Note: Descriptions are shown in the official language in which they were submitted.
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A Lift Mechanism for a Passenger Loading Bridge
Field of the Invention
The invention relates generally to a passenger loading bridge, and in
particular to
lift mechanism including a motor synchronisation apparatus for use in
synchronising the
motors used to lift and lower an end of the loading bridge for alignment with
an airplane
entry.
Background of the Invention
Passenger loading bridges have gained worldwide acceptance for the safety and
convenience they afford passengers. Most major air terminals are provided with
gates,
gangways or passenger loading bridges which extend from the second level of
the
terminal to a parked aircraft. Frequently, these bridges are relatively
immobile since
aircraft can park close to the terminal and be moved away by tugs or tractors.
Commonly, passenger loading bridges have been directed to standaxd size
passenger and cargo aircraft and consequently, have been relatively large in
size and
height. They have not generally been practicable for use with small aircraft
such as, those
employed in feeder lines to smaller or outlying communities. Accordingly,
passengers
typically have had to walk from the terminal over airport tarmac and thence up
a stairway
in order to enter a small aircraft. This exposes passengers to inclement
weather and
hazards such as propellers, cables, and fuelling hoses. It is not desirable to
subject
2o passengers to inclement weather or to potentially dangerous ramp
conditions. Also,
aircraft operations are significantly slowed by allowing passengers onto the
tarmac. For
safety reasons, aircraft and equipment remain stationary while passengers are
on the
tarmac. Security is a concern because passengers can board incorrect aircraft
or tamper
with other craft. In order to increase security, it is a common practice to
board only one
aircraft from the tarmac at any time. With passenger loading bridges in place,
luggage is
loaded, aircraft tests are executed, other aircraft are taxied, and so on
while passengers
board the aircraft. Other aircraft are capable of being boarded simultaneously
when
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sufficient gates exist. It is therefore desirable to provide a passenger
loading bridge for
use at these smaller air terminals to enhance the safety and comfort of
passengers.
Commonly, smaller air terminals are only ground level structures at which
aircraft
park a fixed distance from the terminal building. There frequently are no tugs
available.
This fixed distance is required to enable the aircraft to "power out" or move
away from
the building under its own power without damaging the building with a jet or
propeller
blast, or a physical collision between the aircraft and the terminal. This
distance is
greatest with a Boeing 727-200 aircraft, which is the largest aircraft
normally serving
these smaller terminals. A loading bridge must be easily adjustable to the
different
1 o distances during airport operation in order to service a number of
different aircraft.
Therefore, there has continued to be a need for a highly adjustable and
enclosed
passenger or cargo loading/unloading bridge that can be advantageously
utilized with
such small aircraft.
Large variation in the loading height of different common commuter aircraft
also
requires a loading bridge able to be adjusted over a wide range of heights.
Currently
available loading gates for servicing commuter aircraft are capable of being
raised and
lowered to meet different aircraft heights.
A typical loading bridge is disclosed in U.S. patent No. 5,761,757 to Mitchell
et
al. The loading bridge is comprised of a cab for interfacing with an aircraft,
a bubble
2o section allowing rotation of cab about the bubble section, and a walkway
connecting the
airport, the bubble section and the cab. The walkway is extensible to allow
the cab to
move outward from the airport. As shown in Fig. 1 of the patent, the walkway
is
supported on two standards - one on either side - that are provided with lift
mechanisms.
The lift mechanisms operate in a synchronised fashion through feedback from
one to the
other. Thus, the walkway is raised or lowered in a substantially horizontal
orientation to
prevent tilt within the walkway to one side or another. The standards are on a
mobile base
for swinging the walkway about the bubble section. These features are well
known
features in passenger loading bridge design.
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Failure to synchronise the lifts may result in a single motor performing all
the
work; this is potentially hazardous. As a safety feature, a brake integral to
each motor is
actuated upon failure of either motor and prevents the bridge from collapsing.
Unfortunately, if a brake fails, an entire side of the loading bridge is left
unsupported.
It would be advantageous to provide a passenger loading bridge with improved
safety. It would also be advantageous to provide a simple method of
synchronising the
operation of each of the two motors for use in raising and lowering a
passenger loading
bridge.
Summary of the Invention
1o It is an object of the invention to provide a simple effective apparatus
for
synchronising two motors, such as electric motors, for use in raising and
lowering a
passenger loading bridge. The motors each provide drive for raising or
lowering one side
of the passenger loading bridge. Therefore, in order to maintain a level
loading bridge, it
is necessary that the motors are substantially synchronised.
In accordance with the invention there is provided a lift mechanism for a
passenger loading bridge. The mechanism comprises a first motor including a
drive shaft
having a first end and a second end; a second motor including a drive shaft
having a first
end and a second end; a first standard including a lift for engaging the
passenger loading
bridge and for raising and lowering the passenger loading bridge, the lift
coupled with
2o and driven by the first end of the drive shaft of the first motor; a second
standard
including a lift for engaging the passenger loading bridge and for raising and
lowering the
passenger loading bridge, the lift coupled with and driven by the first end of
the drive
shaft of the second motor; and, a mechanical link between the second end of
the drive
shaft of the first motor to the second end of the drive shaft of the second
motor such that
the drive shafts of the first motor and of the second motor are substantially
restricted to
turning at a same speed.
In accordance with another embodiment of the invention there is provided a
lift
mechanism for a passenger loading bridge. The mechanism comprises a first
motor
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including a drive shaft having a first end and a second end; a second motor
including a
drive shaft having a first end and a second end; a first standard including a
lift for
engaging the passenger loading bridge and for raising and lowering the
passenger loading
bridge, the lift coupled with and driven by the first end of the drive shaft
of the first
motor; a second standard including a lift for engaging the passenger loading
bridge and
for raising and lowering the passenger loading bridge, the lift coupled with
and driven by
the first end of the drive shaft of the second motor; and, a coupler coupling
the second
end of the drive shaft of the first motor to the second end of the drive shaft
of the second
motor such that the drive shafts of the first motor and of the second motor
are
1 o substantially restricted to turning at a same speed.
In accordance with yet another embodiment of the invention there is provided a
lift
mechanism for a passenger loading bridge. The mechanism comprises a first
motor
including a drive shaft having a first end and a second end; a second motor
including the
drive shaft; a first standard including a lift for engaging the passenger
loading bridge and
for raising and lowering the passenger loading bridge, the lift coupled with
and driven by
the first end of the drive shaft; and, a second standard including a lift for
engaging the
passenger loading bridge and for raising and lowering the passenger loading
bridge, the
lift coupled with and driven by the second end of the drive shaft.
According to an embodiment of the invention wherein each motor has a separate
drive
2o shaft, the drive shafts each have an axis of rotation and the axes are
coaxial. For example
a shaft is disposed between and coupled to each second end.
Brief Description of Figures
An exemplary embodiment of the invention will now be described in conjunction
with
the attached drawings, in which:
Fig. 1 is a plan view of a preferred embodiment of the present invention
illustrated in a
fully extended position;
Fig. 2 is a side view of the embodiment of Figure l; and
Fig. 3 is a side view of a lift mechanism according to the invention.
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Detailed Description of Preferred Embodiments
The loading bridge according to the present invention is shown generally at 10
in
Fig. 1. The bridge 10 is supported at a terminal end 31 by a rotunda 20. The
rotunda 20
communicates with the airport terminal (not shown) through a simple
passageway, or an
additional walkway of desired length (not shown). The rotunda 20 is fixed and
supports
the terminal end 31 of the enclosed bridge walkway 30 for hinged movement
about a
horizontal axis for height adjustment, and also for pivotal movement about a
vertical axis
through the rotunda 20. The rotunda 20 may be supported on a raised platform
as shown,
or may be directly at the ground level. Rotation may be about a central axis
or an
1o eccentric axis. The rotunda 20 remains enclosed by flexible curtains during
movement of
the passenger loading bridge 10 maintaining protection from the elements.
Walkway 30
includes two telescopic sections 32, 34 that provide an expansion of
approximately 20
feet. If more expansion is necessary additional telescoping sections may be
added.
Adjacent an aircraft engaging end 33 the walkway 30 is supported by a wheeled
gantry support means 40. The wheeled gantry 40 is powered to drive the
aircraft
engaging end 33 through the arc shown, while the terminal end 31 pivots about
the
rotunda 20. The wheeled gantry 40 also includes standards 42 to either side of
the
walkway 30 each comprising a mechanical screw jack lift for raising and
lowering the
height of the aircraft engaging end 33 of the bridge 10. Other lifting
mechanisms may
2o also be employed to raise the bridge 10. The screw jack lifts are preferred
as they provide
low braking requirements in the event of motor failure and slow decent of the
passenger
loading bridge in case of brake failure. Standards 42 are shown angled with
their
uppermost ends inclined toward the aircraft engaging end 33. This angle
reduces lateral
drag on the tires to prevent excessive wear as the bridge 10 is raised. Of
course, though
this angle has benefit, it is not necessary for carrying out the present
invention.
As is evident to those of skill in the art from a review of Figs. 1 and 2, the
lift
mechanisms within the standards 42 operate synchronously. In order to achieve
this, prior
art loading bridges use electronic synchronisation to slow movement of one
side of the
passenger loading bridge or another in order to synchronise movement of both
sides. This
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is done using sensors and feedback to control one of braking and motor drive
shaft speed.
Though electronic motor synchronisation is well known and widely used, it
would be
preferred to use a simpler more cost effective and reliable method of motor
synchronisation.
Referring to Fig. 3, a detailed view of standards 42 according to the
invention is
shown. A screw 51 extends a length within each standard. The loading bridge is
provided
with brackets (not shown) for mating with the screws 51 to cause the passenger
loading
bridge to rise as the screws 51 are rotated in one direction and to decline as
the screws 51
are rotated in an opposite direction. Bearings interfacing between the screws
51 and
1 o brackets reduce wear and enhance smooth motion of the passenger loading
bridge 10.
The screws 51 are each driven by an electric motor 52. The electric motors 52
include a
drive shaft having a first end 52a and a second end 52b. The electric motors
are selected
to have sufficient power to raise half the weight of the bridge or more.
Preferably, the
electric motors have integral braking systems for preventing turning of the
driven shaft
when the electric motor 52 fails. This in turns prevents the screw 51 from
turning and
locks the loading bridge in place.
According to the invention, the two motors 52 are mechanically synchronised by
coupling the second end of the drive shafts 52b of each motor 52 together.
This coupling
ensures that each driven shaft turns at a same speed thus guaranteeing that
each side of
2o the passenger loading bridge travels at a same speed. In Fig. 3, the
coupling is shown as a
mechanical bar 54 coupled to each second end 52b. Such a configuration
requires, when a
non-flexible bar is used, that the driven shafts have a same axis of rotation.
Of course,
using two motors having a same single driven shaft results in the same
benefits as those
achieved by coupling the second ends 52b together.
Advantageously when the motors 52 each comprise an integral braking system as
is commonly found in motors of the type used in loading bridges, the method of
synchronisation according to the present invention also guarantees that should
one motor
52 or the other motor 52 fail, the integral braking system of the failed motor
prevents
raising or lowering of both sides of the passenger loading bridge. Also,
should either
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braking system fail, there exists in the other motor a duplicate breaking
system for
enhanced safety of passengers using the bridge and safety of personnel
operating the
bridge.
As shown in Fig. 3, the first end 52a of the driven shaft is at 90 degrees to
the
second end 52b. This is useful when a screw lift mechanism is employed. Other
lift
mechanisms may require a first end 52a coaxial to the second end 52b. This
will not
adversely affect operation of the invention. Thus, as used herein, the driven
shaft may
comprise several non-contiguous shafts that are each driven by the motor
either directly
or indirectly. The invention relies on mechanical coupling of driven shafts of
each motor
1 o to ensure that the driven shafts rotate at a substantially same speed.
Because the present invention is implemented in the embodiment described
herein
with a statically coupled shaft for synchronising the two motors 52, it is
rugged, reliable,
inexpensive, and maintenance free. These are highly advantageous for a product
used
outdoors and installed in diverse locations. As such, the inventive
syncronising apparatus
is advantageous for use in loading bridges.
Numerous other embodiment of the invention will be apparent to persons skilled
in the art without departing from the spirit and scope of the invention as
defined in the
appended claims.
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