US3710873A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impact wrench or screwdriver
Assignee: Air Compressors and Tools Ltd
•
Filing: 1970-12-07
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Granted: 1973-01-16
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Expires: 1990-12-07
Abstract
Abstract A pneumatically operated hand-held impact wrench or screwdriver having a hammer member which reciprocates against the action of a spring, said spring being adjustable to vary the value of maximum torque at which the tool operates.
Inventors
- 👤 M Allen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:55
CPC Classifications
B; B25; B25B; B25B23/00; B25B23/14; B25B23/145; B25B23/1453
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
152 words
A pneumatically operated hand-held impact wrench or screwdriver comprising a hammer member which is supported upon a driving shaft for reciprocating movement against the action of a compression spring to cause cyclic engagement and disengagement of hammers upon the hammer member with anvils associated with the driven shaft, and which, when the amplitude of reciprocating movement becomes increased as the torque developed by the tool reaches a predetermined maximum value of torque, operates a valve which interrupts the supply of air to a motor driving the tool, to stop the latter, to prevent a predetermined maximum value of torque being exceeded, characterized in that means are provided for varying the force exerted by said compression spring to vary the value of torque at which the valve is operated when torque is applied by the tool to a fastener by means of a torsion bar attached to the output shaft of the tool.
Claim 2
Dependent Claim
152 words
A pneumatically operated hand-held impact wrench or screwdriver comprising a hammer member which is supported upon a driving shaft for reciprocating movement against the action of a compression spring to cause cyclic engagement and disengagement of hammers upon the hammer member with anvils associated with the driven shaft, and which, when the amplitude of reciprocating movement becomes increased as the torque developed by the tool reaches a predetermined maximum value of torque, operates a valve which interrupts the supply of air to a motor driving the tool, to stop the latter, to prevent a predetermined maximum value of torque being exceeded, characterized in that means are provided for varying the force exerted by said compression spring to vary the value of torque at which the valve is operated when torque is applied by the tool to a fastener by means of a torsion bar attached to the output shaft of the tool.
Claim 3
Dependent Claim
57 words
An impact wrench or screwdriver as claimed in claim 1 in which the compression spring is a helical spring which surrounds the driving shaft and engages either directly or indirectly at one end the hammer member and at the other end a ring having an internal thread which cooperates with the corresponding thread upon the driving shaft.
Claim 4
Dependent Claim
52 words
An impact wrench or screwdriver as claimed in claim 2 in which the ring has a bevel gear thereon which is engageable with a bevel gear on a key insertable from the exterior of the tool to rotate said ring to adjust the value of torque at which the value is operated.
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) | 1976-01-16 | 1976-07-17 | 1977-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-16 | 1980-07-17 | 1981-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-16 | 1984-07-17 | 1985-01-16 | $7700.00 | Window Closed / Lapsed |