# US 10,479,663 B2 · Forklift trucks and masts therefore > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,479,663 B2 - Document ID: US10479663B2 - Status: Granted - Kind: B2 - Application number: 15/267,518 - Filed: 2016-09-16 - Published: 2017-03-16 - Granted: 2019-11-19 - Earliest claimed: 2015-09-16 - Assignees: Hyster-Yale Group, Inc. - Applicants: Hyster-Yale Group, Inc. - Inventors: Barry Warner - Web page: https://patentgrep.com/patent/US10479663B2 ## CPC - B66F 9/22: Hydraulic devices or systems - B66F 9/08: Masts; Guides; Chains - F15B 11/10: in which the servomotor position is a function of the pressure {; Pressure regulators as operating means therefor} - F15B 2211/50: Pressure control - B66F: HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD ({invalid lifting devices A61G7/10; } mounting artificial islands on piles or like supports E02B17/00; scaffolding combined with lifting devices E04G1/22; lifting devices for sliding forms E04G11/24; lifting of buildings E04G23/06; shores or struts E04G25/00; lifts or other hoisting devices on ladders E06C7/12; props for mining E21D15/00) - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR ## Abstract A hydraulic circuit for a lift truck comprises a feed-through cylinder communicating with a free lift cylinder and a lift cylinder. ## Claims ### Claim 1 A hydraulic arrangement for an extensible mast comprising: a hydraulic pump fluidly communicating with a hydraulic reservoir; a hydraulic feed-through cylinder connected to a first mast column such that extension of the feed-through cylinder moves a section of the mast; a first valve arrangement fluidly interposed between the pump and the reservoir on one side of the first valve arrangement and via a first hydraulic line to the feed-through cylinder on another side of the first valve arrangement such that the first valve arrangement controls fluid communication between the pump and the feed-through cylinder and also controls fluid communication between the feed-through cylinder and the reservoir; a hydraulic free-lift cylinder fluidly communicating with the feed-through cylinder such that hydraulic fluid is communicated to and from the free-lift cylinder via the feed-through cylinder; a hydraulic lift cylinder connected to a second mast column such that extension of the lift cylinder moves the section of the mast; a second valve arrangement fluidly interposed between the pump and via a second hydraulic line to the lift cylinder such that the second valve arrangement controls fluid communication between the pump and the lift cylinder; a balance pipe fluidly connecting the feed-through cylinder with the lift cylinder; and a controller operably connected with the first valve arrangement and with the second valve arrangement wherein the controller operates the first valve arrangement and the second valve arrangement. ### Claim 2 A hydraulic arrangement for an extensible mast, comprising: a hydraulic pump fluidly communicating with a hydraulic reservoir; a hydraulic feed-through cylinder connected to a first mast column such that extension of the feed-through cylinder moves a section of the mast; a first valve arrangement fluidly interposed between the pump and the reservoir on one side of the first valve arrangement and the feed-through cylinder on another side of the first valve arrangement such that the first valve arrangement controls fluid communication between the pump and the feed-through cylinder and also controls fluid communication between the feed-through cylinder and the reservoir; a hydraulic free-lift cylinder fluidly communicating with the feed-through cylinder such that hydraulic fluid is communicated to and from the free-lift cylinder via the feed-through cylinder; a hydraulic lift cylinder connected to a second mast column such that extension of the lift cylinder moves the section of the mast; a balance pipe fluidly connecting the feed-through cylinder with the lift cylinder; a second valve arrangement fluidly interposed between the pump and the lift cylinder such that the second valve arrangement controls fluid communication between the pump and the lift cylinder; a controller operably connected with the first valve arrangement and with the second valve arrangement wherein the controller operates the first valve arrangement and the second valve arrangement; a first pressure sensor communicating with the controller and arranged to sense pressure of hydraulic fluid supplied to the feed-through cylinder; and a second pressure sensor communicating with the controller and arranged to sense pressure of hydraulic fluid supplied to the lift cylinder; wherein the controller is configured to operate the first valve arrangement and the second valve arrangement based at least in part on pressures sensed by the first pressure sensor and the second pressure sensor. ### Claim 3 (depends on 2) A hydraulic arrangement according to claim 2, wherein: the mast comprises a three-section mast; the feed-through cylinder comprises a double acting hydraulic cylinder comprising an outer cylinder, an intermediate cylinder contained in the outer cylinder, and an inner cylinder contained in the intermediate cylinder, wherein the feed-through cylinder is connected to the three-section mast such that extension of the intermediate cylinder moves a first section of the three-section mast and extension of the inner cylinder moves a second section of the three-section mast; and the lift cylinder comprises a double acting hydraulic cylinder comprising an outer cylinder, an intermediate cylinder contained in the outer cylinder, and an inner cylinder contained in the intermediate cylinder, wherein the lift cylinder is connected to the three-section mast such that extension of the intermediate cylinder moves the first section of the three-section mast and extension of the inner cylinder moves the second section of the three-section mast. ### Claim 4 (depends on 3) A hydraulic arrangement according to claim 3, wherein the balance pipe fluidly connects an annular space between the intermediate cylinder and the outer cylinder of the feed-through cylinder with an annular space between the intermediate cylinder and the outer cylinder of the lift cylinder. ### Claim 5 (depends on 4) A hydraulic arrangement according to claim 4, further comprising: one or more ports formed in the inner cylinder of the feed-through cylinder to fluidly communicate an interior of the inner cylinder with an annular space formed between the inner cylinder and the intermediate cylinder; one or more ports formed in the intermediate cylinder of the feed-through cylinder to fluidly communicate the annular space formed between the inner cylinder and the intermediate cylinder with an annular space between the intermediate cylinder and the outer cylinder; one or more ports formed in the inner cylinder of the lift cylinder to fluidly communicate an interior of the inner cylinder with an annular space formed between the inner cylinder and the intermediate cylinder; and one or more ports formed in the intermediate cylinder of the lift cylinder to fluidly communicate the annular space formed between the inner cylinder and the intermediate cylinder with an annular space between the intermediate cylinder and the outer cylinder. ### Claim 6 (depends on 5) A hydraulic arrangement according to claim 5, further comprising a check valve located at a bottom end of the inner cylinder of the feed-through cylinder where hydraulic fluid from the pump is introduced to the feed-through cylinder. ### Claim 7 (depends on 6) A hydraulic arrangement according to claim 6, further comprising a mechanical device sized and located such that when the inner cylinder and the intermediate cylinder of the feed-through cylinder are at their lowermost position the check valve located at the bottom end of the inner cylinder is mechanically held open. ### Claim 8 (depends on 7) A hydraulic arrangement according to claim 7, wherein the mechanical device comprises a shelf formed in an inlet where hydraulic fluid from the pump is introduced to the feed-through cylinder. ### Claim 9 (depends on 7) A hydraulic arrangement according to claim 7, wherein the second valve arrangement fluidly communicates with a hydraulic line connected between the first valve arrangement and the feed-through cylinder. ### Claim 10 (depends on 9) A hydraulic arrangement according to claim 9, wherein the second valve arrangement includes a check valve that inhibits, but does not prevent, fluid communication from the lift cylinder to the hydraulic line connected between the first valve arrangement and the feed-through cylinder. ### Claim 11 (depends on 10) A hydraulic arrangement according to claim 10, wherein the first valve arrangement comprises a solenoid valve and the second valve arrangement comprises a solenoid valve. ### Claim 12 A method of operating a lift mast comprising a first section, a second section moveable within the first section, a third section moveable within the second section, and a carriage moveable within the third section, the method comprising: receiving a lift command at a controller; in response to receiving the lift command, activating a pump via the controller and opening a first valve arrangement via the controller such that the pump fluidly communicates with a feed-through cylinder; providing pressurized hydraulic fluid to a free-lift cylinder via the pump through the first valve arrangement and through the feed-through cylinder; and in response to receiving the lift command, keeping a second valve arrangement closed via the controller such that pressurized fluid is communicated from the feed-through cylinder to a lift cylinder via a balance pipe, but pressurized fluid is not supplied to the lift cylinder from the pump through the second valve arrangement. ### Claim 13 (depends on 12) A method of operating a lift mast according to claim 12 further comprising: receiving a first sensor signal at the controller, wherein the first sensor signal indicates that the carriage is within a predetermined distance of the top of the third section; receiving a second sensor signal at the controller, wherein the second sensor signal indicates that the second section is within a predetermined distance from its resting location with respect to the first section; and via the controller and based at least in part on the first sensor signal and the second sensor signal, opening the second valve arrangement, at least partially, to facilitate balancing a pressure increase in both the feed-through cylinder and the lift cylinder. ### Claim 14 (depends on 13) A method of operating a lift mast according to claim 13 further comprising: receiving a third sensor signal at the controller, wherein the third sensor signal indicates a hydraulic pressure associated with the feed-through cylinder; receiving a fourth sensor signal at the controller, wherein the fourth sensor signal indicates a hydraulic pressure associated with the lift cylinder; and via the controller, and based at least in part on the first sensor signal, the second sensor signal, the third sensor signal and the fourth sensor signal, opening the second valve arrangement, at least partially, to facilitate balancing a pressure increase in both the feed-through cylinder and the lift cylinder. ### Claim 15 (depends on 12) A method of operating a lift mast according to claim 12 further comprising: after receiving the lift command at the controller, receiving a lower command at the controller; receiving a first sensor signal at the controller, wherein the first sensor signal indicates that the carriage is within a predetermined distance of the top of the third section; receiving a second sensor signal at the controller, wherein the second sensor signal indicates that the second section is not within a predetermined distance from its resting location with respect to the first section; in response to receiving the lower command, deactivating the pump via the controller; and via the controller, and based at least in part on the first sensor signal and the second sensor signal, opening the first valve arrangement and opening the second valve arrangement to lower the third section and the second section of the mast. ### Claim 16 (depends on 15) A method of operating a lift mast according to claim 15 further comprising: continuing to receive the lower command at the controller; continuing to receive the first sensor signal at the controller, wherein the first sensor signal indicates that the carriage is within a predetermined distance of the top of the third section; continuing to receive the second sensor signal at the controller, wherein the second sensor signal indicates that the second section is within a predetermined distance from its resting location with respect to the first section; via the controller, and based at least in part on the first sensor signal and the second sensor signal, closing the second valve arrangement and operating the first valve arrangement to lower the carriage. ### Claim 17 (depends on 1) A hydraulic arrangement according to claim 1, further comprising: a first pressure sensor communicating with the controller and arranged to sense pressure of hydraulic fluid supplied to the feed-through cylinder; and a second pressure sensor communicating with the controller and arranged to sense pressure of hydraulic fluid supplied to the lift cylinder; wherein the controller is configured to operate the first valve arrangement and the second valve arrangement based at least in part on pressures sensed by the first pressure sensor and the second pressure sensor. ### Claim 18 (depends on 1) A hydraulic arrangement according to claim 1, wherein: the mast comprises a three-section mast; the feed-through cylinder comprises a double acting hydraulic cylinder comprising an outer cylinder, an intermediate cylinder contained in the outer cylinder, and an inner cylinder contained in the intermediate cylinder, wherein the feed-through cylinder is connected to the three-section mast such that extension of the intermediate cylinder moves a first section of the three-section mast and extension of the inner cylinder moves a second section of the three-section mast; and the lift cylinder comprises a double acting hydraulic cylinder comprising an outer cylinder, an intermediate cylinder contained in the outer cylinder, and an inner cylinder contained in the intermediate cylinder, wherein the lift cylinder is connected to the three-section mast such that extension of the intermediate cylinder moves the first section of the three-section mast and extension of the inner cylinder moves the second section of the three-section mast. ### Claim 19 (depends on 18) A hydraulic arrangement according to claim 18, wherein the balance pipe fluidly connects an annular space between the intermediate cylinder and the outer cylinder of the feed-through cylinder with an annular space between the intermediate cylinder and the outer cylinder of the lift cylinder. ### Claim 20 (depends on 19) A hydraulic arrangement according to claim 19, further comprising: one or more ports formed in the inner cylinder of the feed-through cylinder to fluidly communicate an interior of the inner cylinder with an annular space formed between the inner cylinder and the intermediate cylinder; one or more ports formed in the intermediate cylinder of the feed-through cylinder to fluidly communicate the annular space formed between the inner cylinder and the intermediate cylinder with an annular space between the intermediate cylinder and the outer cylinder; one or more ports formed in the inner cylinder of the lift cylinder to fluidly communicate an interior of the inner cylinder with an annular space formed between the inner cylinder and the intermediate cylinder; and one or more ports formed in the intermediate cylinder of the lift cylinder to fluidly communicate the annular space formed between the inner cylinder and the intermediate cylinder with an annular space between the intermediate cylinder and the outer cylinder. ### Claim 21 (depends on 20) A hydraulic arrangement according to claim 20, further comprising a check valve located at a bottom end of the inner cylinder of the feed-through cylinder where hydraulic fluid from the pump is introduced to the feed-through cylinder. ### Claim 22 (depends on 21) A hydraulic arrangement according to claim 21, further comprising a mechanical device sized and located such that when the inner cylinder and the intermediate cylinder of the feed-through cylinder are at their lowermost position the check valve located at the bottom end of the inner cylinder is mechanically held open. ### Claim 23 (depends on 22) A hydraulic arrangement according to claim 22, wherein the mechanical device comprises a shelf formed in an inlet where hydraulic fluid from the pump is introduced to the feed-through cylinder. ### Claim 24 (depends on 22) A hydraulic arrangement according to claim 22, wherein the second valve arrangement fluidly communicates with a hydraulic line connected between the first valve arrangement and the feed-through cylinder. ### Claim 25 (depends on 24) A hydraulic arrangement according to claim 24, wherein the second valve arrangement includes a check valve that inhibits, but does not prevent, fluid communication from the lift cylinder to the hydraulic line connected between the first valve arrangement and the feed-through cylinder. ### Claim 26 (depends on 25) A hydraulic arrangement according to claim 25, wherein the first valve arrangement comprises a solenoid valve and the second valve arrangement comprises a solenoid valve.