TM Series
Operating & Safety Instructions
English/USA – 01/10
29
4.5
CAGE WEIGH SYSTEM
4.5.1 MECHANICAL
VERSION
The Niftylift range of machines are available fitted with mechanical cage weigh systems. These are
configured to sense a vertical cage overload, which when detected will halt the machine movement.
No further use of the platform is then permitted until the overload has been removed. This must be
done in a responsible manner and not one in which a greater hazard might be induced. Therefore, if
the addition of external items such as light fittings; brickwork or tiles etc were allowed into the cage,
the machine would not operate. In order to restore the functions, the excess load should be safely
removed, NOT by discharging them out of the basket to the detriment of persons below.
The mechanical cage weigh system works on the principle of a pre-loaded spring, rated to the cage
safe working load. Excess load in the cage forces the spring to further compress, the movement of
which is detected by a precision micro-switch. With the machine turned ‘On’, this movement first
gives an audible alarm in the cage, as well as a visual indication at both control positions (cage and
base). Additional deflection due to increased load serves to cut off the machine control circuit,
effectively halting all machine movements.
Under the circumstances where the cage overload cannot be removed, the machine can only be
manoeuvred by use of the manual hand pump. Great care must be taken when utilising this facility,
especially if the machine is significantly overloaded; any motion that causes the machine outreach to
increase could induce instability. The machine must be manoeuvred in such a manner as to reduce
outreach, then height, until a safe level is reached to permit the operator to dis-mount or the overload to
be removed.
4.5.2 FUNCTION
The cage overload system is powered from the machine control circuit, so the system is inactive if the
machine is turned ‘Off’.
‘Enabling’ the emergency stops allows the system to become ‘active’, when either the cage or base
key switch is turned ‘On’. If the cage is overloaded, the control circuit will immediately indicate this by
the audible and visual alarm. Pressing the emergency stop or turning the key switch to the ‘Off’
position merely silences the alarm. The alarm will continue to sound as long as the overload persists,
unless the machine is turned ‘Off’.
Whilst the overload is detected, pressing the green button at base or cage will generate no response
from the control circuit. The machine will not function under power until the overload is removed.
Removing the overload as previously described will re-set the system automatically, requiring no
additional intervention from the operator. All machine functions will be restored.
4.5.3 TESTING
At the simplest level, before working on the platform, the function of the cage overload can be checked
by the following method: - Place two men into the cage and a larger quantity of tools than is permitted
to be carried. (Typically 40 kg). The alarm should sound and all functions should be lost. Reducing
the cage contents to the safe working load should silence the alarm and restore the machine operation.
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