Black Bruin BB 4, Product Manual

Page: 37 / 70

External freewheeling valve
The external freewheeling valve is used for disengaging the motor during motion (see
Mechanical freewheeling on page 27).
The freewheeling valve should be normally open, so that the motor will disengage
when the control system is off.
When the motor is disengaged the case drain port (C) should be connected as directly
as possible to the working line ports A and B.
There are multiple possibilities for the external freewheeling valve. Some examples of
these possibilities are described in this chapter.
MECHANICAL FREEWHEELING, CHECK
VALVE
MECHANICAL FREEWHEELING, 2/2 VALVE
Min.
3 bar
A B
C2 C1
*
Figure 34. Motor with mechanical free-
wheeling, external freewheeling valve and
check valve.
Min.
3 bar
A B
C2 C1
Figure 35. Motor with mechanical free-
wheeling and a 2/2-valve to depressurize
work lines to case drain (open loop).
4.3
System Design
Product Manual 37