Lift truck construction

Claim 2

A lifting device comprising a wheeled chassis frame having an extensible and retractable side frame for changing the wheelbase length, a carrier supported on said chassis and being movable to lift a load, shifting means connected to said side frame for extending and retracting said frame to vary the wheelbase length, and dynamometer means connected to said carrier for actuation thereby in accordance with the load moment acting on said carrier and connected to said shifting means to extend and to retract said frame in accordance with the load movement acting on said carrier.

Claim 3

A lifting device, according to claim 1, including a carrier mast pivotally mounted on said chassis for pivotal movement about a substantially horizontal axis and extending upwardly from said chassis, said lift carrier being supported on said mast, hydraulic piston and cylinder means carried on said chassis and connected to said mast for pivoting said mast to effect lifting of said carrier with a load thereon, said dynamometer means comprising said hydraulic piston and cylinder means.

Claim 4

A lifting device, according to claim 2, wherein said dynamometer means includes switching means connected to said fluid piston and cylinder and being responsive to the pressure in said fluid cylinder to actuaTe means for moving said extensible and retractable side frame for changing the wheelbase length.

Claim 5

A lifting device, according to claim 1, wherein said wheel chassis includes a front wheel set having a wheel axis and a rear wheel having a rear wheel axis, said dynamometer means being arranged between said chassis and said front and rear wheel axes.

Claim 6

A lifting device, according to claim 1, wherein said dynamometer means comprises a fluid pressure cylinder, and a piston slidable in said cylinder connected to said carrier.

Claim 7

A lifting device, according to claim 1, including means associated with said dynamometer means for indicating the load which is engaged by said carrier.

Claim 8

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, and dynamometer means connected to said carrier for measuring the load moment acting on said carrier and being connected to actuate said second fluid piston and cylinder combination for extending and retracting said two chassis portions in accordance with the load moment on said carrier.

Claim 9

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, and dynamometer means connected to said carrier for measuring the load moment acting on said carrier and being connected to actuate said second fluid piston and cylinder combination for extending and retracting said two chassis portions in accordance with the load moment on said carrier.

Claim 10

A lifting device, according to claim 7, wherein said dynamometer means comprises said first fluid cylinder and piston combination, a driving circuit for controlling the movement of said movable frame by actuating said second fluid cylinder and piston combination, and a plurality of switches connected in said operating circuit and being responsive to the pressure in said first fluid cylinder and piston combination as determined by the load engaged by said carrier to actuate said drive circuit by separate and distinct proportional amounts.

Claim 11

A lifting device comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means comprising said first fluid cylinder and piston combination, a driving circuit for controlling the movement of said movable frame by actuating said second fluid cylinder and piston combination and a plurality of switches connected in said operating circuit and being responsive to the pressure in said first fluid cylinder and piston combination as determined by the load engaged by said carrier to actuate said drive circuit by separate and distinct proportional amounts, at least one of said movable chassis portions including a blocking membEr preventing movement of said switches and hence actuation of said operating circuit for said second fluid cylinder and piston combination and to prevent relative movement of said movable chassis portions when said chassis portions are located at a proper orientation to produce the desired wheelbase in accordance with the load which is engaged by said carrier.

Claim 12

A lifting device comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means comprising said first fluid cylinder and piston combination, a driving circuit for controlling the movement of said movable frame by actuating said second fluid cylinder and piston combination and a plurality of switches connected in said operating circuit and being responsive to the pressure in said first fluid cylinder and piston combination as determined by the load engaged by said carrier to actuate said drive circuit by separate and distinct proportional amounts, at least one of said movable chassis portions including a blocking membEr preventing movement of said switches and hence actuation of said operating circuit for said second fluid cylinder and piston combination and to prevent relative movement of said movable chassis portions when said chassis portions are located at a proper orientation to produce the desired wheelbase in accordance with the load which is engaged by said carrier.

Claim 13

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means comprising said first fluid cylinder and piston combination, a driving circuit for controlling the movement of said movable frame by actuating said second fluid cylinder and piston combination, and a plurality of switches connected in said operating circuit and be responsive to the pressure in said first fluid cylinder and piston combination as determined by the load engaged by said carrier to actuate said drive circuit by separate and distinct proportional amounts, said plurality of switches comprising electrohydraulic switches each of said switches including hydraulic portions connected to said first fluid cylinder and piston combination and an electrical portion connected to said operating device for said second fluid cylinder and piston combination.

Claim 14

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means comprising said first fluid cylinder and piston combination, a driving circuit for controlling the movement of said movable frame by actuating said second fluid cylinder and piston combination, and a plurality of switches connected in said operating circuit and be responsive to the pressure in said first fluid cylinder and piston combination as determined by the load engaged by said carrier to actuate said drive circuit by separate and distinct proportional amounts, said plurality of switches comprising electrohydraulic switches each of said switches including hydraulic portions connected to said first fluid cylinder and piston combination and an electrical portion connected to said operating device for said second fluid cylinder and piston combination.

Claim 15

A lifting device, according to claim 10, wherein said electrical switch portions of said switches includes a reversing circuit for effecting a reversing movement of said movable frame relative to said other frame.

Claim 16

A lifting device, according to claim 7, wherein said dynamometer means includes a plurality of electrohydraulic switches adapted to be connected to said first fluid cylinder and piston combination for operating said first fluid cylinder and piston combination and damping means associated with said switches.

Claim 17

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means including a hydraulic switch connected to said first fluid cylinder and piston combination and being movable in accordance with the pressure in said first fluid cylinder and piston combination as determined by the load which is being lifted by said carrier, said hydraulic switch including a pistoN arm portion which projects outwardly in accordance with the pressure of said first cylinder and piston combination, a hydraulic control for said second fluid cylinder and piston combination including a pivotal shift lever having a mounting shaft which is rotated by movement thereof and including a blocking cam thereon, said piston arm being movable to a position in which it blocks movement of said lever shaft in one direction but permits movement in an opposite direction for controlling the fluid operation of said second cylinder and piston combination.

Claim 18

A lifting device, comprising a wheeled chassis having front and rear wheels and two chassis portions carrying respective ones of said front and rear wheels which are extensibly and retractably movable in relation to one another for changing the wheelbase length, a mast pivotally mounted on and extending upwardly from said chassis, said mast being pivotal about a substantially horizontal axis, a lift carrier supported on said mast and extending outwardly therefrom, and being movable to lift a load, a first fluid cylinder and piston combination connected between said chassis and said mast for pivoting said mast and shifting said carrier therewith for engaging and lifting a load and for lowering and disengaging a load, a second fluid piston and cylinder combination carried on said chassis and connected to said relatively movable chassis portions for shifting them relatively to change the wheelbase length, dynamometer means connected to said carrier for measuring the load moment acting on said carrier, said dynamometer means including a hydraulic switch connected to said first fluid cylinder and piston combination and being movable in accordance with the pressure in said first fluid cylinder and piston combination as determined by the load which is being lifted by said carrier, said hydraulic switch including a pistoN arm portion which projects outwardly in accordance with the pressure of said first cylinder and piston combination, a hydraulic control for said second fluid cylinder and piston combination including a pivotal shift lever having a mounting shaft which is rotated by movement thereof and including a blocking cam thereon, said piston arm being movable to a position in which it blocks movement of said lever shaft in one direction but permits movement in an opposite direction for controlling the fluid operation of said second cylinder and piston combination.