Patent US3636995A successfully refreshed from Google Patents.
US3636995A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tensioner for saw chain
Assignee: Textron Inc
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Filing: 1970-07-02
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Granted: 1972-01-25
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Expires: 1990-07-02
Abstract
Abstract A chain saw is provided with means for tensioning the cutting chain to compensate for wear and thermal expansion during operation. The chain guide bar is slidably mounted on the chain saw frame so as to be movable longitudinally toward and away from the chain-driving sprocket. A spring-operated cam rotatably mounted on the frame engages a pin on the guide bar to move it in a direction away from the driving sprocket and thereby tighten the chain. The cam has a generally spiral cam contour with equally spaced cusps and intervening concavities.
Inventors
- 👤 Albert K Newman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:33
CPC Classifications
B; B27; B27B; B27B17/00; B27B17/14; B27B17/142
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
178 words
In a chain saw having a frame and a chain-driving sprocket, the combination of a chain guide bar, means mounting said guide bar on said frame in alignment with said sprocket for movement in a longitudinal direction toward and away from said sprocket, an endless chain running on said guide bar and sprocket and driven by said sprocket, and means for automatically tensioning said chain to proper operating tension, said tensioning means comprising an abutment on said guide bar, a cam movably mounted on said frame and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide bar in a direction away from said sprocket to tension said chain upon movement of said cam in a forward direction, and spring means for moving said cam in a forward direction to tighten said chain, said cam contour having alternate high and low increments engageable with said abutment to arrest forward movement of said cam when the chain is under proper tension and to resist movement of said cam in a reverse direction.
Claim 2
Dependent Claim
178 words
In a chain saw having a frame and a chain-driving sprocket, the combination of a chain guide bar, means mounting said guide bar on said frame in alignment with said sprocket for movement in a longitudinal direction toward and away from said sprocket, an endless chain running on said guide bar and sprocket and driven by said sprocket, and means for automatically tensioning said chain to proper operating tension, said tensioning means comprising an abutment on said guide bar, a cam movably mounted on said frame and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide bar in a direction away from said sprocket to tension said chain upon movement of said cam in a forward direction, and spring means for moving said cam in a forward direction to tighten said chain, said cam contour having alternate high and low increments engageable with said abutment to arrest forward movement of said cam when the chain is under proper tension and to resist movement of said cam in a reverse direction.
Claim 3
Dependent Claim
27 words
A combination according to claim 1, in which said cam contour of said cam comprises a series of spaced cusps alternating with concave curves between said cusps.
Claim 4
Dependent Claim
41 words
A combination according to claim 2, in which said abutment comprises a round pin fixed on said guide bar and in which said concave curves of said cam contour have a radius of curvature slightly greater than that of said pin.
Claim 5
Dependent Claim
41 words
A combination according to claim 1, in which said guide bar is provided with a plurality of spaced holes at different distances from said sprocket and in which said abutment comprises a pin removably fixed selectively in one of said holes.
Claim 6
Dependent Claim
38 words
A combination according to claim 1, in which said cam is rotatably mounted and has a generally spiral contour, said spring means comprising a spiral spring acting on said cam to rotate it about its axis of rotation.
Claim 7
Dependent Claim
85 words
A combination according to claim 5, in which said cam contour comprises a series of spaced cusps and concave arcs between said cusps, the distance between said cusps and the axis of rotation of said cam progressively increasing from one terminus of said cam contour to the other, said cusps being substantially equally spaced along said cam contour and the included angles between said cusps with apices at said axis of rotation progressively decreasing with increase of the distance between said cusps and said axis.
Claim 8
Dependent Claim
24 words
A combination according to claim 1, comprising manually operable means for moving said cam in a reverse direction and thereby tensioning said spring means.
Claim 9
Dependent Claim
30 words
A combination according to claim 7, in which said cam is fixed on a rotatable shaft and in which said manually operable means comprises a knob fixed on said shaft.
Claim 10
Dependent Claim
142 words
A combination according to claim 1, in which said guide bar has a longitudinally extending slot in an end portion adjacent said sprocket and in which said mounting means comprise an elongated block received in said slot, said block having a width slightly less than the width of said slot, a length less than the length of said slot by an amount at least equal to the desired range of longitudinal movement of said guide bar and a thickness slightly greater than the thickness of sAid guide bar, guide plates on opposite sides of said block and said guide bar, said block spacing said plates apart a distance slightly greater than the thickness of said guide bar and means securing said plates and said block together, said block and plates firmly supporting said guide bar for free longitudinal movement by said cam.
Claim 11
Dependent Claim
156 words
In a chain saw having a frame and a chain-driving sprocket, the combination of a chain guide bar means mounting said guide bar on said frame in alignment with said sprocket for free movement in a longitudinal direction toward and away from said sprocket, an endless chain running on said guide bar and sprocket and driven by said sprocket, and means for tensioning said chain to proper operating tension, said tensioning means comprising an abutment on said guide bar, a cam movably mounted on said frame and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide bar in a direction away from said sprocket to tension said chain upon movement of said cam in a forward direction and means for progressively moving said cam in a forward direction to tighten said chain and compensate for progressive increase in length of said chain through wear and increase of temperature.
Claim 12
Dependent Claim
156 words
In a chain saw having a frame and a chain-driving sprocket, the combination of a chain guide bar means mounting said guide bar on said frame in alignment with said sprocket for free movement in a longitudinal direction toward and away from said sprocket, an endless chain running on said guide bar and sprocket and driven by said sprocket, and means for tensioning said chain to proper operating tension, said tensioning means comprising an abutment on said guide bar, a cam movably mounted on said frame and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide bar in a direction away from said sprocket to tension said chain upon movement of said cam in a forward direction and means for progressively moving said cam in a forward direction to tighten said chain and compensate for progressive increase in length of said chain through wear and increase of temperature.
Claim 13
Dependent Claim
23 words
A combination according to claim 10, in which said cam contour comprises a plurality of spaced cusps with intervening concavities between said cusps.
Claim 14
Dependent Claim
20 words
A combination according to claim 10, in which said cam is rotatably mounted and said cam contour is generally spiral.
Claim 15
Dependent Claim
31 words
A combination according to claim 12, in which said cam is fixed on a rotatable shaft and means for rotating said cam comprises a manually operable knob fixed on said shaft.
Claim 16
Dependent Claim
137 words
In combination with an endless chain running over a driving sprocket and guide means which is movable toward and away from said driving sprocket to vary the tension of said chain, chain-tensioning means comprising a support, an abutment on said guide means, a cam movably mounted on said support and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide means in a direction to tension said chain upon movement of said cam in a forward direction, and spring means for moving said cam in a forward direction to tighten said chain, said cam contour having alternate high and low increments engageable with said abutment to arrest forward movement of said cam when the chain is under proper tension and to resist movement of said cam in a reverse direction.
Claim 17
Dependent Claim
137 words
In combination with an endless chain running over a driving sprocket and guide means which is movable toward and away from said driving sprocket to vary the tension of said chain, chain-tensioning means comprising a support, an abutment on said guide means, a cam movably mounted on said support and engaging said abutment, said cam having a cam contour for moving said abutment and hence said guide means in a direction to tension said chain upon movement of said cam in a forward direction, and spring means for moving said cam in a forward direction to tighten said chain, said cam contour having alternate high and low increments engageable with said abutment to arrest forward movement of said cam when the chain is under proper tension and to resist movement of said cam in a reverse direction.
Claim 18
Dependent Claim
23 words
Chain-tensioning means according to claim 14, in which said cam contour comprises a series of spaced cusps alternating with concavities between said cusps.
Claim 19
Dependent Claim
29 words
Chain-tensioning means according to claim 15, in which said cam is rotatable and said cam contour is generally spiral, said spring means acting on said cam to rotate it.
References Cited (Backward Citations)
US2316997A
Cited
US3457970A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-24 | 1975-07-26 | 1976-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-24 | 1979-07-26 | 1980-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-24 | 1983-07-26 | 1984-01-25 | $7700.00 | Window Closed / Lapsed |