US4403551A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pneumatically propelled duct motor
Assignee: Post Office
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Filing: 1980-08-20
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Granted: 1983-09-13
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Expires: 2000-08-20
Abstract
Abstract A duct motor for carrying drawing ropes and the like through cable ducts consists of two inflatable gripper bags and a telescopic section. The duct motor is driven by compressed air, and operates by one gripper bag inflating, telescopic section extending, the other gripper bag inflating and the one gripper bag deflating, telescopic section contracting and the cycle being repeated. Compressed air is distributed within the duct motor by a distribution valve and a pair of inflation and deflation valves associated with each gripper bag. One distribution valve is not located between the gripper bags and this valve has a valve stem which is hollow, and is used for conveying compressed air from an input orifice to the remote end of the duct motor i.e. the other gripper bag.
Inventors
- 👤 John R. Slight
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:38
CPC Classifications
H; H02; H02G; H02G1/00; H02G1/06; H02G1/08; H02G1/088
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
289 words
Apparatus for self-propulsion along a duct comprising, in combination, first and second inflatable gripping bags and a telescopic fluid pressure operated unit interconnected between said gripping bags, said unit including a piston and cylinder arranged to extend and contract said telescopic unit, an inflation valve and a deflation valve connected to each of said gripping bags, a distribution valve connected to said telescopic unit for controlling the direction of movement of said unit, said distribution valve connected to a source of compressed air, said distribution valve connected to each of said inflation valve of said first and second gripping bags, said first gripping bag extending to grip said duct upon the actuation of said distribution valve and said inflation valve of said first gripper bag contemporaneous with the actuation of the deflation valve of said second gripper bag, said distribution valve connected to said telescopic unit for expanding said unit to move said second gripper bag along said duct, said distribution valve connected to said inflation valve at said second gripper bag for expanding said second gripper bag into engagement with said duct contemporaneous with the actuation of the deflation valve of said first gripper bag, said distribution valve connected to said telescopic member for contracting same and moving said first gripper bag along said duct towards said second gripper bag, said distribution valve having a hollow valve stem associated therewith, said piston having a piston head connected to a hollow piston rod, said hollow valve stem extending through said piston head into said piston rod whereby said compressed air may be fed to said second gripper bag, said distribution valve being located coaxially with and on a side of said first gripper bag remote from said telescopic member.
Claim 2
Dependent Claim
289 words
Apparatus for self-propulsion along a duct comprising, in combination, first and second inflatable gripping bags and a telescopic fluid pressure operated unit interconnected between said gripping bags, said unit including a piston and cylinder arranged to extend and contract said telescopic unit, an inflation valve and a deflation valve connected to each of said gripping bags, a distribution valve connected to said telescopic unit for controlling the direction of movement of said unit, said distribution valve connected to a source of compressed air, said distribution valve connected to each of said inflation valve of said first and second gripping bags, said first gripping bag extending to grip said duct upon the actuation of said distribution valve and said inflation valve of said first gripper bag contemporaneous with the actuation of the deflation valve of said second gripper bag, said distribution valve connected to said telescopic unit for expanding said unit to move said second gripper bag along said duct, said distribution valve connected to said inflation valve at said second gripper bag for expanding said second gripper bag into engagement with said duct contemporaneous with the actuation of the deflation valve of said first gripper bag, said distribution valve connected to said telescopic member for contracting same and moving said first gripper bag along said duct towards said second gripper bag, said distribution valve having a hollow valve stem associated therewith, said piston having a piston head connected to a hollow piston rod, said hollow valve stem extending through said piston head into said piston rod whereby said compressed air may be fed to said second gripper bag, said distribution valve being located coaxially with and on a side of said first gripper bag remote from said telescopic member.
Claim 3
Dependent Claim
22 words
A duct motor as claimed in claim 1 wherein each deflation and each inflation valve are operated by a single return spring.
Claim 4
Dependent Claim
18 words
A duct motor as claimed in claim 1 wherein said distribution valve is provided with "O" ring seals.
Claim 5
Dependent Claim
45 words
A duct motor as claimed in claim 1 or claim 3 wherein said telescopic member interconnecting said two gripper bags is resistant to bending in a direction transverse to a common axis of said two bags, said bags being located substantially on said common axis.
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) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |