Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to equipment for towing
automobiles and the like.
Various devices are known for use on a tow truck for
towing a vehicle raised by its front or rear end. In particular,
devices are known wherein a palr of L-shaped arms extend from a
transverse boom mounted to a longitudinal boom or "stinger"
extending from the back of a tow truck, the whole of which may be
elevated to lift the towed vehicle. The L.-shaped arms provide
cradles for the front or rear wheels of a disabled vehicle. A
device such as this may be adaptable to a range of vehicle track
widths and wheel sizes, and desirably should be capable of rapid
engagement with the vehicle to be towed and be of a sufficiently
low profile so as to enable its use even with vehicles having low
ground clearance.
It is an objec-t of this invention to provide an improved
device that affords efficient and secure towing.
The present invention is a vehicle towing device
comprising: an elongate stinger adapted for pivotal attachment at
one end to a towing vehicle to extend generally rearwardly of the
towing vehicle; a rigid transverse bar that is fixed to extend
horizontally at the other end of the stinger, said transverse bar
carrying at each end a rearwardly directed wedge shaped scuff
plate extending along the rear lower edge of the transverse bar;
a respective mounting element being associated with each end of
the transverse bar, each mounting element being pivotable: about a
first axis that is parallel to the length of the transverse bar
and is located in front of the bar; and about a second axis at
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rlght ang]es to said first axis, the mounting element extending
rearwardly from said first axis to be supported in bearing
engagement with the upper side of said transverse bar; a pair of
elongate retaining arms each carried by one said mounting element
and comprising an elongate shank extending generally perpendicular
to said second axis, said shank terminating in a wheel-engaging
portion extending laterally of the shank; the arrangement being
such that in use the stinger can be lowered to position said scuff
plates close to the ground, and then moved rearwardly to bring
said scuff plates into engagement with the wheels of a vehicle to
be towed, whereupon each said mounting element can be pivoted
about its second axis to swing the wheel engaging portion of the
associated retaining arm into engagement behind the corresponding
vehicle wheel such that the latter is cradled between such wheel
engaging portion and the opposed scuff plate whereupon the -towing
device can be raised to lift the wheels and thus the end of the
vehicle to be towed, the weight of the vehicle thus supported
acting to urge the mounting element into engagement with the upper
surface of the transverse bar. In use, each retaining arm grips
the wheel of the towed vehicle in co-operation with the scuff
plate mounted on the rear of the associated end of the transverse
bar. Undesired movement of the retaining arms is prevented by the
weight of the vehicle causing each mounting element to bear down
on the corresponding top surface portion of the transverse bar.
Preferably each of said mounting elements is arranged to
be slidable lengthwlse of the transverse so as to enable
adjustment of the device to vehicles of different track widths.
Desirably each of the retaining arms can slide longitudinally
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within each of t~e mounting elements to adjust to different wheel
sizes. The retaining arm can be fixed in any of a multiplicity
of positions within said moun-ting element by a cotter pin
arrangement.
The present invention will be more fully understood
from the drawings and the following description in which speci:Eic
embodiments are illustrated by way of example and in which:
Figure 1 is a fragmentary perspective view of a vehicle
towing device according to the present invention a-ttached to a
towing truck;
Figure 2 is a plan view of the towing device of Figure
1 ;
Figure 3 is a fragmentary perspective view of one side
of the towing device;
Figure 4 is a rear perspective view of the towing
device, certain parts being omitted for reasons of clarity;
Figure 5 is a somewhat schematic longitudinal section
showing the towing device in operation; and
Figure 6 is an end view of a portion of the towing
device shown to enlarge the scale.
A tow truck 1 includes a flat bed 2 and a crane 3
projecting therefrom. A projecting stinger 4 is pivotally mounted
to the rear of the truck and is adapted to be moved in a vertical
plane. The stinger 4 is comprised of a forward portion 5 and a
rear portion 6. Forward portion 5 comprises two laterally spaced
beams having a pair of spaced horizontal rigid plates 7 extending
rearwardly therefrom. Rear portion 6 is pivotally mounted on a
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vertically arranged pin 7a carried between the plates 7 and is
adapted to pivot in a horizontal plane in relation thereto. As is
best shown in Figure 4, the square beams of the forward portion 5
are slidable longitudinally within a corresponding pair of square
section sleeves 5a which are carried on a bracke-t 5b attached to
the lower end of a generally vertically arranged beam 5c~
Movement of the bea~s 5 within the sleeves 5a is controlled by a
hydraulic cylinder assembly 5d connected between the bracket 5b
and the rigid plates 7. It will be appreciated that by
appropriate extension or retraction movement of the hydraulic
cylinder assembly 5d, the rear portion 6 of the stinger can be
moved horizontally relative to the lower end of the ver-tical beam
5c. The upper end o the beam 5c is attached to a pivotal
mounting 5e on the rear portion of the boom of the crane 3 so that
the towing device extends generally downwardly from this pivotal
mounting.
The vertical beam 5c extends within a large notched
cut-out 38 formed in the rear portion of the tow truck 1 as is
best seen in ~igures 1 and 5. The frame structure of the tow
truck is modified to enable the vertical beam 5c to be positioned
relatively close to the axi~ 34 of the rear truck wheels. The
forwardly facing side of the vertical beam 5c is in sliding
engagement with a roller slide plate 35 carried in a pivotal
mounting 36 in the frame of the truck to pivot about a transverse
horizontal axis. A hydraulic ram 3a mounted on the rear of the
truck has a pivotal connection to a rear portion of the crane boom
3 and can be extended or retracted to raise or lower the vehicle
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towing device as required. It will be appreciated that during
such raising and lowering movement, the vertical beam 5c will
slide in contact with the roller slide plate 35, being held
against this by the weight of the towing dev:ice and of any load
supported thereon.
A cross member is fixedly attached to the rear portion 6
of the stinger 4 and is mounted transverse thereto by a rigid
support plate 9 of generally triangular shape. A -transverse bar
10 extends over the entire length of the cross member. Outwardly
of each lateral side of the support plate 9 the transverse bar 10
has a scuff plate 11 fixedly attached to its rear margin and
pro~ecting rearwardly therefrom. The scuff plate 11 is oriented
parallel to the transverse bar 10 and includes a wedge shaped
portion 12 adapted to engage beneath the wheel of a -towed vehicle.
The scuff plate 11 also includes a flat top surface that is
aligned with -the top surface 13 of the transverse bar 10.
An end plate 14 is fixedly mounted to the outboard end
of the transverse bar 10 in a vertical plane and transverse
thereto. The end plate 14 extends beyond the front and rear
margins of the transverse bar 10.
A pivot bar 15 co-extensive with the scuff plate 11 is
in spaced apart and parallel relationship on the front side of
the transverse bar 10. The pivot bar 15 is mounted by attachment
of its opposite ends one in end plate 14 and the other in a
mounting plate 16 carried on the bar 10. A sleeve 17 encloses
the pivot bar 15 and is angularly and axially movable wi-th respect
thereto. A tubular mount 18 is pivotally attached to the sleeve
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17 by means of an attachment pin l9 carried on -the sleeve 17 with
its axis at right angles to the pivot bar 150 The mount 18 is
thus adapted to pivot about two mutually perpendicular axes and,
as will be explained later, is adapted to rest upon the top
surface 13 of cross member and of the scuff plate when the devlce
is in use.
A s~uare-sec-tion wheel retaining arm 20 passes through
a similarly shaped socket 21 in the mount 18 and is slidable
longitudinally therein. The wheel retaining arm 20 can be fixedly
positioned within the socket 21 by means of a pin 22 that engages
aligned holes extending through the socket 21 and a selected one
of a series of corresponding holes 24 through the wheel retaining
arm 20. The arm 20 comprises a shank 25 the distal end of which
is angled downwardly and carries and a wheel retainer 26 mounted
at right angles thereto. The wheel retainer 26 is adaptea to
engage the wheel of a towed vehicle and comprises a rigid bracket
having a transversely extending wedge-shaped portion 27 which in
the operative position confronts the scuff plate ll as seen in
Figure 2.
In use, the wheel retaining arms 20 are adjusted in
position laterally of the bar lO to match the track width of the
vehicle to be towed by sliding the sleeve 17 carrying the mount
18 to an appropriate location along the pivot bar 15. The crane
3 then lowers the device to position the scuff plates ll on the
ground. The wheel retaining arms are swung outwardly to the
position shown in Figure 3 to clear the wheel 30 of the vehicle
and the towing device is pushed backward by the tow truck and/or
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by extension of the cylinder assembly 5d until the scuff plates
11 contact -the front surface of the respective wheel 30 of the
towed vehicle. The wheel retaining arms 20 are then pivoted
inwardly about the pins 19 so as to bring their wedge-shaped
portions 27 behind the w~eels of the towed vehicle. The extension
of each wheel retaining arm 20 is then adjusted ~by withdrawing
the pin 22 and retracting the wheel retaining arm 20)
until the wheel retainer wedge shaped portion 27 contacts or at
least is closely adjacent the rear surface of the wheel 30 of the
towed vehicle, cupping the wheel 30 between the retainer portion
27 and the scuff plate 11. The pins 22 are then replaced 80 as to
prevent further longitudinal movement of the arms and lock -them in
posit iOIl,
The crane 3 can now be lifted to elevate the device, so
that the end of the towed vehicle is lifted by its wheels. The
weight of the towed vehicle bears down on the wheel retaining
arms 20, which in turn causes the mounts 18 to bear down on the
top surface of transverse bar 10 and thereby prevents unwanted
pivotal movement of the retainer arms 20. It will be seen that
such unwanted movement of the wheel retaining arms 20 is prevented
by a combination of downward pressure of the mounting elements on
the transverse bar 18 and upward pressure of the sleeves 17 on the
pivot bars 15.
An additional feature of the preferred embodiment is a
stop means 31, illustrated in Figure 1. The stop means 31 com-
prises a rigid bracket of inverted L-shape having a horizontal
limb 33 fixedly a-ttached to the top of a vertically-positioned
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limb 32. The bracket 3l is removably engaged in a socket 34 fixed
to the mount 15. In use, the stop means bracket 31 may be removed
when the towing device is being positioned under a towed vehicle
and may be replaced when the vehicle has been engaged by the
towing device. The horizontaL limb 33 rests against the front
surface of the wheel 30 of a towed vehicle and prevents
sudden forward movement of the towed vehicle relative to the
towing device during emergency stops.
The construction of the stinger 4 utilizing dual beams
sliding in the square sleeves under the control of the cylinder
,.`~ .` ,~cl
is of particular importance since this arrangement enables the
overall height of the stinger assembly (and hence of the towing
device) to be reduced. This is of importance in view of the
minimal ground clearance afforded in some models of automobiles.
With this construction the height of the stinger 4 amounts to
approximately 4.5 inches, whereas in conventional towing devices
the singer height is of the order of 6 inches or more.
The location of the pivot pin 7a between the stinger 4
and the transverse bar 10 is also important. This spacing in the
embodiment shown is approximately 12 inches which enables the
transverse bar to pivot through substantially 90 to either side
without interfering with the stinger.
Various other modifications and arrangements of the
present invention may occur to those skilled in the art.
Therefore, it is not desired that the invention be limited to the
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specific details illustrated and described above, and it is
intended that the appended claims cover all modifications and
applications which fall within the spirit and scope of the present
invention.
