Note: Descriptions are shown in the official language in which they were submitted.
CA 02339312 2001-02-09
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TITLE: PIVOT LIP DUMP GATE
Background of the Invention
1. Technical Field
The present invention is directed generally to an improved rear gate for
the dump body of a truck, trailer or the like, and more particularly to a
pivot
lip dump gate wherein a shortened hanging upper gate is used in combination
with a lower gate which is pivotable along the bottom edge and actuatable by a
power source for movement between an upright closed position wherein it
secures the upper gate against the dump body and an open dumping position
wherein it serves to direct contents outwardly from the dump body.
2. Description of the Prior Art
Heavy duty dump trucks or trailers of the type used for hauling asphalt
to a paving machine typically have a unitary hanging rear gate pivoted at its
upper end for swinging outwardly upon dumping of thel dump body. Paving
machines typically have a hopper extended transversely across a rearward end
for receiving asphalt from a dump truck as the payer advances across a street,
parking lot or the like for asphalt paving. To be sure that the asphalt is
directed into the hopper and not into the space between the dump body and
payer, prior art dump bodies were generally provided with a fixed
stationary lip extended perhaps 12 inches rearwardly from the dump body.
Problems have occurred with that fixed lip getting caught in the payer as the
dump body approaches or leaves the hopper of the payer. The lip is intended
to guide asphalt into the hopper but, because the lip is fixed, damage and
deformation of the hopper and lip can occur if the lip is not properly moved
into clearance above the hopper before the truck moves away from the paving
machine hopper. Repair of damage to the hopper is likely to be expensive. As
the fixed lip on the dump body becomes bent and deformed over continuous
use, it is both unattractive and difficult to clean with a scraping tool such
as a
shovel. Finally, even a new undamaged fixed lip on a dump body acts as an
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unnecessary and undesirable rearward extension of the dump body during
transport.
Accordingly, a primary object of the present invention is to provide a
pivot lip dump gate for a dump body wherein a vertically shortened hanging
upper gate is used in combination with a lower gate pivoted along its lower
edge for movement between an open dumping position wherein it directs
asphalt outwardly away from the dump body and an upright closed position
wherein it serves to secure the hanging upper gate in the closed position
against the rearward end of the dump body.
Another object is to provide an improved split gate for a dump body
which eliminates the need for a conventional fixed stationary lip at the
rearward end of the dump body.
Another object is to provide a split gate for a dump body wherein a
shorter lower gate serves a double function of a dumping lip in its open
dumping position and as a locking device in its upright closed position for
securing the hanging upper gate in its closed position.
Another object of the invention is provide a split gate for a dump body
wherein the lower gate is power actuated for pivotal movement between its
transport and dumping positions.
Another object is to provide a split gate for a dump body wherein the
shorter lower gate can float or freely pivot upwardly from its open dumping
position to prevent damage to a paving hopper or the like.
Another object is to provide a split gate for a dump body which
eliminates the unnecessary and undesirable rearward extension of a fixed lip
in a transport position of a dump body.
Another object is to provide a split gate for a dump body which is simple
and rugged in construction, economical to manufacture and efficient in
operation.
Summary of the Invention
A pivot lip dump gate for the dump body of a dump truck, trailer or the
like includes an upper gate connected to the side walls of the dump body for
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pivotal movement about a transverse pivot axis adjacent to the top rear
corners of the side walls whereby the upper gate is operative to swing
outwardly from the side walls to an open position and inwardly to a closed
position in engagement with the side walls. A lower gate is connected to the
dump body for pivotal movement about a transverse pivot axis adjacent the
rearward end of the floor between an open position extending rearwardly from
the floor and generally upright closed position closing a lower portion of the
open rearward end of the dump body. The lower gate includes a locking
device or flange which is engageable with the upper gate in the closed
positions of both gates to secure the upper gate in its closed position for
transport. A source of power such as an hydraulic cylinder preferably
connects the lower gate to the dump body and is actuatable to move the
lower gate between its closed transport position and its open dumping
position.
The power source is deactivated upon movement of the lower gate to the
dumping position to enable the lower gate to float and thereby prevent damage
to a payer hopper or the like that the lower gate may contact during the
dumping operation. The lower gate is preferably of substantially shorter
vertical height than the upper gate so as to function much like the fixed
stationary lip of known dump bodies when the lower gate is in its open
dumping position. The lower gate thus not only serves as a floor extenc;r",
fnr
directing asphalt or other contents rearwardly away from the dump body but
also, upon pivotal movement to its closed transport position, it eliminates
the
unnecessary and undesirable rearward extension of a fixed lip and also serves
to secure the hanging upper gate in its closed transport position.
Brief Description of the Drawines
Figure 1 is a partial perspective view of an existing dump body with the
stationary fixed lip bent from use;
Figure 2 is a partial perspective view of a dump body equipped with the
improved pivot lip dump gate of the invention;
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Figures 3, 4 and 5 are partial side elevational views showing the pivot
lip dump gate in its closed, open and dumping positions, respectively;
Figure 6 is a side view of the rearward end of the dump body with the
actuating cylinder shown in dotted lines corresponding to the closed position
of
the pivot lip dump gate;
Figure 7 is a partial side view of the dump body with the actuating
cylinder in dotted lines corresponding to the open dumping position of the
pivot lip dump gate;
Figure 8 is a side view of the pivot lip dump gate in a floating dumping
position with the dump body raised to empty asphalt into a payer hopper;
Figure 9 is a partial perspective view of the rear corner of the dump
body with a portion of the bracket broken away to show the pivotal support for
the lower gate of the pivot lip dump gate in the closed transport position;
and
Figure 10 is a partial perspective view of the rear corner of the dump
body with a portion of the bracket broken away to show the pivotal support of
the lower gate of the pivot lip dump gate in the open dumping position.
Description of the Preferred Embodiment
The pivot lip dump gate of the present invention is an improvement to
resolve problems with the fixed stationary lip 10 of conventional dump bodies
12 of the type illustrated in Figure 1 on a large dump truck 14. The dump
body 12 includes a floor 16, a front wall (not shown), opposite side walls 18
and
20 and a single dump gate 21 closing an open rearward end 22. A lift
mechanism (not shown) is provided for pivotally raising the forward end of the
dump body for dumping contents from the open rearward end. The fixed
stationary lip 10 is provided to direct asphalt or other contents outwardly
away from the dump body into a payer hopper 24 or the like. The fixed lip 10
likewise prevents the contents from being dumped onto the rear wheels 26 or
into the space between the dump body and payer hopper 24 or other such
receptacle. The problem with the fixed lip 10 is that it can strike and damage
the payer hopper and catch on the front edge of the payer hopper as the truck
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separates from the payer if the dump body has not been sufficiently lowered to
provide clearance between the fixed lip 10 and hopper 24. As the fixed lip
becomes bent and deformed over time, it has an unsightly appearance and is
very difficult to clean with a scraping tool such as a shovel. These problems
are resolved by the pivot lip dump gate 30 of the invention.
Figure 2 illustrates the pivot lip dump gate 30 as including a split gate
including a hanging upper gate 32 and a lower gate or lip 34. The upper gate
32 is hingedly connected to the side walls 18 and 20, preferably in the same
manner that a conventional single dump gate 21 is hingedly supported.
Specifically, upper gate 32 is connected to the side walls 18 and 20 by a pair
of
forwardly extending brackets 36, one on each side, which are pivotally
engaged on stub shafts 38 for free swinging movement of the upper gate by
gravity as the dump body is moved from its lowered transport position of
Figure 4 to its raised dumping position of Figure 5. The stub shafts 38
provide
a transverse pivot axis adjacent to top rear corners of the side walls 18 and
20
about which the upper gate 32 is operative to swing outwardly away from the
side walls to an open dumping position, as illustrated in Figure 5, and
inwardly to a closed transport position, as illustrated in Figures 2 and 4. In
the transport position, the upper gate may be engaged against the side walls
18 and 20. It can be seen in the drawings that the rearward end portion of
side walls 18 and 20 are reinforced by appropriate framework 40 for structural
integrity and to support the rear gate.
In a comparison of Figure 2 with Figure 1, it can be seen that the upper
gate 32 is shortened somewhat compared to the unitary single dump gate 21 of
the prior art. The shortened height of the upper gate 32 is compensated for by
lower gate 34 which is likewise connected to the dump body 12 for pivotal
movement about a transverse pivot axis 42 (Figures 6 and 7). That axis 42 is
situated adjacent the rearward end of the dump body floor 16 to enable pivotal
movement of the lower gate 34 between an open dumping position extending
rearwardly from the floor 16 and a generally upright closed transport position
closing a lower portion of the open rearward end 22 of the dump body 12. The
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lower gate is thus generally upright and parallel to the upper gate 32 in the
transport position of the dumping body, as illustrated in Figure 3. The upper
and lower gates 32 and 34 are shown as being of a size and shape to
collectively close the open rearward end 22 of the dump body 12 in the closed
transport positions of both gates 32 and 34.
The lower gate 34 is provided with a locking means such as the
elongated flange 48 which is secured to the rearward face of the lower gate 34
and which extends upwardly beyond the top edge 50 of the lower gate to serve
as a closure lock for securing the upper gate 32 in its closed transport
position.
The continuous flange 48 is preferred to close any gap between the upper and
lower gates 32 and 34, but it alternately could be replaced by one or more
upstanding fingers or posts positioned for accomplishing the same function of
securing the upper gate in its closed position upon lowering of the dump body
and closing of the lower gate 34. The invention is intended to broadly
contemplate any type of engagement means between the upper and lower
gates 32 and 34 which would secure the upper gate in its closed position upon
pivotal movement of the lower gate 34 to its closed transport position.
The pivotal, support of the lower gate 34 is best shown in Figures 6-10.
A generally reshaped bracket 50 extends from the lower end of lower gate 34
and has one end 54 connected to the lower gate 34 and an opposite free end 56
pivotally connected to the cylinder end 58 of hydraulic cylinder 60 housed
within the sidewall framework 40. The cylinder end 62 of hydraulic cylinder
60 is pivotally connected to the dump body by an appropriate coupling for
pivotal movement about a transverse axis 64. Upon retraction of hydraulic
cylinder 60 from the extended position of Figure 6 to the retracted position
of
Figure 7, the reshaped bracket 52 is lifted to pivot lower gate 34 about its
pivot axis 42 from its closed transport position to its lowered dumping
position.
In the lowered dumping position, the lower gate 34 is preferably parallel to
the
dump body floor 16. Hydraulic cylinder 60 is preferably connected to the
hydraulic system of the dump truck and actuatable from the cab of the truck.
Once the lower gate 34 is fully opened, the hydraulic cylinder 60, or any
other
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alternate power source is deactivated to enable the lower gate to float, i.e.,
freely pivot upwardly in the event that an obstruction is encountered
such as the front edge of payer hopper 24, as illustrated in Figure 8.
Whereas hydraulic cylinder 60 is shown as a preferred power source for
pivoting the lower gate 34, it is understood that an electric motor, hand
crank
or any other power source could be substituted for the hydraulic cylinder 60.
Upon a dump truck 14 approaching a hopper 24 for dumping asphalt
into the hopper as illustrated in Figure 8, the lower gate 34 may be
maintained in its raised closed position until the dump body 12 is moved
sufficiently close to provide clearance for lowering of the lower gate 34 into
the
hopper 24 rather than striking the outer wall of the hopper. The lowered
lower gate then serves to direct the asphalt into the hopper so that it is not
spilled between the dump body and hopper. The upper gate 32 is swung
rearwardly out of the way by gravity. If the lower gate contacts the hopper
during the dumping operation, no damage is done because the lower gate is
free to float or pivot. Upon completion of the dumping operation, the floating
condition of the lower gate 34 likewise prevents damage in the event that the
truck body is advanced away from the hopper before the dump body is
sufficiently lowered to provide vertical clearance between the lower gate 34
and hopper 24. Once the dump body is lowered to its transport position, as
illustrated in Figure 4, the upper gate 32 swings to its closed position by
gravity and the hydraulic cylinder 60 may be actuated to pivotally raise the
lower gate 34 to its closed transport position of Figure 3. In that position,
the
locking flange 48 engages the lower edge of upper gate 32 to lock it in its
closed
transport position.
Thus there has been shown and described a pivot lip dump gate which
accomplishes all of the stated objects.
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