The specific braking force of the working brake system is normal. Specific braking forces of the tractor and trailer link. Evaluation of the effectiveness of braking means on the way
In table. Table 3 shows the limit values for the coefficient of uneven braking forces for the wheels of one axle of cars and trailers K N. The total specific braking force developed by the parking brake system must be at least 0.16, or ensure the stationary state of the vehicle of the total mass on the road with a slope of at least 16 %, and for vehicles in running order, on a road with a slope - at least 23% for cars (category M) and at least 31% for trucks (category N).
With such a check, the force applied to the parking brake control must be no more than 40 kgf for cars and no more than 60 kgf for other cars. For freight road trains, the value of the compatibility coefficient of road train links K c for a two-link trailer road train is also determined, which is determined by the formula
where is the total specific braking force of the trailer link and the tractor, respectively (numerical values are given in Table 4).
The value of the coefficient of compatibility of links of the road train K with for a three-link trailer road train, which is determined separately for each pair of interconnected links according to the formulas
K c1 = , K c2 = ,
where K c1 , K c2 are the compatibility coefficients of the road train links, characterizing the ratio of the total specific braking force between the tractor and the first towing device.
The value of the coefficient of compatibility of the links of the road train, according to the requirements of GOST, should not be lower than 0.9. In addition, for trucks and buses with pneumatic brakes, the tightness of the system is checked, which, when the engine is not running, should not allow a pressure drop of more than 0.5 kgf / cm 3 of the lower control limit for 15 minutes with full engagement of the service brake system or in for 30 minutes - with a free brake system. The asynchronous actuation of the brakes along the axes of road trains should not exceed 0.3 s. The values of the braking distance S t, which set the deceleration j set, the response time of the brake system t cf and the initial braking speed V 0 are given in table. 3, 4. These standards are used when evaluating the effectiveness of the braking system of the vehicle when they are tested not on roller stands, but on horizontal, flat, dry areas.
Bench tests have a number of advantages compared to road tests: due to the use of stationary measuring instruments, the accuracy of test results is increased; separate check of each brake mechanism is possible; standard test conditions ensure repeatability of results and comparability of data obtained at different times.
The values of brake forces on the wheels of trucks and buses are given in RD-200RSFSR15-0150-81 "Guidelines for diagnosing the technical condition of the rolling stock of road transport", and on the wheels of cars - in RD-37.009.010-85 ". Guidelines for the organization of diagnostics of passenger cars at the service station of the "Auto maintenance" system.
Bench tests are carried out using brake stands of various models, the range of which is quite diverse (for example, the STS-2 model stand for monitoring the braking systems of cars, small buses, mini-trucks with an axle load of not more than 19600N; the STS-10 stand is designed for testing of brake systems of trucks, trolleybuses and buses; stands of model SD-2M, SD-3K, SD-4 produced by the Chelyabinsk ArZ, KI-8901 produced by the Beregovsky SEZ, etc.).
Indicators of the effectiveness of braking by the service brake system during road tests of vehicles are the values of the braking distance and the force on the control. When testing, braking by the service brake system is carried out in the emergency, full braking mode with a single impact on the control (adjustment of the vehicle's trajectory is not allowed). The initial braking speed is 40 km / h, the time for actuating the brake system control is no more than 0.2 s.
Road tests are carried out on a straight, level, level and dry road with a cement or asphalt concrete surface.
Bench and road tests must be carried out in safe conditions.
The measurement error must be within:
braking distance - 5%;
initial braking speed - 1 km / h;
steady-state deceleration - 4%;
the maximum slope of the braking area - 1%;
braking force - 3%;
efforts on the governing body - 7%;
brake system response time - 0.03 s;
delay time of the brake system - 0.03 s;
deceleration rise time - 0.03 s;
air pressure in a pneumatic or pneumohydraulic brake drive - 5%.
The brake system of the car is considered to have passed the test if the diagnostic parameters correspond to the normative ones. In order for the brake systems of the car to be able to successfully pass the test, it is necessary to carry out qualified maintenance or repair of the main components.
Replacement of brake pads, pads of discs and drums must be carried out on both wheels of the axle. After replacing these parts, it is necessary to let them run in for a run of 300-400 km.
When checking cars in wet weather or after washing, it is advisable to dry the brake mechanisms, especially drum type, by several braking or short movement with the vehicle braked. It is also not recommended to test the brakes of a car with studded tires on roller areal stands, because. the coefficient of adhesion of a steel stud to the steel surface of a drum or platform can be significantly lower.
3.11.2.2. Steering control and testing
The technical condition of the vehicle steering directly affects traffic safety. Therefore, increased requirements are imposed on its condition, which are contained in GOST R 51709-2001 and in the governing documents RD200 RSFSR 15-0150-81, RD 37.009.010-85 and RD200 RSFSR 0086-79. Steering requirements are also contained in the technological documentation for the repair and maintenance of vehicles and in the operating instructions for specific vehicle models. As a result of long-term operation without the necessary adjustments, the play of the steering wheel increases.
The numerical indicator of GOST, which normalizes the operation of the elements of the steering mechanism, is the total play of the steering wheel, which during testing should not exceed the following allowable values:
for cars and trucks and buses created on the basis of their units…………….….10 o;
buses …………………………..20 about;
trucks …………… 25 about.
The total steering play of vehicles can be measured by several instruments. The most common are the electronic backlash meter model K-526, the mechanical backlash meter model K-524, the device model K-402, etc.
Tests on vehicles equipped with power steering are carried out with the engine running. The range of relevant test equipment is varied. One of them is the K-465M installation.
The car is considered to have passed the test if the obtained values of the total backlash do not exceed the allowable values.
When preparing the vehicle for the verification stage, it is necessary to carry out the next maintenance of the components and parts of the steering mechanism, check the level of the working fluid and the tension of the pump drive belt in the power steering system, check the tightening and fixing of the threaded connections of the parts and assemblies, the condition of the anthers and protective covers.
The relationship between the calculated and actual forces of pressing the pads on the wheel for cast iron pads is expressed by the formula:
.
Specific braking force 
depends on the amount of brake pressure and the presence of brake pads and is determined by the formula
, (44)
where 
- the calculated coefficient of friction of the pads of this type;
- total calculated pressing of all blocks of this type in the train, kN;
– weight of the train, t,
6.2.3 Calculation of the specific resistance to train movement
To determine the main specific resistance to the movement of cars, the formula is used
, (46)
where 
is the average speed of the train in the selected interval, m/s;
– actual axial load of wagons, t/axle.
For 
6.2.4 Calculation of the braking distance, braking and deceleration times for full service braking
The braking distance is the distance traveled by the train from the moment the driver's crane handle is moved to the braking position until it comes to a complete stop.
Braking distances 
the train is subdivided into the path covered during the preparation of the brakes ( 
), and the actual stopping distance ( 
):
Value 
takes into account the distance traveled by the train from the moment the brakes are applied to the development of full braking force during the preparation time 
,
, (47)
where 
– initial braking speed, m/s;
- the time of preparation of the brakes for action, s.
,
(48)
where 
– deceleration of the train, m/s 2 , under the action of a retarding force of 1 N/t;
- the main specific resistance to the movement of the electric locomotive, N / t,
– the main specific resistance to the movement of the train, N / t,
are the initial and final velocities in the accepted design interval
– specific resistance to the movement of the train from the slope of the track, N/t;
,
(49)
where 
– actual stopping distance, m;
- the path traveled during the preparation of the brakes for action, m.
Then the time of the brakes
,
(50)
,
(51)
The data obtained are entered in table 3.
7 Evaluation of the effectiveness of braking means on the road
FOLLOWING
The distance traveled by a train in braking mode and the speed reduction time significantly depend both on the characteristics of the train in terms of load, length, type of blocks used, the state and modes of switching on brake devices, and on the speed of movement, track profile, as well as on suitable conditions, t i.e. aggregates of factors independent of each other.
The actual state of externally sound braking equipment can have a significant impact on the output performance of the train's brakes. There are sufficient grounds to believe that the assessment of the distance traveled by the train at the braking stage during the time of speed reduction by 10 km/h is not objective enough. Variable profile is not fully taken into account in the places where autobrakes are tested. To a certain extent, the lack of unified calculation methods for evaluating the results of checking the operation of the brakes and setting distances in official documents also affects.
These reasons and the need for an objective assessment of the effectiveness of brake means cause attempts to solve this problem.
The existing method for evaluating the condition of the brakes in a train is to check their action at the braking stage. The evaluation is based on the distance or time during which the speed of the train decreases by 10 km/h. In this case, the steps of braking by the driver's crane are 0.05 - 0.06 MPa. In winter, the braking stage when checking the operation of the brakes in trains is recommended to be increased to 0.08–0.09 MPa.
Based on local conditions, as a rule, on the basis of the results of experimental trips, the boundary values of the distance traveled by the train when checking the operation of the brakes are set, corresponding to the single smallest calculated (v p = 0.33) and some minimum allowable (v p = 0.28) brake coefficient. Experimental trips to determine control distances to assess the action of the brakes are carried out with trains whose braking equipment, according to external signs, is in good condition, and the estimated pressure of the train (or train) blocks is determined in accordance with the current instructions and the Rules for Traction Calculations for Train Operation (PTR) .
It should be noted that the actual state of outwardly serviceable braking equipment can have a significant impact on the output indicators of the efficiency of train brakes.
Such a practice can give satisfactory results in assessing the effectiveness of the brakes of passenger trains or empty freight trains, where a known proportionality is observed between the effectiveness of brake means at any stage of braking and in the emergency braking mode. With regard to loaded trains, such methods are unacceptable in modern conditions.
The noted facts, combined with the lack of sufficiently correct methods of brake calculations during adjusting braking, can mislead the locomotive crew regarding the true value of the block pressure in the train and, accordingly, the permissible speed, even with the correct activation of all brakes in the train.
The main tool that allows you to actually reduce the amount of speed reduction at a deepened stage and thereby avoid an increase in the travel time of the train when checking the operation of automatic brakes and at the same time introduce an objective assessment of their work along the route is an instrumental method for assessing their effect on actual deceleration. This parameter is measured using electronic speedometers KPD2 and KPDZ.
The digital train deceleration indication makes it possible to instrumentally assess the effect of the train brake at the stage of reducing the pressure in the brake line when checking the brakes along the route. The basis of the technique is the numerical solution of the equation of motion of a train braking on a slope.
As guidelines for the installation of visual signals, at the places of checking the brakes along the route, nomograms-tables of the distances of the speed reduction time by 10 km / h are recommended at various speeds, slopes, train lengths, obtained as a result of computer calculations and subsequent adjustments, and refinements based on experimental data.
An indicator of the effectiveness of the parking brake system is the value of the specific braking force. When testing a vehicle with a permitted maximum mass, the specific braking force must be at least 0.16. for vehicles in running order, the parking brake system must provide a calculated specific braking force equal to 0.6 of the ratio of the curb weight on the axles affected by the parking brake system in curb weight.
Test Methods
Tests on the stands and in road conditions should be carried out with the engine running and disconnected from the transmission, as well as the drives of the additional drive axles and the unlocked transmission differentials. The total mass of diagnostic tools placed on the vehicle must not exceed 25 kg.
Tests must be carried out under safe conditions.
The measurement error must be within the following limits for:
braking distance - ± 5%;
initial braking speed - ±1 km/h;
steady-state deceleration - ±4
Longitudinal slope of the platform for braking - ± 1%;
braking force - ± 3%;
· effort on the control - ± 7%;
· response time of the brake system - ±0.03 s;
delay time of the brake system - ±0.03 s;
Deceleration rise time - ±0.03 s;
· air pressure in pneumatic or pneumohydraulic brake drive - ±5%.
Checking the service brake system when road test
must be carried out in accordance with the following requirements:
Initial speed - 40 km / h;
Correction of the trajectory of the car is not allowed (the steering is in an inviolable state);
Emergency, single, full braking.
When testing the stability of a car, three lanes should be applied to the site, indicating the axis of movement, the right and left boundaries of the corridor. The car must move in a straight line at a set speed along the axis of the corridor. The position of the car after the completion of braking is determined visually by its projection on the supporting surface. In the case of the formation of two or more points of intersection of the obtained projection of the car and the boundaries of the corridor, the value of the stability parameter cannot be considered satisfactory.
Road tests can be carried out using universal linear-angular measuring instruments and a decelerometer, a mechanical device for measuring steady-state deceleration. In addition, there are now specialized electronic devices. The device "Effect" can be referred to them. This device can comprehensively determine a number of parameters (Table 3.4).
Bench tests
braking systems on roller stands are carried out in the presence of a driver and passenger in the front seat of cars of categories M1 and N1. When testing, the condition of the stand rollers is important. Their wear is not allowed until the corrugated surface is completely abraded or the abrasive coating is destroyed. Bench tests are carried out using brake stands of various models. The range of these devices is quite diverse. Therefore, when choosing a brake tester, it is necessary to be guided by the technical characteristics of the vehicle being tested.
The brake stand model STS-2 is designed to control the efficiency of braking systems and braking stability of passenger cars, buses of a small class, mini-trucks with an axle load not exceeding 19600 N, with a track width of 1200 ... 1820 mm. Its technical data are given in table. 3.5.
The brake tester STS-10 is designed for diagnosing the brake systems of trucks, buses, trolleybuses, trailers as part of road trains with a track gauge of 1500 ... 2160 mm, a vehicle wheel diameter of 968 ... 1300 mm. Its technical data are given in table. 3.6.
Full flow smoke meters
In addition to devices operating on the principle of partial measurement of the exhaust gas flow, continuous smoke meters with transverse scanning of the total exhaust gas flow are used. Full-flow smoke meters can be used to measure exhaust smoke in transient conditions, since the difference in smoke readings along the arrow of the device ...
Calculation of the need for the main types of resources
Types of resources: -Water circulating, fresh. - Energy thermal, electrical. The calculated norms of these resources are calculated according to a methodology based on the use of specific norms for one work post, depending on the capacity of the enterprise, the type of car and the ambient temperature. Calculation of consumption of circulating, fresh...
The volume of the package and the number of packages in the lot
The volume of the package is calculated by the formula: Vmn=B* H* L, m3, where B is the width of the transport package in the stack of goods, m; L is the length of the transport package in the stack of goods, m; H - the height of the transport package in the stack of goods, m. The number of packages in the lot - according to the formula: where Q - the volume of cargo transportation, kg; Mp-ma...
where Κ o - the actual force of pressing the brake pads on the wheelset (per axle), kN;
n o - the number of brake axles in the train;
φ k - block. If we take the average value of the friction coefficient for all pads the same, then formula (1) will take the expression
, N. (2)
Specific braking force of a passenger train
, N/kN. (3)
For freight train
, N/kN. (4)
The ratio of the sum of the forces applied by the brake pads to the weight of the train is called actual braking coefficient
, kN/kN (5)
then equation (3) takes the form, N/kN:
, N/kN. (6)
In the case when the train has cars with different pressure of the brake pads on the wheel, the brake calculations according to formula (6) become cumbersome, since the quantities φ to and K must be determined for each block separately. In these cases, a simpler method is usually used - cast method. It is based on the replacement of the actual friction coefficient of the pads on the wheels, which depends on the pressing force TO, another value - calculated friction coefficient φ cr, not dependent on force TO.
Actual coefficient of friction φ k for standard cast iron pads is determined by the empirical formula
, (7)
a is determined by the empirical formula
, (8)
Actual coefficient of friction φ k for composite pads is determined by the formula
, (9)
For determining φ kr are accepted conditional average forces pressing pads on a wheel pair: cast iron - K h= 26.5 kN (2.7 tf), composite - K to= 15.7 kN (1.6 tf). Substituting the values K h And K to into formulas (7), (8) and (9), we get:
for cast iron pads
; (10)
for cast iron pads with high phosphorus content
; (11)
for composite pads
. (12)
The values of the calculated friction coefficients of the pads on the wheels, calculated by formulas 10, 11 and 12, are shown in Table 1.
In order to maintain the same braking force during braking, it is necessary to valid change the pressing force of the pads on the wheel pair estimated pressing force. The calculated pressing force is determined from the condition of equality of braking forces:
, (13)
where 
, kN (fourteen)
After substituting the values φ to and φ cr into equation (14), the following expressions are obtained: for standard cast iron pads
, kN; (15)
for cast iron pads with high phosphorus content
, kN; (16)
The value of the calculated coefficient of friction φ kr brake pads
Table 1
| Speed v, km/h | Cast iron standard | Cast iron with phosphorus | Composite |
| 0,270 0,198 0,162 0,140 0,126 0,116 0,108 0,102 0,097 0,093 | 0,3 0,218 0,178 0,154 0,138 0,127 0,119 0,112 0,107 0,102 | 0,360 0,339 0,332 0,309 0,297 0,288 0,280 0,273 0,267 0,262 |
for composite pads
, kN (17)
The calculated forces of pressing the pads on the wheels are calculated for each type of rolling stock and are given in the form of standards established in the operating instructions for automatic brakes, tables 2 and 3.
Calculated pressing forces on one cast-iron brake block of locomotives
table 2
Estimated pressing forces on one brake shoe of freight and passenger cars
Table 3
| Wagon type | brake pads | Pressing force on the block, kN | |||
| Material | Number | Laden | Middle | Empty | |
| Freight Four-axle gondola cars Four-axle platforms, covered wagons, tanks Six-axle gondola cars Eight-axle gondola cars Eight-axle tanks Refrigerated Passenger All-metal weight, kN 530-620 480-520 With disc brake With speed control | Cast iron Composite Cast iron Composite Cast iron Composite Cast iron Composite Cast iron Composite Cast iron Composite Cast iron Composite Cast iron Composite lining Cast iron | 38,2 11,6 23,5 10,3 18,5 8,8 7,5 52,0 | 14,8 23,4 15,4 21,8 13,5 7,4 - - - - - - | 12,6 8,2 12,8 8,5 12,4 7,5 8,6 7,5 4,3 - - - - - - |
If there are cars with cast-iron and composite blocks in the same train, then the pressing force of the blocks on the axle is recalculated for one type of block (usually cast-iron), taking into account the equal efficiency of the brakes, table 4.
Estimated forces of pressing the brake pads of cars in terms of cast iron
Table 4
| Wagon type | Estimated brake pad pressure TO p, kN/axle |
| All-metal passenger cars with tare weight: q = 520 kN (53 tf) q = 470 kN (48 tf), but? 520 kN q = 412 kN (42 tf), but? 470 kN VL-RITS all-metal passenger cars with KE brake and cast-iron brake shoes: in passenger mode in high-speed mode All-metal passenger cars of RIC size on TVZ-TsNII “M” bogies with KE brake and composite brake shoes (in terms of cast-iron shoes): in the passenger mode in the high-speed mode Passenger cars with a length of 20.2 m or less Other cars in the passenger fleet Freight cars equipped with cast-iron blocks, in the mode: laden medium light Freight cars equipped with composite blocks (in terms of cast-iron blocks), in the mode: loaded medium empty Four-axle isothermal and baggage all-metal cars with one-way braking Refrigerated rolling stock cars with cast iron brake shoes in the mode: loaded with medium empty Refrigerated rolling stock cars with composite brake shoes (in terms of cast iron shoes) in the mode: medium empty German |
The total estimated pressure of the brake pads is calculated by the number of cars of each type ( n 4 ,n 6 ,n 8) included in the train, the number of axles of the locomotive of a given series ( n k) and the estimated pressure on one brake axle for each type of wagon and locomotive
If not all axles in the composition are brake, then this should be taken into account when calculating the total pressure of the brake pads. For this purpose, the total brake pressure for the composition (4 n 4 TO p4 + 6 n 6 TO p6 + 8 n 8 TO p8) is multiplied by a factor equal to the proportion of brake axles in the train. If the proportion of brake axles is specified for each type of wagon, then the corresponding coefficients are multiplied by each of the terms in expression (18).
After calculating the total estimated pressure of the brake pads of the train, the value is determined calculated braking coefficient
. (19)
The calculated braking coefficient characterizes the degree to which the train is provided with braking means. The more ϑ p, the greater the braking effect will be created by the braking forces, the faster the train will stop and at a shorter distance. In order to ensure the safety of the movement of trains, Russian Railways has established the minimum values of the calculated brake coefficients:
for freight trains at speeds up to 90 km/h - 0.33;
for refrigerated and diesel trains at speeds up to 120 km/h - 0.6;
for passenger trains:
at speeds up to 120 km / h - 0.6;
at speeds up to 140 km / h - 0.78;
at speeds up to 160 km / h - 0.8.
The full value of the calculated braking coefficient and the corresponding specific braking force are realized only during emergency braking.
In braking calculations for stopping at stations and separate points provided for by the train schedule, as well as in the event of a decrease in speed in front of a predetermined place, service braking is used with the calculated braking coefficient:
for freight trains - 0.5 J R,
for passenger, electric and diesel trains - 0.6 J R,
in the case of full service braking, take 0.8 J R.
When using braking calculations to determine the minimum distance between floor constant signals, the value of the calculated braking coefficient is taken as 0.8 J R.
Traction calculation rules recommend not to take into account the pneumatic brakes of the locomotive and its weight when determining the braking force. cargo trains moving on sections with slopes up to -20 ‰. That is, in formula (5.19) one can eliminate P, and in formula (18) eliminate the term n l TO rl.
Example. Determine the total and specific braking force of a freight train with a weight of 40,000 kN, formed from 60 four-axle gondola cars equipped with composite blocks. The speed of the train at the beginning of braking is 60 km/h, the number of braking axles is 80%.
1. Calculated pressing force on one brake axle of four-axle gondola cars in laden mode (see table 3)
where n k is the number of brake pads per axle.
2. Number of brake axles in the train
where a T- the number of brake axles in the train, a T = 80% = 0,8.
3. The total force of pressing the brake pads on the axis of the train
4. Friction coefficient of composite pads
5. Total braking force of the train (according to formula 5.2)
6. Specific braking force b t, N/kN, with train weight P + Q
N/kN.
To check on the stands, the automatic telephone exchange is sequentially installed with the wheels of each of the axles on the rollers of the stand. Disconnect the engine from the transmission, additional drive axles and unlock the transmission differentials, start the engine and set the minimum stable speed of the crankshaft. Measurements are carried out according to the manual (instruction) for the operation of the roller stand. For roller stands that do not provide measurement of the mass attributable to the wheels of the vehicle, use weight measuring devices or reference data on the mass of the vehicle. Measurements and registration of indicators on the stand are performed for each axle of the vehicle and the indicators of the specific braking force and the relative difference in the braking forces of the axle wheels are calculated.
For road trains, when checking on the stands, the values of the specific braking force must be determined separately for the tractor and trailer (semi-trailer) equipped with brake control. The obtained values are compared with the standards.
When checking the efficiency of vehicle braking on the road without measuring the braking distance, it is allowed to directly measure the indicators of steady-state deceleration and the response time of the brake system or calculate the indicator of the braking distance based on the results of measuring steady-state deceleration, the delay time of the brake system and the deceleration rise time at a given initial braking speed.
Methodology for calculating the indicators of braking efficiency and vehicle stability during braking
The specific braking force y t is calculated from the results of checking the braking forces Pt on the wheels of the vehicle separately for the tractor and trailer (semi-trailer) according to the formula
where ΣP T - the sum of the braking forces P t on the wheels of the tractor or trailer (semi-trailer), N;
M - the mass of the tractor or trailer (semi-trailer) during the test, equal to the quotient of dividing the sum of all reactions of the supporting surface on the wheels of the vehicle in a stationary state to the acceleration of free fall, kg;
g- free fall acceleration, m /s 2 .
Relative difference F(percentage) of braking forces of the axle wheels are calculated from the results of braking force checks R t on PBX wheels according to the formula:
[G1] 
where P T pr, R t lion - braking forces on the right and left wheels of the checked axle of the vehicle, respectively, N;
P t max - the largest of the specified braking forces.
The resulting value of F is compared with the maximum allowable. Measurements and calculations are repeated for the wheels of each axle of the vehicle.
Stopping distance calculation allowed S t(in meters) for the initial braking speed v 0 according to the results of checks of the deceleration indicators of the vehicle during braking (see Appendix D) according to the formula:
[G1] 
t is the delay time of the braking system, s;
t n is the rise time of the deceleration, s;
j set ~ steady-state deceleration, m/s 2 .
The stability of the vehicle during braking in road conditions is checked by performing braking within the normative traffic corridor. The axis, right and left boundaries of the traffic corridor are previously marked with parallel markings on the road surface. Before braking, the vehicle must move in a straight line with a set initial speed along the axis of the corridor. The exit of the vehicle by any part of it outside the normative corridor of movement is established visually by the position of the projection of the vehicle on the supporting surface or by the device for checking brake systems in road conditions when the measured value of the displacement of the vehicle in the transverse direction exceeds half the difference in the width of the standard traffic corridor and the maximum width of the vehicle .
When checking on the road the effectiveness of braking by the service brake system and the stability of the vehicle during braking, deviations of the initial braking speed from the set value (40 km/h) are allowed no more than ±4 km/h. In this case, the braking distance standards must be recalculated according to the following method:
Methodology for recalculating the braking distance standards depending on the initial braking speed of the vehicle
The braking distance standards (in meters) for vehicle braking with an initial speed V0 different from the standard one can be calculated using the formula:
where v 0 is the initial braking speed of the vehicle, km/h;
j mouth ~ steady-state deceleration, m/s 2 ;
BUT - coefficient characterizing the response time of the brake system.
When recalculating the standards of the braking distance S,- coefficient values should be used BUT and steady-state deceleration at the mouth for various categories of vehicles, shown in Table 7.
Table 7
ATS is considered to have passed the test of braking efficiency and stability when braking by the service brake system, if the calculated values of these indicators correspond to the given standards. For vehicles not equipped with ABS, instead of meeting the specific braking force of the standards, it is allowed to block all wheels of the vehicle on the rollers of the stand.