RE 95528/05.2016,
Bosch Rexroth AG
Counterbalance valve |
BVD/BVE Series 52
Safety instructions
15
Safety instructions
Failure to observe any of the following points can lead to
uncontrolled operating conditions with serious personal
injury and material damage.
▶ The counterbalance valve does
not
replace the mechani-
cal holding brake. If necessary, provide mechanical
braking systems.
▶ The mechanical holding brake in the winch gearbox
must only be effective after the counterbalance spool
has closed. Otherwise, the brake will be subject to wear.
▶ Note the maximum permissible cracking pressure of the
holding brake. If necessary, use the integrated pressure
reducing valve as a brake release valve with reduced
high pressure (version “L”).
▶ Counterbalance valves should only be operated in combi-
nation with close-by secondary pressure relief valves in
order to protect the motor against pressure peaks.
The motor port plate already contains the secondary
pressure relief valves.
▶ Cavitation must be prevented for safety reasons – see
project planning notes for remedial measures
▶ During and shortly after operation, there is a risk of getting
burnt on the axial piston unit and especially on the sole-
noids. Take appropriate safety measures (e.g. by wearing
protective clothing).
▶ Moving parts in control equipment (e.g. valve spools)
can, under certain circumstances get stuck in position
as a result of contamination (e.g. impure hydraulic fluid,
abrasion, or residual dirt from components). As a result,
the hydraulic fluid flow and the build-up of torque in the
axial piston unit can no longer respond correctly to the
operator's specifications. Even the use of various filter
elements (external or internal flow filter) will not rule
out a fault but merely reduce the risk.
The machine/system manufacturer must test whether
remedial measures are needed on the machine for the
application concerned in order to set the consumer
being driven to a safe position (e.g. safe stop) and if
necessary to ensure it is properly implemented.
▶ Moving parts in high-pressure relief valves may in certain
circumstances become stuck in an undefined position
due to contamination (e.g. contaminated hydraulic
fluid). This can result in restriction or loss of the load
holding function in lifting winches.
The machine/system manufacturer must check whether
additional measures are required on the machine for the
relevant application in order to keep the load in a safe
position and ensure they are properly implemented.
▶ When using the axial piston motor in winch drives, make
certain that the technical limit values are not exceeded
under all operating conditions. If the axial piston motor
is extremely overloaded (e.g., if the maximum permis-
sible rotational speeds are exceeded during weighing of
the anchor while the ship is in motion), the rotary group
may be damaged and, in the worst case, the axial piston
motor may burst. The machine manufacturer/system
manufacturer is to undertake additional measures, up to
and including encapsulation.
