Note: Descriptions are shown in the official language in which they were submitted.
2171665
-- 1 --
IMPROVEMENTS IN PLATFORM LIFTS
The invention relates to improvements in platform
lifts which can be used to raise a load, such as a
handicapped person in a wheelchair, to a higher level.
For handicapped persons of limited mobility or those
confined to wheelchairs, it is particularly difficult to
climb steps or to be carried up steps. In some cases it
is possible to install a lift at a site separate from the
steps, but in other cases this may not be convenient or
possible. In such cases, the lift must be readily
available for use by the disabled person, but in its
stowed position the lift must not obstruct normal use of
the steps.
A number of lifts have been devised which lift
passengers or loads through changes in level to avoid the
need to mount steps. These generally comprise low rise
vertical lifting platforms. The main problem with such
lifts is the need to bridge the horizontal gap between
the edges of the platform and the top step. This can be
done with a hinged bridge plate, but such a plate tends
to obstruct normal use of the steps. Alternatively, a
series of lifting bridge plates can be installed, with
one on each step. The plates are picked up by the
platform as it rises. These lifts have the disadvantage
that they have to be specially made and installed for
each application, which tends to expensive.
Another alternative solution is the use of a lift
mounted on rails fixed to a support structure at the side
of the staircase. Such lifts have a platform which can
be pivoted to an upright position and parked vertically
at the top or bottom of the stairs awaiting use. For
use, the platform is pivoted to a horizontal position.
However, this arrangement tends to be expensive and
requires too much space to operate. For just a few steps
2 1 7 ~ 665
-- 2
such an arrangement is impractical.
It is therefore an object of the present invention
to provide a platform lift which overcomes these
disadvantages.
According to the invention there is provided a
platform lift comprising a base, a substantially
horizontal platform, said platform providing a through
path for both vehicles and pedestrians, said platform
being located above and attached to said base by means of
an operating mechanism comprising a radial linkage and
associated drive means, which platform is movable from a
first position to a second position in a substantially
arcuate path by means of said operating mechanism, the
first and second positions being vertically separated and
the platform extending forwardly from the base as it is
raised from the first to the second position.
Preferably the radial linkage comprises at least one
deformable parallelogram comprising a base, a pair of
side arms each of which is pivotally connected at one end
to the base and at another end to a fourth arm attached
to the platform, in which drive means comprise extensible
actuator means which are pivotally connected at one end
to a moveable part of the lift and at another end to a
fixed point, such that as the actuator means extends or
contracts the parallelogram is caused to deform to raise
or lower the platform.
There will now be described, by way of example only,
a preferred embodiment of the invention, with reference
to the accompanying drawings in which:-
Fig. 1 is a front perspective view of a platformlift in its lowered position;
Fig. 2 is a side elevation of the platform lift of
Figure 1;
2171665
-- 3
Fig. 3 is a side elevation of the platform lift of
Fig. 1 in a partially raised position; and
Fig. 4 is a side elevation of the platform lift of
Fig. 1 in a fully raised position.
The lift 10 is located adjacent a step or set of
steps 22. The lift 10 comprises a platform 11 which is
sufficiently wide to receive a wheelchair or any other
load to be raised. The platform 11 may have side walls
12 to guide the wheelchair into position and hand rails
13 for the wheelchair or other user to hold on to during
the lifting operation.
The side walls 12 may also act as load supporting
shear panels.
The lift 10 is provided with a ramp 14 attached to
the platform 11 on an opposite side of the platform 11 to
the steps 22 to enable a smooth entry and exit from the
platform 11 at ground level.
The lift 10 is mounted on a base 15. The base 15 is
affixed to the ground adjacent the steps 22. The
platform 11 is attached to the base 15 by means of at
least one deformable parallelogram arrangement. The
parallelogram comprises a lower arm 18 which is affixed
to or forms part of the base 15 and a pair of pivoting
side arms 19 attached at one of their ends to the lower
arm 18 and at their other ends to the platform 11. A
section of the platform 11 itself may constitute the
fourth arm of the parallelogram or a separate arm may be
attached to the platform 11. The connections between the
arms 18, 19 and the platform 11 is pivotal. In a
preferred embodiment of the invention a parallelogram is
provided on opposite sides of the platform.
Connected between the base 15 and one of the side
arms 19 is an extendible hydraulic actuator
2 1 ~ ~ 66~
-- 4
20. Actuators 20 may be provided on just one or both
sides of the platform 11. Power means are provided which
cause the actuator 20 to extend and contract.
The term actuators is intended to cover hydraulic
jacks, electric actuators or any other powered means
capable of extending and contracting.
A synchronising link may be provided between one or
both pairs of side arms of the parallelogram.
When the lift 10 is in its lowered position, the
actuator 20 is contracted and the parallelogram is in a
flattened or obtuse angled state. The platform 11 is
thus positioned at ground level. A wheelchair user can
roll himself up the ramp 14 onto the platform 11 or any
other type of load placed on the platform 11. The power
means are operable either by the lift user which actuates
the actuator 20 so that it extends. As it extends, it
pushes the side arm 19 to which it is attached from a
substantially horizontal position through approximately
90 to a substantially vertical position as shown in
Figure 4. The parallelogram moves from its obtuse angled
state to a generally right angled state, without the need
for the side arms 19 to pass the vertical position. The
platform 11 thus swings in a continuous arc from its
ground level position at the foot of the steps 22 to a
raised position adjacent the top of the steps 22 so that
the wheelchair user or load can roll or~be rolled/lifted
off the platform 11 onto the top of the steps 22.
To lower a wheelchair user or load, entry is
effected onto the platform 11 from the top of the steps
22. The power means are actuated which cause the
hydraulic actuator 20 to contract. The parallelogram is
pulled sideways into an obtuse or flattened state and the
platform 11 is lowered. The wheelchair user or load can
roll or be rolledtlifted off the platform 11 at ground
level.
2171665
-- 5
Although the actuator 20 is described as being
attached between a side arm of the parallelogram and the
base plate 15, it may be attached at any other points
such that the parallelogram can be caused to deform in
the required manner e.g. to the base plate and the
platform, to a side arm and a step etc. As the side arms
do not need to pass through the vertical position, the
use of a single acting hydraulic actuator means that the
lift can be lowered, under gravity in the case of power
failure.
The platform ll may be attached to the side arms la
by means of fixed or removable pins or other suitable
fixing means. The fourth arm or sides of the platform 11
maybe provided with a series of vertical holes so that
the side arms 19 may be attached with removable fixings
or spigots located on the side arms at different vertical
positions. This means that the platform 11 height may be
varied to suit different applications without having to
change the stroke of the actuator.
