U.S. patent application number 12/394169 was filed with the patent office on 2010-09-02 for powered screed and method of operating.
This patent application is currently assigned to TRIMBLE NAVIGATION LIMITED. Invention is credited to Kent Kahle.
Application Number | 20100221067 12/394169 |
Document ID | / |
Family ID | 42667170 |
Filed Date | 2010-09-02 |
United States Patent
Application |
20100221067 |
Kind Code |
A1 |
Kahle; Kent |
September 2, 2010 |
POWERED SCREED AND METHOD OF OPERATING
Abstract
A lightweight, powered screed machine for screeding the surface
of a quantity of concrete having a pair of rails extending to
either side, includes a frame having a handle arrangement, for
manual engagement by an operator, and an elongated screed blade
extending between the support rails. The machine further includes a
powered vibration mechanism mounted on the frame. A pair of posts
or masts are provided with one of the pair of posts attached to the
frame adjacent each end of the blade and extending upward. Each of
a pair of supports is positioned adjacent an associated end of the
blade. Each support has rollers for engaging and riding on one of
the pair of support rails, and each of the supports is attached to
the frame so as to support the frame over the concrete. Each of the
supports includes a linear actuator for raising and lowering the
frame adjacent the rail. A pair of laser receivers is provided with
each of the pair of laser receivers mounted on an associated one of
the pair of posts. A control controls the linear actuators such
that the screed blade is maintained at a desired height as the
screed blade is moved over the concrete.
Inventors: |
Kahle; Kent; (Dayton,
OH) |
Correspondence
Address: |
DINSMORE & SHOHL LLP
FIFTH THIRD CENTER, ONE SOUTH MAIN STREET, SUITE 1300
DAYTON
OH
45402-2023
US
|
Assignee: |
TRIMBLE NAVIGATION LIMITED
Sunnyvale
CA
|
Family ID: |
42667170 |
Appl. No.: |
12/394169 |
Filed: |
February 27, 2009 |
Current U.S.
Class: |
404/75 ;
404/118 |
Current CPC
Class: |
E04F 21/242 20130101;
E04G 21/10 20130101; E04F 21/244 20130101; E01C 19/44 20130101 |
Class at
Publication: |
404/75 ;
404/118 |
International
Class: |
E01C 7/32 20060101
E01C007/32; E01C 19/22 20060101 E01C019/22 |
Claims
1. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete having a pair of rails extending to
either side, comprising: a frame including a handle arrangement,
for manual engagement by an operator, and an elongated screed blade
extending between said support rails, a powered vibration mechanism
mounted on said frame, a pair of posts, one of said pair of posts
attached to said frame adjacent each end of said blade and
extending upward, a pair of supports, each of said pair of supports
positioned adjacent an associated end of said blade, each support
having rollers for engaging and riding on one of said pair of
support rails, each of said supports attached to said frame so as
to support said frame over said concrete, each of said supports
including a linear actuator for raising and lowering said frame
adjacent said rail, a pair of laser receivers, each of said pair of
laser receivers mounted on an associated one of said pair of posts,
and a control for controlling said linear actuators such that said
screed blade is maintained at a desired height as said screed blade
is moved over said concrete.
2. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, in which said
powered vibration mechanism comprises a gasoline motor driving a
rotating, off-center weight.
3. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, in which said
powered vibration mechanism comprises an electric motor driving a
rotating, off-center weight.
4. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, in which said
control for controlling said linear actuators such that said screed
blade is maintained at a desired height as said screed blade is
moved over said concrete comprises a pair of control circuits, each
control circuit controlling the linear actuator included in an
associated one of said pair of supports.
5. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 4, in which each of
said pair of control circuits is mounted on an associated one of
said pair of posts.
6. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, further comprising
a pair of displays, each of said pair of displays mounted on an
associated one of said pair of supports, said displays being
responsive to said control and to said laser receivers for
providing a display of the operation of the screed machine.
7. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, in which said
linear actuator in each of said pair of supports comprises an
electric motor for raising and lowering said frame.
8. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, in which each of
said pair of laser receivers includes an adjustable mount for
attachment to an associated one of said pair of posts at a desired
height for reception of a beam of laser light.
9. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 1, further comprising
a laser transmitter for projecting a reference beam of laser light
to said pair of laser receivers.
10. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete having a pair of rails extending to
either side, comprising: a frame including a handle arrangement,
for manual engagement by an operator, and an elongated screed blade
extending between said support rails, a powered vibration mechanism
mounted on said frame, a pair of masts, one of said pair of masts
attached to said frame adjacent each end of said blade and
extending upward, a pair of supports, each of said pair of supports
positioned adjacent an associated end of said blade, each support
configured to engage and ride on one of said pair of support rails,
each of said supports attached to said frame so as to support said
frame over said concrete, each of said supports including an
electric motor for raising and lowering said frame adjacent said
rail, a pair of laser receivers, each of said pair of laser
receivers mounted on an associated one of said pair of masts, a
pair of control circuits, one of said pair of control circuits
mounted on each of said pair of masts, for controlling said
electric motor of the support attached to the frame at the
associated end of said blade, such that said screed blade is
maintained at a desired height as said screed blade is moved over
said concrete, and a laser transmitter for projecting a reference
beam of laser light for reception by said pair of laser
receivers.
11. The lightweight, powered screed machine of claim 10, in which
said laser transmitter projects a substantially horizontal beam of
laser light that rotates about a substantially vertical axis to
define a generally horizontal reference plane of laser light.
12. The lightweight, powered screed machine of claim 10, in which
said powered vibration mechanism comprises a gasoline motor driving
a rotating, off-center weight.
13. The lightweight, powered screed machine of claim 10, in which
said powered vibration mechanism comprises an electric motor
driving a rotating, off-center weight.
14. The lightweight, powered screed machine of claim 10, in which
each of said pair of control circuits operates independently of the
other of said pair of control circuits.
15. The lightweight, powered screed machine of claim 14, in which
each of said pair of control circuits is mounted on an associated
one of said pair of masts.
16. The lightweight, powered screed machine of claim 10, further
comprising a pair of displays, each of said pair of displays
mounted on an associated one of said pair of supports, said
displays being responsive to the control circuit mounted on the
associated mast and to the laser receiver mounted on the associated
mast for providing a display of the operation of the screed
machine.
17. The lightweight, powered screed machine of claim 10, in which
each of said pair of laser receivers includes an adjustable mount
for attachment to an associated one of said pair of masts at a
desired height for reception of a beam of laser light.
18. A method of operating a powered screed of the type having a
frame including a handle arrangement for manual engagement by an
operator, and an elongated screed blade extending between said
support rails, and a powered vibration mechanism mounted on said
frame, and in which a pair of rails extends to either side a
quantity of concrete, comprising the steps of: providing a pair of
masts attached to the frame adjacent each end of the blade and
extending upward, providing a pair of supports at each end of the
blade for riding on the support rails, each support attached to the
frame and including a linear actuator for raising and lowering the
frame and blade over the concrete, providing a pair of laser
receivers, each such receiver mounted on one of the pair of masts,
projecting a beam of laser light for reception by said pair of
laser receivers, maintaining said screed blade at a desired height
as said blade is moved manually over the surface of the concrete by
operating said linear actuator in each of said pair of
supports.
19. The method of claim 18 in which said step of maintaining said
screed blade at a desired height includes the step of operating
said linear actuator to move said screed blade in dependence upon
the relative height of the laser light which is received by said
laser receivers.
20. The method of claim 18 in which said step of providing a pair
of supports at each end of the blade for riding on the support
rails, each support attached to the frame and including a linear
actuator for raising and lowering the frame and blade over the
concrete includes the step of providing a pair of supports at each
end of the blade for riding on the support rails, each support
attached to the frame and including an electric motor for raising
and lowering the frame and blade over the concrete.
21. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete having at least one rail adjacent the
quantity of concrete, comprising: a frame including a handle
arrangement, for manual engagement by an operator, and an elongated
screed blade extending between said support rails, a powered
vibration mechanism mounted on said frame, at least one post
attached to said frame adjacent an end of said blade and extending
upward, at least one support positioned adjacent an associated end
of said blade, said support having rollers for engaging and riding
on said at least one rail, said support attached to said frame so
as to support said frame over said concrete, said support including
a linear actuator for raising and lowering said frame adjacent said
rail, at least one laser receiver, said laser receiver mounted on
said at least one post, and a control for controlling said linear
actuator such that said screed blade is maintained at a desired
height as said screed blade is moved over said concrete.
22. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 21, in which said
control for controlling said linear actuator such that said screed
blade is maintained at a desired height as said screed blade is
moved over said concrete comprises a control circuit, said control
circuit controlling said linear actuator included said support.
23. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 22, in which said
control circuit is mounted on said post.
24. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 21, in which said
linear actuator comprises an electric motor for raising and
lowering said frame.
25. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete according to claim 21, further comprising
a laser transmitter for projecting a reference beam of laser light
to said laser receiver.
26. A lightweight, powered screed machine for screeding the surface
of a quantity of concrete having a pair of rails extending to
either side, comprising: a frame including a handle arrangement,
for manual engagement by an operator, and an elongated screed blade
extending between said support rails, a powered vibration mechanism
mounted on said frame, a pair of masts, one of said pair of masts
attached to said frame adjacent each end of said blade and
extending upward, a pair of supports, each of said pair of supports
positioned adjacent an associated end of said blade, each support
configured to engage and ride on one of said pair of support rails,
each of said supports attached to said frame so as to support said
frame over said concrete, each of said supports including an
electric motor for raising and lowering said frame adjacent said
rail, a pair of laser receivers, each of said pair of laser
receivers mounted on an associated one of said pair of masts, a
pair of control circuits, one of said pair of control circuits
mounted on each of said pair of masts, for controlling said
electric motor of the support attached to the frame at the
associated end of said blade, such that said screed blade is
maintained at a desired height as said screed blade is moved over
said concrete, a laser transmitter for projecting a reference beam
of laser light for reception by said pair of laser receivers, a
third mast, said third mast being adjacent to one of said pair of
masts attached to said frame, a third support, positioned adjacent
an associated end of said blade and one of said pair of supports,
said third support configured to engage and ride on one of said
pair of support rails, said third support attached to said one of
said pair of supports, said third support including an electric
motor for changing the pitch angle of the screed as said third
support is raised and lowered on said rail, a third laser receiver
mounted on said third mast, and a third control circuit mounted on
said third mast for controlling said electric motor of the third
support such that said screed blade is maintained at a desired
pitch as the blade is moved over said concrete.
27. The lightweight, powered screed machine of claim 26, in which
said laser transmitter projects a substantially horizontal beam of
laser light that rotates about a substantially vertical axis to
define a generally horizontal reference plane of laser light.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] This relates to a system for controlling the movement of a
lightweight screed machine. More specifically, this relates to a
system for controlling the vertical movement of a lightweight
screed machine of the type that is manually moved generally
horizontally over the surface of a quantity of concrete as the
concrete cures to finish the surface at a desired height. The
weight of the screed machine is supported on a pair of rails to
some degree.
[0004] In concrete construction operations, after concrete is
poured and spread, it is commonly finished by drawing a tool,
called a screed, over the surface of the concrete. This process
removes excess concrete and results in the top surface of the
concrete being positioned at the proper elevation and grade.
Numerous types of screeding devices have been used, both hand tools
and powered tools of various sizes.
[0005] Hand screeding has commonly been accomplished with a manual
screed device having a straight lower edge. This produces a flat
upper surface on the concrete. The screed device is moved back and
forth in a direction parallel to the screed edge in a sawing
motion, while slowly advancing the screed across the concrete
surface in a direction perpendicular to the screed edge. This is
time consuming and labor intensive. Powered screed devices have
been commonly used in construction for finishing larger areas of
concrete, such as for example in finishing concrete slabs on
highways, bridge decks, and deck slabs. Such screed devices may
incorporate powered vibration mechanisms. Such mechanisms may
include a rotated mass that has an off-center center of gravity.
These mechanisms are commonly powered with electric motors or
gasoline engines. Vibrating screed devices can finish relatively
dry concrete more quickly, and are less fatiguing for operators,
than are hand screed devices.
[0006] Lightweight powered screed devices typically include a
vibration mechanism mounted on the frame of the screed machine, and
a pair of handles that the screed operator uses to maneuver the
screed manually over the surface of the concrete as the concrete is
curing. Such lightweight powered screed devices are relatively easy
to operate when smaller concrete areas, such as sidewalks and
driveways, are being surfaced. Some skill is nevertheless required
for the operator to achieve a smooth, uniform surface at the
desired surface height, and the level of skill required increases
with the size of the surface on which the screed device is to be
used. It is common to provide a pair of screed support rails to
either side of the concrete area being surfaced, and to support
most of the weight of the screed device on these rails as the
operator moves the screed machine along the curing concrete
surface.
[0007] Larger screed machines have commonly used sophisticated
automatic positioning controls to insure that that the larger
expanses of concrete over which they operate are properly finished.
Such machines are typically hydraulically powered, and the
orientation and movement of the screed head is also controlled
hydraulically. Typically, hydraulic cylinders connected to each end
of the screed head raise and lower the ends independently. It has
been common to determine the elevation of each end of the screed
head by using a laser transmitter which provides a rotating beam of
laser light, effectively producing a reference plane of laser
light, and a pair of laser receivers. The laser receivers are
mounted at each end of the screed head to detect the reference beam
of laser light. The ends of the screed head are then raised or
lowered hydraulically to produce the desired elevation for the
concrete surface.
[0008] While large, hydraulically powered, screed machines have
used sophisticated laser-based control arrangements to finish large
areas of concrete surface at desired elevations, operating
lightweight, powered screed devices has been largely accomplished
without controls, and has remained a process that requires a
certain amount of operator skill to achieve the best results.
SUMMARY OF THE INVENTION
[0009] A lightweight, powered screed machine for screeding the
surface of a quantity of concrete having a pair of rails extending
to either side, includes a frame having a handle arrangement, for
manual engagement by an operator, and an elongated screed blade
extending between the support rails. The machine further includes a
powered vibration mechanism mounted on the frame. A pair of posts
are provided with one of the pair of posts attached to the frame
adjacent each end of the blade and extending upward. Each of a pair
of supports is positioned adjacent an associated end of the blade.
Each support has rollers for engaging and riding on one of the pair
of support rails, and each of the supports is attached to the frame
so as to support the frame over the concrete. Each of the supports
includes a linear actuator for raising and lowering the frame
adjacent the rail. A pair of laser receivers is provided, with each
of the pair of laser receivers mounted on an associated one of the
pair of posts. A control controls the linear actuators such that
the screed blade is maintained at a desired height as the screed
blade is moved over the concrete.
[0010] The machine may include a third mast, the third mast being
adjacent to one of the pair of masts attached to the frame
adjacent. A third support, positioned adjacent an associated end of
the blade and one of the pair of supports, is configured to engage
and ride on one of the pair of support rails. The third support is
attached to one of the pair of supports, and includes an electric
motor for changing the pitch angle of the screed as the third
support is raised and lowered on the rail. A third laser receiver
is mounted on the third mast. A third control circuit is also
mounted on the third mast for controlling the electric motor of the
third support such that the screed blade is maintained at a desired
pitch as the blade is moved over the concrete.
[0011] The powered vibration mechanism may comprise a gasoline
motor driving a rotating, off-center weight. The powered vibration
mechanism may comprise an electric motor driving a rotating,
off-center weight. The control for controlling the linear actuators
such that the screed blade is maintained at a desired height as the
screed blade is moved over the concrete may comprise a pair of
control circuits, each control circuit controlling the linear
actuator included in an associated one of the pair of supports.
Each of the pair of control circuits may be mounted on an
associated one of the pair of posts. A pair of displays may be
provided with each of the pair of displays mounted on an associated
one of the pair of supports. The displays are responsive to the
control and to the laser receivers for providing a display of the
operation of the screed machine. The linear actuator in each of the
pair of supports may comprise an electric motor for raising and
lowering the frame. Each of the pair of laser receivers may include
an adjustable mount for attachment to an associated one of the pair
of posts at a desired height for reception of a beam of laser
light. The machine may further include a laser transmitter for
projecting a reference beam of laser light to the pair of laser
receivers.
[0012] A lightweight, powered screed machine for screeding the
surface of a quantity of concrete having a pair of rails extending
to either side, includes a frame having a handle arrangement, for
manual engagement by an operator, and an elongated screed blade
extending between the support rails. The machine further includes a
powered vibration mechanism mounted on the frame. A pair of masts
are provided with one of the pair of masts attached to the frame
adjacent each end of the blade and extending upward. A pair of
supports is provided with each of the pair of supports positioned
adjacent an associated end of the blade. Each support is configured
to engage and ride on one of the pair of support rails. Each of the
supports is attached to the frame to support the frame over the
concrete, and each of the supports includes an electric motor for
raising and lowering the frame adjacent the rail. Each of a pair of
laser receivers is mounted on an associated one of the pair of
masts. Each of a pair of control circuits is also mounted on
associated one of the pair of masts for controlling the electric
motor of the support attached to the frame at the associated end of
the blade. The screed blade is maintained at a desired height as it
is moved over the concrete. A laser transmitter projects a
reference beam of laser light for reception by the pair of laser
receivers. The laser transmitter may project a substantially
horizontal beam of laser light that rotates about a substantially
vertical axis to define a generally horizontal reference plane of
laser light.
[0013] The powered vibration mechanism may comprise a gasoline
motor driving a rotating, off-center weight. The powered vibration
mechanism may alternatively comprise an electric motor driving a
rotating, off-center weight. Each of the pair of control circuits
operates independently of the other of the pair of control
circuits. Each of the pair of control circuits is mounted on an
associated one of the pair of masts. The machine may further
comprise a pair of displays, with each of the pair of displays
mounted on an associated one of the pair of supports. The displays
are responsive to the control circuit mounted on the associated
mast, and to the laser receiver mounted on the associated mast, for
providing a display of the operation of the screed machine. Each of
the pair of laser receivers may include an adjustable mount for
attachment to an associated one of the pair of masts at a desired
height for reception of a beam of laser light.
[0014] A method of operating a powered screed of the type having a
frame including a handle arrangement for manual engagement by an
operator, and an elongated screed blade extending between the
support rails, and a powered vibration mechanism mounted on the
frame, and in which a pair of rails extends to either side a
quantity of concrete, may comprising the steps of providing a pair
of masts attached to the frame adjacent each end of the blade and
extending upward; and providing a pair of supports at each end of
the blade for riding on the support rails, with each support being
attached to the frame and including a linear actuator for raising
and lowering the frame and blade over the concrete. The method
further includes the steps of providing a pair of laser receivers,
each such receiver mounted on one of the pair of masts; projecting
a beam of laser light for reception by the pair of laser receivers;
and maintaining the screed blade at a desired height as the blade
is moved manually over the surface of the concrete by operating the
linear actuator in each of the pair of supports. The step of
maintaining the screed blade at a desired height may include the
step of operating the linear actuator to move the screed blade in
dependence upon the relative height of the laser light which is
received by the laser receivers. Further, the step of providing a
pair of supports at each end of the blade for riding on the support
rails, each support being attached to the frame and including a
linear actuator for raising and lowering the frame and blade over
the concrete may include the step of providing a pair of supports
at each end of the blade for riding on the support rails. Each of
the supports is attached to the frame and includes an electric
motor for raising and lowering the frame and blade over the
concrete.
[0015] A lightweight, powered screed machine for screeding the
surface of a quantity of concrete having at least one rail adjacent
the quantity of concrete, includes a frame having a handle
arrangement for manual engagement by an operator, and an elongated
screed blade extending between the support rails. A powered
vibration mechanism is mounted on the frame. At least one post is
attached to the frame adjacent an end of the blade and extends
upward. At least one support is positioned adjacent an associated
end of the blade. The support has rollers for engaging and riding
on the at least one rail. The support is attached to the frame to
support the frame over the concrete. The support includes a linear
actuator for raising and lowering the frame adjacent the rail. At
least one laser receiver is mounted on the at least one post. A
control is provided for controlling the linear actuator such that
the screed blade is maintained at a desired height as the screed
blade is moved over the concrete. The control for controlling may
include a control circuit. The control circuit may be mounted on
the post, and the linear actuator may comprise an electric motor
for raising and lowering the frame. A laser transmitter may be
provided for projecting a reference beam of laser light to the
laser receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of an embodiment of the
lightweight, powered screed machine;
[0017] FIG. 2 is a schematic diagram of a control for the screed
machine; and
[0018] FIG. 3 is a perspective view of a second embodiment of the
lightweight, powered screed machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] FIGS. 1 and 2 illustrate an embodiment of the lightweight,
powered screed machine 10. The machine 10 is positioned to smooth
the surface of a quantity of concrete 12. A pair of rails 14 and 16
extend to either side of the concrete 12. The machine 10 has a
frame 18 including a handle arrangement 19. The handle arrangement
includes a pair of handles 20 and 22 that are grasped by the
operator and used to pull the machine across the surface of the
concrete 12. It will be appreciated, of course, that other types of
handles may be used instead of the twin handles 20 and 22 that are
shown. The handle arrangement is used by the operator to pull the
machine generally to the right, as seen in FIG. 1. The frame 18
includes an elongated screed blade 24 that extends between the
support rails 14 and 16, as well as channel members 19, and support
elements 21 which extend between the screed blade 24 and the
channel members 19 at each end of the screed blade 24.
[0020] The machine 10 includes a pair of posts or masts 26 and 28
that are attached to the frame 18, adjacent each end of the blade
18, and extend upward. A pair of supports 30 and 32 are provided
adjacent the ends of the blade 24. Each support 30 and 32 includes
a number of rollers 34 that engage and ride the support rails 14
and 16. Each of the supports 30 and 32 engages the channel members
19 of the frame 18 to support the frame 18 over the concrete 12.
The supports 30 and 32 include linear actuators 36 for raising and
lowering the frame 18 adjacent the rails upon which the supports
ride. The linear actuators 36 may each comprise an electric motor
37 driving a threaded shaft 39 which raises and lowers an end of
the frame 18. The channel members 19 each define threaded openings
through which one of the threaded shafts 39 extends. Rotation of a
threaded shaft 39 raises or lowers associated channel member 19.
Channel members 19 also define openings which permit them to slide
vertically on support posts 23.
[0021] A pair of laser receivers 38 and 40 are provided to sense
illumination by a beam of laser light and to provide output signals
indicating the relative positions of the beam striking the
receivers. Each of the pair of laser receivers 38 and 40 is mounted
on an associated one of the pair of masts 26 and 28 by an
adjustable mount 42 and 44, respectively. The adjustable mounts 42
and 44 permit the heights of the receivers 38 and 40 to be altered
so that the receivers are illuminated by a reference beam of laser
light 46 from laser transmitter 48.
[0022] A control, comprising a pair of control circuits 50 and 52,
controls the linear actuators 36 such that the screed blade 24 is
maintained at a desired height as the screed blade 24 is moved over
the concrete 12. Each control circuit controls the linear actuator
36 included in an associated one of the pair of supports 30 and 32.
Control circuit 50 is responsive to laser receiver 38 to control
the linear actuator 36 in support 30, while control circuit 52 is
responsive to the laser receiver 40 to control the linear actuator
36 in support 32. Each of the pair of control circuits 50 and 52 is
mounted on an associated one of the pair of posts or masts 26 and
28.
[0023] A powered vibration mechanism 54 is also mounted on the
frame 18. The powered vibration mechanism 54 may include a gasoline
motor driving a rotating, off-center weight arrangement.
Alternatively, the powered vibration mechanism 54 may be an
electric motor driving a rotating, off-center weight. The vibration
mechanism vibrates the frame 18 and the screed blade 24, and
facilitates the movement of the blade 24 over the surface of the
curing concrete 12.
[0024] A pair of displays 56 and 58 are each mounted on an
associated one of the pair of supports 26 and 28, respectively. The
displays 56 and 58 are responsive to the controls 50 and 52,
respectively, and to the laser receivers 38 and 40, respectively,
for providing a display of the operation of the screed machine
10.
[0025] Laser transmitter 48 projects a reference beam of laser
light 46 to the pair of laser receivers 38 and 40. The laser
transmitter 48 projects a substantially horizontal beam 46 of laser
light that rotates about a substantially vertical axis to define a
generally horizontal reference plane of laser light. A horizontal
reference plane may be used when screeding a horizontal surface on
the concrete. If desired, however, the axis of rotation of the beam
46 can be slightly tilted by a specified pitch to produce a
reference plane of laser light which is also slightly tilted. The
tilted reference plane can be used to screed a concrete surface
which is tilted at the same angle.
[0026] FIG. 2 illustrates the control circuit 50 in greater detail
and shows the interconnections between the control circuit 50, the
laser receiver 38, the display 56, and the motor 37. The control 50
includes a switch 60. When the end of the screed blade 24 is set at
a desired position, the operator actuates switch 60 to store in
memory 62 a signal then being received from laser receiver 38. The
comparator 64 then compares the measured elevation from the laser
receiver 38 with the stored elevation in the memory 62. When the
comparator 64 determines that the measured and sensed elevations
are no longer equal, the comparator 64 provides an output on 66
related to the difference in elevations to the motor drive circuit
68, which then drives motor 36 in the appropriate direction to
reduce this difference. The display 56 receives both the signal
from laser receiver 38 which indicates measured elevation and the
signal on 66 which indicates the difference between the desired
elevation and the measured elevation. The screed blade 24 is
maintained at a desired height as the blade 24 is moved manually
over the surface of the concrete 12 by operating the linear
actuators 36 in the supports 30 and 32.
[0027] It will be appreciated that the control arrangement
essentially provides separate control for each end of the screed
blade which is unrelated to the elevation control for the other end
of the screed blade. It will be appreciated, however, that if
desired, the outputs from both of the laser receivers 38 and 40 may
be used by a single control circuit to control both motors 37.
[0028] It will be appreciated that the control circuits 50, 52,
motors 37, and displays 56, 58 all required electrical power.
Further, in the instance in which the vibration 54 mechanism
includes an electric motor, this requires electric power, as well.
The power may be supplied from an external power source through
power cables, or it may be provided by means of batteries carried
on the screed machine 10. If the vibration mechanism includes a
gasoline engine, the engine may be used to drive a small generator
to produce the needed electric power.
[0029] Reference is made to FIG. 3, which illustrates a second
embodiment of the lightweight, powered screed machine. Many of the
elements of the screed machine shown in FIG. 3 are the same as
those of the screed machine shown in FIG. 1, and they have
therefore been designated with the same reference numerals. The
screed machine of FIG. 3 provides for control of the pitch angle of
the screed 24 as it is pulled across the surface of the concrete
12. To accomplish this, the screed machine includes a third mast
70. The third mast 70 is generally adjacent to one of the other
masts 28 and is attached to the frame 18. The channel member 19'
extends between the support 30 and a third support 72 and attaches
the two supports together. The third support 72 is positioned
adjacent an associated end of the blade and one of the pair of
supports 26. The third support is configured to engage and ride on
the support rail 14. The third support 72 has the same type of
linear actuator 36, including an electric motor 37, as the other
supports 30 and 32. When the motor 37 is driven to raise or lower
the support 72, the channel member 19' is tilted, with the result
that the pitch angle of the screed 24 is adjusted. A third laser
receiver 74 is mounted on the third mast 70. A third control
circuit 76 is mounted on the third mast 70 for controlling the
electric motor 37 of the third support 72 such that the screed
blade 24 is maintained at a desired pitch as the blade is moved
over the concrete 12.
[0030] Although particular embodiments have been described above
for purposes of illustration, it will be appreciated by those
skilled in the art that numerous variations in these embodiments
may be made. For example, the disclosed method may be used in
conjunction with the operation of a drag box for laying asphalt or
similar material.
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