Rotating wedge for blocking up the dumping platform of a truck in dumping position

A pivoted wedge for blocking up the dumping platform of a truck in dumping position. The wedge comprises a main body in which are rotatably mounted a pair of driven rollers designed for riding on the frame of the truck and allowing translation of the body along the frame, and a driving roller designed for riding on the frame of the dumping platform. The driving roller which forms part of the wedge, positively engages the driven rollers and rotates them in the opposite direction towards the junction between the frame of the truck and the frame of the platform when the dumping platform is moving down, thus causing movement of the wedge towards said junction and self-blocking of the platform in dumping position. This wedge which automatically blocks up to the platform of a truck in dumping position in the case of failure of the hydraulic mechanism used for rising up the platform, can advantageously be used as safety device by a mechanic who has to work under the platform of a dumping truck.

The present invention relates to a pivoted wedge that can be used as a 
safety device for blocking up the dumping platform of a truck in dumping 
position. 
More particularly, the present invention relates to a pivoted wedge that 
automatically blocks up the platform of the dumping truck in dumping 
position in the case of failure of the hydraulic mechanism used for rising 
up the platform and thus advantageously allows a mechanic to work under 
the platform of the dumping truck without risk of being crushed. 
It is well known that numerous accidents have been caused in garages by 
accidental fall of a dumping platform over the frame of a dumping truck 
because of failure of the hydraulic mechanism used for rising up the 
platform, while a mechanic was working under the platform. 
A few devices have already been proposed for blocking up the platform of a 
truck in dumping position and thus avoiding or at least reducing such 
accidents. For example, U.S. Pat. No. 2,427,381 issued on Sept. 16, 1947 
discloses a chock for dumped vehicle comprising a right-angle clamp that 
can be fixedly bolted onto the frame of the truck to avoid that the chock 
slides along the frame. This clamp is provided with a leg to which is 
pivotably secured a head that engages and supports the platform. It is 
obvious that tools and labour are necessary for mounting such a chock onto 
the frame of a dumping truck in a safety manner. It is also obvious that 
such a chock is subjected to shearing forces that make it dangerous, such 
forces being generated by the weight of the platform when the same bears 
against the pivot of the head secured to the clamp fixed onto the frame of 
the truck. 
Similarly, U.S. Pat. No. 2,082,139 issued on June 1st, 1937 dislcoses a 
safety bracket for dumping vehicles, having substantially the same 
drawbacks as the chock disclosed in U.S. Pat. No. 2,427,381. Indeed, the 
safety bracket disclosed in this patent comprises a metallic base provided 
with a post on the upper end of which is rigidly mounted a head. This head 
includes a rockable, notched plate that is engageable beneath the 
longitudinal beam of the dumping platform. The bracket therefore must be 
mounted between the platform and the frame of the truck only at very 
specific points of said platform when one of the cross beams of the 
platform intersects the frame of said platform. Indeed, it is compulsory 
that one of the cross beam of the platform be engaged in the recess or 
notch provided in the head of the bracket to prevent longitudinal movement 
thereof. As a result, the safety bracket dislcosed in U.S. Pat. No. 
2,082,139 must be located and mounted in a very careful manner between the 
platform and the frame of the truck. 
In both cases, the chock or bracket disclosed in the above patents does not 
ensure self-blocking of the dumping platform when the same is moving 
downwards. In both cases too, the disclosed chock or bracket are subjected 
to shearing forces that make them hazardous in use. 
A first object of the present invention is to provide a safety wedge that 
overcomes the above mentioned drawbacks. 
Another object of the present invention is to provide a pivoted wedge for 
use as safety device by a mechanic who has to work under a dumped vehicle, 
which wedge provides self blocking up of the platform in dumping position 
in the case of failure of the hydraulic mechanism used for rising up the 
platform. 
In accordance with the invention, these objects are achieved with a pivoted 
wedge comprising a main body in which are rotatably mounted a pair of 
driven means designed for riding on the frame of the truck and allowing 
translation of the body along said frame, and a driving means designed for 
riding on the frame of the dumping platform. The driving means positively 
engages both driven means and rotate them in the opposite direction toward 
the junction between the frame of the truck and the frame of the platform 
when the dumping platform is moving down, thus causing movement of the 
wedge toward the junction and thus self-block of the platform in dumping 
position. 
In accordance with a preferred embodiment of the invention, the driven 
means comprise first and second cylinders spaced apart from each other. 
These cylinders are both mounted about first and second shafts extending 
parallel to each other in a same horizontal plane inside the body. On the 
other hand, the driving means comprises a third cylinder pivotably mounted 
about a third shaft extending parallel to the first and second shafts 
inside the body. This third cylinder has an axis substantially coaxial 
with the axis of its shaft and is in contact with the first and second 
cylinders. A supporting element is tangentially fixed to the third 
cylinder so as to rotate together with it. This element is designed for 
supporting the frame of the platform. 
Preferably, the inner diameter of the third cylinder is substantially 
larger than the external diameter of the third shaft so as to create a 
slack and thus allow the third cylinder to freely rotate about its shaft. 
The presence of such a slack avoids internal wear of the third cylinder 
and makes the use of lubrificating material unnecessary. 
Advantageously, the supporting element comprises a base member extended by 
a pair of lateral projections which all together define a U-shaped bracket 
in which the frame of the platform may engage.

FIG. 1 represents a dumping truck 2 having a very conventional structure 
with a frame 4 at the rear of which a dumping platform 6 is pivotably 
mounted about hinges 8. A hydraulic jack 10 is used for rising up the 
platform 6 in dumping position. In order to block up the platform in 
dumping position, a wedge 12 is mounted between the frame 4 and the 
platform 6. As shown in greater details on FIGS. 2 and 3, the wedge 12 
comprises a body 14 including two parallel plates 16 and 16' spaced apart 
from each other. 
The wedge 12 also comprises two cylinders 18 and 18' rotatively mounted 
about a pair of hollow shafts 20 and 20' extending between, and fixed to, 
the plates 16 and 16'. The shafts 20 and 20' are parallel to each other 
and extend in a same horizontal plane parallel to the frame 4 of the 
truck. The cylinders 18 and 18' bear and ride onto a beam 22 of the frame 
4. They are both designed for moving the body 14 in translation along the 
frame. Each of the plates 16 and 16' extends under the level at which the 
cylinders 18 and 18' bear against the beam and they both define guiding 
surfaces 24 and 24' in which the beam 22 is engaged. 
The third cylinder 26 is rotatively mounted about a third bollow shaft 28 
extending between, and fixed to, the plates 16 and 16'. This third 
cylinder is rigidly connected to a supporting element 30 by means of a 
spacer 32. The supporting element 30 is designed for receiving a 
longitudinal reinforcing beam 34 of the frame of the platform 6. For this 
purpose, the supporting element 30 comprises a base member 36 laterally 
extended by a pair of projecting members 38 and 38' which together define 
a U-shaped bracket in which the beam 34 engages. The cylinder 26 is 
parallel to the cylinders 18 and 18' and in contact therewith. The ends of 
the shafts 20, 20' and 28 extend through the wedge body 14 outwards the 
plates 16 and 16' and are rigidly fixed to the same by weldings 40 (see 
FIG. 3). 
It should be noted that the axis of the cylinder 26 is coaxial with the 
axis of its shaft 28. 
It should also be noted that the inner diameter of the cylinder 26 is 
larger than the external diameter of its shaft 28 so as to create a slack 
42 and thus allow this cylinder 26 to freely rotate about its shaft 28. 
This arrangement is particularly interesting because the presence of such 
a slack avoids internal wear of the cylinder 26 and makes use of a 
lubrificating oil unnecessary. It should further be noted that the 
presence of a shaft 28 for supporting the cylinder 26 is not essential and 
that, accordingly, the shaft 28 could be removed without preventing or 
reducing the efficiency of the wedge as, even in this case, the cylinder 
26 could still rotate directly against the cylinders 18 and 18' with which 
the cylinder 26 is in contact. Actually, the advantage of using a shaft 28 
is only to make the cylinder 26 and the supporting element 30 connected 
thereto, an integral part of the wedge and avoid that the cyclinder 30 and 
element 30 be lost when the wedge is not in use. 
Slacks 44 and 44' can also be provided between the inner surfaces of the 
cylinders 18 and 18' and the peripherical surfaces of their shafts 20 and 
20'. As can be easily understood, these slacks do not extend however all 
around the shafts but only in the lower parts thereof opposed to the 
points where the cylinders 18 and 18' are in contact with the cylinder 26 
that they support together with its supporting element 30, and are pressed 
against their own shafts by the weight of the cylinder 26 and its 
supporting element 30. 
The operation of the above described wedge is obvious with reference to 
FIG. 2 of the drawings. When, in the case of failure of the hydraulic 
mechanism or circuit of the truck, the platform is moving down from its 
dumping positions, its beam 34 pivots downwards in the direction indicated 
by the arrow A and simultaneously rotates the supporting member 30 in 
which it has been engaged about its cylinder 26 which rotates in the 
direction indicated by the arrow B. The cylinder 26 in turn rotates the 
cylinders 18 and 18' in the direction indicated by the arrows C and C' 
respectively. This rotation of the cylinders 18 and 18' causes the wedge 
12 to move in the direction shown by the arrow D towards the rear end of 
the truck frame and thus to block the platform in dumping position. In 
other words, the wedge 12 permits to counterbalance the horizontal 
component of the force which is exerted by the weight of platform and has 
the propensity of moving the wedge out of its position, by an equivalent 
force directed in the opposite direction (see arrow D) towards the rear 
end of the frame of the truck.