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Bosch Rexroth AG

RE 95310/01.09

LLC Load Limiting Control

5/12

Important features

• The ratio in which the power reduction is distributed be-

tween pump 1 and pump 2 in the event of a limit load can be

set as a parameter. Depending on the parameter setting, the

power reduction may be distributed evenly between the two

pumps, or the division may be asymmetrical.

A second distribution value of the power reduction can be

set as an optional additional parameter. An external switch

can then be used to switch between the two methods

(power sharing mode switch).

• The total maximum permitted pump power can be reduced

using an external potentiometer.

• An additional temperature mode is possible if a diesel engine

with a CAN-bus interface is used. If the temperature passes

above or below the limits set as parameters, power is re-

duced to a user-deﬁnable level.

• Power modes: Switches between three different permissible

hydraulic powers. These arise from the permissible speed

drops that are speciﬁed differently for each power mode.

• Precision mode: A valve is controlled depending on the posi-

tion of a dial potentiometer. The drop in LS pressure caused

by the valve can be used to slow operating functions, e. g. for

precision work.

• Automatic speed reduction: If no operating function is

requested for a longer period of time, the diesel engine

switches to idle mode to reduce fuel consumption. For this

purpose, a pressure switch (normally closed contact) must

be installed in an appropriate location. At low LS pressure,

the pressure switch closes, signaling to the controller that

automatic speed reduction is requested.

• If a diesel engine with a CAN-bus interface is used, the pres-

ent output currents from pump 1 and pump 2 are sent via the

CAN bus every 100 ms. This includes the power sharing set

externally with a potentiometer and, if relevant, error mes-

sages.

• The second proportional solenoid output can be used for

limp home mode or for controlling a valve for the ﬁne mode

(parameterizable). Under normal circumstances this output

produces a constant 100 %; this value falls to 0 % in the

event of an error. Thus, the pumps can be switched by an

external valve to an operating mode that enables the device

to be run with no electronics.

• The inputs and outputs of the controller are monitored (for

cable break, short-circuit). In the event of an error or if the

safety switch is actuated, the drive is stopped immediately.

All of the above errors as well as errors in the CAN commu-

nication with the diesel engine and excessively high or low

engine temperature can be indicated by a ﬂashing code on a

connected error lamp.

• All errors that occur are stored in the controller and can also

be read later in plain text form using BODAS service.

Important parameters

For a diesel engine with a CAN-bus interface:

• Diesel engine data (speciﬁed speed and actual speed via

CAN bus, speciﬁed torque and actual torque via CAN bus,

dynamic behavior, permissible speed drop)

• CAN bus (baud rate, controller addresses, signal priorities)

• Conﬁguration (number of pumps and limp home mode,

power sharing, hydraulic concept, speciﬁed-speed source)

• Minimum and maximum magnetic current for pumps 1 and 2

• Load limiting control (dynamic controller data)

• Function (minimum/maximum temperatures, power reduc-

tion)

For a diesel engine without a CAN-bus interface:

• Diesel engine data (actual speed from sensor, number of

teeth on ﬂywheel, dynamic behavior, permissible speed drop)

• Potentiometer for speciﬁed speed and power sharing

• Conﬁguration (number of pumps and limp home mode,

power sharing, hydraulic concept, speciﬁed speed source)

• Minimum and maximum magnetic current for pumps 1 and 2

• Load limiting control (dynamic controller data)

Variant LLCA