Extendable counterweight for cranes and method of manipulating

Claim 3

The method as defined by claim 1, and the additional step of engaging the flexible suspension element with guide means on the counterweight and crane to produce a variable length slack suspension loop in the flexible element which is lengthened or shortened in response to retraction or extension of said movable boom section.

Claim 4

The method as defined by claim 1, and the additional step of operating said hydraulic ram at reduced power for raising and lowering the counterweight in comparison to its full power operation for extending and retracting the telescoping boom.

Claim 5

The method of manipulating a crane counterweight as defined by claim 1 including the additional steps of raising the counterweight to an elevation above the coupling elevation of the counterweight with a crane mounted support carriage, shifting the support carriage toward a coupling position with respect to the counterweight, and then lowering the counterweight into coupling engagement with the carriage and subsequently moving the carriage to shift the counterweight substantially horizontally to a desired use position.

Claim 6

The method as defined by claim 1, and the additional step of coupling the elevated counterweight to a movable part of the crane so that the movable part then bodily supports the counterweight.

Claim 7

In a crane, a crane boom having an extensible and retractable boom section, a counterweight support structure on the crane, a counterweight, said counterweight support structure including a horizontally extensible and retractable counterweight support carriage, a fluid pressure operated ram connected with said support carriage to extend it toward and retract it from said counterweight, said counterweight adapted to be coupled to and removed from the support structure, means on the crane boom connected to extend and retract said boom section, and a suspension means detachably connectable between said counterweight and the rear portion of said extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the support carriage on operation of said fluid pressure operated ram to extend said support carriage toward said counterweight, and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane after operation of said fluid pressure operated ram to retract said support carriage from said counterweight.

Claim 8

In a crane, a crane boom having an extensible and retractable boom section, a counterweight support structure on the crane, a counterweight, said counterweight support structure including a horizontally extensible and retractable counterweight support carriage, a fluid pressure operated ram connected with said support carriage to extend it toward and retract it from said counterweight, said counterweight adapted to be coupled to and removed from the support structure, means on the crane boom connected to extend and retract said boom section, and a suspension means detachably connectable between said counterweight and the rear portion of said extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the support carriage on operation of said fluid pressure operated ram to extend said support carriage toward said counterweight, and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane after operation of said fluid pressure operated ram to retract said support carriage from said counterweight.

Claim 9

The structure of claim 6, and said suspension means including a flexible suspension element having a connection with the counterweight and a connection with the rear portion of said extensible and retractable boom section.

Claim 10

The structure of claim 7, and said flexible suspension element comprising a single length of cable having one end detachably connected to the extensible and retractable boom section and its opposite end detachably connected to a fixed structural member on the crane.

Claim 11

The struCture of claim 8, and first and second cable guide elements on the crane and counterweight and said cable engaging both guide elements between its connected ends to form a variable length counterweight suspension loop.

Claim 12

In a crane, a crane boom having an extensible and retractable boom section, a shiftable counterweight support carriage on the crane comprising upper and lower pairs of carriage arms, guide members on the crane receiving said carriage arms telescopically, upper and lower carriage crossbars interconnecting the pairs of arms near their outer ends, a counterweight having upper and lower coupling elements thereon adapted to be engaged with said crossbars in counterweight supporting relationship and disengaged with said crossbars, power means connected with said support carriage to shift the same substantially horizontally with relation to the counterweight, and a suspension means connectable between said counterweight and the extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the crossbars and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane.

Claim 13

In a crane, a crane boom having an extensible and retractable boom section, a shiftable counterweight support carriage on the crane comprising upper and lower pairs of carriage arms, guide members on the crane receiving said carriage arms telescopically, upper and lower carriage crossbars interconnecting the pairs of arms near their outer ends, a counterweight having upper and lower coupling elements thereon adapted to be engaged with said crossbars in counterweight supporting relationship and disengaged with said crossbars, power means connected with said support carriage to shift the same substantially horizontally with relation to the counterweight, and a suspension means connectable between said counterweight and the extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the crossbars and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane.

Claim 14

The structure of claim 10, and interengaging latch means on the crane and support carriage operable to latch the support carriage in a retracted position relative to the crane.

Claim 15

The structure of claim 10, and said coupling elements on the counterweight comprising upper and lower laterally spaced pairs of downwardly facing hooks engageable over the tops of the carriage crossbars.

Claim 16

The structure of claim 10, and wear pads on the bottoms of the guide members near their outer ends frictionally engaging the bottoms of the carriage arms, and guide rollers on the leading ends of the carriage arms operable within the guide members.

Claim 17

The structure of claim 6, and said means on the boom having a connection with the extensible and retractable boom section being another fluid pressure operated ram, a movable sensing element on the crane above the counterweight adapted to be engaged by the counterweight as the latter is elevated by the suspension means, a motive fluid control circuit for operating said another ram, and control valve means connected in said motive fluid control circuit and connected for operation by movement of the sensing element to interrupt extension of said boom section by interrupting the flow of motive fluid in said control circuit to said another ram.

Claim 18

In a crane, a crane boom having an extensible and retractable boom section, a counterweight support structure on the crane, said counterweight support structure including a horizontally extensible and retractable counterweight carriage on the crane, a fluid pressure operated ram connected with said carriage to operate it, another ram on the crane boom connected with the extensible and retractable boom section, a counterweight adapter to be coupled to and removed from the support structure, a suspension means connectable between said counterweight and the extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the support structure and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane, a pump for supplying motive fluid to both of said rams at a volumetric rate and pressure which operates the boom ram at less than full power, and manually operable control valve means interconnected between the pump and said rams and allowing selective extension and retraction thereof.

Claim 19

In a crane, a crane boom having an extensible and retractable boom section, a counterweight support structure on the crane, said counterweight support structure including a horizontally extensible and retractable counterweight carriage on the crane, a fluid pressure operated ram connected with said carriage to operate it, another ram on the crane boom connected with the extensible and retractable boom section, a counterweight adapter to be coupled to and removed from the support structure, a suspension means connectable between said counterweight and the extensible and retractable boom section so that movement of the boom section in one direction can elevate the counterweight in the vertical plane onto the crane and enable it to be coupled to the support structure and movement of the boom section in the opposite direction can lower the counterweight in the vertical plane off of the crane, a pump for supplying motive fluid to both of said rams at a volumetric rate and pressure which operates the boom ram at less than full power, and manually operable control valve means interconnected between the pump and said rams and allowing selective extension and retraction thereof.

Claim 20

The structure of claim 15, and said control valve means including a pair of three-way valves connected respectively with the carriage operating ram and the boom ram.