Bosch Rexroth Tightening System 350, Manual

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104 /641 Bosch Rexroth AG | Tightening Technology 3 608 878 300
System 350 | 3 608 878 300/2019-03
Calculation basis PL and PFHd or MTTFd
For the Rexroth Tightening System 350 , the PFHd or MTTFd value is specified in addition to the
performance level (PL). As within the safety function of the tightening system, one uses also
electromechanical components with a limited number of switching cycles, the following scenario is
assumed for calculating the PFHd value:
• A cycle takes 15 seconds
• The system is operated in 3-shift operation without standstill days, i.e. Sundays, public holidays,
company holidays, etc.
These assumptions result in a value of 2.1 million switching cycles per year.
CAUTION
Risk of injury due to non-compliance with the system-specific requirements
on an emergency OFF system.
Risk of short circuit, risk of injury.

The user is obliged to maintain the system-specific requirements for an emergency OFF system.

When designing the emergency OFF circuit, the user must observe the rules for the short-circuit-
and cross-circuit-proof laying. When using external mains contactors in superior emergency OFF
circuits, observe the restarting time for the component.

Check that the emergency OFF circuit is functioning correctly before commissioning the
tightening system.

Observe the local, system-specific regulations and requirements; proper use of tools, lifting, and
transport equipment; as well as the relevant standards, provisions, and accident prevention
regulations.