Extrapolated Total Deceleration - Bosch BSA 7 Series Product Description

R
The minimum axle brake pressure required to
operate mechanical brake cylinders is p
F [N]
F
B
F
max
0
0.4
Fig. 8: Extrapolation of the measured characteristic curve (thick)
for one-point extrapolation
The characteristic curve (rule of three) permits
calculation of the force F
B
pressure p :
B
p - 0.4 bar
B
F = x F
B max
p - 0.4 bar
max
8.4.2 Two-point extrapolation
i
In Germany, two-point extrapolation is used to
calculate deceleration in general inspections (HU) as
per sec. 29 of the StVZO.
Extrapolation is based on the following assumptions:
R
Brake force F is a linear function of the pressure p
fed into the brake cylinders (axle brake pressure
Px).
R
The brake force is measured in the range F
R
The axle brake pressure is measured in the range p
... p .
max
Beissbarth GmbH
= 0.4 bar.
1
p [bar]
p p
max B
corresponding to the design
... F
1 max
Calculation methods | BSA 7xxx / 8xxx | 33
F [N]
F
B
F
max
F
1
p
1
Fig. 9: Extrapolation of the measured characteristic curve (thick)
for two-point extrapolation
The slope m of the characteristic curve permits
calculation of the force F
pressure p :
B
F = F + m (p - p
B max B
8.4.3

Extrapolated total deceleration

If the extrapolated brake forces F
known, the total deceleration can be calculated as
follows:
S F
Bi
Z = x 100 %
G
total
Z Extrapolated total deceleration in percent
F Extrapolated brake force of the wheel i
Bi
G Gross permissible weight of the vehicle
total
i
With passenger cars the difference between curb
weight and gross permissible weight is generally
. negligible. The measured brake forces can be
referenced to the gross permissible weight of the
1
vehicle without the need for conversion.
p p
max B
corresponding to the design
B
F - F
max 1
); m =
max
p - p
max 1
for all wheels i are
Bi
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1 691 806 123 2017-06-23
en
p [bar]