nifty TrackDrive TD120T Series Operating/Safety Instructions Manual page 51

A4 INTERLOCKING OF CONTROL POSITIONS
The interlocking of the control positions is PL c in accordance with ISO 13849-1:2008 as required by
BS EN 280:2013+A1 2015.
1. The limits of the safety-related parts to the category selected and any fault exclusions;
The physical interlocks between the multiple control positions are controlled through primarily electrical
means such that neither position takes sole command unless selected. The alternate control position
is then rendered inoperative by isolation of that control circuit. Proper maintenance and daily safety
checks to be observed.
Since the physical installation of the electrical contacts is the means by which the control circuit
operates it is imperative that the functionality is retained. If the internal wiring is interfered with the
control isolation could be lost or altered in a way that promotes a dangerous mode of operation.
Reasonably foreseeable misuse
2. The limits of the SRP/CS and any fault exclusion, for which, when essential for maintaining the
selected category or categories and safety performance, appropriate information (e.g. for
modification, maintenance and repair) shall be given to ensure the continued justification of the fault
exclusion(s);
Do not alter, modify or disable in any way the controls, safety devices, interlocks or any other part of
the machine.
Maintenance must only be carried on by appropriately trained and competent persons, who are
conversant with all modes of operation, speeds and characteristics of this model.
3. The effects of deviations from the specified performance on the safety function(s);
If the interlocking of the control positions does not function as intended it is possible that the Niftylift
may allow modes of operation that render it potentially dangerous.
If the controls do not remain independent in their operation, damage to the Niftylift, other equipment
and properties, injury or loss of life of the operator and surrounding persons may be a risk.
4. Clear descriptions of the interfaces to the SRP/CS and protective devices;
Each control position is capable of being energised by means of a key operated 'mode selector' which
electrically isolates the other circuit when one is selected. The reliability of this function depends on
the correct device operator in conjunction with the appropriate contact and internal wiring.
5. Response time
Operation of the mode selector key switch is immediate. Control authority is transferred over and no
residual power functions remain with the alternate control position, other than gravity descent (if used.)
6. Operating limits (including environmental conditions);
All components within the control interlock system are rated to the environmental conditions
acceptable for the machine; see Section 2.2.
7. Indications and alarms;
None, other than by key position.
8. Muting and suspension of safety functions;
None.
English/USA – 02/17
TrackDrive (TD) Series
Operating & Safety Instructions
49