A concrete strike-off vibrator is characterized by a manifold member having at least one cylinder assembly disposed in a force-transmitting relationship therewithin. The manifold includes a pressurized fluid inlet adapted to introduce a pressurized fluid into the interior volume of the manifold. The cylinder assembly includes a piston adapted to define first and second volumes within the cylinder assembly and has associated therewith an intake for introducing pressurized fluid from the interior volume of the manifold into the first and second volumes defined within the cylinder assembly. Included is an exhaust isolated from the intake and from the interior volume of the manifold for venting the first and the second volumes within the interior of the cylinder assembly.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to concrete strike-off vibrators and in particular, 
to a concrete strike-off vibrator having a pressurized fluid manifold 
communicating with the interiors of each of a plurality of cylinder 
assemblies disposed in a force-transmitting relationship within the 
manifold. 
2. Description of the Prior Art 
After a section of concrete has been layed, it is desirable to level the 
surface of that concrete to eliminate any undulations or discontinuities 
in the surface thereof. For this purpose the prior art utilizes a device 
known as a strike-off vibrator or a "crazy board". The strike-off vibrator 
is an elongated member having a flat strike-off surface thereon which is 
placed in contact with the upper surface of the concrete to be leveled. A 
plurality of fluid actuated piston-cylinder assemblies are mounted on the 
elongated strike-off member with each piston-cylinder assembly being 
provided with a separate pressurized fluid supply line. 
A piston is disposed with each of the enclosed cylinders and moves within 
the cylinders in response to the introduction of pressurized fluid 
thereinto. The reaction forces generated by the collision of the piston 
member within the cylinder assemblies in response to the introduction of 
pressurized fluid is imparted to the elongated strike-off member and 
transmitted thereby to the concrete. The concrete responds to the 
vibratory motion of the stike-off member and undulations and 
discontinuities in the surface of the concrete are eliminated after 
passage of the strike-off vibrator thereover. 
Current vibrators require, as discussed above, separate fluid inlet lines 
connecting a source of pressurized fluid, usually pressurized air, to each 
of the plurality of piston-cylinder assemblies disposed along the 
strike-off member. Such separate and independent fluid connections are 
disadvantageous, however, because of the unnecessary complexity of 
interconnections that is generated thereby. Furthermore, in practice it 
has been observed that individual ones of the fluid inlet lines have a 
tendency to separate themselves from their associated piston-cylinder 
assembly so that the introduction of pressurized fluid into that 
piston-cylinder assembly is terminated. Such an occurrence has the effect 
of reducing the vibratory motion and forces generated by the strike-off 
vibrator with a concommitant reduction in the efficiency of the leveling 
of the concrete. 
It would be advantageous, therefore, to eliminate the heretofore complex 
fluid connection arrangements necessitated by the prior art. Accordingly, 
it is of advantage to provide a concrete strike-off vibrator utilizing a 
manifold member having an interior volume adapted to receive pressurized 
fluid thereinto. Furthermore, it is advantageous to provide a manifold 
adapted to receive a plurality of individual piston-cylinder assemblies 
therewithin in a force-transmitting relationship, each piston-cylinder 
assembly being interchangeably mounted and communicable with the interior 
of the manifold so that only a single pressurized fluid inlet is required 
to supply pressurized fluid to each piston-cylinder assembly associated 
with the strike-off. 
SUMMARY OF THE INVENTION 
This invention relates to a concrete strike-off vibrator which includes a 
manifold member having an internal volume and a pressurized fluid inlet 
adapted to permit the introduction of pressurized fluid thereinto. At 
least one but preferably a plurality of cylinder assemblies is disposed in 
interchangeable and threaded force-transmitting relationship with said 
manifold. Each of the cylinder assemblies includes a piston adapted to 
define a first and a second volume within the cylinder assembly. Intake 
means for introducing a pressurized fluid from the interior volume of the 
manifold into each of the first and second volumes defined by the piston 
within the cylinder assembly is provided. Furthermore, exhaust means 
isolated from the interior volume of the manifold and from the intake 
means communicate with each of the first and the second volumes of each 
cylinder assembly to vent fluid therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Throughout the following description similar reference numerals refer to 
similar elements in all figures of the drawings. 
Referring to FIGS. 1 and 2, elevational views entirely in section of a 
concrete strike-off vibrator 10 embodying the teachings of this invention 
are illustrated. The vibrator 10 includes generally a manifold member 12 
having a plurality of cylinder assemblies generally indicated by reference 
numeral 14 disposed in a force-transmitting relationship therewithin. For 
clarity, only one cylinder assembly 14 is illustrated in FIGS. 1 and 2, 
yet it is understood that any predetermined number of such cylinder 
assemblies 14 may be disposed within the manifold 12. Each cylinder 
assembly includes intake means generally indicated by reference numeral 16 
for introducing prespressurized fluid from the interior of the manifold 12 
into the cylinder assembly 14 and exhaust means generally indicated by 
reference numeral 18 for venting fluid from the interior of the cylinder 
assembly, the exhaust means 18 being isolated from the intake means 16 in 
a manner more clearly set forth herein. 
It is understood that the manifold 12 is a generally rectangular elongated 
member having a contacting surface 22 adapted to engage the surface of a 
section of concrete so that discontinuities and imperfections in that 
concrete surface may be eliminated therefrom. The manifold member and 
contacting surface 22 thereof may be of any predetermined axial length, 
typically of a length coextensive with the section of concrete to be 
operated on thereby. The manifold member 12 defines an interior volume 
generally indicated by reference numeral 24, with a pressurized fluid 
inlet 26 being provided at any predetermined location on the manifold 12. 
The pressurized fluid inlet 26 is connected to a source 28 of pressurized 
fluid, typically compressed air, as indicated diagrammatically on FIGS. 1 
and 2. With the connection provided between the source 28 of pressurized 
fluid and the inlet 26, it can be appreciated that the interior volume 24 
of the manifold member 12 has fluid, as compressed air, disposed therein 
at a pressure substantially equal to the pressure of the source 28. 
The cylinder assemblies 14 are disposed predetermined distances one from 
the other within the manifold member 12. Typically, to strike-off a 12 
foot wide section of concrete, six cylinder assemblies 14 are utilized, 
with the spacing between cylinder assemblies 14 within the manifold member 
12 being substantially equal. The manifold member 12 includes an upper 
surface having a plurality of threaded openings 30 therein. The threaded 
openings 30 are spaced predetermined distances apart in order to receive a 
cylinder assembly 14 in a manner to be made more clear herein. 
Each of the cylinder assemblies 14 includes a substantially cylindrical 
sleeve 32 having a plurality of threads 34 disposed on the upper external 
surface thereof. The sleeve 32 of the cylinder assembly 14 has a radially 
extending fluid inlet port 38 provided therein for a purpose to be more 
clear herein. 
Each of the cylinder assemblies 14 includes a barrel element 42 disposed 
concentrically within and in close-fitting relationship with the interior 
of the sleeve 32. The barrel 42 is an open-ended hollow cylindrical member 
having a bottom or lower impact surface 44 and an open end 46. Internally 
disposed threads 48 are provided adjacent the open end 46 of the barrel 
42. The barrel 42 has a radial fluid inlet port 50 provided therein, the 
port 50 communicating with a circumferentially extending groove 52 
disposed about the interior surface thereof. The fluid inlet ports 38 (in 
the sleeve 32) and 50 (in the barrel 42) register one with the other. 
A flanged cap 54 having a threaded projection 56 thereon is adapted to be 
received within the internal threads 48 provided adjacent the open end 46 
of the barrel 42. The cap 54 has an impact surface 58 thereon and a groove 
59 on the underside of the head thereof. The cooperative association of 
the cap 54, threaded into the barrel 42, defines an enclosed volume 
bounded by the interior surface of the barrel 42, the impact surface 44, 
and the impact surface 58 on the interior of the cylinder assembly 14. 
A free floating piston member 60 having upper and lower impact surfaces 61A 
and 61B, respectively, is provided within the interior volume of the 
cylinder assembly 14. In operation, the piston 60 is adapted to define 
first (upper) and second (lower) volumes 62A and 62B (respectively shown 
in FIGS. 1 and 2) on the interior of the cylinder assembly 14. The piston 
60 includes a first and a second fluid conduit 64A and 64B, respectively. 
The conduit 64A communicates with the upper volume 62A while the conduit 
64B is in fluid communication with the lower volume 62B. 
The intake means 16 associated with each of the cylinder assemblies 14 
comprises the radially registered fluid inlet ports 38 and 50 
communicating with the circumferentially extending groove 52 on the 
interior of the barrel 42 and the fluid conduits 64 disposed within the 
piston 60. As the piston 60 moves within the enclosed volume on the 
interior of the cylinder assembly 14, one or the other of the fluid 
conduits 64 is alternately placed in communication with the groove 52 to 
thereby selectively permit the introduction of a pressurized fluid from 
the interior volume 24 of the manifold member 12 to the interior volumes 
62A and 62B defined by the piston 60 within the cylinder assembly 14. The 
piston reacts to the pressurized fluid within the appropriate one of the 
volumes 62 by displacing within the cylinder to generate an impacting 
force between the corresponding impact surfaces on the piston and the 
cylinder. 
The exhaust means 18 includes first and second passage arrangements 
provided within the barrel 42. With reference to FIGS. 1, 2 and 3, the 
passage arrangements included within the exhaust means may be best 
illustrated. The first passage arrangement includes a first plurality of 
substantially radially extending outlet ports 68 communicating with the 
first (upper) volume 62A (FIG. 1). Each of the fluid outlet ports 68 is in 
communication with one of a set of axially extending channels 70 provided 
on the exterior surface of the barrel 42. The second passage arrangement 
whereby the second (lower) volume 62B (FIG. 2) may be vented to a region 
external to the volume 24 of the manifold member 12 includes a second set 
of substantially radially extending fluid outlet ports 74 each of which 
communicates with a selected one of a plurality of axially extending 
channel 76 provided on the exterior surface of the barrel 42. As best seen 
in FIG. 3, the first passage arrangement (comprising ports 68 and channels 
70) is isolated from and out of fluid communication with the second 
passage arrangement (comprising ports 74 and channels 76). Each of the 
passage arrangements comprising the exhaust means 18 conducts pressurized 
fluid from the respective one of the volumes 62 with which the passage 
arrangements are associated to a region, such as the atmosphere, external 
to the interior volume 24 of the manifold member 12. 
As noted above, in the embodiment of the invention shown in FIGS. 1 and 2, 
the underside of the head of the flanged cap 54 has the circumferential 
groove 59 disposed therein. The groove 59 is in next axial adjacency to 
the ends or termini of the fluid outlet channels 70 and 76. 
Having described a preferred embodiment of the invention the operation 
thereof is next discussed. To level a section of concrete, the concrete 
strike-off vibrator 10 embodying the teachings of this invention is 
disposed, in a quiescent condition across the width of a section of 
concrete to be leveled thereby with the contacting surface 22 disposed in 
contact with the surface to be leveled. Pressurized fluid from the source 
28 thereof is conducted to the pressurized fluid inlet 26 to actuate of 
the strike-off 10. It is noted that a vibrator embodying the teachings of 
this invention utilizes and requires only one connection (usually a 
rubberized hose) between the source 28 of pressurized fluid and the 
manifold member 12. This is in contradistinction to the prior art 
strike-off vibrators which required a rubberized hose connection between 
each individual one of the cylinder assemblies mounted on the vibrator 
with the source of pressurized fluid. As pointed out above, the individual 
connections are disadvantageous in that they have a tendency to become 
loose or separated as well as being unduly complex when effecting 
connections and disconnections. 
As with strike-offs in the prior art, vibratory force is generated and 
imparted to the contacting surface 22 by reaction forces generated by the 
contact of the piston surfaces 61A and 61B contacting respectively against 
the impact surface 58 of the cap 54 and the impact surface 44 of the 
barrel 42. Thus, reciprocal movement of the piston 60 within the volume 
defined on the interior of the cylinder assembly generates collisions 
between the upper and lower surfaces of the piston and the upper and lower 
surfaces of the cylinder. These collisions generate reaction forces which 
are transmitted to the manifold 12 and tend to vibrate the manifold 12 and 
the contacting surface 22 thereof. The vibratory forces generated in the 
manifold are transmitted through the contact surface 22 to level the 
concrete section over which it is disposed. 
Through the provision of the strike off vibrator embodying these teachings, 
it may be appreciated that only one rubberized hose connection or the like 
is required in order to supply pressurized fluid to each of the cylinder 
assemblies. Introduction of pressurized fluid into the interior volume 24 
of the manifold member 12 defines regions of pressurized fluid surrounding 
each cylinder assembly 14. Pressurized fluid is admitted into the volumes 
62A and 62B defined above and below the piston 60 through the intake means 
16 comprising registered fluid ports 38 (in the sleeve 32) and 50 (in the 
barrel 42), the groove 52 (disposed circumferentially about the interior 
surface of the barrel 42) and one or the other of the fluid conduits 64A 
or 64B. Communication of either of the conduits 64A or 64B with the 
circumferential groove 52 serves to admit pressurized fluid from the 
interior volume of the manifold member into the respective one of the 
volumes 62A or 62B with which the conduit 64 is associated. Thus, it may 
be appreciated that the piston 60 is reciprocated within the volume of the 
cylinder assembly 14 so as to generate reaction forces due to the forceful 
contact of the upper or lower surfaces of the piston with the upper and 
lower bounding surfaces of the cylinder. 
Any damping effect generated by the presence of fluid within one or the 
other of the volumes 62 is eliminated by the venting of fluid trapped 
within a volume through the exhaust means 18. The exhaust means 18 
comprises the sets of radial fluid ports 68 and 74 cooperating with the 
sets of channels 70 and 76 defined on the surface of the barrel 42. Thus, 
for example, in an upstroke (shown as movement of the piston 60 from the 
position shown in FIG. 1 to the position shown in FIG. 2), pressurized 
fluid admitted through the intake means 16 and the conduit 64B pressurizes 
the volume 62B urging the piston upwardly (as viewed in FIGS. 1 and 2). In 
order to eliminate the cushioning effect of fluid in the volume 62A as the 
piston 60 moves upwardly, fluid collected within the volume 62A is urged 
radially outwardly through the opposed fluid ports 68 by the approaching 
piston 60 and is conducted by the axially disposed channels 70 to the 
atmosphere or to a region external to the interior volume 24. In like 
manner, in a down stroke (shown as the movement of the piston from the 
position shown in FIG. 2 to the position shown in FIG. 1) pressurized 
fluid admitted through the intake means 16 including the conduit 64A 
pressurizes the volume 62A urging the piston downwardly (as viewed in 
FIGS. 1 and 2). To eliminate the cushioning effect of fluid trapped in the 
volume 62B the portion of the exhaust means 18 including the opposed 
radial ports 74 and substantially axial channels 76 conduct fluid present 
in the lower volume 62B to a region external of the interior volume 24 of 
the manifold 12. 
It thus may be appreciated that a separate intake route is available to 
conduct pressurized fluid from the interior volume 24 into each of the 
volumes 62 disposed above and below the piston 60. Likewise, separate and 
isolated exhaust arrangements are provided to vent the appropriate volume 
62 to a region external to the interior volume 24. The exhaust 
arrangements for the volumes 62 are isolated from communication one with 
the other and with the intake means 16. Further, the ports 68 or 74 
associated with each of the volumes 62 are equiangularly disposed in 
communication with the volume vented thereby to prevent localized cushion 
effects due to the inefficient drainage of pressurized fluid from the 
volume. 
Having described a preferred embodiment of this invention those skilled in 
the art may effect numerous modifications thereto in light of the 
description thereof herein-before recited. It is understood that those 
modifications remain within the contemplation of this invention as defined 
in the appended claims.