US3843147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pallet truck
Assignee: HILL AND CO AB
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Filing: 1972-11-10
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Granted: 1974-10-22
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Expires: 1992-11-10
Abstract
Abstract A pallet truck with a truck-raising piston that may be actuated hydraulically by a two-piston unit in response to one of three selected positions of a handle in a draw-bar simultaneously used for pumping hydraulic fluid into the two-piston unit so as to raise the truck with full power or with reduced power or to set the truck in its quiescent position.
Inventors
- 👤 Y Fredricson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:01
CPC Classifications
B; B62; B62B; B62B3/00; B62B3/04; B62B3/06; B62B3/0618; B62B5/00; B62B5/06; B62B5/063
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
273 words
A pallet truck comprising fork means for supporting a load, wheels mounted at both ends of said fork means for engaging a base, hydrualic jack means in a housing mounted on an axle supporting one of said wheels for raising and lowering said fork means with respect to said base, said jack means including a first piston for engaging said fork means and a two-piston unit having second and third hydraulic pistons for hydraulically actuating said first piston, a change-over device mounted on and within said housing having three pOsitions for controlling operation of said two-piston unit, drawbar means for the truck and handle means in said drawbar means including means for engaging and setting said change-over device to any selected one of its three positions wherein (a) with said change-over device set in its first position hydraulic fluid is unobstructedly supplied by the second and third pistons to the first piston for raising the fork means with full power, (b) with the change-over device set in its second position the hydraulic fluid flow from one of the second and third pistons to the first piston becomes inactive, while the flow of hydraulic fluid from the other of the second and third pistons to the first piston causes the fork means to be raised with reduced power, and (c) with the changeover device set in its third position the hydraulic fluid from the second and third pistons to the first piston becomes inactive concurrently with hydraulic fluid that has previously actuated the first piston having a free outlet so as to unload the first piston for setting the latter in its quiescent position.
Claim 2
Dependent Claim
273 words
A pallet truck comprising fork means for supporting a load, wheels mounted at both ends of said fork means for engaging a base, hydrualic jack means in a housing mounted on an axle supporting one of said wheels for raising and lowering said fork means with respect to said base, said jack means including a first piston for engaging said fork means and a two-piston unit having second and third hydraulic pistons for hydraulically actuating said first piston, a change-over device mounted on and within said housing having three pOsitions for controlling operation of said two-piston unit, drawbar means for the truck and handle means in said drawbar means including means for engaging and setting said change-over device to any selected one of its three positions wherein (a) with said change-over device set in its first position hydraulic fluid is unobstructedly supplied by the second and third pistons to the first piston for raising the fork means with full power, (b) with the change-over device set in its second position the hydraulic fluid flow from one of the second and third pistons to the first piston becomes inactive, while the flow of hydraulic fluid from the other of the second and third pistons to the first piston causes the fork means to be raised with reduced power, and (c) with the changeover device set in its third position the hydraulic fluid from the second and third pistons to the first piston becomes inactive concurrently with hydraulic fluid that has previously actuated the first piston having a free outlet so as to unload the first piston for setting the latter in its quiescent position.
Claim 3
Dependent Claim
31 words
A pallet truck as defined in claim 1, wherein said change-over device is located between the two-piston unit and the first piston and comprises pin means actuated by said handle means.
Claim 4
Dependent Claim
53 words
A pallet truck as defined in claim 2, wherein a valve cooperates with one piston of the two-piston unit, said pin means opening said valve when the change-over device is set to its second position for causing the flow of hydraulic fluid from said one piston to the first piston to become inactive.
Claim 5
Dependent Claim
67 words
A pallet truck as defined in claim 3, wherein said valve comprises a ball engaging second pin means against the bias of spring means with the change-over device in its third position, said second pin means opening a second valve cooperating with the other piston of the two-piston unit for causing the flow of hydraulic fluid from said other piston to the first piston to become inactive.
Claim 6
Dependent Claim
16 words
A pallet truck as defined in claim 4, wherein also said second valve comprises a ball.
Claim 7
Dependent Claim
18 words
A pallet truck as defined in claim 1, wherein pedal means are provided for actuating said two-piston unit.
Claim 8
Dependent Claim
21 words
A pallet truck as defined in claim 1, wherein said draw-bar means cooperate with pedal means for actuating said two-piston unit.
Claim 9
Dependent Claim
38 words
A pallet truck as defined in claim 1, wherein said change-over device is connected to said handle means in said draw-bar means by a transfer rod forming part of said means for engaging and setting the change-over device.
Claim 10
Dependent Claim
22 words
A pallet truck as defined in claim 8, wherein said transfer rod is adjustable to three individual positions in said draw-bar means.
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) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |