Page - 84/90
AF9ZP0BA - EPS-ACW REACH TRUCK - User Manual
16 SAFETY REQUIREMENTS &
RECOMMENDATIONS
U
According EN1175 and ISO13849, we consider the arrangement
documented in this manual suited to work in Manual Mode and Loop Mode
only (target is PLd and Category #3). Obviously, the lift truck manufacturer
is responsible for the final system and, to fulfil the norms, the lift truck
manufacturer is called to adopt special analysis, design principles and
cares against the faults of the components of the system that are not in
charge of Zapi but affect the safety. Particular attention must be paid for
those of these components which cannot be monitored/diagnosed by the
Zapi assembly (let’s consider an example: the shaft of the Steering Wheel is
totally in charge of the Lift Truck manufacturer and there is no chance the
Zapi system can detect a failure in that component. This component, in
case fails to a loosened condition, compromises the safety).
These analysis, design principles and cares pass through two steps:
1) The lift truck manufacturer, according its own FMEA can conclude that, a
fault in a component that is not redundant (and not covered by the
diagnosis), shall not lead to a lost of safety (no countermeasure required).
2) The lift truck manufacturer, according its own FMEA can conclude that, a
fault in a component that is not redundant (and not covered by the
diagnosis), shall lead to a lost of safety (a failure of that component must
be avoided with proper cares: fault exclusion case).
U
VERY IMPORTANT: among the components of the system that are not in
charge of Zapi there is the unit in the truck designated to lead the traction
to a safe state in case of an alarm in the steering system (typically a VMC =
Vehicle Master Control; but in general it can be any unit in the truck. In the
next we refer to this unit as a TMC=Traction Master Control). This is a major
safety issue and the LIFT TRUCK MANUFACTURER is responsible for
coordinating the communication between different suppliers and
furthermore for testing and validating that this alarm information will be
properly handled in the destination site and leading to a traction safe state
when the steering system is no longer operative. This problem is even
more dramatic in case the unit assigned to stop the traction IS NOT A ZAPI
unit (see also 16.2).
16.1 Fault exclusions
16.1.1 Mechanical coupling
U
According EN1175 and ISO13849, a case of fault exclusion must be applied
to the mechanical coupling between motor shaft and steered wheel. The
