Safety Device for a Passenger Transport Installation
The invention relates to a safety device and to a method for safeguarding the
operation of a passenger transport installation, such as for example an escalator,
or a moving walkway, the steps or the pallets of which are each coupled to an
entraining element on a traction component, for example a drive chain.
DE 196 06 317 A1 discloses a device for monitoring the raising and/or lowering
of individual steps of the step belt of escalators, the steps being provided with
rollers supported on guide tracks and being held between endless drive chains
provided in the region of the balustrade base, comprising at least one safety
device provided substantially in the cross-over bend from the horizontal into the
inclined run, in particular halting the drive of the escalator. The safety device
contains at least one component mounted directly or indirectly resiliency with
respect to the steps, operatively connected to a switch-off device and extending
towards the steps of the step belt, said component being positioned a specifiable
distance away from the continuous steps beneath the step belt, the component
co-operating directly or indirectly with an apparatus provided in the region of the
steps and bringing about the deflection of the component. This safety device thus
detects an undesired deflection of a step from the path of travel intended for it.
With this device it is in principle possible to be able to detect the
raising/lowering of individual steps within a step belt of an escalator when a load
is applied to it. However, this is not possible when the step belt is not loaded, i.e.
is not transporting any passengers, because if there are defects in the region of
the step or pallet articulation, lowering of the respective step does not occur,
rather it only occurs when subjected to a load, for example by a person.

Depending on the local occurrence of the damage it may possibly be too late for
detection and for the switching off of the escalator or moving walkway drive for
the person triggering the incident in order to prevent personal injury.
The prior art includes a series of publications which are concerned with the
general topic of "missing step detection". Reference is only made here to DE 100
27 490 A1 and DE 10 2008 009 458 A1.
In both publications the respectively used sensor checks for missing steps by it
being aligned to the pins of the step or pallet rollers provided outside of the
respective drive chain.
JP 2007 076 823 A shows another safety device in which the axle of the rollers
of an escalator step sitting on it is monitored so that if one of these rollers is
damaged, the operation of the escalator is shut down.
Therefore, these devices can not be used for this specific application, namely
where a connection between components connected to one another is broken
within the traction components in the operating state.
When using plate link chains as the traction component for the steps or pallets of
the passenger transport installation, individual links of the plate link chain are
connected to a step or pallet lug by pins. There are a number of solutions here,
namely to provide on each inner side of the plate link chain in the step section a
pin piece that is operatively connected to the respective step/pallet lug, or else a
continuous axle extending between the two plate link chains via the step or pin
lugs.

Reference is made here/for example, to DE 296 03 962 U1 which is concerned
with the fitting and removal of a continuous step or pallet axle.
The entraining element being used here can be in the form of a complete or
hollow pin or of a continuous axle, and it can serve to receive corresponding end
regions of chain pins, by means of which the latter are then connected to the
respective step or pallet component by means of the operative connection to the
respective entraining element.
Independently of the type of design of the entraining element, relative movement
in the respective fitting region between the respective chain pin and the
corresponding entraining element is prevented structurally by safety elements, for
example in the form of screws and/or safety plates, being used.
Over the course of the service life of an escalator or of a moving walkway,
servicing work is carried out at regular intervals or, if required, necessary repairs
are made to damaged components.
In many cases this servicing work is not carried out by the manufacturer of these
escalators/moving walkways, but by subcontractors. In many cases employees
are used here who are familiar with the escalator/moving walkway product in
general, but do not always have training relating to the respective product or the
structural design of individual components of the product. In the aforementioned
activities it can therefore be the case that safety elements, as described in DE 296
03 962 U1, are possibly either not fitted at all or are only refitted carelessly
during repair or maintenance work. As a result of the vibrations that occur in the
operating state of the escalator/the moving walkway it can therefore be the case
that safety elements that have been fitted carelessly become loose, and so there is

relative movement between the aforementioned components in the chain
pin/entraining element connection region, and in the worst case this can lead to
the connection being broken and the respective step/pallet dropping.
It is the object of the subject matter of the invention to provide an improved
method in order to guarantee the operational reliability of a passenger transport
installation by eliminating the aforementioned problems that arise in the prior art.
It is therefore the object of the subject matter of the invention to be able to react
to the causes of faults or to damage in the specific region of a step/pallet
connection at a traction component before the damage becomes perceivable due
to a faulty deflection of a step or pallet.
This object is achieved by a method according to Claim 1 and by a safety device
according to Claim 7.
The basic idea behind the invention is to monitor the connection elements
between a traction component and a step or pallet of a passenger transport
installation. These connection elements relate first and foremost to an entraining
element that constitutes the connection link between a drive chain and a
step/pallet. The entraining element is often coupled on the chain side to a chain
pin and on the step or pallet side by means of a pallet lug, in such cases both the
chain pin and the pallet lug forming part of the connection elements.
According to the invention there is disposed on the entraining element side a
triggering element which, when it is detected that a specifiable movement of the
entraining element from its position securing the connection between the traction
component and the step has taken place, or when the lack of at least one safety

element is detected, triggers the alarm state, and optionally halts the drive of the
passenger transport installation. Moreover, the alarm state can include the
forwarding of the alarm by radio or the like to a safety or maintenance person.
One can assume that there has been a movement of the entraining element if, on
the one hand, the connection between the entraining element and the chain pin
and/or, on the other hand, the connection between the entraining element and
the pallet lug is broken. The invention thus provides improved safety monitoring
because a safety risk is detected before the step or pallet is brought out of its
running position.
Advantageous further developments of the subject matter of the invention can be
taken from the corresponding method subclaims 2 to 6.
The specifiable movement of the entraining element that can be detected by the
triggering element can be a relative movement of the entraining element with
respect to the step or pallet. In this case the triggering element is disposed on its
corresponding step/pallet.
However, the triggering element can also be located stationarily within the
transport section or return section, due to which the number of triggering
elements required for the entire escalator or moving walkway is considerably
reduced. If the triggering element is disposed within the transport section, it is
advantageous to place it in the region which is not visible to the passenger.
According to one advantageous embodiment the triggering element is a
mechanical button which is positioned a specifiable distance away from the
respective entraining element or from its path of travel specified by the

circulation of the passenger transport installation so that the button detects the
dubious movement of the entraining element when the entraining element strikes
the button.
In order to be able to detect the lack of an entraining element, an additional
button system can be provided: there can thus be located, for example, stationary
in the return section a button which a pulse transmitter element in the form of a
contact plate provided on each step or pallet strikes, by means of which, when
the passenger transport installation is running, a frequency signal is generated
that identifies the number of detected steps per unit of time dependency upon
the operating speed of the passenger transport installation. The lack of an
entraining. element is then detected by deviations from a predetermined
frequency.
According to one alternative the triggering element can also be a sensor that
works in a contact-free manner and which is aligned to the circumferential
surface of the entraining element and measures its movement. If this movement
exceeds a specified target value, an alarm is triggered by the safety device or
optionally the drive of the passenger transport installation is halted.
The object of the invention is also achieved by a safety device for implementing
the checking and monitoring process described above. The safety device has at
least one triggering element that is disposed, for example, in the non-visible
region of the transport and/or return section of the steps or pallets of the
passenger transport installation on the entraining element side such that the
triggering element triggers the alarm state if there is a movement of the respective
entraining element with respect to the steps or pallet or if at least one safety
element is missing. A triggering element can also be fitted to each of the

individual steps or pallets, by means of which a relative movement of the
entraining element with respect to the step or pallet can then be detected.
Advantageous further developments of the subject matter of the invention can be
taken from the corresponding object subclaims 7-9.
Therefore, as opposed to the prior art, a safety device intended for the very
specific application of a step/pallet fastening is presented which has a simple
structure and is, moreover, very effective because even with small relative
movements between the operatively connected components it can halt the drive
of the escalator/the moving walkway.
The triggering element can be a mechanical button which is positioned a
specifiable distance away from the entraining element, the button being able to
halt the drive of the passenger transport installation when it comes into contact
with the entraining element.
With regard to detection of axial movement of the entraining element the button
can advantageously be positioned such that it comes into contact with the free
end of the entraining element.
Alternatively, the triggering element can also be a sensor working in a contact-
free manner, which measures a relative movement of the entraining element, and
when a specifiable path of the entraining element is exceeded halts the drive of
the passenger transport installation.
According to another idea behind the invention the respective triggering element
is disposed in the non-visible region of the passenger transport installation.

Preferably, two triggering elements lying opposite one another between the
traction components running parallel to one another are disposed at a specifiable
point of the transport and/or return section of the traction component for each
step or pallet.
In contrast to the prior art the respectively used triggering element is disposed
within, i.e. between, the traction component(s) and so is able to monitor the
connection established here between the chain pins and the entraining elements
in different forms as required.
The subject matter of the invention is shown in the drawings using an exemplary
embodiment and is described below. The drawings show as follows:
Figure 1 a section through a step together with an illustration of
different entraining elements connected to a safety device;
Figure 2 a section through a step together with an illustration of
different entraining elements connected to a safety device;
Figures 3 and 4 a section and a side view of a pallet belt together with a
safety device;
Figures 5 and 6 a side view and detailed section of Figure 1 together with a
safety device.
Figure 1 shows a section through a step 1 in the visible region of the step belt
(forward motion) of a passenger transport installation (not shown in detail). In a

mirror-image illustration one can see two step parts 1',1". One can also see a
respective traction component 2 in the form of a plate link chain which is
connected on the outside to a chain roller 4 by means of a chain pin 3. The
chain pin 3 is connected to an entraining element 5, 6 on the side of the traction
component 2 turned away from the chain roller 4. The entraining element 5 (left-
hand part of Figure 1) is in the form of a pin piece that passes through the step
lug 7 of the step 1'. The pin piece 5 is connected to the step lug 7 by means of
safety elements 8 that are only suggested. An axial relative movement between
the chain pin 3 and the pin piece 5 is therefore not possible.
In the right part of Figure 1 an entraining element in the form of a continuous
axle 6 is shown. For better clarification reference is made to the subject matter of
DE 296 03 962 U1. Similarly to the pin piece 5, the entraining element 6 in the
form of a continuous axle is also connected to the corresponding step lug 10 by
means of safety elements 9 that are only suggested. In this figure safety devices
11, 12, which are only suggested here, are in the form of mechanical buttons
which will be described in more detail in the following figures.
Similarly to Figure 1, Figure 2 shows a step 13 in the return section, divided into
step parts 13', 13". Here too traction components 14 in the form of plate link
chains are provided which are operatively connected to chain rollers 15. In this
example the chain rollers 15 are moved between guide elements 16, 17.
As already suggested in Figure 1, in the left part of Figure 2 a pin piece 18 is
provided as an entraining element, while in the right part of Figure 2 a
continuous axle 19 is suggested as an entraining element. The respective
entraining element 18, 19 is operatively connected by the corresponding step lug
22, 23 to the entraining element 18, 19 by means of safety elements 20, 21,

which are also only suggested, so that axial relative movement between the
chain pin 24 and the respective entraining element 18, 19 is not possible.
Here too safety devices 25, 26 are provided which, in this example, are provided
as buttons that work in a contact-free manner and that are aligned to the
circumferential surface of the respective entraining element 18, 19. As soon as
the entraining element is moved out of its safety position, the button detects said
movement when a threshold value is exceeded and can thus trigger the alarm. If
an axial movement of the entraining element is detected, the triggering element
should be disposed on the free end of the chain pin.
Figures 3 and 4 show another configuration in a sectional and side view of the
arrangement of a safety device 27. One can see the transport section 28 for the
pallets 29 and the return section 30 for the pallets 29.
The safety device 27 is provided in the non-visible region 31, i.e. between the
transport section 28 and the return section 30, and is connected to a frame part
33 of the passenger transport installation by a holder 32. In order to give a better
overview, only a single safety device 27 is shown here in the form of a button
that works in a contact-free manner. In this example a moulded safety plate 34 is
provided which is operatively connected on the one hand to the pallet lug 36
and on the other hand to the entraining element 37 by a screw 35. If this safety
plate 34, to which the safety device 27 is aligned, has not been re-fitted following
a repair or maintenance work, as the safety device 27 passes through the return
section 30 the lack of safety plate 34 is detected and the drive of the passenger
transport installation, which is not illustrated any further, is halted.
Figures 5 and 6 are also to be analysed similarly to Figures 1 and 2. One can see

a respective step 38 here. One can also see a traction component 39 in the form
of a plate link chain and a chain roller 41 connected to the traction component
39 by a pin 40. The chain pin 40 co-operates with a pin piece 42 as an
entraining element. As described in the previous figures, the pin piece 42 is
secured with respect to the step lug 7.
One can also see a safety device 43 in the form of a mechanical button 43'
which, in this example, is positioned a defined distance, approx. 5 mm, behind
the free end 44 of the pin piece 42.
If the lock between the step lug 7 and the pin piece 42 has not been re-
established following maintenance or repair work, the pin piece 42 will slide out
of its position as a result of the vibrations produced in the operating state of the
passenger transport installation and finally come to rest against the button 43'.
When the button 43' comes into contact with the end 44 of the pin piece 42 the
drive of the passenger transport installation, not illustrated any further, will be
halted immediately by the safety device 43.

Claims
1. A method for safeguarding the operation of a passenger transport
installation, including the monitoring of an entraining element (5, 6, 18, 19, 37,
42) that acts as a safety member between a traction component (2, 14, 39) and a
step (1, 13, 38) or pallet (29) of the passenger transport installation, there being
disposed on the entraining element side a triggering element (11, 12, 25, 26, 27,
43) which, when it is detected that a specifiable movement of the entraining
element (5, 6, 18, 19, 37, 42) from its position safeguarding the connection
between the traction component and the step has taken place, or when the lack
of the entraining element is detected, triggers an alarm state.
2. The method according to claim 1,
characterised in that the specifiable movement that can be determined by the
triggering element (11, 12, 25, 26, 27, 43) is a relative movement of the
entraining element (5, 6, 18, 19, 37, 42) with respect to the step (1, 13, 38) or
pallet (29).
3. The method according to claim 1 or 2,
characterised in that the alarm state includes the halting of the drive of the
passenger transport installation.
4. The method according to any of the preceding claims,
characterised in that the triggering element (11, 12, 43) is a mechanical button
which is positioned a specifiable distance away from the entraining element (42),
the button (11, 12, 43) detecting the specifiable movement of the entraining
element when it comes into contact with the entraining element (42) and
triggering the alarm state.

5. The method according to any of claims 1 to 3,
characterised in that the triggering element (25, 26, 27) is a sensor that works in a
contact-free manner and which is aligned to the circumferential surface of the
entraining element (18, 19) and measures its movement as a specifiable path of
the entraining element (18, 19), and when this is exceeded or if the entraining
element or a safety element provided to fix the latter in position is missing
triggers the alarm state.
6. The method according to any of the preceding claims, .
characterised in that the triggering element (11, 12, 25, 26, 27, 43) generates a
frequency signaJ that identifies the counting rate of entraining elements (5, 6, 18,
19, 37, 42) per unit of time and the dependency of the operating speed of the
passenger transport installation during operation of the latter and triggers the
alarm state when there is a deviation from a specifiable frequency value.
7. The safety device of a passenger transport installation, the steps (1, 13, 38)
or pallets (29) of which are respectively connected to at least one traction
component (2, 14, 39) by means of an entraining element (5, 6, 18, 19, 37, 42),
the safety device having a triggering element (11, 12, 25, 26, 27, 43) that is
disposed on the entraining element side such that when it is detected that a
specifiable movement of the respective entraining element (5, 6, 18, 19, 37, 42)
from its position safeguarding the connection between the traction component
and the step has taken place, or when the lack of the entraining element is
detected, the triggering element (11, 12, 25, 26, 27, 43) triggers an alarm state.
8. The safety device according to claim 7,
characterised in that the triggering element (11, 12, 43) is a mechanical button

that is positioned a specifiable distance away from the entraining element (5, 6,
18,19,42).
9. The safety device according to claim 7,
characterised in that the triggering element (25, 26, 27) is a sensor working in a
contact-free manner and which is aligned to the outer circumferential surface of
the entraining element (18, 19).
10. The safety device according to any of claims 7 to 9,
characterised in that the triggering element (11, 12, 25, 26, 27, 43) is disposed
by means of a holder (32) in the non-visible region (31) of the transport (28)
and/or return section (30) of the steps (1, 13, 38) or pallets (29).
11. The safety device according to any of claims 7 to 10,
characterised in that the triggering of the alarm state includes the halting of the
drive of the passenger transport installation.