User Manual

14/20 Bosch Rexroth AG
DRC Travel Drive Control
RE 95 320/06.06
Reversing operation
Travel direction change (reversing) is performed via the direc-
tion switch. The vehicle is decelerated and then reaccelerated
in the opposite direction. The reaction behavior can be speci-
fi ed in parameters.
Load limiting control
The integrated load limiting control reduces the accepted hy-
draulic power in the event of overloading of the diesel engine. It
can be activated or deactivated via parameters.
The most important feature of the travel drive control is the
measurement of the set and actual speeds of the diesel en-
gine.
• The set speed of the diesel engine is measured via the accel-
eration pedal position (via analog input or via CAN bus).
• The actual speed is measured via a speed sensor (via fre-
quency input or CAN bus).
Through the comparison of the set and actual speeds, it is pos-
sible to detect an overload of the diesel engine. In the event of
a potential overload, the electronics reduce the power input of
the hydraulic pump and of the variable motor:
• The load limiting control calculates the current speed drop of
the diesel engine from the set and actual speed values.
• The current speed drop is compared to the parameterizable
limit values. Different limit values can be parameterized for
different set speeds.
• As long as the accepted hydraulic power does not exceed
the installed diesel power, the speed drop will not exceed
the parameterized limit values. The load limiting control does
not engage.
• If the speed drop of the diesel engine exceeds the limit
values, the load limiting control engages:
– The pump power is reduced (the swivel angle is reduced).
– If a variable motor is used, the motor power is also re-
duced
(the swivel angle is increased).
The controller calculates the available pump power or motor
power. The control behavior can be set on the basis of the
factors of the individual controller elements. You can set the
P, I and D factors separately for the closed loop control of the
pump power and the motor power.
The software contains default values for the parameters of the
closed loop control. To achieve optimal behavior, these param-
eters must be individually tuned to the respective machine.
Overheating protection
Requirement for this function is a diesel engine with a CAN-
bus interface and an available temperature signal. The tempera-
ture of the diesel engine is transmitted via the CAN bus. It is
compared to a parameterizable limit value. As soon as the limit
value is exceeded, overheating protection engages:
• The pump power is reduced. If a variable motor is used, the
motor power is reduced as well.
• The accepted hydraulic power is limited until the diesel tem-
perature is 5 °C below the parameterized maximum tempera-
ture.
Overheating protection can be activated or deactivated via
parameters.
Diesel protection
When traveling downhill, the machine supports itself on the
diesel engine ("engine brake"). To protect the diesel engine
from overspeeding, the hydraulic transmission ratio is in-
creased. The requirement for this function is the use of variable
motors.
• The diesel engine speed is compared to a parameterizable
limit value.
• As soon as the diesel engine speed exceeds the limit value,
diesel protection engages:
– The motor power of the variable motor is increased.
– Diesel protection can be activated or deactivated via
parameters.
Speed limiting
In order to adhere to country-specifi c regulations, the maximum
speed of the vehicle is defi ned. It is stored in a parameter
during commissioning. The requirement for this function is a
connected speed sensor on the hydraulic motor.
In addition, a potentiometer can be used to limit the vehicle
speed during operation. For example, to simplify driving and
working with attachments such as brushes.
The speed sensor on the hydraulic motor delivers the actual
value and the set maximum speed serves as the setpoint value
for a PI controller. Speed limiting can be activated or deacti-
vated via parameters.
Seat switch
A seat-switch input can be parameterized as a safety function.
Travel is possible only when the seat switch is closed.
Special function
The special function directly outputs the digital signal from the
"special function" input to the "special function" output.
Note that when in the open state, the switch must be connect-
ed to ground; when in the closed state, it must be connected
to battery voltage.