Bosch BSA 250 Betriebsanleitung Seite 49

12. Calculating the brake force
The following calculations are performed automatically by the
brake system analyser. They are intended solely for manual
evaluation or as background information.
12.1 Notes on calculating the braking factor
(in accordance with Annex VIII, StVZO)
12.1.1 Brake force and delay
Brake force is measured in kN for each wheel. Adding together
the brake force for all wheels gives the total brake force F
vehicle.
From this, the percentage braking factor and the maximum delay
can be calculated as follows:
2
- maximum delay a [m/s ] =
total brake force x 9.81
total vehicle weight [force]
- braking factor z [%] =
total brake force x 100
total vehicle weight [force]
These are the calculations commonly used for passenger cars,
whereby G always represents the total vehicle weight force. In
the case of passenger cars, the difference between the unladen
weight and the total permissible weight is usually insignificant, so
that the measured brake force can be assumed to apply to the
total permissible weight of the vehicle without the need to perform
any further calculation.
12.2 Calculating the braking factor
12.2.1 Total brake force F
The brake force acting on individual wheels should be measured
while the force applied to the pedal is kept at the same level in
each case. The total brake force is determined by adding together
all the measured values.
Example:
LH front wheel = 2,400
RH front wheel = 1,900
LH rear wheel = 1,750
RH rear wheel = 1,550
Total brake force F = 7,600
tot
The total brake force was achieved with a force of 0.5 kN applied
to the pedal.
1 689 979 689 22.01.03
F x 9.81
tot
=
G
F x 100
tot
=
G
tot
N
N
N
N
N
12.2.2 Maximum braking factor z in %
total of all brake forces (N)
z =
total permissible weight force of vehicle (N)
The total permissible weight force (N) is calculated by multiplying
the total permissible weight (kg) by the acceleration due to gravity
g (g = 9.81 m/s
Example:
Total vehicle weight (mass) G
for the
Approx. acceleration due to gravity g (9.81 m/s
tot
Total brake force F
main brakes (SBS)
7,600
z =
1,350 x 10
2
).
measured for
tot
x 100 = 56.3 %
x 100
1,350 kg
2 2
) 10 m/s
7,600 N
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