US3756423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overload warning apparatus
Assignee: NORTHWEST ENGINEERING Co A CORP OF
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Filing: 1971-12-21
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Granted: 1973-09-04
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Expires: 1991-12-21
Abstract
Abstract An overload warning apparatus for cranes having a vertically angularly movable boom includes a boom radius cam coupled to the boom to be moved w1th changes in the angular elevaton of the boom, an allowable load cam, and adjustable linkages connecting the two cams and connecting the allowable load cam to a pointer. One linkage can be manually adjusted to reflet different actual boom lengths, and another linkage can be manually adjusted to reflect different hoist tackle ratios, so that the pointer will give an indication of the maximum allowable or safe load on the hoist cable. A second pointer is responsive to a load cell which measures the actual load on the hoist cable. Coincidence of the pointers indicates that the maximum allowable or safe load on the hoist cable has been reached.
Inventors
- 👤 R Rathi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:20
CPC Classifications
B; B66; B66C; B66C23/00; B66C23/88; B66C23/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
353 words
An overload warning apparatus for a crane having a boom that is pivoted for angular movement in a vertical plane, a hoist cable working on said boom through a hoist tackle for hoisting loads, and measuring means responsive to the load on said hoist cable, said warning apparatus comprising: a first cam coupled to the boom for movement in response to changes in the angular elevation of said boom, said first cam having a cam surface each point of which represents the working radius of a given boom length at a particular angular elevation of the boom; a second cam having a cam surface each point of which represents the maximum allowable load on said hoist cable corresponding to a given hoist tackle ratio at a particular actual working radius of the boom; a first cam follower riding the cam surface of said first cam and being moved in an amount proportional to changes in the working radius of said given boom length as the elevation of said boom changes; means for modifying the motion of said first cam follower to reflect differences between the actual boom length and said given boom length, and for transmitting the modified motion of said first cam follower to said second cam; a linearly movable second cam follower riding said cam surface of said second cam and being moved in an amount proportional to changes in the maximum allowable load on said hoist cable corresponding to said given tackle ratio at a particular actual working radius of the boom; a linearly movable transmission member spaced from said second cam follower; a link pivotally connecting said second cam follower and said transmission member; means for pivotally mounting said link at different points between said second cam follower and said transmission member corresponding to different hoist tackle ratios; said transmission member being moved in an amount proportiOnal to changes in the maximum allowable hoist cable load corresponding to the actual hoist tackle ratio at a particular actual working radius of the boom; and means for comparing the output of said measuring means with the output of said transmission member.
Claim 2
Dependent Claim
353 words
An overload warning apparatus for a crane having a boom that is pivoted for angular movement in a vertical plane, a hoist cable working on said boom through a hoist tackle for hoisting loads, and measuring means responsive to the load on said hoist cable, said warning apparatus comprising: a first cam coupled to the boom for movement in response to changes in the angular elevation of said boom, said first cam having a cam surface each point of which represents the working radius of a given boom length at a particular angular elevation of the boom; a second cam having a cam surface each point of which represents the maximum allowable load on said hoist cable corresponding to a given hoist tackle ratio at a particular actual working radius of the boom; a first cam follower riding the cam surface of said first cam and being moved in an amount proportional to changes in the working radius of said given boom length as the elevation of said boom changes; means for modifying the motion of said first cam follower to reflect differences between the actual boom length and said given boom length, and for transmitting the modified motion of said first cam follower to said second cam; a linearly movable second cam follower riding said cam surface of said second cam and being moved in an amount proportional to changes in the maximum allowable load on said hoist cable corresponding to said given tackle ratio at a particular actual working radius of the boom; a linearly movable transmission member spaced from said second cam follower; a link pivotally connecting said second cam follower and said transmission member; means for pivotally mounting said link at different points between said second cam follower and said transmission member corresponding to different hoist tackle ratios; said transmission member being moved in an amount proportiOnal to changes in the maximum allowable hoist cable load corresponding to the actual hoist tackle ratio at a particular actual working radius of the boom; and means for comparing the output of said measuring means with the output of said transmission member.
Claim 3
Dependent Claim
120 words
The warning apparatus of claim 1 wherein said first cam follower is linearly movable and wherein said means for modifying and transmitting the motion of said first cam follower comprises: a linearly movable second transmission member spaced from said first cam follower and operatively connected to said second cam; a second link pivotally connecting said second transmission member and said first cam follower; and means for pivotally mounting said second link at different points between said second transmission member and said first cam follower corresponding to different particular lengths of the boom; said second transmission member being thereby moved in an amount proportional to changes in the particular actual working radius of the boom corresponding to the actual length thereof.
Claim 4
Dependent Claim
57 words
The warning apparatus of claim 1 wherein said comparing means includes a first pointer the movement of which is controlled by said measuring means, and a second pointer the movement of which is controlled by said transmission member, the movement of the two pointers into coincidence indicating that the maximum allowable hoist cable load has been reached.
Claim 5
Dependent Claim
74 words
The warning apparatus of claim 1 wherein said link is formed with a number of spaced apertures and said mounting means includes a removable pivot pin and a supporting plate having a horizontal bank of spaced apertures, each aperture in said supporting plate bank cooperating with an aperture in said link to form a number of operative pairs, and said pivot pin being engageable with a selected one of said operative pairs of apertures.
Claim 6
Dependent Claim
121 words
The warning apparatus of claim 2 wherein said second link is formed with a bank of spaced apertures, and said mounting means includes a removable pivot pin and a supporting plate having a horizontal bank of spaced apertures, each aperture in said supporting plate bank cooperating with an aperture in said second link to form a number of operative pairs, said pivot pin being engageable with a selected one of said operative pairs of apertures, and wherein the spacing of the apertures in each bank compensates for changes in actual boom length from the given boom length as well as for changes in boom weight corresponding to said boom length changes, thereby resulting in modified motion of said first cam follower.
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) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |