US 2514626 A
Description (OCR text may contain errors)
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v sMooTx-'IING RIFINISHING TRowEx.
Filed sept. 22, 1947 1 Inventor By.V
Patented July 11, 1950 2,514,626 SMOOTHING OR FINISHING TROWEL Samuel Clipson, London, England Application September 22, 1947, Serial No. 775,556 In Great Britain October 4, 1946 3 Claims.
This invention relates to hand trowels or screeds, particularly for use in finishing or smoothing the surfaces of slurries applied to walls, ceilings and the like.
I h'ave found that with certain so-called wallsurfacing compositions, a better finish is obtained by subjecting the hand screed when in use to a rapid vibratory motion.
Accordingly, the invention provides, as a new article of manufacture, a hand screed incorporating pressure fluid operated means whereby it can be subjected to transverse vibration while being manipulated over the surface to be finished or smoothed.
Preferably, the said pressure uid operated means comprises a plunger-type vibrator fixed on the blade of the screed, the plunger of the vibrator working in a cylinder suitably ported for the supply of motive fluid and for the exhaust of the expanded fluid as required to set up rapid vibration by repeated impact of the plunger against the ends of the cylinder.
The screed proper may be of any desired size and cross-sectional shape (fiat, arcuate and so forth).
One form of vibrating hand screed is illustrated on the accompanying drawing, on which:
Fig. 1 is a face view of the screed;
Fig. 2 is a corresponding end view; and
Fig. 3 shows the vibrator in longitudinal section on line III-III of Fig. 2.
The screed blade I is secured to a bent metal strap 2 by a bolt 3 and nut 4, and the strap is secured by a bolt 5 and nut 6 to the cylinder 1 of a. plunger type vibrator. An elongated handle 8 for holding and manipulating the screed is secured by bolts 9 and nuts I0 to a yoke I I which is also secured to the vibrator cylinder 1 by means of the bolt 5 and nut 6.
As shown in Fig. 3 the barrel of the vibrator cylinder 1 is stepped as also is the plunger I2` therein. A connection I3 for pressure air opens into the part of the barrel of larger diameter. Further, this part of the barrel has a series of exhaust ports I4, while the part of smaller diameter has a series oi.' exhaust ports I5. The plunger I2 Ihas an axial passage I6 open to its larger end and communicating with radial ports I'I opening to the periphery oi.' its smaller part.
When pressure iluid is admitted via I3 it first moves the plunger to the left in Fig. 3, air in the larger part of the barrel then exhausting via ports I4. As the plunger reaches the end of this stroke these ports are closed and pressure air passes via ports I1 and passage I6 to the larger end of the plunger to return the plunger. During the return stroke air in advance of the plunger is exhausted via ports I5. Thus, the plunger is rapidly reciprocated so long as pressure air is supplied to the connection I3.
This rapid reciprocation of the plunger I2 vibrates the cylinder 1 and therefore the screed so that the working surface Ia of blade I is subjected to a tamping action whilst it is manipulated over the surface to be smoothed or finished. This movement produces coacting cornponents of forces that are effective in establishing both an impacting action and a smoothing action through the trowel blade on the surface being treated.
Reference 'is made to my copendng patent application Serial Number 775,555, filed September 22, 1947 for Compositions for Surfacing Walls, Ceilings and the Like, for an explanation of the compositions with which the smoothing or iinishing trowel of my invention is employed. Reference is also made to my copending application Serial Number 6,233 led February 4, 1948 and patented as Patent No. 2,504,805, for Method and Apparatus for Applying Slurries to Structural Surfaces, for information regarding the appli cator and method of employing the same.
l. A hand screedl for use in finishing the surface of slurries applied to structural surfaces comprising in combination a cylinder, a bracket having an angularly inturned portion attached at one end to said cylinder, an elongated trowel blade secured to the inturned portion of said bracket, a working surface on said trowel blade, a handle secured to the side of said cylinder opposite said bracket, a reciprocating piston in said cylinder, and means for rapidly reciprocating said piston whereby rapid Vibratory pulses are transmitted to said trowel blade in the direction of movement of the piston and with a component normal to the working surface of the trowel blade.
2. A hand screed as set forth in claim 1 in which said handle is secured to the side of said cylinder through a yoke that extends at an angle with respect to the axis of said housing.
3. A hand screed as set forth in claim 1 in which said handle is constituted by a transversely extending bar projecting substantially parallel to the axis of said trowel blade.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS