US3739862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reciprocating air hammer
Assignee: KENT AIR TOOL Co
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Filing: 1971-08-11
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Granted: 1973-06-19
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Expires: 1991-08-11
Abstract
Abstract The hammer barrel is supported by a rear header and, in turn, supports a front header. A piston is reciprocated in the barrel under the control of a reversible kick valve. The piston drives a tappet and moil which are supported for reciprocation by the front header. The tappet is continually biased to full extended position by a metering cutt-off valve which is subject continually to live air and which can seat to cut off the air supply to the barrel and stop the hammer when the tappet is substantially fully extended. The metering cut-off valve controls the rate of flow of live air so as to prevent excessively violent responses of the piston thereto. The metering cut-off valve is mounted in, and guided by, an air inlet fitting, the two providing a sub-assembly which can be installed as a unit in the rear header of the barrel. An axially free floating rigid stainless steel rod constrains the metering cut-off valve and tappet to coaxial movement together in substantially fixed axially spaced relation and unseats the metering cut-off valve when the tappet is retracted rearwardly by forcing the moil against the work. One end of the rod abuts the metering cut-off valve and the other end abuts the tappet, but the rod is not fixedly attached to either. The rod is supported for axial reciprocation by a bore in the piston and by a fixed rear bushing in the barrel. A valve spool on the tappet closes a vent when the tappet is extended and opens the vent when the tappet is retracted, thereby controlling venting of the barrel bore.
Inventors
- 👤 S Gunning
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:01
CPC Classifications
B; B25; B25D; B25D9/00; B25D9/14
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
271 words
In a reciprocating air hammer: a moil member; a moil driving tappet member; a body supporting the members for reciprocation to extended and retracted positions, respectively; a power cylinder bore coaxial with the tappet member; a power piston in the bore cylinder reciprocable relative to the body and to the tappet member from a retracted starting position to an extended position wherein it delivers a blow on the tappet member, and from the extended position to the starting position; said body having a live air inlet connected with said bore; valve means for successively alternately connecting the bore at one face of the power piston to said inlet for admitting air under pressure for driving the power Piston on its power stroke, and at the opposite face of the power piston for driving the power piston on its return stroke; characterized in that: a metering cut-off valve is connected to the body inlet and is connectable to a source of air pressurized to a predetermined pressure, and is operative in all open positions, to meter the live air admitted to the power cylinder bore by way of the inlet and valve means, in all open positions of the metering valve, to a rate of flow substantially less than that at which the piston would operate if connected to said source for free and unrestricted flow of the pressurized air to said valve means, and for stopping the admission of air to the power cylinder bore while the valve is closed; and means drivingly connect the valve and tappet for opening and closing the valve in fixed relation to the tappet positions.
Claim 2
Dependent Claim
271 words
In a reciprocating air hammer: a moil member; a moil driving tappet member; a body supporting the members for reciprocation to extended and retracted positions, respectively; a power cylinder bore coaxial with the tappet member; a power piston in the bore cylinder reciprocable relative to the body and to the tappet member from a retracted starting position to an extended position wherein it delivers a blow on the tappet member, and from the extended position to the starting position; said body having a live air inlet connected with said bore; valve means for successively alternately connecting the bore at one face of the power piston to said inlet for admitting air under pressure for driving the power Piston on its power stroke, and at the opposite face of the power piston for driving the power piston on its return stroke; characterized in that: a metering cut-off valve is connected to the body inlet and is connectable to a source of air pressurized to a predetermined pressure, and is operative in all open positions, to meter the live air admitted to the power cylinder bore by way of the inlet and valve means, in all open positions of the metering valve, to a rate of flow substantially less than that at which the piston would operate if connected to said source for free and unrestricted flow of the pressurized air to said valve means, and for stopping the admission of air to the power cylinder bore while the valve is closed; and means drivingly connect the valve and tappet for opening and closing the valve in fixed relation to the tappet positions.
Claim 3
Dependent Claim
60 words
The structure according to claim 1 wherein the metering valve includes a valving bore connected to said inlet, and a metering and cut-off valve plug mounted in the valving bore for reciprocation axially thereof, and defining with the valve bore wall a restrictive flow passage operative to restrict the flow through said bore in all open positions of the plug.
Claim 4
Dependent Claim
44 words
The structure according to claim 2 wherein the valve is a separate unit and further includes an inlet fitting, the valving bore is in the fitting, and said fitting, with the valve plug installed therein, is connectable as a subassembly unit to the body.
Claim 5
Dependent Claim
61 words
The structure according to claim 3 wherein the valve plug has a stem and passage means for admitting live air continuously from the inlet end of the fitting to the space behind the plug, and the plug has an annular metering portion coaxial with, and slightly less in diameter than, the portion of the bore in which the plug is reciprocable.
Claim 6
Dependent Claim
125 words
The structure according to claim 1 wherein the tappet includes a stem extending into the power cylinder bore and a spool on the outer end of the stem; the body has an exhaust duct with an inlet port positioned so that it is closed by the spool when the tappet is in a retracted position and is uncovered by the spool when the tappet is in an extended position; said stem has passage means continually connected to the power cylinder bore at the end of the power cylinder bore adjacent to the tappet; and said passage means have an outlet open for communication with said exhaust duct while the tappet is in said extended position and closed while the tappet is in said retracted position.
Claim 7
Dependent Claim
112 words
The structure according to claim 1 wherein the means drivingly connecting the valve and tappet is a rigid rod having axially spaced abutments thereon and being incompressible between said abutments; said rod is free floating relative to the tappet and valve; said valve includes a plug; one of said abutments has an end face abuttable with a complementary abutment surface on said plug and the other of said abutments has a face abuttable with a complementary abutment surface on the tappet; and the distance between said faces closely approximating, but being slightly less than, the distance between the complementary abutment surfaces when the plug is seated and the tappet is fully extended.
Claim 8
Dependent Claim
247 words
In a reciprocating air hammer: a moil member; a moil driving tappet member; a body supporting the members for reciprocation to extended and retracted positions, respectively; a power cylinder bore coaxial with the tappet member; a power piston in the bore cylinder reciprocable relative to the body and to the tappet member from a netracted starting position to an extended position wherein it delivers a blow on the tappet member, and from the extended position to the starting position; valve means for successively alternately connecting the bore at one face of the power piston to said inlet for admitting air under pressure for driving the power piston on its power stroke, and at the opposite face of the power piston for driving the power piston on its return stroke; characterized in that: said body has a live air inlet bore coaxial with, and connected to, the power cylinder bore; a cut-off valve plug is movable in the inlet bore to open and seated positions, respectively; a rigid rod, having axially spaced abutments thereon and being incompressible axially between said abutments, is mounted for free floating movement axially relative to said power cylinder bore; said abutments have abuttable faces facing away from each other endwise of the rod and abuttable, respectively, with complementary abutment surfaces on the plug and tappet, respectively; the distance between said faces closely approximating, but slightly less than, the distance between said surfaces when the plug is seated and the tappet is fully extended.
Claim 9
Dependent Claim
247 words
In a reciprocating air hammer: a moil member; a moil driving tappet member; a body supporting the members for reciprocation to extended and retracted positions, respectively; a power cylinder bore coaxial with the tappet member; a power piston in the bore cylinder reciprocable relative to the body and to the tappet member from a netracted starting position to an extended position wherein it delivers a blow on the tappet member, and from the extended position to the starting position; valve means for successively alternately connecting the bore at one face of the power piston to said inlet for admitting air under pressure for driving the power piston on its power stroke, and at the opposite face of the power piston for driving the power piston on its return stroke; characterized in that: said body has a live air inlet bore coaxial with, and connected to, the power cylinder bore; a cut-off valve plug is movable in the inlet bore to open and seated positions, respectively; a rigid rod, having axially spaced abutments thereon and being incompressible axially between said abutments, is mounted for free floating movement axially relative to said power cylinder bore; said abutments have abuttable faces facing away from each other endwise of the rod and abuttable, respectively, with complementary abutment surfaces on the plug and tappet, respectively; the distance between said faces closely approximating, but slightly less than, the distance between said surfaces when the plug is seated and the tappet is fully extended.
Claim 10
Dependent Claim
58 words
The structure according to claim 7 wherein the body has an exhaust valve with an exhaust port; a valving spool on the tappet is reciprocable therein upon reciprocation of the tappet and is positioned relative to the exhaust port to close the port when the tappet is extended and to open the port when the tappet is retracted.
Claim 11
Dependent Claim
39 words
The structure according to claim 7 wherein the effective area of the plug, at its inlet face, is such that, when seated and subjected to live air, the plug yieldably holds the tappet and moil in fully extended position.
Claim 12
Dependent Claim
12 words
The structure according to claim 7 wherein the rod is stainless steel.
Claim 13
Dependent Claim
86 words
The structure according to claim 7 wherein the effective area of the plug, at its inlet face, is sufficiently greater than the effective area at its outlet face so that, while unseated and subjected to live air, the plug yieldably moves the tappet member and moil member to fully extended position against forces urging the tappet member and moil member toward retracted positions, other than forces of predetermined intensity applied directly by the work to the moil member for driving the moil member toward retracted positions.
Claim 14
Dependent Claim
27 words
The structure according to claim 11 wherein the cut-off valve is also a metering valve which, when open, meters the flow of air to the valve means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |