Note: Descriptions are shown in the official language in which they were submitted.
CA 02958442 2017-02-20
POWERED TRAILER MOVING DEVICE
Description
FIELD OF THE INVENTION
The present invention relates to a device for moving an un-powered vehicle
hereinafter
referred to as a trailer, when the trailer is not attached to a tow vehicle.
The present
invention is especially advantageous in a situation where a trailer is to be
moved into or
out of a parking space where obstructions or other constraints would impede or
prohibit
the use of a tow vehicle. A further advantage of the present invention is the
ability to
move the trailer into or out of a parking space with improved control and
accuracy as
compared to moving the trailer by means of an attached tow vehicle.
BACKGROUND OF THE INVENTION
In the prior art, Canadian Patent application CA 2964253, Donald Banwart, laid
open
March 26, 2015, describes a self-powered converter dolly, and further
references a
number of related prior art patents. These patents are specific to
applications involving
commercial fifth wheel "semi" trailers and involve mechanisms and devices
specific to
that application. Other known powered trailer dollies are referenced below.
Historically, utility trailers and camping trailers which are too heavy to be
moved by
hand require the use of a tow vehicle while being parked or maneuvered at low
speed
from one place to another. Backing a trailer by means of a tow vehicle is
particularly
difficult due to the articulation of the trailer with respect to the tow
vehicle combined with
limited visibility from the driver's seat in a tow vehicle. A second person is
often
required to provide signals to the driver in order to back a trailer safely.
One solution for
smaller trailers is a non-powered two-wheeled trailer dolly with a hitch ball
mounted so
as to transmit the tongue weight of the trailer to the ground via the dolly
tires. An
elongate handle on the dolly facilitates steering and applying motive force by
hand. A
1
CA 02958442 2017-02-20
manual dolly requires significant strength on the part of the person moving
the trailer
and is limited to smooth, level rolling surfaces and limited trailer weights_
It is common
for RV dealers to use a forklift to pick up the tongue of a trailer and make
use of the
power and maneuverability of a forklift to move a trailer to a desired
location. Another
solution for some trailer owners is to mount a hitch ball onto a small off-
road vehicle,
commonly called a "quad", for the purpose of moving a trailer to a desired
location.
However both the forklift and quad methods are not useful when the trailer is
to be
parked at a remote location without access to these machines, for example when
parking a camping trailer in a small campsite, or when parking a utility
trailer for loading
or unloading in a constrained space. A known powered two-wheeled dolly design
incorporates a threaded collar below the hitch ball wherein the collar is
tightened
against the underside of the trailer coupler in order to prevent the dolly
from tilting due
to the driving force of the dolly's wheels. A moment is generated by the
driving force of
the dolly's wheels and the resistance to movement of the trailer transmitted
though the
hitch ball. Because of the narrow width of the coupler and the much larger
distance of
the hitch ball from the ground, the resistive forces between the coupler and
the
threaded collar are very large compared to the driving force of the dolly's
wheels,
perhaps by a factor of 10 or more. Furthermore, the resistive force against
the coupler
is vertically upward tending to lift the trailer coupler off of the hitch
ball. Trailer couplers
are designed to accept large forces in a horizontal direction and downward
forces due
to the tongue weight of the trailer, but uplift is resisted only by a
mechanical latch
designed only to prevent inadvertent disconnection of the trailer. As a
result, when
moving a heavy trailer up a slope or on uneven terrain, it is possible that
the coupler
could be damaged, or the hitch ball could pull out of the coupler. Another
known
powered dolly design includes additional idler wheels or casters to resist the
above
described moment. However, the force on the idler wheels is vertical and
consequently
reduces the amount of weight on the driving wheels of the powered dolly and
therefore
reduces the ability of the dolly to move a heavy trailer against a slope or
obstacle.
There exists a need for a practical and portable means for moving trailers
into and out
of parking spaces.
2
CA 02958442 2017-02-20
SUMMARY OF THE INVENTION
It is an object of this invention to provide an apparatus for moving a non-
powered
vehicle with the following advantages over prior art:
a) To provide a powered drive means whereby a trailer may be maneuvered
without
being connected to a tow vehicle.
b) To provide a portable powered trailer dolly with a connection to the
trailer whereby
the motive forces are resolved with an adequate safety factor.
c) To provide a powered drive means whereby a trailer can be safely maneuvered
by
one person.
d) To provide a powered drive means integrally mounted to a trailer so as to
be
available for use at any location with minimal set-up effort.
The apparatus for moving a non-powered vehicle comprises:
A trailer with at least two wheels and two tires,
A motor,
At least two drive wheels,
At least one drive mechanism connecting the motor to at least one of the drive
wheels,
A frame,
A control means.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the present invention will be better understood
by
reference to the accompanying drawings, wherein:
3
CA 02958442 2017-02-20
Fig. 1 depicts a plan view of a trailer with a portable powered dolly attached
to the
trailer.
Fig. 2 depicts a side elevation of a trailer with a portable powered dolly
attached to the
trailer.
Fig. 3 depicts a plan view of a portable powered dolly attached in an
articulated position
to a trailer.
Fig. 4 depicts a side elevation of a portable powered dolly attached to a
trailer at a
larger scale.
Fig. 5 depicts a plan view of a portable powered dolly attached to a trailer
at a larger
scale.
Fig. 6 depicts a side elevation of a trailer, partially cut away, with an
integral drive
mechanism mounted to the trailer frame.
Fig. 7 depicts a plan view of a trailer frame with an integral drive mechanism
mounted
to the trailer frame.
Fig. 8 depicts an end elevation of an integral drive mechanism mounted to the
trailer
frame.
Fig. 9 depicts a drive arrangement of an integral drive mechanism mounted to a
trailer
frame where the drive mechanism is in a driving position.
Fig. 10 depicts a drive arrangement of an integral drive mechanism mounted to
a trailer
frame where the drive mechanism is in a towing position.
Fig. 11 depicts a plan view of a dual drive arrangement.
Fig. 12 depicts an end elevation of a dual drive arrangement.
Fig. 13 depicts a plan view of an alternative dual drive arrangement.
Fig. 14 depicts a side elevation of an alternative dual drive arrangement
where the drive
mechanism is in a driving position.
4
CA 02958442 2017-02-20
Fig. 15 depicts a side elevation of an alternative dual drive arrangement
where the drive
mechanism is in a towing position.
Fig. 16 depicts a plan view of an alternative pivot geometry wherein the drive
mechanism is in a driving position.
Fig. 17 depicts a plan view of an alternative pivot geometry wherein the drive
mechanism is in a towing position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in Figs. 1 and 2, according to a first preferred embodiment of the
present
invention, a trailer 10 is connected to a powered dolly 12 resembling a
conventional
two-wheeled trailer dolly with the addition of a drive means and a clamp
device 14. In
Fig. 3, the powered dolly 12 is shown in a position to steer the trailer 10 in
a curved
path. The Clamp device 14 remains in line with the longitudinal axis 16 of the
trailer 10.
A differential 18 incorporated into the drive means of the powered dolly 12
allows the
powered dolly 12 to be rotated about the hitch ball 20 without requiring the
drive wheels
22 to slip on the roadway surface. As shown in Fig. 4, one end of clamp device
14 is
rigidly connected to the trailer jack stub shaft 24, while the opposite end of
clamp device
14 is mounted via two bearings 26 onto hitch ball support shaft 28. It can be
seen that
Dim. B is approximately twice Dim. A. By considering the forces and moments
applied
by the driving of the drive wheels 22, it can be further deduced that the
motive force of
powered dolly 12 against trailer 10 is resolved through the clamp device 14
and hitch
ball 20 wherein the lateral force at the hitch ball 20 is in a horizontal
direction and
approximately double the horizontal force at the dolly axle 30, and the
horizontal force
at the clamp device 14 is in the opposite horizontal direction and
approximately triple
the horizontal force at the dolly axle 30. With proper mechanical design
applied to the
above described geometry, the connection between powered dolly 12 and trailer
10 can
be made very strong and reliable. The trailer coupler 32 is designed to accept
large
forces in a horizontal direction so there is no risk of the coupler 32 being
damaged or
disengaging from the hitch ball 20 while the trailer 10 is being moved by
powered dolly
5
CA 02958442 2017-02-20
12. As shown in Fig. 5, the arrangement of the powered dolly 12 components
includes
a motor 34, drive chains and sprockets 36, a drive shaft 38 on which is
mounted a
differential 18. The motor 34 comprises an electric motor which may be powered
from
the trailer battery, or alternatively from a source of electric power
independent from the
trailer. A control switch 40 is mounted onto elongate handle 42. It should be
noted that
this first embodiment of the present invention is not suitable for use with a
"fifth wheel"
style of trailer 10. Another limitation to this first embodiment of the
present invention is
the need to transport the apparatus separately from the trailer 10 for use at
remote
locations.
In a second preferred embodiment of the present invention as shown in Figs. 6
and 7,
drive wheels 22 are in tangential contact with trailer tires 46 and the drive
wheels 22 are
held against the trailer tires 46 by means of linear actuators 48. The linear
actuators 48
comprise commercially available electric screw actuators, or alternatively
hydraulic or
air cylinders, or air diaphragm pots. Drive wheels 22 are fixed onto drive
shaft 50.
Drive shaft 50 is pivotally connected to the trailer frame 52 via pivot arm
54, drive shaft
bearing 53, and pivot bearing 56. The tongue weight of the trailer 10 is
supported by
swivel caster 58 which is mounted onto the trailer jack stub shaft 24. When
both drive
wheels 22 are held in contact with their respective trailer tires 46, and the
drive shaft 50
is caused to rotate by motor 60, the trailer 10 moves forward or backward in a
straight
line. When only one drive wheel 22 is held in contact with its respective
trailer tire 46 by
its respective linear actuator 48, and the opposite drive wheel 22 is
disengaged from
contact with its respective trailer tire 46 by its respective linear actuator
48, and an
electric brake 62 is applied on the same side of the trailer 10 as the
disengaged drive
wheel 22, and the drive shaft 50 is caused to rotate by motor 34, the trailer
10 will be
caused to turn on an arc approximately centered on the trailer tire 46 on the
same side
of trailer 10 as the electric brake 62 is applied. The swivel caster 58
rotates accordingly
in response to the turning of the trailer 10. The trailer 10 can therefore be
maneuvered
and steered controllably by selective engagement and disengagement of a drive
wheel
22 by partially retracting its respective linear actuator 48, and by selective
application of
6
CA 02958442 2017-02-20
the respective electric brake 62. As shown in Fig.8, drive base 64 is
supported from the
drive shaft 50 via self-aligning bearings 66 and from parallel arms 68.
Parallel arms 68
are supported from cross bar 70 which is fixed to trailer frame 52. In Fig.9
it is seen
that drive base 64 is located by the position of drive shaft 50 which is
determined by the
extended state of linear actuators 48 (refer to Fig.6). Parallel arms 68
support the end
of the drive base 64 opposite from the drive shaft 50 and prevent the drive
base 64
from rotating about the drive shaft 50. In Fig.10 it is seen that drive base
64 is located
by the position of drive shaft 50 which is determined by the retracted state
of linear
actuators 48 (refer to Fig.6). Parallel arms 68 support the end of the drive
base 64
opposite from the drive shaft 50 and hold the drive base 64 in a retracted
position which
would be the normal position of the drive base 64 when the apparatus of the
present
invention is not being used to move the trailer 10. The motor 34 comprises an
electric
motor which may be powered from the trailer battery, or alternatively from a
source of
electric power independent from the trailer. The motor 34 may comprise a
hydraulic
motor powered from a hydraulic pump on board the trailer. The motor 34 may
comprise
an internal combustion motor. The control means (not illustrated) includes a
minimum
of forward-stop-reverse, and left-straight-right switch positions. The control
means may
include wireless communication means, and may include sophisticated logic in
order to
translate the operator's inputs into the desired motion of the trailer. The
control means
may further include a means to prevent towing the trailer 10 while the
mechanisms of
the present invention are not in the correct state for towing.
In a third preferred embodiment of the present invention, the features and
functions are
as described for the second preferred embodiment, except a differential 18 is
incorporated into the drive shaft 50 to allow the trailer 10 to turn by
selectively applying
a trailer brake 62 without disengaging a drive wheel 22 from contact with a
respective
trailer tire 46.
In a fourth preferred embodiment of the present invention, as shown in Figs.
11 and 12,
two drive wheels 22 are each independently driven by a complete drive assembly
7
CA 02958442 2017-02-20
comprising one drive wheel 22 fixed onto one drive shaft 50, one driven
sprocket 78
fixed to drive shaft 50, one drive base 64 and one motor 34. Drive shafts 50
are
pivotally connected to the trailer frame 52 via pivot arm 54 drive shaft
bearing 53 and
pivot bearing 56. When both drive wheels 22 are held in contact with their
respective
trailer tires 46 by linear actuators 48, and both drive shafts 50 are caused
to rotate by
motor 34, the trailer 10 moves forward or backward in a straight line. When
one motor
34 is stopped while the other motor 34 is running, the trailer 10 is caused to
turn on an
arc approximately centered on the trailer tire 46 on the same side of trailer
10 as the
motor 34 is stopped. Furthermore it can be deduced that any difference in
speed
between the two motors 34 will cause the trailer 10 to turn in an arc. If one
motor 34 is
reversed while the other motor 34 is running, the trailer can be caused to
rotate about
an axis approximately centered between the trailer tires 46. The swivel caster
58
rotates accordingly in response to the turning of the trailer 10. The trailer
10 can
therefore be maneuvered and steered controllably by selectively starting,
stopping,
reversing or varying the speed of the motors 34. Drive base 64 is supported
from the
drive shaft 50 via self-aligning bearings 66 and from parallel arms 68.
Parallel arms 68
are supported from cross bar 70 which is fixed to trailer frame 52. Drive
shaft 50 is
supported from pivot arms 54 via pivot bearings 56. In Fig.9 it is seen that
drive base
64 is located by the position of drive shaft 50 which is determined by the
extended state
of linear actuators 48 (refer to Fig.6). Parallel arms 68 support the end of
the drive
base 64 opposite from the drive shaft 50 and prevent the drive base 64 from
rotating
about the drive shaft 50. In Fig.10 it is seen that drive base 64 is located
by the
position of drive shaft 50 which is determined by the retracted state of
linear actuators
48 (refer to Fig.6). Parallel arms 68 support the end of the drive base 64
opposite from
the drive shaft 50 and hold the drive base 64 in a retracted position which
would be the
normal position of the drive base 64 when the apparatus of the present
invention is not
being used to move the trailer 10. The linear actuators 48 comprise
commercially
available electric screw actuators, or alternatively hydraulic or air
cylinders, or air
diaphragm pots. The motor 34 comprises an electric motor which may be powered
from the trailer battery, or alternatively from a source of electric power
independent from
the trailer. The motor 34 may comprise a hydraulic motor powered from a
hydraulic
8
CA 02958442 2017-02-20
pump on board the trailer. The motor 34 may comprise an internal combustion
motor.
The control means (not illustrated) includes a minimum of forward-stop-
reverse, and
left-straight-right switch positions. The control means may include wireless
communication means, and may include sophisticated logic in order to translate
the
operator's inputs into the desired motion of the trailer. The control means
may further
include a means to prevent towing the trailer 10 while the mechanisms of the
present
invention are not in the correct state for towing.
In a fifth preferred embodiment of the present invention, as shown in Figs.
13, 14 and
15, two drive wheels 22 are each independently driven by a drive assembly
comprising
one drive wheel 22 fixed directly onto the output shaft of a speed reducer 76,
and one
motor 34. The drive assembly is pivotally connected to the trailer frame 52
via pivot
arm 54, two pivot bearings 56, and pivot pin 78. When both drive wheels 22 are
held in
contact with their respective trailer tires 46 by linear actuators 48, and
both drive wheels
22 are caused to rotate by respective motors 34, the trailer 10 (refer to Fig.
6) moves
forward or backward in a straight line. When one motor 34 is stopped while the
other
motor 34 is running, the trailer 10 is caused to turn on an arc approximately
centered on
the trailer tire 46 on the same side of trailer 10 as the motor 34 is stopped.
Furthermore
it can be deduced that any difference in speed between the two motors 34 will
cause
the trailer 10 to turn in an arc. If one motor 34 is reversed while the other
motor 34 is
running, the trailer can be caused to rotate about an axis approximately
centered
between the trailer tires 46. The swivel caster 58 (refer to Fig. 6) rotates
accordingly in
response to the turning of the trailer 10. The trailer 10 can therefore be
maneuvered
and steered controllably by selectively starting, stopping, reversing or
varying the speed
of the motors 34. In Fig.14 it is seen that drive wheel 22 is located by the
extended
state of linear actuator 48 so that the drive wheel 22 is engaged in a driving
position, in
tangential contact with the trailer tire 46. In Fig.15 it is seen that drive
wheel 22 is
located by the retracted state of linear actuator 48 which would be the normal
position
of the drive wheel 22 when the apparatus of the present invention is not being
used to
move the trailer 10. The linear actuators 48 comprise commercially available
electric
9
CA 02958442 2017-02-20
screw actuators, or alternatively hydraulic or air cylinders, or air diaphragm
pots. The
motor 34 comprises an electric motor which may be powered from the trailer
battery, or
alternatively from a source of electric power independent from the trailer.
The motor 34
may comprise a hydraulic motor powered from a hydraulic pump on board the
trailer.
The control means (not illustrated) includes a minimum of forward-stop-
reverse, and
left-straight-right switch positions. The control means may include wireless
communication means, and may include sophisticated logic in order to translate
the
operator's inputs into the desired motion of the trailer. The control means
may further
include a means to prevent towing the trailer 10 while the mechanisms of the
present
invention are not in the correct state for towing. Figs. 16 and 17 depict an
alternative
pivot geometry for the drive assembly of this fifth preferred embodiment of
the present
invention wherein the pivot pin 78 axis is approximately vertical. In Fig.16
it is seen that
drive wheel 22 is located by the extended state of linear actuator 48 so that
the drive
wheel 22 is engaged in a driving position, in tangential contact with the
trailer tire 46. In
Fig.17 it is seen that drive wheel 22 is located by the retracted state of
linear actuator
48 which would be the normal position of the drive wheel 22 when the apparatus
of the
present invention is not being used to move the trailer 10.
As will be apparent to those skilled in the art in the light of the foregoing
disclosure,
many alterations and modifications are possible in the practice of this
invention without
departing from the spirit or scope thereof. Accordingly, the scope of the
invention is to
be construed in accordance with the substance defined by the following claims.
