Commission Delegated Regulation (EU) 2015/68Show full title

2. Symbols U.K.

2.1. Units used U.K.

2.1.1.

Mass: kg;

2.1.2.

Force: N;

2.1.3.

Acceleration due to gravity: g = 9,81 m/s²

2.1.4.

Torques and moments: Nm;

2.1.5.

Areas: cm²;

2.1.6.

Pressures: kPa;

2.1.7.

Lengths: unit specified in each case.

2.2. Symbols valid for all types of brakes (see Figure 1 of Appendix 1) U.K.

2.2.1. G_A

:

towed vehicle's technically permissible ‘maximum mass’ as declared by the manufacturer;

2.2.2. G′_A

:

towed vehicle's ‘maximum mass’ capable of being braked by the control device, as declared by the manufacturer;

2.2.3. G_B

:

towed vehicle's ‘maximum mass’ capable of being braked by joint operation of all of the towed vehicle's brakes

G_B = n · G_Bo

2.2.4. G_Bo

:

fraction of towed vehicle's permissible maximum mass capable of being braked by one brake, as declared by the manufacturer;

2.2.5. B*

:

required braking force;

2.2.6. B

:

required braking force taking account of rolling resistance;

2.2.7. D*

:

permissible thrust on coupling;

2.2.8. D

:

thrust on coupling;

2.2.9. P′

:

control device output force;

2.2.10. K

:

supplementary force of control device, conventionally designated by the force D corresponding to the point of intersection with the axis of the abscissae of the extrapolated curve expressing P′ in terms of D, measured with the device in the mid-travel position (see Figures 2 and 3 of Appendix 1);

2.2.11. K_A

:

force threshold of control device, i.e., the maximum thrust on the coupling head which can be applied for a short period of time without generating an output force from the control device. The symbol K_A is conventionally applied to the force measured when the coupling head begins to be pushed home at a speed of 10 to 15 mm/s, the control device transmission being uncoupled;

2.2.12. D₁

:

the maximum force applied to the coupling head when it is being pushed home at a speed of s mm/s + 10 %, the transmission being uncoupled;

2.2.13. D₂

:

the maximum force applied to the coupling head when it is being pulled at a speed of s mm/s + 10 % out of the position of maximum compression, the transmission being uncoupled;

2.2.14. η_Ho

:

efficiency of inertia control device;

2.2.15. η_H1

:

efficiency of transmission system;

2.2.16. η_H

:

overall efficiency of control device and transmission η_H = η_Ho · η_H1;

2.2.17. s

:

travel of control device in millimetres;

[F1 2.2.18. s′

:

effective (useful) travel of control device in millimetres, determined as required by point 10.4;]

2.2.19. s″

:

spare travel of master cylinder, measured in millimetres at coupling head;

2.2.19.1. s_Hz

:

stroke of the master cylinder in millimetres according to Figure 8 of Appendix 1;

2.2.19.2. s″_Hz

:

spare travel of the master cylinder in millimetres at piston rod, according to Figure 8 of Appendix 1;

2.2.20. s_o

:

loss of travel, i.e., travel in millimetres of the coupling head when the latter is so actuated as to move from 300 mm above to 300 mm below the horizontal, the transmission remaining stationary;

2.2.21. 2s_B

:

brake-shoe lift (brake-shoe application travel), in millimetres, measured on diameter parallel to applying device, the brakes not being adjusted during the test;

2.2.22. 2s_B*

:

minimum brake shoe centre lift (minimum brake shoe application travel) (in millimetres) for wheel brakes with drum brakes

;

2r being the diameter of the brake drum in millimetres (see Figure 4 of Appendix 1).

For wheel brakes with disc brakes with hydraulic transmission

Where:

V₆₀

=

fluid volume absorbed by one wheel brake at a pressure corresponding to a braking force of 1,2 B* = 0,6 · G_Bo and a maximum tyre radius;

and

2r_A

=

outer diameter of brake disc (V₆₀ in cm³, F_RZ in cm² and r_A in mm).

[F1 2.2.23. M*

:

braking torque as specified by the manufacturer. This braking torque shall produce at least the prescribed braking force B*;]

2.2.23.1. M_T

:

test braking torque in the case where no overload protector is fitted (according to point 6.2.1);

[F1 2.2.24. R

:

dynamic tyre rolling radius. As an alternative for vehicles of categories Ra and Sa, the static loaded radius, as specified by the tyre manufacturer, may be used instead of the dynamic tyre rolling radius;]

2.2.25. n

:

number of brakes.

2.2.26. M_r

:

maximum braking torque resulting from the maximum permissible travel s_r or the maximum permissible fluid volume V_r when the towed vehicle moves rearward (including rolling resistance = 0,01 · g · G_Bo);

2.2.27. s_r

:

maximum permissible travel at the brake control lever when the towed vehicle moves rearward;

2.2.28. V_r

:

maximum permissible fluid volume absorbed by one braking wheel when the towed vehicle moves rearward;

Textual Amendments

F1 Substituted by Commission Delegated Regulation (EU) 2016/1788 of 14 July 2016 amending Regulation (EU) No 167/2013 of the European Parliament and of the Council as regards the list of requirements for vehicle EU type-approval, and amending and correcting Commission Delegated Regulations (EU) No 1322/2014, (EU) 2015/96, (EU) 2015/68 and (EU) 2015/208 with regard to vehicle construction and general requirements, to environmental and propulsion unit performance requirements, to vehicle braking requirements and to vehicle functional safety requirements (Text with EEA relevance).

2.3. Symbols valid for mechanical-transmission braking systems (see Figure 5 of Appendix 1 ) U.K.

2.3.1. i_Ho

:

reduction ratio between travel of coupling head and travel of lever at output side of control device;

2.3.2. i_H1

:

reduction ratio between travel of lever at output side of control device and travel of brake lever (gearing down of transmission);

2.3.3. i_H

:

reduction ratio between travel of coupling head and travel of brake lever

i_H = i_Ho · i_H1

2.3.4. i_g

:

reduction ratio between travel of brake lever and lift (application travel) at brake-shoe centre (see Figure 4 of Appendix 1);

2.3.5. P

:

force applied to the brake control lever; (see Figure 4 of Appendix 1);

2.3.6. P_o

:

brake-retraction force when the towed vehicle moves forward, i.e., in graph M = f(P), the value of the force P at the point of intersection of the extrapolation of this function with the abscissa (see Figure 6 of Appendix 1);

2.3.6.1. P_or

:

brake-retraction force when the towed vehicle moves rearward (see Figure 6 of Appendix 1);

2.3.7. P*

:

force applied to the brake control lever to produce the braking force B*;

2.3.8. P_T

:

test force according to point 6.2.1;

2.3.9. ρ

:

characteristic of the brake when the towed vehicle moves forward as defined from:

M = ρ (P – P_o)

2.3.9.1. ρ_r

:

characteristic of the brake when the towed vehicle moves rearward as defined from:

M_r = ρ_r (P_r – P_or)

2.3.10. s_cf

:

rear cable or rod travel at compensator when brakes operate in forward direction(1);

2.3.11. s_cr

:

rear cable or rod travel at compensator when brakes operate in rearward direction(1);

2.3.12. s_cd

:

differential travel at compensator when only one brake operates in the forward direction and the other in the reverse direction(1);

Where: s_{cd =} s_cr – s_cf (see Figure 5A of Appendix 1);

2.4. Symbols valid for hydraulic-transmission braking systems (see Figure 8 of Appendix 1) U.K.

2.4.1. i_h

:

reduction ratio between travel of coupling head and travel of piston in master cylinder;

2.4.2. i′_g

:

reduction ratio between travel of cylinder thrust point and lift (application travel) of brake-shoe centre;

2.4.3. F_RZ

:

surface area of piston of one wheel cylinder for drum brake(s); for disc brake(s), sum of the surface area of the caliper piston(s) on one side of the disc;

2.4.4. F_HZ

:

surface area of piston in master cylinder;

2.4.5. p

:

hydraulic pressure in brake cylinder;

2.4.6. p_o

:

retraction pressure in the brake cylinder when the towed vehicle moves forward; i.e., in graph of M = f(p), the value of the pressure p at the point of intersection of the extrapolation of this function with the abscissa (see Figure 7 of Appendix 1);

2.4.6.1. p_or

:

brake retraction pressure when the towed vehicle moves rearward (see Figure 7 of Appendix 1 );

2.4.7. p*

:

hydraulic pressure in the brake cylinder to produce the braking force B*;

2.4.8. p_T

:

test pressure according to point 6.2.1:

2.4.9. ρ′

:

characteristic of the brake when the towed vehicle moves forward as defined from:

M = ρ′ (p – p_o)

2.4.9.1. ρ′_r

:

characteristic of the brake when the towed vehicle moves rearward as defined from:

M_r = ρ′_r (p_r – p_or)

2.5. Symbols with respect to the braking requirements relating to overload protectors U.K.

2.5.1. D_op

:

application force at the input side of the control device, at which the overload protector is activated

2.5.2. M_op

:

brake torque at which the overload protector is activated (as declared by the manufacturer)

2.5.3. M_Top

:

minimum test braking torque in the case when an overload protector is fitted (according to point 6.2.2.2).

2.5.4. P_op_min

:

force applied to the brake at which the overload protector is activated (according to point 6.2.2.1).

2.5.5. P_op_max

:

maximum force (when the coupling head is pushed fully home) which is applied by the overload protector to the brake (according to point 6.2.2.3).

2.5.6. p_op_min

:

pressure applied to the brake at which the overload protector is activated (according to point 6.2.2.1).

2.5.7. p_op_max

:

maximum hydraulic pressure (when the coupling head is pushed fully home) which is applied by the overload protector to the brake actuator (according to point 6.2.2.3).

2.5.8. P_Top

:

minimum test brake force in the case when an overload protector is fitted (according to point 6.2.2.2).

2.5.9. p_Top

:

minimum test brake pressure in the case when an overload protector is fitted (according to point 6.2.2.2).

2.6 Types of vehicle classes with regard to inertia braking systems U.K.

2.6.1. Vehicle Class A U.K.

Vehicle Class A means vehicles of categories R1, R2 and S1

2.6.2. Vehicle Class B U.K.

Vehicle Class B means vehicles with a mass exceeding 3 500 kg and not exceeding 8 000 kg of categories R3 and S2

2.6.3. Vehicle Class C U.K.

Vehicle Class C1 means vehicles of categories R and S with maximum design speed not exceeding 30 km/h

Vehicle Class C2 means vehicles of categories R and S with maximum design speed not exceeding 40 km/h

Vehicle Class C3 means vehicles of categories R and S with maximum design speed exceeding 40 km/h

(1)

Points 2.3.10, 2.3.11 and 2.3.12 only apply to the parking braking system differential travel calculation method.