# US 2021/0276850 A1 · Actuator failure detection and scissor lift load sensing systems and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0276850 A1 - Document ID: US20210276850A1 - Status: Published application - Kind: A1 - Application number: 17/328,885 - Filed: 2021-05-24 - Published: 2021-09-09 - Earliest claimed: 2019-04-05 - Assignees: Oshkosh Corporation - Applicants: Oshkosh Corporation - Inventors: David Lombardo; Eko Prasetiawan; Louis Bafile - Web page: https://patentgrep.com/patent/US20210276850A1 ## CPC - B66F 17/006: {for working platforms} - B66F 11/042: {actuated by lazy-tongs mechanisms or articulated levers} - B66F 11/044: {Working platforms suspended from booms} - G01G 19/08: for incorporation in vehicles - F16H 25/2204: {with balls} - F16H 25/2472: {Safety nuts} - F16H 2025/2081: {Parallel arrangement of drive motor to screw axis} - 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) - G01G: WEIGHING (sorting by weighing B07C5/16) - F16H: GEARING ## Abstract A lift device comprises a base, a retractable lift mechanism, a work platform, a linear actuator, and a lift controller. The retractable lift mechanism has a first end coupled to the base and is moveable between an extended position and a retracted position. The work platform is coupled to and supported by a second end of the retractable lift mechanism. The linear actuator is configured to selectively move the retractable lift mechanism between the extended position and the retracted position. The linear actuator comprises a central screw rod, an electric motor configured to provide rotational actuation to the central screw rod, and a nut assembly configured to translate the rotational actuation of the central screw rod into linear motion. The lift controller is configured to receive a lift command from an operator, monitor at least one lift characteristic associated with the linear actuator, and selectively inhibit the lift command. ## Claims ### Claim 1 A lift device, comprising: a base having a plurality of wheels; a retractable lift mechanism having a first end coupled to the base and being moveable between an extended position and a retracted position; a work platform configured to support a load, the work platform coupled to and supported by a second end of the retractable lift mechanism; a linear actuator configured to selectively move the retractable lift mechanism between the extended position and the retracted position, the linear actuator comprising: a central screw rod; an electric motor configured to provide rotational actuation to the central screw rod; and a nut assembly comprising a primary nut mechanism configured to translate the rotational actuation of the central screw rod into linear motion of the nut assembly; and a lift controller configured to receive a lift command from an operator and monitor at least one lift characteristic associated with the linear actuator; wherein the lift controller selectively inhibits the lift command based on the at least one lift characteristic. ### Claim 2 (depends on 1) The lift device of claim 1, wherein the primary nut mechanism is a ball screw nut. ### Claim 3 (depends on 1) The lift device of claim 1, the nut assembly further comprising a secondary nut mechanism, wherein the secondary nut mechanism is a backup jam nut. ### Claim 4 (depends on 1) The lift device of claim 1, wherein the at least one lift characteristic includes a required torque for the electric motor. ### Claim 5 (depends on 4) The lift device of claim 4, the lift command further comprising a descend command, wherein, upon determining that the required torque is greater than an allowed torque, the lift controller further configured to provide an alert. ### Claim 6 (depends on 4) The lift device of claim 4, the lift command further comprising an ascend command, wherein, upon determining that the required torque is greater than an allowed torque, the lift controller is configured to inhibit the lift command. ### Claim 7 (depends on 4) The lift device of claim 4, wherein, upon determining that the required torque is less than an allowed torque, the lift controller is configured to allow the lift command. ### Claim 8 (depends on 1) The lift device of claim 1, wherein the lift controller is configured to inhibit the lift command upon determining that the primary nut mechanism is not engaged. ### Claim 9 A lift device, comprising: a base having a plurality of wheels; a retractable lift mechanism having a first end coupled to the base and being moveable between an extended position and a retracted position; a work platform configured to support a load, the work platform coupled to and supported by a second end of the retractable lift mechanism; a linear actuator configured to selectively move the retractable lift mechanism between the extended position and the retracted position; and a lift controller configured to: receive a lift command from an operator; monitor at least one lift characteristic associated with the linear actuator, the at least one lift characteristic having a measured value; inhibit, based on the monitored at least one lift characteristic, the lift command. ### Claim 10 (depends on 9) The lift device of claim 9, the linear actuator further including a lift characteristic sensor. ### Claim 11 (depends on 10) The lift device of claim 10, the lift controller further configured to receive lift characteristic data from the lift characteristic sensor, wherein the monitored at least one lift characteristic is based on the lift characteristic data. ### Claim 12 (depends on 9) The lift device of claim 9, the lift controller further configured to determine an allowable lift characteristic range, the allowable lift characteristic range associated with the monitored at least one lift characteristic. ### Claim 13 (depends on 12) The lift device of claim 12, wherein, upon determining that the measured value of the monitored at least one lift characteristic is not within the allowable lift characteristic range, the lift controller is further configured to inhibit the lift command. ### Claim 14 (depends on 13) The lift device of claim 13, wherein the monitored at least one lift characteristic includes a drive power efficiency of the linear actuator. ### Claim 15 (depends on 13) The lift device of claim 13, wherein the monitored at least one lift characteristic includes a height of the work platform and a required motor torque to move the work platform. ### Claim 16 (depends on 13) The lift device of claim 13, the linear actuator further including an electric motor, wherein the monitored at least one lift characteristic includes an electrical current of the electric motor. ### Claim 17 A lift device, comprising: a base having a plurality of wheels; a retractable lift mechanism having a first end coupled to the base and being moveable between an extended position and a retracted position; a work platform configured to support a load, the work platform coupled to and supported by a second end of the retractable lift mechanism; a linear actuator configured to selectively move the retractable lift mechanism between the extended position and the retracted position, the linear actuator comprising: a central screw rod; an electric motor configured to provide rotational actuation to the central screw rod; and a nut assembly comprising: a first nut mechanism configured to translate the rotational actuation of the central screw rod into translational motion; and a second nut mechanism configured to translate the rotation actuation of the central screw rod into translational motion, wherein the linear actuator includes a first lift characteristic associated with the first nut mechanism and a second lift characteristic associated with the second nut mechanism; and a lift controller configured to receive a lift command and determine whether a monitored lift characteristic is substantially similar to the first lift characteristic or the second lift characteristic. ### Claim 18 (depends on 17) The lift device of claim 17, the lift controller further configured to, based on a determination that the monitored lift characteristic is substantially similar to the first lift characteristic, allow the lift command. ### Claim 19 (depends on 17) The lift device of claim 17, the lift controller further configured to, based on a determination that the monitored lift characteristic is substantially similar to the second lift characteristic, inhibit the lift command. ### Claim 20 (depends on 19) The lift device of claim 19, wherein, the determination that the monitored lift characteristic is substantially similar to the second lift characteristic is associated with a failure of the first nut mechanism.