1. Field of the Invention
The present invention concerns a jack-hammer, and particularly its structure and the assembly of the various parts thereof.
2. Description of the Prior Art
Basically, a jack-hammer includes a cylindrical body housing having a reciprocating piston therein which is reciprocally moved by the action of compressed air distributed by an oscillating pellet.
Usually, this cylindrical body is made of forged steel and machined so as to obtain:
a guiding hole for guiding the tool or working pick; PA1 a seat located inside the cylinder to limit the forward stroke of the piston; PA1 compressed air distributing channels, one of them leading to the front of the cylinder and the other to the rear of the said cylinder; and PA1 a housing for the compressed air distribution unit, controlled, for example, by a check valve which is itself controlled by a lever pivotally mounted on the jack-hammer handle. PA1 a cylindrical tube which is the body of the device; PA1 a counterbored sleeve, including a central, axial hole; this counterbored sleeve is at least partially fitted lengthwise inside the tube at one end along the axis of the cylindrical tube; PA1 a distributor unit comprising two parts mounted on the opposite end of the tube and closes off the rear end of the tube; PA1 detachable mounts to assemble and lock together the tube, the two distributor parts, a catch or pin and a moulded part fitted around the tube to channel the compressed air flow system; PA1 a casing made of a shock absorbing material and protecting most of the operating areas of the tube, but constructed of a material which is strong enough to form the handle of the machine; and PA1 a piston moving between a stop piece formed by the rear end of the guiding sleeve of the pick or tool and the front wall of a part of the detachable air distribution system. PA1 a relief channel connecting the distributor to the front part of the cylinder by the first insert of the die; and PA1 an air muffler and exhaust chamber communicating with holes provided on the side wall of the cylinder tube by the second insert of the die. PA1 lightness of the device which can operate in any position; PA1 reliability and easy replacement of the distributor, compressed air feeding control unit (the normal check valve being replaced by a swiveling block); and PA1 safety lock of the air through the casing, the elasticity of which allows for the quick removal of the cotter pin.
One of the disadvantages of the above systems is that the machining of such a cylindrical body housing is often complex and this can cause the cost of the jack-hammer to be high.
Furthermore, the access to the various components in the cylindrical body housing is accomplished with difficulty which complicates the maintenance of the jack-hammer in corroding conditions (such as for example, public work sites, mines and the like).
Finally, the cost of the jack-hammer is also increased when equipped with a muffler or noise abatement system as well as with a handle shock absorbing system.
The purpose of this invention is to overcome these disadvantages, and to build a light and economical jack-hammer, and still improve its reliability and efficiency, and greatly facilitate its maintenance. All of these results are achieved by the present invention which provides a new structure adapted to a silent jack-hammer and which provides a shock absorber equiped handle.