.

5 INSTEAD OF GOST 28307-89


Information about changes to this standard is published in the annual information index "National Standards", and the text of changes and amendments in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, a corresponding notice will be published in the monthly information index "National Standards". Relevant information, notices and texts are posted in the public information system - on the information website of the Federal Agency for Technical Regulation and Metrology on the Internet.

1 area of ​​use

1 area of ​​use

This standard applies to tractor trailers, semi-trailers, chassis of tractor trailers and semi-trailers and machines based on them (tanks, house cars for transporting timber and other long loads, transporting animals and birds, trailers and semi-trailers with installed technological equipment for various purposes) .

This standard establishes the nomenclature of indicators and methods for their determination for all types of tests of the above types of transport and transport-technological machines (hereinafter referred to as trailers and semi-trailers).

This standard does not apply to tractor trailers and semi-trailers with active drive.

2 Normative references

This standard uses normative references to the following standards:

UNECE Regulation No. 13 - Revision 10 Uniform braking provisions for vehicles of categories M, N and O

UNECE Regulation No. 58 - Revision 1 Uniform provisions concerning the approval of: I. rear protective devices; II. vehicles with regard to the installation of type-approved rear protective devices; III. vehicles with regard to their rear protection

GOST 10000-75

Note - On the territory of the Russian Federation, GOST R 52746-2007 Tractor trailers and semi-trailers is in force. General technical requirements


GOST 12.2.002-91 Occupational safety standards system. Agricultural machinery. Safety assessment methods

GOST 12.2.002.3-91 Occupational safety standards system. Agricultural and forestry vehicles. Determination of braking characteristics

GOST 2349-75 Hook-and-loop traction devices for automobile and tractor trains. Basic parameters and dimensions. Technical requirements

GOST 3481-79 Agricultural tractors. Traction coupling devices. Types, basic parameters and dimensions

GOST 4364-81 Pneumatic brake systems of motor vehicles. General technical requirements

GOST 8769-75 External lighting devices for vehicles, buses, trolleybuses, tractors, trailers and semi-trailers. Quantity, location, color, visibility angles

GOST 16504-81 State product testing system. Testing and quality control of products. Basic terms and definitions

GOST 20915-2011 Agricultural machinery. Methods for determining test conditions

GOST 21623-76 Maintenance and repair system for equipment. Indicators for assessing maintainability. Terms and Definitions

GOST 23181-78 Hydraulic brake drives for motor vehicles. General technical requirements

GOST 26025-83 Agricultural and forestry machines and tractors. Methods for measuring design parameters

GOST 26026-83 Agricultural and forestry machines and tractors. Methods for assessing serviceability for maintenance

GOST 26955-86 Mobile agricultural machinery. Rules for the impact of movers on the soil

GOST 28305-89 Agricultural and forestry machines and tractors. Rules for acceptance for testing

GOST 30748-2001 Agricultural tractors. Determining the maximum speed

Note - When using this standard, it is advisable to check the validity of reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annual information index "National Standards", which was published as of January 1 of the current year, and on issues of the monthly information index "National Standards" for the current year. If the reference standard is replaced (modified), then when using this standard, you should be guided by the replacing (modified) standard. If the referenced standard is canceled without replacement, then the provision in which the reference to it is given applies to the extent that this reference is not affected.

3 Terms and definitions

This standard uses the terms according to GOST 16504, GOST 10000, as well as the following term with the corresponding definition:

rated load: The maximum mass of cargo carried by a trailer (semi-trailer), set by the manufacturer.

4 Types of tests and general requirements for their implementation

4.1 At the design stage of trailers (semi-trailers), the following types of tests can be carried out:

- preliminary;

- acceptance.

4.2 At the stage of production of trailers (semi-trailers), the following types of tests can be carried out:

- qualification tests of samples of the installation series (the first industrial batch);

- acceptance;

- periodic;

- typical;

- certification.

4.3 In accordance with the goals and objectives of the tests, it is allowed to combine tests of various types.

4.4 A typical test program includes types of assessments in accordance with Table 1.

Table 1

4.5 The program of preliminary tests is developed by the developer, acceptance tests - by the acceptance committee.

5 Test preparation

5.1 The procedure for providing trailers and semi-trailers for testing - in accordance with GOST 28305.

5.2 Upon receipt of trailers and semi-trailers for testing, the completeness of their delivery must be checked in accordance with the technical documentation.

5.3 Before testing, a run-in, adjustment of mechanisms and controls should be carried out in accordance with the operation manual.

5.4 The evaluation of the quality indicators of the technological process should be carried out under conditions typical for the operation of this type of trailers and semi-trailers. The parameters characterizing the operating conditions of trailers and semi-trailers during testing must be within the limits corresponding to the requirements of the regulatory document for the product under test.

Comparative evaluation of machines should be carried out under comparable conditions.

5.5 Methods for determining test conditions - according to GOST 20915.

5.6 When transporting goods on the roads of the general network and in the field, the roads must be in good condition throughout the route.

5.7 When testing, you should use measuring instruments, tools and equipment, the measurement error of which should not be more than,%:

±1.0 - linear dimensions;

+2.5 - angular dimensions;

±1.0 - masses;

+1.0 - volume;

±2.5 - forces;

±1.0 - time;

±2.0 - speed;

±2.0 - pressure;

±2.0 - temperature.

5.8 The measuring instruments and equipment used must be verified in accordance with the rules in force.

6 Parameter estimation methods

6.1 Evaluation of technical parameters

6.1.1 The range of technical parameters to be evaluated - according to the technical documentation for the trailer (semi-trailer).

For trailers and semi-trailers for agricultural purposes, a list of technical parameters characterizing the design is given in Appendix A.

6.1.2 An assessment of the general requirements for the design of trailers and semi-trailers should be carried out for compliance with GOST 10000.

6.1.3 Measurements of overall dimensions, masses, minimum turning radii are carried out in accordance with GOST 26025.

The capacity of the platform (tank) is determined by calculation or by filling it with loose (liquid) cargo of known density with the determination of its actual mass.

Weight and dimensional characteristics are determined for trailers and semi-trailers with main and extension sides (if any).

6.1.4 Determination of the maximum transport speed is carried out according to GOST 30748.

6.1.5 Determination of the geometric parameters of towing devices, the type and design of coupling devices is carried out in accordance with GOST 2349.

When assessing the compliance of aggregability elements with the requirements of GOST 3481, the following mechanisms are subject to verification:

- hitch;

- hydraulic equipment;

- braking device;

- electrical equipment.

The design of these mechanisms must provide for the impossibility of spontaneous disconnection of the tractor from the attached trailer (semi-trailer).

6.1.6 The width of the traffic corridor when turning the transport unit, m (see Figure 1), is calculated by the formula

where - the largest turning radius of the transport unit, m;

The smallest turning radius of the transport unit, m

Figure 1 - Determining the width of the traffic corridor when turning the transport unit

6.1.7 The time of lifting the platform loaded to the nominal load capacity, the time of lowering the empty platform, the vertical static load on the tractor traction hook from the semi-trailer coupling loop during unloading is determined by raising and lowering the platform three times in each direction and finding the average values ​​of the corresponding values.

6.1.8 The maximum pressure in the hydraulic system should be determined when lifting the platform loaded to the rated capacity.

6.1.9 When determining the parameters of the hydraulic tipper platform lifting device, the operability of the platform lifting limitation device should be determined.

6.1.10 The limiting angle of the platform rise (the angle of inclination of the floor of the raised platform) should be determined on a flat horizontal platform when the platform is raised without load.

6.1.11 The limiting angle of the platform rise (the angle of inclination of the platform floor) is measured by a goniometer installed:

- at the left and right sides - during rear unloading;

- at the front and rear sides - for side unloading.

The protractor must be installed on the floor of the platform at a distance of no more than 0.3 m from the side walls (for rear unloading) and no more than 0.5 m from the side towards which unloading is carried out (for side unloading). The measurement result is taken as the average values ​​when the platform is lifted three times in each direction.

6.1.12 The specific pressure of the wheels on the soil is determined in accordance with GOST 26955.

6.2 Evaluation of the quality of the technological process

6.2.1 The range of functional indicators characterizing the quality of the technological process, and the conditions for their determination - in accordance with the industry normative and technical documentation.

6.2.2 For trailers and semi-trailers for agricultural purposes, the following should be carried out:

- energy assessment;

- agrotechnical assessment;

- operational and technological assessment;

- economic evaluation.

Conducting assessments - in accordance with national regulations.

6.3 Evaluation of safety and ergonomic design

6.3.1 The assessment of the safety and ergonomics of the design of trailers and semi-trailers should be carried out with the determination of the following indicators:

- general safety requirements for the design;

- specific safety requirements in accordance with the functional purpose;

- the presence of warning labels;

- the presence and design of protective fences;

- exclusion of the possibility of spontaneous switching on (off) of the controls and regulation;

- safety of aggregation;

- static stability;

- stability during rear unloading;

- the presence of external lighting devices, their color and location;

- efficiency of braking systems;

- forces of resistance to movement of controls and regulation;

- design and strength of the rear protective device;

- stability of the rectilinear movement of the transport unit;

- the effectiveness of the recoil stops;

- pressure transmitted by the semi-trailer support to the soil.

6.3.2 General safety requirements for the design - according to GOST 10000.

6.3.3 The safety assessment of machines made on the chassis of tractor trailers and semi-trailers should be carried out in accordance with the regulatory document that establishes safety requirements for specific types of machines.

6.3.4 The presence of warning inscriptions, wheel chocks, images of the maximum speed limit sign, places for mooring and installation of jacks are determined by visual inspection.

6.3.5 Checking the design and strength of the rear protective device is carried out according to UNECE N 58.

6.3.6 Exclusion of the possibility of spontaneous activation (deactivation) of the controls, the safety of aggregation, the presence and operability of non-removable safety chains (cables), the presence and operability of a device (stop) for fixing an unloaded platform in a raised position, the presence and operability of the support on the towing device of semi-trailers determine testing.

6.3.7 The angle of transverse static stability is determined according to GOST 12.2.002.

6.3.8 The methodology for assessing the stability of a trailer (semi-trailer) during rear unloading is given in Appendix B.

6.3.9 Assessment of the presence, color and location of external lighting devices is carried out in accordance with GOST 8769.

6.3.10 Evaluation of the effectiveness of the working and parking brake systems is carried out in accordance with GOST 12.2.002.3.

It is allowed to evaluate the effectiveness of the working brake system along the braking distance of the tractor train under the conditions specified in GOST 12.2.002.3.

Evaluation of the effectiveness of the inertial braking system is carried out according to UNECE N 13.

6.3.11 The evaluation of the response time of the pneumatic brake actuator is carried out according to GOST 4364; hydraulic brake drive - according to GOST 23181.

6.3.12 The stability of the rectilinear movement of the transport unit is determined when driving at maximum speed on a flat horizontal section of the road.

The criterion for the stability of rectilinear movement is the location of the transport unit in the corridor, the width of which does not exceed 0.5 m of its maximum width.

6.3.13 Evaluation of the effectiveness of wheel chocks is carried out when installing a trailer (semi-trailer) loaded to the nominal load capacity on an ascent and descent with a slope of 15%. It is allowed to carry out the assessment by the calculation method in accordance with the methodology given in Appendix B.

6.3.14 The pressure transmitted by the support to the soil is determined for a loaded semi-trailer by calculating the ratio of the vertical static load transmitted through the support to the soil to the support area.

6.4 Reliability assessment

6.4.1 Reliability assessment should be carried out according to industry normative documentation with the definition of indicators established by the design documentation for the trailer (semi-trailer).

6.4.2 Reliability is assessed based on the results of tests under the conditions specified in the regulatory document for the product.

It is allowed to assess the reliability of mass-produced trailers and semi-trailers based on the results of observations in real operation.

6.4.3 To reduce the test period, it is allowed to conduct accelerated reliability tests under modes that reproduce operational loads.

Accelerated tests are carried out at special test sites or on stands according to special programs. Accelerated test program - according to the test report or its annex.

6.4.4 It is allowed to determine the time of the main work by calculating the operating time in physical units and productivity for the test period.

6.4.5 During the test period, records of identified failures and damages should be kept.

6.4.6 Determining the time and labor costs for finding and eliminating failures should be carried out by operational timing. Operation duration measurement error - no more than ±5 s.

The classification of the elements of the employment time of each contractor during repair and maintenance is carried out according to GOST 21623.

The complexity of performing individual repair operations is determined by summing up the time spent on the performance of the technological operation by each performer.

It is allowed to determine the time and labor costs for finding and eliminating failures and damages according to the standards approved in the prescribed manner.

6.4.7 Assessment of suitability for maintenance is carried out in accordance with GOST 26026.

6.4.8 Reliability indicators should be determined by the operating time, measured by the main work time, and evaluated by comparing actual reliability indicators with standard values ​​or indicators of an analogue product.

The deviation of operating hours of compared vehicles should not exceed 20% under comparable operating conditions.

6.4.9 For trailers and semi-trailers for agricultural purposes, the definition of reliability indicators and the form of their presentation - in accordance with *.
________________
* See section Bibliography. - Database manufacturer's note.

Annex A (mandatory). List of technical parameters for trailers and semi-trailers for agricultural purposes

Annex A
(mandatory)

The list of technical parameters for trailers and semi-trailers for agricultural purposes includes:

- type (trailer/semi-trailer);

- aggregability (traction class of tractors);

- maximum transport speed in kilometers per hour;

- the mass of the equipped trailer (semi-trailer) in kilograms;

- total weight of the trailer (semi-trailer) in kilograms;

- distribution of the total mass on the supports:

a) on the hitch,

b) on the front axle (front bogie),

c) on the rear axle (rear bogie);

- overall dimensions in millimeters:

a) length

b) width

c) height;

- overall dimensions during unloading in millimeters:

a) when unloading backwards:

1) length,

2) height,

b) when unloading on the side:

1) width,

2) height;

- base in millimeters:

a) a trailer (semi-trailer),

b) front/rear bogie;

- track width in millimeters;

- minimum turning radius in meters:

a) internal

b) external;

- the width of the turning lane of the transport unit;

- ground clearance in millimeters;

- internal dimensions of the platform in millimeters:

a) length

b) width

c) height;

- platform (tank) capacity in cubic meters;

- loading height in millimeters:

a) according to the floor level of the platform,

b) along the upper edge of the sides;

- suspension type;

- type and geometric parameters of the towing device;

- vertical static load on the tractor traction hook from the trailer coupling loop;

- type of electrical system;

- direction of unloading (back, to the side);

- pressure in the hydraulic system of the dumping plant in megapascals;

- vertical static load on the tractor traction hook from the semi-trailer coupling loop during unloading;

- lifting time of the platform loaded to the rated load capacity in seconds:

a) back

b) on the side;

- empty platform lowering time in seconds:

a) for rear unloading,

b) when unloading on the side;

- the limiting angle of the platform in degrees;

- the angle of inclination of the floor of the platform in degrees;

- type of brake system drive:

a) working

b) parking;

- pressure in the pneumatic / hydraulic system in megapascals;

- tires:

b) size;

- tire pressure in megapascals;

- specific pressure of the wheels on the soil in megapascals.

Annex B (mandatory). Method for determining the limiting angle of lateral stability during rear unloading of a trailer (semi-trailer)

Annex B
(mandatory)

The trailer (semi-trailer) is mounted on a platform that can be tilted relative to one of its sides. The surface of the platform must be level, firm and strong to prevent possible deformations affecting the test. Steel plates 1 mm thick are placed under the wheels, having dimensions, large tire contact patches. Tire pressure must be equal to the nominal pressure specified by the manufacturer. For semi-trailers, the drawbar is positioned at the height specified by the manufacturer by means of a mechanical support mounted on the platform or by direct connection to the tractor also mounted on the platform. The steered wheels are set to the position of rectilinear motion. Measures must be taken to prevent the trailer (semi-trailer) from tipping over.

During the test, there shall be no load acting vertically upwards on the coupling device of the trailer (semi-trailer).

A test load equal to one quarter of the rated load capacity is applied in one of the forward quarters of the platform at the center of that forward quarter at a height equal to half the height of the sides. The platform is inclined with a slope of 8% (5°), then slowly and evenly raise the platform of the trailer (semi-trailer) until it reaches the upper position.

During the test, at least one of the unloaded tires shall remain in contact with the ground.

Contact with the supporting surface is considered to be maintained if, when a force of 50 N is applied, the steel plate does not move laterally under the tire.

Annex B (recommended). Method for evaluating the effectiveness of wheel chocks using the equivalent force method

Tests should be carried out on a dry site or a paved road (asphalt, concrete) at an air temperature from minus 10 °C to plus 30 °C.

The trailer (semi-trailer) must be loaded to the nominal load capacity, the air pressure in the tires of the wheels must correspond to the value specified in the operation manual.

To the trailer (semi-trailer) installed on a flat horizontal surface with wheel chocks installed under the wheels by the tractor, a horizontal force is applied, equivalent to the value of the projection of the gravity force of the trailer (semi-trailer), installed on a slope of 15%, onto the road surface.

Equivalent force, N, is calculated by the formula

where is the equivalent force, N;

- gross weight of the trailer (semi-trailer), kg;

- acceleration equal to 9.81 m/s.
__________________
* The formula and its explication correspond to the original. - Database manufacturer's note.

Tests are carried out for directions corresponding to the installation of the trailer (semi-trailer) on the ascent and descent at least three times for each direction.

Evaluation of the effectiveness of wheel chocks is carried out by the absence of movement of the trailer (semi-trailer) under the influence of the applied equivalent force, provided that there are no deformations of the wheel chocks.

Bibliography

UDC 631.373.001.4:006.354 MKS 65.060.10

Keywords: tractor trailers, semi-trailers, chassis of tractor trailers and semi-trailers, test methods
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Electronic text of the document
prepared by CJSC "Kodeks" and checked against:
official publication
M.: Standartinform, 2014