US3908560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Counterbalancing system for a drafting table or the like
Assignee: ONWAY CONSTRUCTION Co LIM
•
Filing: 1973-09-21
•
Granted: 1975-09-30
•
Expires: 1993-09-21
Abstract
Abstract In a drafting table having a fixed support, an arm pivotally connected to the support about a first horizontal axis, and a drawing board pivotally connected to the arm about a second horizontal axis which is spaced from but parallel to the first axis, there is provided a counterbalancing system comprising cam members and spring members operably interconnected with the support, the arm, and the drawing board, the counterbalancing system, within a predetermined range of angular settings of the drawing board about the second horizontal axis and of the arm about the first horizontal axis, substantially counterbalancing the turning moments exerted by the weight of the arm and the drawing board about their respective axes as well as compensating for turning moments exerted about said axes by portions of the counterbalancing system itself.
Inventors
- 👤 George Irwin Horner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:31
CPC Classifications
A; A47; A47B; A47B27/00; A47B27/04; A47B27/06
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
442 words
Apparatus comprising a first member, a second member pivotally connected to the first member about a first horizontal axis, a third member pivotally connected to the second member about a second horizontal axis which is spaced from but parallel to the first axis, a first counterbalancing system between said first and second members, and a second counterbalancing system between said second and third members, each counterbalancing system comprising a counterbalancing cam member having an noncircular cam surface, and a spring biased member which is disposed around the cam surface of the counterbalancing cam member and which acts between the two members which are pivotally connected about the respective horizontal axis, with the counterbalancing cam member being fixed relative to one of said two members and with the spring biased member reacting against the other of said two members, wherein a further cam member having a non-circular cam surface is fixed relative to the third member with the spring biased member of the first counterbalancing system disposed around the cam surface of said further cam member, and wherein said counterbalancing cam of said first system and said further cam member are so configured that, within a predetermined range of angular settings of the third member about thE second horizontal axis and of the second member about the first horizontal axis, the algebraic sum of: (W3 X da) + (Fa X db) + (Fb X dc) is substantially zero, and the algebraic sum of: (W3 X dd) + (W2 X de) + (Fc X df) is substantially zero, in which W3 weight of the third member, W2 weight of the second member, Fa force exerted by the spring biased member of the second counterbalancing system on the counterbalancing cam member thereof, Fb force exerted by the spring biased member of the first counterbalancing system on said further cam member, Fc force exerted by the spring biased member of the first counterbalancing system on the second member, da perpendicular distance of the second horizontal axis from the line of action of W3 through the centre of gravity of the third member, db perpendicular distance of the second horizontal axis from the line of action of Fa, dc perpendicular distance of the second horizontal axis from the line of action of Fb, dd perpendicular distance of the first horizontal axis from the line of action of W3 through the center of gravity of the third member, de perpendicular distance of the first horizontal axis from the line of action of W2 through the centre of gravity of the second member, and df perpendicular distance of the first horizontal axis from the line of action of Fc.
Claim 2
Dependent Claim
442 words
Apparatus comprising a first member, a second member pivotally connected to the first member about a first horizontal axis, a third member pivotally connected to the second member about a second horizontal axis which is spaced from but parallel to the first axis, a first counterbalancing system between said first and second members, and a second counterbalancing system between said second and third members, each counterbalancing system comprising a counterbalancing cam member having an noncircular cam surface, and a spring biased member which is disposed around the cam surface of the counterbalancing cam member and which acts between the two members which are pivotally connected about the respective horizontal axis, with the counterbalancing cam member being fixed relative to one of said two members and with the spring biased member reacting against the other of said two members, wherein a further cam member having a non-circular cam surface is fixed relative to the third member with the spring biased member of the first counterbalancing system disposed around the cam surface of said further cam member, and wherein said counterbalancing cam of said first system and said further cam member are so configured that, within a predetermined range of angular settings of the third member about thE second horizontal axis and of the second member about the first horizontal axis, the algebraic sum of: (W3 X da) + (Fa X db) + (Fb X dc) is substantially zero, and the algebraic sum of: (W3 X dd) + (W2 X de) + (Fc X df) is substantially zero, in which W3 weight of the third member, W2 weight of the second member, Fa force exerted by the spring biased member of the second counterbalancing system on the counterbalancing cam member thereof, Fb force exerted by the spring biased member of the first counterbalancing system on said further cam member, Fc force exerted by the spring biased member of the first counterbalancing system on the second member, da perpendicular distance of the second horizontal axis from the line of action of W3 through the centre of gravity of the third member, db perpendicular distance of the second horizontal axis from the line of action of Fa, dc perpendicular distance of the second horizontal axis from the line of action of Fb, dd perpendicular distance of the first horizontal axis from the line of action of W3 through the center of gravity of the third member, de perpendicular distance of the first horizontal axis from the line of action of W2 through the centre of gravity of the second member, and df perpendicular distance of the first horizontal axis from the line of action of Fc.
Claim 3
Dependent Claim
33 words
Apparatus according to claim 1, wherein the apparatus comprises a drafting table, the first member comprising a fixed support, the second member comprising an arm, and the third member comprising a drawing board.
Claim 4
Dependent Claim
99 words
Apparatus according to claim 1, wherein in the first counterbalancing system the counterbalancing cam member is fixed relative to the first member, one end of the spring biased member being fixed relative to the first member and the other end of the spring biased member being fixed relative to the second member, and wherein in the second counterbalancing system the cam member is fixed relative to the third member, one end of the spring biased member being fixed relative to the second member and the other end of the spring biased member being fixed relative to the third member.
Claim 5
Dependent Claim
60 words
Apparatus according to claim 1, wherein the spring biased member of the first counterbalancing system comprises a flexible member and a coil spring, one end of the flexible member being secured to the counterbalancing cam member of the first counterbalancing system and the other end of the flexible member being connected to said coil spring of the first counterbalancing system.
Claim 6
Dependent Claim
86 words
Apparatus according to claim 4, wherein the spring biased member of the first counterbalancing system further comprises a lever, one end of said lever being pivotally mounted to the second member about a horizontal axis which is spaced from but parallel to said first and second horizontal axes, and the other end of said lever being connected to the coil spring of the first counterbalancing system, with the lever between the ends thereof being in bearing contact with the cam surface of said further cam member.
Claim 7
Dependent Claim
60 words
Apparatus according to claim 16, wherein the spring biased member of the second counterbalancing system comprises a flexible member and a coil spring, one end of said flexible member being secured to the counterbalancing cam member of the second counterbalancing system and the other end of said flexible member being connected to said coil spring of the second counterbalancing system.
Claim 8
Dependent Claim
54 words
Apparatus according to claim 6, wherein the counterbalancing cam member of the second counterbalancing system is constituted by a cam member presentiNg two cam lobes, said one end of said flexible member of the spring biased member of the second counterbalancing system being secured to said cam member between the two cam lobes thereof.
Claim 9
Dependent Claim
103 words
Apparatus according to claim 5, wherein the further cam member is constituted by two spaced, paralell cam member portions each of which presents a portion of the cam surface of said further cam member, the lever of the spring biased member of the first counterbalancing system being partially movable between said two cam member portions, and the lever presenting between the ends thereof freely rotatable bearing rollers which are in bearing contact with said portions of the cam surface presented by said two cam member portions thereby to provide said bearing contact between the lever and the cam surface of said further cam.
Claim 10
Dependent Claim
29 words
Apparatus according to claim 1, wherein an adjustment weight is movably mounted on the third member for adjusting the location of the centre of gravity of the third member.
Claim 11
Dependent Claim
199 words
Apparatus according to claim 1, wherein a first braking mechanism is provided for locking the pivotal connection of the second member relative to the first member about the first horizontal axis, and a second braking mechanism is provided for locking the pivotal connection of the third member relative to the second member about the second horizontal axis, each of said braking mechanisms having an operative condition in which the pivotal connection between the respective members is locked and an inoperative condition in which the pivotal connection between the respective members is unlocked, an actuating member being provided for each of the braking mechanisms with each actuating member being connected to the respective braking mechanism and being movable between a first position in which the respective braking mechanism is in the operative condition thereof and a second position in which the respective braking mechanism is in the operative condition thereof, and a manually operable member being provided for movement of the actuating members between the first and second positions thereof with the manually operable member being selectively locatable for such movement of both actuating members, or of one of the actuating members, or of the other of the actuating members.
Claim 12
Dependent Claim
65 words
Apparatus according to claim 10, wherein the apparatus comprises a drafting table, the first member comprises a fixed support, the second member comprises an arm, and the third member comprises a drawing board, the drawing board having a main under face and a front edge, and the manually operable member being disposed adjacent to said main under face and front edge of the drawing board.
Claim 13
Dependent Claim
66 words
Apparatus according to claim 10, wherein the connections between the actuating members and the respective braking mechanisms are constituted by flexible cables by means of which the respective braking mechanisms may be urged towards one of the conditions consisting of the operative and inoperative conditions thereof, springs biasing the respective braking mechanisms towards the other of the conditions consisting of the respective and inoperative conditions thereof.
Claim 14
Dependent Claim
113 words
Apparatus according to claim 10, wherein each braking mechanism comprises a disc which is mounted on one of the respective members, a bracket which is mounted on the other of the respective members and which has two spaced limbs defining therebetween a slot through which said disc is disposed, and a plug screw-threadedly mounted in one of said limbs and turnable for movement of the plug into and out of secure locking engagement with said disc, the braking mechanism, with said plug in secure locking engagement with said disc, being in the operative condition thereof, and, with said plug out of secure locking engagement with said disc, being in the inoperative condition thereof.
Claim 15
Dependent Claim
31 words
Apparatus according to claim 13, wherein a further plug is screw-threadedly mounted in the the other of said limbs of the bracket for adjustment of the effective width of said slot.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |