Tow bar block and tow bar assembly

A spacer block for a tow bar which has a central support having an opening therethrough to receive the tow bar and a plurality of faces disposed around the central support. Each face has a different configuration adapted to conform to the shape of support elements provided on the underside of a vehicle. The faces are connected to the central support by a plurality of webs which absorb impact, forces which would otherwise be transmitted to the automobile by the towing apparatus while the vehicle is being towed.

BACKGROUND OF THE INVENTION 
This invention relates to devices for towing automobiles and other motor 
vehicles and, in particular, to tow bar blocks which are positioned on a 
tow bar to support the vehicle while it is being towed. 
In recent years, automobile manufacturers have recommended various measures 
be taken when towing vehicles to prevent the tow equipment from damaging 
the automobile body or finish. These measures are particularly important 
in cars made from lightweight material or cars having aerodynamic spoilers 
or air dams which can easily be damaged by such equipment during towing. 
One measure recommended is to use a tow bar which consists of an elongated 
four-by-four wooden timber with two inverted U-shaped wooden tow blocks 
slidably mounted on the timber. The blocks are constructed so that they 
present a flat surface on the top of the inverted U. The tow bar 
arrangement described above is used with a standard sling-type crossbar 
towing device. The tow bar is positioned between the sling and the 
automobile undercarriage with the flat surfaces of the spacer blocks 
oriented upwardly to support the automobile. The spacer blocks are 
positioned to engage support elements on the underside of the car provided 
by the manufacturer to bear the weight of the car during towing. If the 
tow bar assembly were not used, the lightweight aerodynamic spoilers, 
bumpers or air dams of some cars would have to bear much of the vehicle's 
weight during towing which, of course, these parts were not designed to 
do. 
Different cars have differently configured towing support elements. A flat 
surfaced tow block is not always satisfactory. The tow blocks can slip 
from or damage the support elements. The wooden tow blocks can also split 
if they are subjected even to moderate impact forces over time. If the 
blocks split or shift, the vehicle can shift while being towed such that 
the parts of the vehicle not designed to bear the weight of the vehicle 
are forced to do so, causing damage to the vehicle. Lastly, the wooden 
blocks are quite rigid and do not provide significant cushioning between 
the vehicle and the tow bar. The resulting shocks transmitted to the 
vehicle through the wooden tow bar blocks may damage the car, too. 
SUMMARY OF THE INVENTION 
The present invention is a tow bar block which includes a central opening 
therethrough adapted to receive a wooden tow bar. A plurality of faces are 
spaced from the central opening facing outwardly with respect thereto. At 
least two faces have a differing configuration adapted to conform to the 
differing configurations of vehicle support elements. 
Alternatively, or possibly in addition thereto, the different faces are 
spaced at different intervals from the central opening to accommodate 
different vehicles. Preferably, the central opening is defined by a 
central support member joined to the faces by a plurality of webs which 
flex to absorb the impact of the tow bar blocks against the vehicle 
support elements. 
Because each face is configured to accommodate a different vehicle, the 
same tow block can be used to tow a variety of different vehicles, 
minimizing the risk of slippage. Furthermore, the differing shapes enhance 
the chances that each face has a shape which is better adapted to receive 
its corresponding support element on the vehicle being towed. This reduces 
the risk that the vehicle will slip from the block. Finally, since the 
webs flex to absorb impact, the vehicle being towed is protected against 
vibration damage. Therefore, the tow bar block of the present invention 
overcomes many of the deficiences of the U-shaped wooden tow bar blocks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Illustrated in FIGS. 1, 4 and 5 is a tow bar assembly 10 employing the 
spacer blocks 12 of the present invention. Each spacer block 12 includes a 
central support 14 having an opening 16 therethrough which slidably 
receives the tow bar 18. Each block 12 also includes four faces 20, 22, 24 
and 26 disposed around and operably connected to central support 14 by a 
plurality of webs 15 which flex to absorb impact forces. Each face has a 
different configuration adapted to conform to the different shapes of 
different vehicle support elements. 
Preferably, the tow bar blocks of the present invention are molded from a 
tough polymeric material to provide the resilience desired in the webs to 
absorb impact. Specifically, an ionomeric material such as that sold by E. 
I. du Pont under the trademark SURLYN is desirable. Such ionomeric 
materials have high impact strength yet permit a certain desired 
flexibility in the webs. Ionomeric materials are also resistant to 
abrasion which is obviously desirable in the spacer blocks of the present 
invention. They also do not scratch automobile paint, chrome and other 
finishes like the wood spacer blocks. 
Pigments can also be added to the SURLYN such that the spacer blocks are a 
bright, visible color such as orange. The spacer bar assembly can be 
placed on the roadside while not in use and serve as a warning for traffic 
when a stranded vehicle is being serviced on the roadside. 
Central support 14 (FIGS. 1 and 2) basically has four walls and a 
rectangular lateral cross section with a large rectangular opening 16 
extending axially through it. Opening 16 is preferably polygonal, square 
or rectangular in cross section as shown in FIGS. 1 and 2 so that it 
conforms to and closely receives tow bar 18, which also has basically the 
same lateral cross-sectional shape. The polygonal cross-sectional shape of 
the opening 16 and tow bar 18 prevents the tow bar block 12 from rotating 
on tow bar 18. The proper faces 22, 24, 26, 28 for towing can be selected 
simply by rotating the entire tow bar assembly about the longitudinal axis 
of tow bar 18. 
As shown in FIG. 2, each face of each spacer block 12 has a different 
configuration. Face 20, for instance, is flat and has a plurality of 
grooves 21 in the surface for gripping the surface of the vehicle support 
element. Face 20 as shown in FIGS. 4 and 5 is used to support a vehicle 
having planar support elements 28 mounted beneath the rear bumper 38 of 
vehicle 30. The distance between the top of face 20 and the tow bar 18 is 
sufficient such that the tow bar will not contact the decorative shroud 40 
positioned underneath bumper 38. 
Face 22, on the other hand, is provided a generally sloping portion 42 
which slopes toward a stop 44 which juts outwardly from face 22. The 
slopping portion 42 of face 22 is designed as shown in FIGS. 6 and 7 to 
support the underside of a bumper 34. Stop 44 extends behind the bumper to 
prevent the tow bar assembly from sliding forwardly and being dislodged 
from underneath the bumper. 
Face 24 is similar to face 20 inasmuch as it is planar. However, it does 
not have the gripping surface and is not positioned quite as far from tow 
bar 18 as is face 20. This differential spacing allows blocks 12 to 
accommodate different vehicles having different clearance distances below 
the vehicle support elements. 
Face 26 also has a configuration different from the other faces inasmuch as 
it is provided with a depression 60 which can be used to support the 
bottom of a rounded bumper so as to prevent it from being scratched by the 
towing equipment. The tow bar assembly can also be positioned such that 
depression 60 engages a rounded chassis member underneath the front or 
rear of a vehicle to avoid having a bumper support the weight of the car. 
Depression 60 can also engage the rear axle of a vehicle with the tow bar 
assembly 10 positioned parallel to and beneath the axle to prevent tow 
chains from damaging or being tangled with the vehicle's exhaust system. 
Faces 20, 22, 24 and 26 extend in a continuous band around central support 
14 and are connected thereto by a series of flexible webs 15. Webs 15 
include a central web 62 which lies on a plane perpendicular to the axis 
of opening 16, extends outwardly from central support 14, and connects 
with each of the faces. Lying on planes perpendicular to central web 62 
and on either side thereof are a plurality of lateral webs 64 which 
reinforce the assembly. 
This combination of lateral webs and the central web adds structural 
integrity to the spacer block while absorbing impact forces. If central 
web 62 were not provided, for instance, there might be too much flex in 
webs 64 which would allow the faces to rock perpendicularly with respect 
to tow bar 18 when an automobile is carried on one of the faces. 
Similarly, if only a central web 62 were included, the faces would have a 
tendency to rock from side to side parallel to the tow bar. The integral 
structural entity formed by the perpendicular webs 62 and 64 prevents the 
faces from moving or wobbling laterally either parallel or perpendicular 
to the tow bar under load. However, the structure has sufficient 
flexibility such that it absorbs much of the impact transmitted to the 
automobile from the towing apparatus. 
In use, the T-hook sling chains 66 of the sling tow assembly 32 are 
connected to the frame of the car at the end of the car to be lifted 
during towing. Two tow blocks 12 are slid over the ends of tow bar 18, a 
wooden four-by-four timber. Tow bar 18 is placed across sling chains 66 
with the appropriate faces of the tow bar blocks oriented upwardly to 
register with the correspondingly configured support surfaces of the 
support elements (support elements 28 or 34 in the case of FIGS. 4 or 6). 
Planar face 20, for instance, on each of the two spacer blocks 12 on the 
tow bar is positioned face up to engage one of the planar support elements 
28 of vehicle 30 (FIGS. 4 and 5). Vehicle 30 can then be towed as shown in 
FIG. 4 with the tow bar assembly 10 supporting it, by a conventional 
sling-type tow assembly 32. Vehicles with support elements having 
different configurations can be towed with the same tow bar assembly 
simply by rotating the tow bar assembly from the position shown in FIG. 4 
so that a face having the appropriate shape is presented to the support 
elements, as shown in FIGS. 6 and 7 where faces 22 are used to engage 
correspondingly configured bumper 34. 
As used in this specification, the term "support elements" designates not 
only the type of support element 28 shown in FIGS. 4 and 5, but also 
elements such as axles, control arms and bumpers which can support the 
vehicle's weight without damage. Tow bar blocks 12 are then slidably 
positioned laterally along tow bar 18 such that as the tow bar assembly 10 
is moved upwardly, the tow bar block faces selected will register with the 
support elements (28 or 34) of the automobile. 
Crossbar 68 of the sling tow assembly 32 is then positioned against the 
front of the tow bar 18. If spacer blocks 12 are spacedly positioned 
sufficiently close together, the crossbar 68 may, in fact, contact the 
forward or lower portions of tow bar blocks 12 as shown in FIG. 7. 
The safety chains 70 are then attached around the front or rear axles of 
the car, depending, of course, on which end is being towed. The sling tow 
assembly can then be raised such that the appropriate faces of the spacer 
blocks contact the support elements with the tow bar assembly positioned 
between the T-hook chains 66 and the car body. 
The tow bar assembly of the present invention can be used to tow severely 
damaged vehicles. Specifically, the tow bar assembly can be positioned 
underneath the damaged vehicle to get a higher lift than would otherwise 
be possible without it by orienting face 20 upwardly. The extra lift 
provided by the tow bar assembly may make it possible to tow a vehicle 
having a severely bent frame which would cause the vehicle to drag while 
being towed without the tow bar assembly. Furthermore, grooves 21 afford a 
secure lift of a damaged vehicle. The use of the tow bar assembly 
illustrated on the vehicle 46 shown in FIGS. 6 and 7 is to protect the air 
dam 48 of vehicle 46. The T-hook chains 66 can be positioned underneath 
the spacer blocks 12 or tow bar 18 out of contact with sheet metal air dam 
48. Similarly, the crossbar 68 of sling assembly 32 can be positioned 
against the lower portions of spacer blocks 12 as shown in FIGS. 6 and 7. 
If the tow bar assembly 10 were not used on vehicle 46 when towing it by 
the front bumper as is customary with the type of vehicle shown, the 
T-hook chains 66 would scrape against the bottom of air dam 48, scratch 
its finish and very likely bend it out of shape. Likewise, crossbar 68 
would be placed against the bumper scratching the chrome. The tow bar 
assembly using blocks 12 of the present invention not only prevents such 
damage, but it will stay in the protective position shown in FIGS. 6 and 7 
by the engagement of stops 44 with the rear side of the front bumper 34. 
Using a tow bar assembly with the novel spacer blocks of the present 
invention, destructive contact between any of the towing equipment and 
bodies, fenders or bumpers of the car can be avoided. In fact, in many 
cases the only contact between the towing equipment and the car occurs at 
the spacer block faces and the ends of the T-hook chains and safety 
chains, none of which are in contact with parts of the car which are 
likely to be damaged by towing equipment. 
While one form of the invention has been shown and described, other forms 
will be apparent to those skilled in the art. Therefore, it will be 
understood that the embodiment shown in the drawings and described above 
is merely for illustrative purposes and is not intended to limit the scope 
of the invention which is defined by the claims which follow.