Lift truck mast

Claim 2

An extensible mast having collapsed and extended positions, comprising: a first upright, a second upright slidably received on the first and extensible longitudinally therefrom, a load carriage, load carriage support means reciprocally supporting the load carriage on the second upright, a power lift system operably connected to reciprocate the load carriage and second upright simultaneously at first and second differential rates of travel, latch operator means on the load carriage having a raised position corresponding to a raised position of the load carriage, and latch means operable for attaching the load carriage support means to the second upright for travel therewith at the first differential rate and actuated by said latch operator means at said raised position to disconnect substantially simultaneously the load carriage support means from the second upright and attach it to the load carriage for travel therewith at the second differential rate, whereby the mast reaches an extended position by employing said simultaneous differential rates of travel.

Claim 3

An extensible mast according to claim 1 wherein: the load carriage support means includes a third upright, said third upright being slidably received on the second and extensible longitudinally therefrom, other latch means operable for attaching the second upright to the first during reciprocation of the load carriage between its lowered and an intermediate raised position, and other latch operator means on the lift cylinder having a raised position corresponding to the intermediate raised position of the load carriage operable to disconnect substantially simultaneously the second upright from the first and connect it to the lift cylinder.

Claim 4

An extensible mast according to claim 2 wherein said other latch means comprises a pair of spaced hook elements facing in opposite directions and pivoted on the second upright on a common fore and aft extending axis, first dog means on the first upright engageable with one of the hook elements for preventing extension of the mast, second dog means movable with said lift cylinder engageable with said other hook element at said intermediate raised position for attaching the second upright thereto, and said first and second dog means cooperating during extension or retraction of the mast to jointly pivot said hook elements, the first hook element pivoted out of engagement with the first dog means and the second into engagement with the second dog means during extension and in the reverse on retraction of the mast.

Claim 5

An extensible mast according to claim 3 wherein said latch means comprises a pair of spaced hook elements facing in opposite directions pivoted on said third upright on a common transversely extending axis, third dog means on the second upright engageable with one of the hook elements for preventing extension of the third upright, fourth dog means on the load carriage engageable with the other hook element for attaching the third upright to the load carriage at its highest point of travel in the third upright, and said third and fourth dog means cooperating during extension or retraction of the mast to jointly pivot said hook elements, the first hook element pivoted out of engagement with the third dog means and the second into engagement with the fourth dog means during extension and in the reverse upon retraction of the mast.

Claim 6

An extensible mast having collapsed and extended positions, comprising: a first upright, a second upright slidably received in the first and extensible longitudinally therefrom, a third upright slidably received in the second and extensible longitudinally therefrom, a load carriage, means reciprocally supporting the load carriage on one of the uprights, the one upright on the second and the second on the other upright, a power lift system operably connected to reciprocate the load carriage, the second upright, and the other upright including, extensible lift means, said power lift system being operable to provide a greater rate of travel for said load carriage than the rate of extension of said lift means, an extensible lift means component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in the one upright, first latch means mounted on the second upright operable for attaching it to the other upright during reciprocation of the load carriage between its lowered and free lift positions, second latch means mounted on the one upright operable for attaching it to the second upright during reciprocation of the load carriage between its lowered and uppermost positions, said first latch means being actuated at the first intermediate position of said lift means component to connect substantially simultaneously the second upright to said lift means component and disconnect it from the other upright during extension of the mast, and said second latch means being actuated by the load carriage at its uppr most position to connect substantially simultaneously the one upright to the load carriage and disconnect it from the second upright whereby during extension of the mast the second upright and one upright move jointly relative to the other upright between said first and second intermediate positions of said lift means component and thereafter the one upright moves differentially at said greater rate of travel relative to said second upright and the above sequence being reversed in retraction of the mast.

Claim 7

An extensible mast having collapsed and extended positions, comprising: a first upright, a second upright slidably received in the first and extensible longitudinally therefrom, a third upright slidably received in the second and extensible longitudinally therefrom, a load carriage, means reciprocally supporting the load carriage on one of the uprights, the one upright on the second and the second on the other upright, a power lift system operably connected to reciprocate the load carriage, the second upright, and the other upright including, extensible lift means, said power lift system being operable to provide a greater rate of travel for said load carriage than the rate of extension of said lift means, an extensible lift means component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in the one upright, first latch means mounted on the second upright operable for attaching it to the other upright during reciprocation of the load carriage between its lowered and free lift positions, second latch means mounted on the one upright operable for attaching it to the second upright during reciprocation of the load carriage between its lowered and uppermost positions, said first latch means being actuated at the first intermediate position of said lift means component to connect substantially simultaneously the second upright to said lift means component and disconnect it from the other upright during extension of the mast, and said second latch means being actuated by the load carriage at its uppr most position to connect substantially simultaneously the one upright to the load carriage and disconnect it from the second upright whereby during extension of the mast the second upright and one upright move jointly relative to the other upright between said first and second intermediate positions of said lift means component and thereafter the one upright moves differentially at said greater rate of travel relative to said second upright and the above sequence being reversed in retraction of the mast.

Claim 8

An extensible mast having collapsed and extended positions, comprising: a. a first upright; b. a second upright slidably received in the first and extensible longitudinally therefrom; c. a third upright slidably received in the second and extensible longitudinally therefrom; d. a load carriage e. means reciprocally supporting load carriage on the third upright, the third on the second and the latter on the first; f. a power lift system operably connected to reciprocate the load carriage and the second and third uprights including a stationary lift cylinder, said power lift system being operable to provide a greater rate of travel for said load carriage than the rate of extension of said lift cylinder g. an extensible cylinder component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in said third upright, h. first, second and third transverse structural members on said first, second and third uprights nested one above the other in the collapsed position of the mast, i. a first pair of spaced hook elements facing in opposite directions on opposite sides of and pivotally mounted on said second structural member on a common fore and aft extending shaft, j. each said first hook elements comprising an elongated downwardly extending hook portion and an offset upper detent portion and at least one being splined on the end of the shaft, k. first dog means mounted on said first structural member and aligned with the detent portion of one of said first hook elements and being engageable therewith to pivot the hook portion thereof into locking engagement with the first dog means between the lowered and free lift positions of the load carriage, l. second dog means mounted on said cylinder component and aligned with the detent portion on said other first hook element and being engageable therewith to pivot the hook portion thereof out of engagement with said first dog means and substantially simultaneously pivot said other hook portion into locking engagement with said second dog means at the free lift position of the load carriage enabling said second and third uprights to more jointly relative to the first upright, m. a second pair of hook elements facing in opposite directions pivoted on the third transverse structural member on a common transverse extending axis parallel to said third structural member, n. each said second hook elements comprising an elongated, downwardly extending hook portion and an upper off-set detent portion, o. third dog means mounted on said second upright aligned and being engageable with the detent portion of one of said second hook elements to pivot the hook portion thereof into locking engagement with said third dog means between the lowered and uppermost position of the load carriage, and p. fourth dog means mounted on the load carriage and aligned with the detent portion of said other second hook element and being engageable therewith to pivot the hook portion thereof into locking engagement with the fourth dog means substantially simultaneously disengaging said one hook portion at the uppermost position of the load carriage enabling said second and third uprights to move differentially relative to each other when lowering the mast from the extended to the collapsed position.

Claim 9

An extensible mast having collapsed and extended positions, comprising: a. a first upright; b. a second upright slidably received in the first and extensible longitudinally therefrom; c. a third upright slidably received in the second and extensible longitudinally therefrom; d. a load carriage e. means reciprocally supporting load carriage on the third upright, the third on the second and the latter on the first; f. a power lift system operably connected to reciprocate the load carriage and the second and third uprights including a stationary lift cylinder, said power lift system being operable to provide a greater rate of travel for said load carriage than the rate of extension of said lift cylinder g. an extensible cylinder component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in said third upright, h. first, second and third transverse structural members on said first, second and third uprights nested one above the other in the collapsed position of the mast, i. a first pair of spaced hook elements facing in opposite directions on opposite sides of and pivotally mounted on said second structural member on a common fore and aft extending shaft, j. each said first hook elements comprising an elongated downwardly extending hook portion and an offset upper detent portion and at least one being splined on the end of the shaft, k. first dog means mounted on said first structural member and aligned with the detent portion of one of said first hook elements and being engageable therewith to pivot the hook portion thereof into locking engagement with the first dog means between the lowered and free lift positions of the load carriage, l. second dog means mounted on said cylinder component and aligned with the detent portion on said other first hook element and being engageable therewith to pivot the hook portion thereof out of engagement with said first dog means and substantially simultaneously pivot said other hook portion into locking engagement with said second dog means at the free lift position of the load carriage enabling said second and third uprights to more jointly relative to the first upright, m. a second pair of hook elements facing in opposite directions pivoted on the third transverse structural member on a common transverse extending axis parallel to said third structural member, n. each said second hook elements comprising an elongated, downwardly extending hook portion and an upper off-set detent portion, o. third dog means mounted on said second upright aligned and being engageable with the detent portion of one of said second hook elements to pivot the hook portion thereof into locking engagement with said third dog means between the lowered and uppermost position of the load carriage, and p. fourth dog means mounted on the load carriage and aligned with the detent portion of said other second hook element and being engageable therewith to pivot the hook portion thereof into locking engagement with the fourth dog means substantially simultaneously disengaging said one hook portion at the uppermost position of the load carriage enabling said second and third uprights to move differentially relative to each other when lowering the mast from the extended to the collapsed position.

Claim 10

An extensible lift truck mast having collapsed and extended positions comprising a first upright, a second upright slidably received in the first and extensible longitudinally therefrom, a third upright slidably received in the second and extensible longitudinally therefrom, a load carriage, means reciprocally supporting the load carriage on the third upright, the third on the second and the latter on the first, a power lift system operably connected to reciprocate the load carriage and the second and third uprights including a stationary lift cylinder, an extensible cylinder component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in the third upright, first latch means mounted on the second upright operable for attaching it to the first upright during reciprocation of the load carriage between its lowered and free lift positions, second latch means mounted on the third upright operable for attaching it to the second upright during reciprocation of the load carriage between its lowered and uppermost positions, said first latch means being actuated at the first intermediate position of the cylinder component to simultaneously connect the second upright to the cylinder component and disconnect it from the first upright during extension of the mast, said second latch means being actuated by the load carriage at its uppermost position to simultaneously connect the third upright to the load carriage and disconnect it from the second upright during extension of the mast and the sequence being reversed when retracting the mast, each upright comprising parallel, laterally spaced rail members, which when nested with the adjacent rail members of the other upright, overlap outer to intermediate and intermediate to inner to define parallel, longitudinally extending trackways, each rail member having spaced end flanges separated by a web portion and offset forwardly toward the load carriage such that the end flanges of one laterally overlap with the end flanges of the adjacent rail member and the web portions overlap in a fore and aft direction between the end flanges, a pair of rollers mounted on the web portions of the outer rail members facing inwardly at the upper end of the first upright, second and third pairs of rollers mounted on the web portions of the intermediate rail members facing respectively outwardly at one end and inwardly at the opposite end of the second upright, and a fourth pair of rollers mounted on the web portions of the inner rail members facing outwardly at the lower end of the third upright, said first and second pairs of rollers situated in common, parallel trackways and said third and fourth pairs of rollers situated in common, parallel trackways inwardly of said other trackways, and the rear end flanges of each rail member providing transversely extending trackway portions engageable with the rollers of the adjacent nested upright and said web portions diverging from the plane of the adjacent roller and tangentially contacting the rollers at the peripheral edge thereof whereby any side thrust loads are taken generally parallel to the axis of the rollers and forward bending loads of the mast are taken radially by the rollers.

Claim 11

An extensible lift truck mast having collapsed and extended positions comprising a first upright, a second upright slidably received in the first and extensible longitudinally therefrom, a third upright slidably received in the second and extensible longitudinally therefrom, a load carriage, means reciprocally supporting the load carriage on the third upright, the third on the second and the latter on the first, a power lift system operably connected to reciprocate the load carriage and the second and third uprights including a stationary lift cylinder, an extensible cylinder component having a first intermediate raised position corresponding to a free lift position of the load carriage adjacent the top of the collapsed mast and a second intermediate raised position corresponding to the uppermost position of the load carriage in the third upright, first latch means mounted on the second upright operable for attaching it to the first upright during reciprocation of the load carriage between its lowered and free lift positions, second latch means mounted on the third upright operable for attaching it to the second upright during reciprocation of the load carriage between its lowered and uppermost positions, said first latch means being actuated at the first intermediate position of the cylinder component to simultaneously connect the second upright to the cylinder component and disconnect it from the first upright during extension of the mast, said second latch means being actuated by the load carriage at its uppermost position to simultaneously connect the third upright to the load carriage and disconnect it from the second upright during extension of the mast and the sequence being reversed when retracting the mast, each upright comprising parallel, laterally spaced rail members, which when nested with the adjacent rail members of the other upright, overlap outer to intermediate and intermediate to inner to define parallel, longitudinally extending trackways, each rail member having spaced end flanges separated by a web portion and offset forwardly toward the load carriage such that the end flanges of one laterally overlap with the end flanges of the adjacent rail member and the web portions overlap in a fore and aft direction between the end flanges, a pair of rollers mounted on the web portions of the outer rail members facing inwardly at the upper end of the first upright, second and third pairs of rollers mounted on the web portions of the intermediate rail members facing respectively outwardly at one end and inwardly at the opposite end of the second upright, and a fourth pair of rollers mounted on the web portions of the inner rail members facing outwardly at the lower end of the third upright, said first and second pairs of rollers situated in common, parallel trackways and said third and fourth pairs of rollers situated in common, parallel trackways inwardly of said other trackways, and the rear end flanges of each rail member providing transversely extending trackway portions engageable with the rollers of the adjacent nested upright and said web portions diverging from the plane of the adjacent roller and tangentially contacting the rollers at the peripheral edge thereof whereby any side thrust loads are taken generally parallel to the axis of the rollers and forward bending loads of the mast are taken radially by the rollers.

Claim 12

An extensible lift truck mast according to claim 7 wherein each rail member has a generally I-shaped cross section having spaced end flanges separated by a central web portion, said web portion including a straight section of uniform thickness extending rearwardly from the forward end flange, said pairs of rollers being mounted on said straight sections and a tapered section gradually increasing in thickness toward the rear end flange and tangentially contacting the rollers of the nested upright adjacent the peripheral outer circumferential edge at an angle of between 1* and 20*.

Claim 13

An extensible lift truck mast according to claim 8 wherein the tangential angle of contact is between 2* and 6*.

Claim 14

An extensible lift truck mast according to claim 9 wherein the tanGential angle of contact is approximately 3 1/2 *.