# US 11,440,772 B2 · Elevator pit ladder apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,440,772 B2 - Document ID: US11440772B2 - Status: Granted - Kind: B2 - Application number: 16/494,769 - Filed: 2017-03-30 - Published: 2020-02-06 - Granted: 2022-09-13 - Earliest claimed: 2017-03-30 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Hironobu Kamada - Web page: https://patentgrep.com/patent/US11440772B2 ## CPC - B66B 5/0087: {Devices facilitating maintenance, repair or inspection tasks (devices incorporated in the buffer B66B5/288; railings on top of the car B66B11/0226)} - B66B 11/0005: {Constructional features of hoistways} - E06C 9/06: movably mounted - E06C 9/08: with rigid longitudinal members - E06C 9/12: laterally displaceable - B66B: ELEVATORS; ESCALATORS OR MOVING WALKWAYS ({apparatus for raising or lowering persons on theatrical stages or the like A63J5/12} ; funicular railbound systems with rigid ground-supported tracks and cable traction, e.g. cliff railways, B61B9/00; arrangements of ammunition handlers in vessels B63G3/00; hoists, lifts, or conveyors for loading or unloading in general B65G; braking or detent devices controlling normal movements of winding drums or barrels B66D; ship-lifting devices E02C; garages for many vehicles with mechanical means for lifting vehicles E04H6/12; hoists for feeding ammunition or projectiles to launching apparatus or to loading mechanisms F41A9/00) - E06C: LADDERS (E04F11/00 takes precedence; step-stools A47C12/00; adaptation of ladders to use on ships B63B, to use on aircraft B64; scaffolding E04G) ## Abstract A mechanism that allows a ladder to be moved to either a use position or a retracted position. The ladder can be moved from the retracted position to the use position with a minimal effort, and the ladder moves by itself from the use position to the retracted position. A pit ladder apparatus for an elevator according to the present invention includes a position change means to be provided in a fixing metal frame fixed to the hoistway and allowing a ladder to be moved to either the use position when the ladder is used or the retracted position for retracting the ladder when it is not used so as not to interfere with operation of the elevator. ## Claims ### Claim 1 A pit ladder apparatus for use in a hoistway of an elevator to access between an elevator hall and a pit, the pit ladder apparatus comprising: a ladder; and a position change means to be fixed to the hoistway, the position change means for moving the ladder to either a use position where the ladder is used or a retracted position for retracting the ladder when not used so as not to interfere with operation of the elevator, the position change means including a counter weight and one or more mounting arms that are supported so as to swing freely in a seesaw manner, wherein the ladder is mounted to one end of each of the mounting arms, the counter weight is mounted to the other end of each of the mounting arms, and a moment on a side of the counter weight is set larger than a moment on a side of the ladder. ### Claim 2 (depends on 1) The pit ladder apparatus for an elevator according to claim 1, wherein: a pair of the mounting arms is disposed apart from each other in a horizontal direction, a first rotation axis is located at one end of the pair of mounting arms, the counter weight is mounted to another end of the pair of mounting arms so as to be sandwiched between them, the ladder is mounted to the first rotation axis so as to be freely rotatable on a side higher than a center of gravity of the ladder, and a second rotation axis is located between the ladder and the counter weight to support the pair of mounting arms so that the pair of mounting arms can swing freely in the seesaw manner, and the ladder and the counter weight are disposed at either end of the pair of mounting arms. ### Claim 3 (depends on 2) The pit ladder apparatus for an elevator according to claim 2, wherein the counter weight includes stacked weights. ### Claim 4 (depends on 3) The pit ladder apparatus for an elevator according to claim 3, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 5 (depends on 2) The pit ladder apparatus for an elevator according to claim 2, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 6 (depends on 1) The pit ladder apparatus for an elevator according to claim 1, wherein the counter weight includes stacked weights. ### Claim 7 (depends on 6) The pit ladder apparatus for an elevator according to claim 6, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 8 (depends on 1) The pit ladder apparatus for an elevator according to claim 1, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 9 A pit ladder apparatus for use in a hoistway of an elevator to access between an elevator hall and a pit, the pit ladder apparatus comprising: a ladder; and a counter weight and one or more mounting arms that are pivotally supported to move the ladder to either a use position where the ladder is used or a retracted position for retracting the ladder when not used so as not to interfere with operation of the elevator, wherein the ladder is mounted to one end of each of the mounting arms, the counter weight is mounted to the other end of each of the mounting arms, and a moment on a side of the counter weight is set larger than a moment on a side of the ladder. ### Claim 10 (depends on 9) The pit ladder apparatus for an elevator according to claim 9, wherein: a pair of the mounting arms is disposed apart from each other in a horizontal direction, a first rotation axis is located at one end of the pair of mounting arms, the counter weight is mounted to another end of the pair of mounting arms so as to be sandwiched between them, the ladder is mounted to the first rotation axis so as to be freely rotatable on a side higher than a center of gravity of the ladder, and a second rotation axis is located between the ladder and the counter weight to support the pair of mounting arms so that the pair of mounting arms can swing freely in a seesaw manner, and the ladder and the counter weight are disposed at either end of the pair of mounting arms. ### Claim 11 (depends on 10) The pit ladder apparatus for an elevator according to claim 10, wherein the counter weight includes stacked weights. ### Claim 12 (depends on 11) The pit ladder apparatus for an elevator according to claim 11, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 13 (depends on 10) The pit ladder apparatus for an elevator according to claim 10, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 14 (depends on 9) The pit ladder apparatus for an elevator according to claim 9, wherein the counter weight includes stacked weights. ### Claim 15 (depends on 14) The pit ladder apparatus for an elevator according to claim 14, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor. ### Claim 16 (depends on 9) The pit ladder apparatus for an elevator according to claim 9, wherein a lower end of the ladder at the use position is disposed to be in contact with a pit floor.