Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: POWER LIFT SYSTEM
FIELD OF THE INVENTION
The present invention relates to power lift systems and in
particular relates to a power lift system for lifting heavy materials for
example
masonry or stone products. The system can be erected and dismantled in a
straightforward and time efficient manner.
BACKGROUND OF THE INVENTION
There are a number of power lift systems that have been proposed
for use in association with scaffolding type systems. These systems are
designed
to be self standing or erected in close proximity to a building wall and
temporarily connected thereto for additional stability. Such power lift
systems
are designed to assist workmen with respect to the construction and/or repair
of
a structure where a crane or elevator is not suitable or available.
Power lift systems that operate on the basis of a stabilized vertical
upright with a moveable platform that slides on the vertical upright are
known.
Examples of such systems are shown in United States Patent 6,883,643, United
States Patent 5,884,725 and Unites States Patent 4,382,488.
United States Patent 4,382,488 discloses a pump jack pole system
having a hydraulic pump jack used to move a slide member up and down a pole
upright.
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Vertical lift systems that are effectively powered by the workmen
are desirable in that the cost of a manual pump jack or a manual crank for
lifting
of a platform is inexpensive, however there is a problem with respect to
providing a safe and cost-effective system that is easy and convenient to use.
The purpose of such a lift system includes lifting often heavy material to a
higher
level. As the weight of this product substantially increases the convenience
of a
manually driven system is severely compromised.
The present invention is directed to a lifting system that is suitable
for lifting of a substantial weight for example in excess of 2,000 lbs. but is
also
useful in lifting lighter loads and providing an adjustable height work
platform.
The system is based on an upright member having a rack portion of
one side that cooperates with a gear drive carried and the carrier that slides
up
and down the upright member. An electric motor is used to drive the gear drive
and determine the position of the carrier on the upright. The vertical upright
can
be used in pairs for larger platforms and work surfaces however it is also
possible to use a single upright system.
SUMMARY OF THE INVENTION
A power lift system according to the present invention comprises at
least one vertical lift combination with each vertical lift combination
comprising
an upright member and an associated carrier. The upright member has a rack
portion on an exterior surface thereof with the rack portion extending in a
length
of the upright member. The carrier is mounted on and moveable in the length of
the upright member with the carrier sleeving the upright member. The carrier
includes an open slot on a surface thereof opposite the rack portion with the
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open slot extending in the length of the carrier. The vertical lift
combination
includes a self braking motor drive and gear train mounted on the carrier. The
carrier includes a drive port on a surface of the carrier opposite the open
slot
with a gear of the gear train extending through the drive port and engaging
the
rack portion. The carrier above and below the motor drive includes means for
releasably receiving load arms with the load arms supporting a work surface
outwardly of the carrier.
In an aspect of the invention, the power lift system includes at least
two vertical lift combinations spaced apart from each other and maintained in
a
parallel manner.
In a further aspect of the invention, the system has two power lift
combinations and the carriers jointly secure a work platform between the
upright members.
In yet a further aspect of the invention, each upright member includes
a series of securement ports aligned with the open slot of the associated
carrier.
In a different aspect of the invention, the system includes a tie off
member to releasably engagable with any of the securement ports to form a
mechanical connection with the upright member. The tie off member is elongate
and extends through the open slot of the carrier as the carrier moves past the
tie
off member.
In a related aspect of the invention, the tie off member is a rigid
member and includes means for fixedly securing the rigid member to a building
structure to maintain the upright in a vertical orientation.
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In a preferred aspect of the invention, the system includes guide wire
securing members engagable with the uprights adjacent an upper edge of the
uprights.
According to an aspect of the invention, the system includes two
uprights with two carriers and the drive motors of the carrier are commonly
controlled to operate in a synchronized manner.
In yet a further aspect of the invention the means for releasably
receiving load arms includes two pairs of carrier bars on opposite sides of
the
carrier. Each pair of carrier bars is rigidly secured to the carrier and
generally
perpendicular to a length of the carrier. The pairs of carrier bars define
parallel
securing slots on opposite sides of the carrier sized to slidably receive a
securing
fork of the load arms. The system includes means for releasably maintaining
the
securing fork between the pairs of carrier bars.
In a preferred aspect of the invention, the load arms extends forwardly
and rearwardly of the carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings
wherein:
Figure 1 is a perspective view of the system using a single upright member;
Figure 2 is a perspective view of the system using two vertical members;
Figure 3 is a partial perspective view of a single pole lifting system showing
additional details of the slideable carrier;
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Figure 4a is a partial exploded perspective view of the slideable carrier, the
drive thereof and the cooperation with the vertical upright member;
Figure 4b is a sectional view through the vertical pole member;
Figure 5 is a sectional view showing the slideable carrier, the motor drive
thereof and the gears associated with the motor and the rack provided on
the upright member;
Figure 6 is a partial perspective view showing the securement of a work
platform to one side of the carrier;
Figure 7 is a partial perspective view showing an extension member used
for lifting of a further upright member to a first upright member;
Figure 8 is a side view showing the extension member secured on one
upright member and the process for lifting and securing a second upright
member; and
Figures 9 and 10 are perspective view of an alternate embodiment of the
slidable carrier.
DETAILED DESCRIPTION
The power lift system 2 shown in Figure 1 is in an erected position
adjacent the house 1. The power lift system 2 includes one or more vertical
uprights 4, a powered lift platform 6, side stabilizing cables 8 and vertical
standoffs 10. The vertical upright 4 can be stacked one on top of the other by
means of a connector extension 12. In the example shown in Figure 1, there is
a
base vertical upright 10a connected to a second vertical upright 10b. The
intermediate connector 12 extends the vertical uprights and also includes
spigot
portions that are received within each of the vertical uprights to add
stability.
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In an alternate arrangement a connecting spigot is provided at an
upper end of the vertical upright. This spigot receives a base of an upright
whereby a separate intermediate connector is not required. Preferably the
connecting spigot is welded to partially extend from the vertical upright.
In Figure 1, a one tier work platform 18a is shown that is attached
to and moves with the slidable carrier 20. This platform 18 can be used as a
working surface for the workmen and/or to lift material to a desired height.
In Figure 2, the power lift system 2 is shown with two vertical
uprights 4 generally positioned at opposite sides of the work platform 18b.
The
work platform includes hinged or removable sections 19 to allow the work
platform 18b to slide onto the carrier. In the example of Figure 2, two rigid
vertical standoffs 10 are shown in combination with a rigid cross brace member
14 provided between the uprights.
The partial perspective view of Figure 3 shows additional details of
a single vertical upright in this case supporting a two tier work platform
18c.
Also visible in this figure is the intermediate connector 12 joining a base
upright
4a and a first raised upright 4b. The two-tier work platform 18c includes the
first
work surface 21 (suitable as a walk surface for workmen) and a raised or table
work surface 23.
Details of the cooperation between an upright 4 and the slidable
carrier 20 are shown in Figure 4a. The vertical upright 4 includes on a rear
surface thereof the rack 30 for cooperation and engagement with gear 28
associated with the drive gear 26 powered by the motor 27. The gear 28 extends
through the port 29 provided in the slidable carrier 20. The front face of the
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slidable carrier 20 includes an open slot portion 22 that allows the carrier
20 to
slide past various structural members that are used to connect the pole and
stabilize the pole such as the vertical standoffs 10. In this way the slidable
carrier
20 can pass upwardly along the connected uprights and move past any vertical
standoffs 10. The hinged sections 19 of the work platform 18 can be opened to
allow the platform to move past the standoffs 10.
The slidable carrier 20 includes upper carrier bars 40 on opposite
sides of the slide carrier and these will receive and engage structural
members
associated with the work platform or lifting arms. The carrier bars 40 are
provided in pairs with a first pair of carrier bars on one side of the carrier
and a
second pair of carrier bars are provided on an opposite side of the carrier.
The
retaining plates 42 engage of these structural members and retain the
structural
members at the sides of the slidable carrier (see Figure 6). A lower set of
carrier
bars 50 are provided near the base of the slidable carrier 20 and include
retaining
plates 52. Bearings 62 are provided on the rear face of the slidable carrier
20 and
a similar set of bearings 64 are provided on the front face 51 of the slidable
carrier 20. These bearings are located top and bottom of the slidable carrier
and
oppose binding of the slide carrier with the upright member.
In an alternate embodiment the slidable carrier 20 is extended and
side bearings are provided above the upper carrier bars 40 on each side of the
carrier and below the lower carrier bars 50 on each side of the carrier. These
additional bearings counter any side loads that may occur for example due to
non equally distributed loads being lifted. Also this alternate embodiment is
more robust and durable (see Figures 9 and 10).
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The upright 4 as shown in Figure 1 and the cross section of Figure 4b
is tubular and generally of a square Cross section. Similarly the carrier is
elongate
and of a generally square cross section sized to snugly slide along the
upright
The motor 27 is an electric reversible motor that includes its own
brake system. There are various manufacturers of these motors but the motor
locks
when not operating and therefore the carrier is maintained in a fixed location
unless
the motor is operating. One example of a suitable electric motor is sold by
Nord
Gear as UNICASE TM, Helical worm gear box 3hp SIC32-100400LH. This provides a
positive brake mechanism for the slidable carrier 20.
Returning to Figure 4a, in addition to the pairs of upper and lower
carrier bars 40 and 30, the slidable carrier 20 includes a series of
reinforcing wraps
60 that are welded to the slidable carrier. These reinforcing Wraps oppose any
tendency of the carrier to open or spread and thereby increase the size of the
open
slot 22. These wraps provide positive reinforcement that avoids any force
tending
to open the slidable carrier. The reinforcing wraps are typically welded to
the
slidable carrier 20. Similarly, the rack 30 is a separate member as shown in
Figure
4b that has been secured within the vertical upright 4. It is desirable to cut
a slot in
the vertical member and weld the separate rack member 30 into the slot. This
two
part assembly simplifies manufacture of the rack and the upright.
Various ports are provided at the side of the upright members as well
as on the front face for securement of structural members or accessories.
Figure 6 shows securement of the walker arm 70 to the slidable carrier
20. The walker arm 70 includes opposed members 72 and 74 that are spaced to
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closely engage the slidable carrier 20 and to be positioned between the upper
or
lower carrier bars and secured therebetwee.n. A series of tabs 76 include
threaded
ports for effectively securing of the work platform 78 to the walker arms. The
large
open 'CY shaped opening 80 provided between the two members 72 and 74, allow
the walker arm to extend to the front and to the rear of the slidable carrier
20. One
portion of the arms will receive the rear part of the work surface 78 and the
forwardly extending portion of the walker arms, defined by members 72 and 74,
will receive the work surface SO. Note, that work surface 80 includes a
slidable
portion that allows it to be positioned either side of the slidable carrier 20
and
allows movement past standoff members 10.
Pig-u.res 7 and 8 show one particular embodiment where the extension
member 100 includes securing arms 102, 104, having securing hooks 106 and 108.
These securing hooks 106 and 108 can be placed within the ports 110, provided
in
the side of the vertical uprights 4. Two sets of hooks are provided to
opposite sides
of member 100 to allow it to be positioned to either side of the vertical
upright
member. A large pulley 112 is provided at one end of the extension member and
a
rope and hook arrangement passes therethrough and allows a second vertical
member to be drawn up and placed on top of a lower vertical member; this
aspect is
generally shown in Figure 8. This provides a simple mechanism for initially
erecting the desired vertical members one on top of the other and using
appropriate
standoff members and stabilizing cables for securing of the structure. This
extension member 100 is also helpful in taking the system down. An
intermediate
connector has not been shown but would be present to provide the connection
between the upright members or the upright would include an integral spigot.
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Figures 9 and 10 are perspective views of an alternate slidable carrier
120 having a modified arrangement for mounting of the electric motor drive 124
as
well as including side bearings 132, 134, 136 and 138 provided in pairs to
opposite
sides of the slidable carrier. The alternate slidable carrier is in contrast
to the
slidable carrier 20 of the earlier figures that included slide plates provided
on the
sides of the carrier. A slidable carrier with slide plates can be used where
low side
loads are exerted on the slidable carrier the additional bearings 132, 134,
136 and
138 are preferred particular for applications where side loads are higher.
The electric motor drive 124 has a two-way elearical motor 150 in
combination with a transmission drive 152 that drives the drive gear 154 that
is in
mesh with the rack 30 of the vertical upright. The electric motor 150 and
transmission 152 are mounted on a mounting plate 160 that extends to one side
of
the slidable carrier 120 and is secured preferably by welding to the slidable
carrier
on two sides thereof. This provides a strong "L" shaped mounting plate for the
electric motor 150 arid transmission 152 that overlaps with the slidable
carrier. As
can be appreciated due to the extra bearings provided on the alternate
slidable
carrier the length of the carrier has increased.
With the arrangement as shown in Figures 9 and 10, the electric motor
and transmission are provided to one side of the carrier and generally are in
close
proximity and extend in the length of the slidable carrier. This provides a
compact
and space efficient design that is rugged and less subject to damage.
As can be appreciated, the power lift system of the present invention
provides a simple arrangement for raising of various loads to different
elevations
and can quickly be erected and dismantled as required. The components are
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relatively rugged and cost effective to manufacture. The slidable carrier 20
is
adapted to allow for a single level work surface or a multi-level work surface
as
may required for different jobsite applications. For example, some projects
may
have a users walk platform n using the lower carrier bars 50 and a raised or
table type
platform using the upper bars 50 and provided to the rear of the carrier.
The system also allows easy conversion from a one post system to a
two post system or more. This provides versatility as may be required from job
to
job for lifting of different weights and/or applications.
The system is particularly designed for lifting of weights in excess of
2000 lbs. that may be required for certain jobs, particularly masonry or
replacement
window applications.
Although preferred embodiments of the invention, which are
described here in detail, may be understood by those skilled in the art; there
are
variations we have made thereto without departing from the scope of the
appended
claims.
