POUNDER UNITS

Abstract: A pounder unit for attachment to a pounder or scabbler for hard around surfaces, that is to say for dressing stone or like material surfaces by percussion. The unit comprises a frame, a single cylinder, and a tool (6) removably inserted into the cylinder. A piston is completely received in the cylinder and reciprocable for striking the tool. Means are provided for fastening the frame to a pounder. The unit can be fastened in a position so as to project and extend into otherwise-inaccessible corners of the surface under treatment.

Description: TIT E POUNDER UNITS DESCRIPTION TECHNICAL FIELD The invention relates to pounder units for attachment to pounders or scabblers for roughening, abrading or removing projections from hard ground surfaces. DISCLOSURE OF THE INVENTION The invention provides a pounder unit comprising a frame, a single cylinder mounted upon or within the frame, a tool removably inserted into an end of the cylinder, a piston completely received in the cylinder and reciprocable under motive fluid pressure therein for striking the tool, means for fastening the frame to a pounder, and a valve for admitting motive fluid to the cylinder. Preferably, the frame comprises a single casting, and the fastening means bolt holes whereby the unit may be attached to the front surface of a pounder or scabbier. Thus the unit can be made to project from the pounder itself, and thus to extend into corners of the surface under treatment which cannot be reached by the tools of the pounder itself. DRAWINGS Figure 1 is a top plan of a unit according to the invention; Figure 2 is a section YY of Figure 1 omitting the cylinder, tool and piston for clarity; Figure 3 is a section ZZ of Figure 1; and Figure 4 is a truncated section through a cylinder, showing the tool and piston as ' used in the above Figure ■ BEST MODE OF CARRYING OUT THE INVENTION With particular reference to Figures 1 to 3, the unit comprises a single frame casting 20 having a single cylinder 26 (Figure 4) mounted therein by means of a bolt 28. A tool 6 is removably inserted into a (lower) *Lo end of the cylinder 26. A piston 25 is completely received in the cylinder 26 and reciprocable under motive fluid pressure therein for striking the tool 6.. Bolt holes 22 (Figure 2) comprise means for fastening the casting 20 to a pounder (not shown) . A control __ valve 24 is provided for admitting motive fluid to the cylinder 26. An air inlet 10 admits motive fluid into a passage 12 i the casting 20. In the passage 12 is a venturi tube (not shown) below 2o which is a blocked drill hole and above which is a filter 16 through which oil seeps from a reservoir 17. Replenishment of the .oil in the reservoir 17 is effect through an inlet 19. A pressure equalization tube 13 exten _>ds from the inlet end of the passage 12 up into t 25 reservoir 17 through a top plate (not shown) . Air "gU /,, entraining a lubricating mist goes from the passage 12 to an inlet chamber 21 and thence to the control valve 24. The control valve assembly 24 is a conventional clack valve for supplying the motive air alternately to opposite working faces of a piston to cause the piston to reciprocate. The cylinder 26 is inserted downwardly into the frame casting 20, the control valve assembly 24 inserted over it, and the whole retained in position by o the top plate (not shown) . From Figure 4, it can be seen that motive air is directed by the control valve assembly 24 alternately to a pneumatic working, chamber 29 above the piston to drive the piston downwardly, and through a vertical bore 30 and ■ j_5 a radial bore 31 in the cylinder wall to a pneumatic chamber 32 below the piston to raise the piston for a repeat working stroke. At the extremes of piston movement, motive air is exhausted through passages 33,, 34 and 35 in the cylinder wall to an exhaust chamber 36 2o between the cylinder 26 and the frame casting 20, whence it may be directed to a silencer (not shown) or to jets (not shown) arranged to clear away the chippings produced in use. At the downward limitof its travel, when the piston 25 25 has cleared the exhaust passage 33, it impacts a stem 37 ■ of the tool 6. The stem 37 is slidably received in a bush 38 in the cylinder 26, and the tool 6 is retained in the cylinder by means of a beehive spring (not show engaging annular grooves 40 and 41 in the cylinder 26 and the tool 6 respectively. By removal of the beehive springs, the tools 6 can eas be removed from the cylinders 26, for example for replacement when tungsten carbide teeth 42 thereon become worn.

Claims: CLAIMS 1. A pounder unit comprising a frame, a single cylinder mounted upon or within the frame, a tool removably inserted into an end of the cylinder, a piston completely received in the cylinder and reciprocable under motive fluid pressure therein for striking the tool, means for fastening the frame to a pounder, and a valve for admitting motive fluid to the cylinder. 2. A pounder unit according to claim 1 in which the frame comprises a single casting. 3. A pounder unit according to claim 1 or claim 2 in which the fastening means comprises bolt holes. 4. A pounder unit as herein described with reference to the drawings.

Inventors: FURBY J
Applicants: FURBY J, JOAD ENG LTD
Application year: 1979
Main classification: B25D17
IPC codes: B25D17, B28D1