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US3820631A
Expired / Lapsed
US
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Platform lift mechanism
Assignee: PEARNE & LACY MACHINE COMPANY INC A CORP OF N C
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Filing: 1973-03-08
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Granted: 1974-06-28
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Expires: 1993-03-08
Abstract
Abstract A work platform or cargo loader having a mobile base and a vertically translatable platform associated with the base is disclosed. The platform is connected to the base for translation by a linkage which includes a first pair of parallel struts each pivoted at one end to the base and pivoted at the other end to the platform so as to form acute angles with the base and platform. A second pair of parallel struts is provided with each strut pivoted at one end to the base and at the other end to the platform so as to form acute angles with the base and platform. Adjacent, non-parallel struts are pivotally connected to each other, and the pivoted mid-portion of each strut includes oppositely directed, fluid power cylinders each having a ram mounted therein so that the struts are extensible along their axes. Each ram is mechanically interlocked to each other ram to ensure substantially identical values of incremental movement among the rams even if the platform is unequally loaded.
Inventors
- 👤 T King
- 👤 F Pearne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:19
CPC Classifications
E; E04; E04G; E04G1/00; E04G1/18; E04G1/22; B; B66; B66F; B66F11/00; B66F11/04; B66F11/042
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
111 words
A lift mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts having components which are linearly movable relative to each other to raise and lower the platform, power means to move said components, said power means including means to mechanically interlock the components of each strut to each other, to mechanically interlock those components to the components of the other strut, and to mechanically ensure substantially identical values of incremental movement among all of said components.
Claim 2
Dependent Claim
111 words
A lift mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts having components which are linearly movable relative to each other to raise and lower the platform, power means to move said components, said power means including means to mechanically interlock the components of each strut to each other, to mechanically interlock those components to the components of the other strut, and to mechanically ensure substantially identical values of incremental movement among all of said components.
Claim 3
Dependent Claim
70 words
A lift mechanism according to claim 1, wherein said means to mechanically interlock the strut components includes first rotatable means connecting the components of one of said struts, and second rotatable means connecting the components of the other strut, shaft means connecting said first and second rotatable means so that said first and second rotatable means are rotatable in equal angular increments as said components move relative to each other.
Claim 4
Dependent Claim
101 words
A lift mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts having components which are linearly movable relative to each other to raise and lower the platform, each strut having gear means to move said components, means to interlock the components of each strut to the components of each other strut to ensure substantially identical values of incremental movement between or among all of said components.
Claim 5
Dependent Claim
101 words
A lift mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts having components which are linearly movable relative to each other to raise and lower the platform, each strut having gear means to move said components, means to interlock the components of each strut to the components of each other strut to ensure substantially identical values of incremental movement between or among all of said components.
Claim 6
Dependent Claim
47 words
A lift mechanism according to claim 3, wherein each of said struts includes a central section pivotally connected to the central section of the other strut included in said pair and wherein said pivotally connected strut ends are components linearly movable with respect to said central sections.
Claim 7
Dependent Claim
15 words
A lift mechanism according to claim 4, wherein two pairs of crossed struts are provided.
Claim 8
Dependent Claim
134 words
A lift Mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts comprising a centrally located housing and a pair of oppoitely directed cylinders axially extending in opposite directions from said housing, a piston in each cylinder defining a pressure chamber with said cylinder, means to admit fluid pressure to each pressure chamber to move said piston relative to said cylinders, means to mechanically interlock the pistons of each strut to each other, to mechanically interlock those pistons to the pistons of the other strut, and to mechanically ensure substantially identical values of incremental movement among all of said pistons.
Claim 9
Dependent Claim
134 words
A lift Mechanism comprising a base, a support platform above said base, a pair of crossed struts angularly related to each other and pivotally connected at one end to the base and pivotally connected at their other ends to the support platform, each of said struts comprising a centrally located housing and a pair of oppoitely directed cylinders axially extending in opposite directions from said housing, a piston in each cylinder defining a pressure chamber with said cylinder, means to admit fluid pressure to each pressure chamber to move said piston relative to said cylinders, means to mechanically interlock the pistons of each strut to each other, to mechanically interlock those pistons to the pistons of the other strut, and to mechanically ensure substantially identical values of incremental movement among all of said pistons.
Claim 10
Dependent Claim
73 words
A lift mechanism according to claim 6, wherein said means to mechanically interlock said pistons comprises a screw shaft threadedly associated with each piston and being rotatable upon movement of said piston, each shaft extending into said housing and having a miter gear fixed thereto, a cross shaft extending through each housing and having a miter gear in each housing cooperating with the miter gears associated with the end of each screw shaft.
Claim 11
Dependent Claim
31 words
A platform lift mechanism according to claim 7, wherein a brake means is provided on said cross shaft to positively lock said pistons in a predetermined position relative to said cylinders.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |