US3786902A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Load-lifting mechanism for a lift truck
Assignee: OLOFSSON Corp A CORPORATION OF MICHIGAN
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Filing: 1972-05-08
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Granted: 1974-01-22
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Expires: 1992-05-08
Abstract
Abstract A load-lifting mechanism for lift trucks in which an extensible three-stage mast carries a load-lifting carriage and is vertically actuated by a hydraulic ram and associated loadlifting chains. A simple piston and cylinder ram operates to elevate the carriage through a full free lift travel on the upper, inner mast section in the collapsed condition of the mast via a system of two sets of chains and associated lifting bar and lifting bracket. One set of chains is trained over the piston of the ram and coupled at its opposite ends to the lower mast section via the ram cylinder and the lifting bracket which is guided for limited travel on the intermediate mast section. The other set of chains is trained over the lifting bracket and coupled at one end to the inner mast and at its other end to the lifting bar which engages the carriage during free lift thereof and then couples to the stationary outer mast via the ram cylinder during mast extension. A latch system automatically couples the inner and outer mast sections during free lift of the carriage and interconnects the carriage and inner mast section during extension of the mast.
Inventors
- 👤 K Ramsey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:38
CPC Classifications
B; B66; B66F; B66F9/00; B66F9/06; B66F9/075; B66F9/08
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
327 words
An extensible upright multi-stage, load-lifting mast adapted for mounting on a lift truck, said mast comprising first, second and third telescopic mast sections, a carriage mounted on and movable vertically for free lift travel with respect to said third mast section, a ram having cylinder and plunger elements with one of said elements operably connected to said first mast section, a lifting bracket mounted on the movable vertically with respect to said second mast section between upper and lower stops connected to said second mast section, escapement means operable in the upward load lifting mode to latch said third mast section to said first mast section to restrain upward movement of said third mast section during free lift travel of said carriage on said third mast section and to latch said carriage at the upper limit of its free lift travel to said third mast section and to release said third mast from its latched connection to said first mast section in response to upward extension of said second and third mast sections said escapement means in the load lowering mode of said mast being operable to relatch said third and first mast sections upon return thereof to their fully telescoped condition and to release said latched connection of said carriage to said first mast section, first flexible element means coupled to the other one of said ram elements and operably connected to said first mast section and to said bracket, a lifting bar movable vertically with respect to said first mast section, second flexible element means coupled to said bracket and operably connected to said third mast section and to said lifting bar, means releasably supporting said carriage on said lifting bar during the free lift range of travel of said carriage and bar stop means releasably connecting said lifting bar to said first mast section in response to upward movement of said carriage to the upper limit of its free lift travel and vice versa.
Claim 2
Dependent Claim
327 words
An extensible upright multi-stage, load-lifting mast adapted for mounting on a lift truck, said mast comprising first, second and third telescopic mast sections, a carriage mounted on and movable vertically for free lift travel with respect to said third mast section, a ram having cylinder and plunger elements with one of said elements operably connected to said first mast section, a lifting bracket mounted on the movable vertically with respect to said second mast section between upper and lower stops connected to said second mast section, escapement means operable in the upward load lifting mode to latch said third mast section to said first mast section to restrain upward movement of said third mast section during free lift travel of said carriage on said third mast section and to latch said carriage at the upper limit of its free lift travel to said third mast section and to release said third mast from its latched connection to said first mast section in response to upward extension of said second and third mast sections said escapement means in the load lowering mode of said mast being operable to relatch said third and first mast sections upon return thereof to their fully telescoped condition and to release said latched connection of said carriage to said first mast section, first flexible element means coupled to the other one of said ram elements and operably connected to said first mast section and to said bracket, a lifting bar movable vertically with respect to said first mast section, second flexible element means coupled to said bracket and operably connected to said third mast section and to said lifting bar, means releasably supporting said carriage on said lifting bar during the free lift range of travel of said carriage and bar stop means releasably connecting said lifting bar to said first mast section in response to upward movement of said carriage to the upper limit of its free lift travel and vice versa.
Claim 3
Dependent Claim
23 words
The mast as set forth in claim 1 wherein said one ram element comprises a cylinder and said plunger telescopes within said cylinder.
Claim 4
Dependent Claim
43 words
The mast as set forth in claim 2 wherein said plunger constitutes the only movable plunger of said ram and said plunger extends from the upper end of said cylinder, said cylinder being fixed at it lower end to said first mast section.
Claim 5
Dependent Claim
46 words
The mast as set forth in claim 3 wherein said first mast section is adapted to be directly supported on a lift truck to serve as the lowermost section of said mast and is adapted to be restrained against vertical movement relative to the lift truck.
Claim 6
Dependent Claim
23 words
The mast as set forth in claim 1 wherein said mast sections have cooperative roller means providing rolling engagement between said mast sections.
Claim 7
Dependent Claim
136 words
The mast as set forth in claim 1 wherein said escapement means comprises latch means movably mounted on said third section adjacent the upper end thereof, a first actuating means mounted on said carriage and a second actuating means mounted on said first mast section adjacent the upper end thereof, and a latch restraining means mounted on said third mast section adjacent said latch means, said latch restraining means having an over-center relationship with said latch means defining first and second stable over-center positions of said latch means, said latch means being restrained in said first position by interengagement of said second actuator means, said latch means and said latch restraining means, said latch means being maintained in said second position by interengagement of said first actuator means, said latch means and said latch restraining means.
Claim 8
Dependent Claim
147 words
The mast as set forth in claim 6 wherein said latch means comprises a plate having convex surfaces at one end converging to an apex and an oblong slot having its longitudinal axis aligned with said apex, said plate also having side surfaces juxtaposeD to said slot with a notch formed in each of said side surfaces, a retaining pin extending through said slot to capture said plate for loose pivotal motion and limited bodily movement relative to said pin, said restraining means comprising a roller mounted with its axis parallel to said pin and for rolling engagement with said curved surfaces of said plate, said roller being disposed below said pin and aligned therewith in the direction of carriage travel and mast extension, said first and second actuator means each having rounded portions adapted to engage the associated notches and to have limited journalling motion therein.
Claim 9
Dependent Claim
117 words
The mast as set forth in claim 7 wherein said second actuator means comprises an equalizer member pivotally mounted on said first mast section for movement about an axis extending perpendicular to carriage travel and mast extension and perpendicular to the lateral dimension of said mast, said equalizer member carrying first and second latch engaging portions at the opposite ends thereof, said latch means comprising a pair of said plates spaced laterally from one another relative to said third mast section, said first latch engaging portion being adapted to engage the associated notch of one of said plates and said second latch engaging portion being adapted to engage the associated notch of the other of said plates.
Claim 10
Dependent Claim
130 words
The mast as set forth in claim 1 wherein said lifting bracket comprises a generally U-shaped framework having first and second upright sleeves, first and second guide rods mounted on said second mast section spaced laterally on either side of the longitudinal centerline thereof, said rods extending slidably through said sleeves of said bracket, said bracket having side plates disposed in spaced relation on the opposite sides of said ram, and pulley means rotatably mounted on said bracket, said second flexible element means being trained over said bracket pulley means and extending downwardly therefrom with one end of said second flexible element means being affixed to the lower end of said third mast section and the other end of said second flexible element means being connected to said lifting bar.
Claim 11
Dependent Claim
55 words
The mast as set forth in claim 9 wherein said plunger extends upwardly from said cylinder and carries pulley means at the upper end thereof, said first flexible element means being trained over said plunger pulley means and extending downwardly therefrom with one end connected to said cylinder and the other end to said bracket.
Claim 12
Dependent Claim
98 words
The mast as set forth in claim 1 wherein said lifting bar comprises a bar extending laterally of said mast adjacent said ram and said second flexible element means comprises a pair of chains, one connected to each of the opposite ends of said bar, said carriage having a pair of laterally spaced upright struts each having a notch for receiving the associated end of said bar therein, said chains extending through said carriage between and adjacent said upright struts to thereby assist in guiding said bar into releasable carriage lifting engagement in the notches of said carriage.
Claim 13
Dependent Claim
41 words
The mast as set forth in claim 1 wherein said lifting bar and said bar stop means have cooperative interengaging releasable detent means adapted to yieldably retain said lifting bar against said bar stop means when said mast sections are extended.
Claim 14
Dependent Claim
55 words
The mast as set forth in claim 1 wherein said bar stop means is affixed to said ram and oriented relative thereto such that said lifting bar and said second flexible element means exert a restraining force on said ram in the extended condition of the mast tending to resist tilting forces on said ram.
Claim 15
Dependent Claim
51 words
The mast as set forth in claim 13 wherein said second mast section has restraining means interengageable with said ram in the telescoped condition of said mast to thereby support said ram against tilting forces when said lifting bar is disengaged from said bar stop means and is supporting said carriage.
Claim 16
Dependent Claim
46 words
The mast as set forth in claim 14 wherein sAid restraining means comprises hook means secured to said second mast section, and a chain bracket affixed to said ram adapted to releasably engage with said hook means and being connected to said second flexible element means.
Claim 17
Dependent Claim
98 words
The mast as set forth in claim 1 further including a fourth mast section telescopically connected with said first mast section and having a subjacent relationship with said first, second and third mast sections in the extended condition of said mast, said ram having a third element movable relative to said first two mentioned ram elements, flexible element means coupled to said third ram element and operable to extend said first mast section relative to said fourth mast section in response to movement of said third ram element to at least one of said first two ram elements.
Claim 18
Dependent Claim
100 words
The mast as set forth in claim 1 further including a fourth mast section telescopically connected with said first mast section and having a subjacent relationship with said first, second and third mast sections in the extended condition of said mast, pulley means mounted on said first mast section and third flexible element means trained on said pulley means and connected at one end to said second mast section and at the other end to said fourth mast section whereby relative movement of said second and fourth mast sections moves said first mast section relative to said fourth mast section.
Claim 19
Dependent Claim
164 words
An extensible upright multi-stage, loadlifting mast adapted for mounting on a lift truck, said mast comprising a plurality of telescopic mast sections, a carriage mounted on and movable vertically with respect to one of said mast sections, a ram operably connected to said one mast section, a lifting bracket mounted on and movable vertically with respect to said mast between upper and lower stops connected to said mast, flexible element means coupled to said ram and operably connected to said mast and to said bracket, a lifting bar movable vertically with respect to said mast, said flexible element means being coupled to said bracket and operably connected to said mast and to said lifting bar, means releasably supporting said carriage on said lifting bar during travel of said carriage on said one mast section and bar connector means releasably connecting said lifting bar to said ram in response to upward movement of said carriage to a predetermined point in its travel and vice versa.
Claim 20
Dependent Claim
164 words
An extensible upright multi-stage, loadlifting mast adapted for mounting on a lift truck, said mast comprising a plurality of telescopic mast sections, a carriage mounted on and movable vertically with respect to one of said mast sections, a ram operably connected to said one mast section, a lifting bracket mounted on and movable vertically with respect to said mast between upper and lower stops connected to said mast, flexible element means coupled to said ram and operably connected to said mast and to said bracket, a lifting bar movable vertically with respect to said mast, said flexible element means being coupled to said bracket and operably connected to said mast and to said lifting bar, means releasably supporting said carriage on said lifting bar during travel of said carriage on said one mast section and bar connector means releasably connecting said lifting bar to said ram in response to upward movement of said carriage to a predetermined point in its travel and vice versa.
Claim 21
Dependent Claim
41 words
The mast as set forth in claim 18 wherein said lifting bar and said bar connector means have cooperative interengaging releasable detent means adapted to yieldably retain said lifting bar against said bar connector means when said mast sections are extended.
Claim 22
Dependent Claim
54 words
The mast as set forth in claim 18 wherein said bar connector means is connected to said ram and oriented relative thereto such that said lifting bar and said flexible element means exert a restraining force on said ram in the extended condition of the mast tending to resist tilting forces on said ram.
Claim 23
Dependent Claim
53 words
The mast as set forth in claim 20 wherein another one of said mast sections has restraining means interengageable with said ram in the telescoped condition of said mast to thereby support said ram against tilting forces when said lifting bar is disengaged from said bar connector means and is supporting said carriage.
Claim 24
Dependent Claim
45 words
The mast as set forth in claim 21 wherein said restraining means comprises hook means secured to said other mast section, and a chain bracket affixed to said ram adapted to releasably engage with said hook means and being connected to said flexible element means.
Claim 25
Dependent Claim
268 words
An extensible upright multi-stage, load-lifting mast adapted for mounting on a lift truck, said mast comprising a plurality of mast sections, a carriage mounted on and movable vertically for travel with respect to one of said mast sections, a ram operably connected to another of said mast sections, a lifting bracket mounted on and movable vertically with respect to said mast between upper and lower stops connected to said mast, escaPement means operable in the upward load lifting mode to latch said one mast section to said other section of said mast to restrain upward movement of said one mast section during travel of said carriage thereon and to latch said carriage to said one mast section and to release said one mast from its latched connection to said other mast section in response to upward extension of said mast, said escapement means in the load lowering mode of said mast being operable to relatch said one and other mast sections upon return thereof to telescoped condition and to release said latched connection of said carriage to said one mast section, flexible elements means coupled to said ram and operably connected to said mast and to said bracket, a lifting bar movable vertically with respect to said mast, said flexible element means being coupled to said bracket and operably connected to said mast and to said lifting bar, means releasably supporting said carriage on said lifting bar during travel of said carriage and bar stop means releasably connecting said lifting bar to said mast in response to latching said carriage to said one mast section and vice versa.
Claim 26
Dependent Claim
268 words
An extensible upright multi-stage, load-lifting mast adapted for mounting on a lift truck, said mast comprising a plurality of mast sections, a carriage mounted on and movable vertically for travel with respect to one of said mast sections, a ram operably connected to another of said mast sections, a lifting bracket mounted on and movable vertically with respect to said mast between upper and lower stops connected to said mast, escaPement means operable in the upward load lifting mode to latch said one mast section to said other section of said mast to restrain upward movement of said one mast section during travel of said carriage thereon and to latch said carriage to said one mast section and to release said one mast from its latched connection to said other mast section in response to upward extension of said mast, said escapement means in the load lowering mode of said mast being operable to relatch said one and other mast sections upon return thereof to telescoped condition and to release said latched connection of said carriage to said one mast section, flexible elements means coupled to said ram and operably connected to said mast and to said bracket, a lifting bar movable vertically with respect to said mast, said flexible element means being coupled to said bracket and operably connected to said mast and to said lifting bar, means releasably supporting said carriage on said lifting bar during travel of said carriage and bar stop means releasably connecting said lifting bar to said mast in response to latching said carriage to said one mast section and vice versa.
Claim 27
Dependent Claim
21 words
The mast as set forth in claim 23 wherein said ram comprises a cylinder and a plunger telescopable within said cylinder.
Claim 28
Dependent Claim
32 words
The mast as set forth in claim 24 wherein said plunger extends from the upper end of said cylinder, said cylinder being fixed at its lower end to said one mast section.
Claim 29
Dependent Claim
46 words
The mast as set forth in claim 25 wherein said other mast section is adapted to be directly supported on a lift truck to serve as the lowermost section of said mast and is adapted to be restrained against vertical movement relative to the lift truck.
Claim 30
Dependent Claim
155 words
In a lift truck mast having relatively movable load-lifting means and escapement means for releasably interconnecting said load-lifting means, the improvement comprising latch means movably mounted for pivotal and bodily movement on a first one of said mast load-lifting means, a first actuating means mounted on a second one of said load lifting means and a second actuating means mounted on a third one of said load lifting means, and a latch restraining means mounted on said first lifting means adjacent said latch means, said latch restraining means having an over-center relationship with said latch means defining first and second stable over-center positions of said latch means, said latch means being restrained in said first position by interengagement of said second actuator means, said latch means and said latch restraining means, said latch means being maintained in said second position by interengagement of said first actuator means, said latch means and said latch restraining means.
Claim 31
Dependent Claim
155 words
In a lift truck mast having relatively movable load-lifting means and escapement means for releasably interconnecting said load-lifting means, the improvement comprising latch means movably mounted for pivotal and bodily movement on a first one of said mast load-lifting means, a first actuating means mounted on a second one of said load lifting means and a second actuating means mounted on a third one of said load lifting means, and a latch restraining means mounted on said first lifting means adjacent said latch means, said latch restraining means having an over-center relationship with said latch means defining first and second stable over-center positions of said latch means, said latch means being restrained in said first position by interengagement of said second actuator means, said latch means and said latch restraining means, said latch means being maintained in said second position by interengagement of said first actuator means, said latch means and said latch restraining means.
Claim 32
Dependent Claim
147 words
The mast as set forth in claim 27 wherein said latch means comprises a plate having convex surfaces at one end converging to an apex and an oblong slot having its longitudinal axis aligned with said apex, said plate also having side surfaces juxtaposed to said slot with a notch formed in each of said side surfaces, a retaining pin extending through said slot to capture said plate for loose pivotal motion and limited bodily movement relative to said pin, said restraining means comprising a roller mounted with its axis parallel to said pin and for rolling engagement with said curved surfaces of said plate, said roller being disposed below said pin and aligned therewith in the direction of carriage travel and mast extension, said first and second actuator means each having rounded portions adapted to engage the associated notches and to have limited journalling motion therein.
Claim 33
Dependent Claim
117 words
The mast as set forth in claim 28 wherein said second actuator means comprises an equalizer member pivotally mounted on said third lifting means for movement about an axis extending perpendicular to carriage travel and mast extension and perpendicular to the lateral dimension of said mast, said equalizer member carrying first and second latch engaging portions at the opposite ends thereof, said latch means coMprising a pair of said plates spaced laterally from one another relative to said one lifting means, said first latch engaging portion being adapted to engage the associated notch of one of said plates and said second latch engaging portion being adapted to engage the associated notch of the other of said plates.
References Cited (Backward Citations)
US2502465A
Cited
US2987140A
Cited
US3051265A
Cited
US3221840A
Cited
US3269561A
Cited
US3338335A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |