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

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

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

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

i_H = i_Ho · i_H1

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

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

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);

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

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

test force according to point 6.2.1;

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

M = ρ (P – P_o)

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

M_r = ρ_r (P_r – P_or)

rear cable or rod travel at compensator when brakes operate in forward direction^f1;

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

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

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