Road structure – process – or apparatus – Apparatus – Material distribution means
Reexamination Certificate
1999-07-29
2001-01-16
Lillis, Eileen D. (Department: 3673)
Road structure, process, or apparatus
Apparatus
Material distribution means
C404S118000
Reexamination Certificate
active
06174105
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to paving machines, and more particularly to strike-off devices for paving screeds.
Screed assemblies
1
used with paving machines to level paving material, typically asphalt, applied by the machine onto a generally horizontal base surface
2
are well known, an example of such being depicted in
FIGS. 1 and 2
. Such screed assemblies
1
often include both a main screed
3
and one or more pairs of screed extensions
4
connected with the main screed
3
. The screed extension
4
may either be fixedly attached (e.g., bolted) to an end of the main screed
3
(or an outer end of another screed extension
4
) or movably attached to the main screed
3
. Movably attached screed extensions
4
are commonly referred to as “extendible screeds” and are laterally displaceable with respect to the main screed
3
, typically by means of hydraulic cylinders (not shown) so as to either be extended outwardly substantially beyond the outer ends
3
b
of the main screed
3
or retracted into centralized positions. Both types of screed extensions
4
enable the screed assembly
1
to be adjusted for use in paving different base surfaces
2
of various widths.
Further, screed assemblies
1
having one or more strike-off devices
5
disposed frontwardly (i.e., with respect to the direction of paving machine travel
11
) of the screed sections
3
,
4
are also known. Particularly with paving screeds
1
having front-mounted extendible screeds
4
, the strike-off devices
5
prevent paving material from accumulating in front of the main screed
3
and thus prevent uneven distribution of paving material across the width of the screed assembly
1
. Such known strike-off assemblies
5
typically include a strike-off member or plate
6
movably attached to the main screed
3
such that the vertical position of the plate
6
is adjustable. The strike-off member/plate
6
has a working edge
6
a
at the lower end of the plate
6
which establishes a first height/thickness of paving material prior to leveling by the working surfaces
3
a
,
4
a
of the screed assembly
1
. Thus, it is important to control the vertical position of the strike-off working edge
6
a
to ensure that it is at a desired distanced above the working surfaces
3
a
,
4
a
(see
FIG. 2
) determined to provide optimal performance of the paving screed assembly
1
.
Further, in order to control the depth of the finished “mat” of paving material, the “angle of attack” &agr; of the screed assembly
1
(
FIG. 2
) may often have to be adjusted. First, the main screed
3
is “tilted” frontwardly or rearwardly to position the main screed working surface
3
a
at the desired angle &agr;. As the strike-off plate
6
and screed extensions
4
are attached to the main screed
3
, varying the angle a of the main screed
3
causes both the screed extensions
4
and the strike-off plate
6
to move vertically upwardly or downwardly. Thus, the screed extension
4
must first be adjusted vertically to the proper height, which in the known assembly
1
of
FIGS. 1 and 2
, requires moving two cylindrical posts
8
at the upper end of each screed extension
4
within an associated bushing
9
extending through a support member
7
, a pair of the support members
7
connecting each screed extension
4
to the main screed
3
. Therefore, four separate adjustments may be required to properly position the two extensions
4
, although preferably a vertical positioning device
15
is configured to simultaneously adjust the pair of posts
8
for each screed extension
4
so that the operator need only make two adjustments (i.e., one for each extension
4
).
Further, the strike-off plate
6
must also be adjusted to position the strike-off working edge
6
a
at the proper height, which with the two devices
5
depicted in
FIGS. 1 and 2
, requires adjusting two pairs of threaded rods
5
a
which connect each plate
6
to the main screed
3
(specifically to a separate support member
7
). Therefore, properly positioning the strike-off device
5
requires another four separate adjustment steps. Thus, whenever the angle of attack a of the main screed
3
is adjusted, at least six and potentially eight separate adjustment steps may be required to position both the screed extensions
4
and the strike-off plate
6
of the known strike-off device
5
at proper working heights.
Therefore, it is desirable to provide a strike-off device for a screed assembly in which the number of adjustment steps required to properly position both the screed extensions and the strike-off plates after a change in the angle of attack a is less than that required for previously known strike-off devices.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a strike-off device for a screed assembly for leveling paving material upon a generally horizontal base surface. The screed assembly includes a main screed and a screed extension attached to the main screed, the screed extension having a generally vertical front surface and a generally horizontal working surface. The strike-off device comprises a strike-off member disposed frontwardly of and adjustably connected with the screed extension. The member has a generally horizontal working edge extending laterally along the front vertical surface of the screed extension. Further, the strike-off member is displaceable vertically with respect to the base surface so as to adjust a vertical position of the working is edge with respect to the screed extension working surface.
In another aspect, the present invention is a strike-off device for a paving screed having a main screed and a screed extension attached to the main screed. The screed extension having a generally vertical front surface. The strike-off device comprises a strike-off plate disposed frontwardly of and adjacent to the screed extension. The plate has a generally horizontal working edge extending laterally along the front vertical surface of the screed extension. A connective member extends between the strike-off plate and the screed extension and is configured to movably attach the plate to the screed extension.
REFERENCES:
patent: 4379653 (1983-04-01), Brown
patent: 6056474 (2000-05-01), Nolan
Hargis Paul L.
Holmes Ted E.
Hartmann Gary S.
Lillis Eileen D.
Ussai Mark A.
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