Sheet stacker

Claim 2

In a sheet stacker having a frame, a table and means for moving the table up and down with respect to the frame, the improvement for leveling the table regardless of unbalanced loads thereon and comprising a first torsion bar at one side of the table, a second torsion bar at the opposite side of the table, pairs of sprockets fixed at both ends of both torsion bars, pairs of leveling chains at both ends of said torsion bars, anchor means anchoring each such chain to the frame above the table, said chain extending downwardly from its said anchor means and around the bottom of a sprocket on an end of a torsion bar and thence laterally across the table and around the top of a sprocket on an end of a torsion bar at the other side of the table and thence downwardly and means anchoring the chain to the frame below the table whereby unbalanced forces tending to tilt the table will be transmitted by said torsion bars from one side of the table to the other to tend to balance said forces and maintain the table level, corresponding chains of each pair of chains being anchored to the frame above the table and above the ends of said first torsion bar at said one side of the table and other corresponding chains of each pair of chains being anchored to the frame above the table and above the ends of said second torsion bar at said opposite side of said table, the chains of each pair having side-by-side runs extending across the table.

Claim 3

The improvement of claim 1 in which said pairs of sprockets include an inner sprocket and outer sprocket, one chain of each pair being trained around inner sprockets on the ends of said torsion bars and the other chain of each pair being trained around outer sprockets on the ends of said torsion bars.

Claim 4

In a sheet stacker having a frame and having a lift table movably mounted on the frame for upward and downward movement, and having means for raising and lowering the lift table, the improvement comprising two torsion bars each journaled to opposite sides of said lift table and extending thereacross, inner and outer sprockets rigidly attached to each end of each torsion bar, a first leveling chain rigidly attached at one end to said frame above one corner of said lift table and rigidly attached at the other end to said frame below an opposite corner of said lift table, said first leveling chain being entrained under the inner sprocket at one end of one torsion bar and being entrained over the inner sprocket at the corresponding end of the other torsion bar, a second leveling chain rigidly attached at one end to said frame above the bottom end of said first leveling chain and rigidly attached at the other end to said frame below the upper end of said first leveling chain, said second leveling chain being entrained over the outer sprocket of said one torsion bar and being entrained under the outer sprocket of said other torsion bar, a third leveling chain rigidly attached at one end to said frame above the other end of said one torsion bar and rigidly attached at the other end to said frame below the other end of said other torsion bar, said third leveling chain being entrained under the inner sprocket at the other end of said one torsion bar and being entrained over the inner sprocket at the other end of said other torsion bar, and a fourth leveling chain rigidly attached at one end to said frame under the upper end of said third chain and rigidly attached at the other end to said frame over the lower end of said third chain, and said fourth leveling chain being entrained over the outer sprocket of said one torsion bar and being entrained under the outer sprocket of said other torsion bar, thereby equalizing upward and downward forces applied to any portion of said lift table.

Claim 5

In a sheet stacker having a frame and having a lift table movably mounted on the frame for upward and downward movement, and having means for raising and lowering the lift table, the improvement comprising two torsion bars each journaled to opposite sides of said lift table and extending thereacross, inner and outer sprockets rigidly attached to each end of each torsion bar, a first leveling chain rigidly attached at one end to said frame above one corner of said lift table and rigidly attached at the other end to said frame below an opposite corner of said lift table, said first leveling chain being entrained under the inner sprocket at one end of one torsion bar and being entrained over the inner sprocket at the corresponding end of the other torsion bar, a second leveling chain rigidly attached at one end to said frame above the bottom end of said first leveling chain and rigidly attached at the other end to said frame below the upper end of said first leveling chain, said second leveling chain being entrained over the outer sprocket of said one torsion bar and being entrained under the outer sprocket of said other torsion bar, a third leveling chain rigidly attached at one end to said frame above the other end of said one torsion bar and rigidly attached at the other end to said frame below the other end of said other torsion bar, said third leveling chain being entrained under the inner sprocket at the other end of said one torsion bar and being entrained over the inner sprocket at the other end of said other torsion bar, and a fourth leveling chain rigidly attached at one end to said frame under the upper end of said third chain and rigidly attached at the other end to said frame over the lower end of said third chain, and said fourth leveling chain being entrained over the outer sprocket of said one torsion bar and being entrained under the outer sprocket of said other torsion bar, thereby equalizing upward and downward forces applied to any portion of said lift table.

Claim 6

In a sheet stacker having a frame and having a lift table movably mounted on the frame for upward and downward movement, and having means for raising and lowering the lift table, the improvement wherein said means for raising said lift table includes at least one hydraulic cylinder coupled to said lift table and pump means for forcing hydraulic fluid into said cylinder to raise said lift table, said pump means including a relatively high capacity pump for raising said lift table at a relatively high speed and a relatively low capacity pump for raising said lift table at a relatively low speed, a plurality of rollers journaled to said lift table and forming the upper surface thereof, a plurality of sprockets coupled to alternate rollers, a drive chain operatively engaged with said sprockets for driving the rollers coupled thereto, a hydraulic motor operatively engaged with said drive chain for driving the same, and hydraulic valve means selectively coupling said low capacity pump to said hydraulic motor to drive the motor at a relatively low speed and selectively coupling said high capacity pump to said hydraulic motor to drive the motor at a relatively high speed.

Claim 7

In a sheet stacker having a frame and having a lift table movably mounted on the frame for upward and downward movement, and having means for raising and lowering the lift table, the improvement wherein said means for raising said lift table includes at least one hydraulic cylinder coupled to said lift table and pump means for forcing hydraulic fluid into said cylinder to raise said lift table, said pump means including a relatively high capacity pump for raising said lift table at a relatively high speed and a relatively low capacity pump for raising said lift table at a relatively low speed, a plurality of rollers journaled to said lift table and forming the upper surface thereof, a plurality of sprockets coupled to alternate rollers, a drive chain operatively engaged with said sprockets for driving the rollers coupled thereto, a hydraulic motor operatively engaged with said drive chain for driving the same, and hydraulic valve means selectively coupling said low capacity pump to said hydraulic motor to drive the motor at a relatively low speed and selectively coupling said high capacity pump to said hydraulic motor to drive the motor at a relatively high speed.

Claim 8

The sheet stacker defined in claim 4 wherein said hydraulic motor is mounted on said frame above a corner of said lift table, and further comprising a loop in said drive chain extending downwardly from said hydraulic motor to said roller sprockets, an idler sprocket journal to said frame below said corner of said lift table, and a second loop in said drive chain extending downwardly from said roller sprockets to said idler sprocket, whereby movement of said drive chain will drive said roller sprockets regardless of the vertical position of said lift table.

Claim 9

The sheet stacker defined in claim 5 and further comprising a second idler sprocket journaled to said lift table above the first mentioned idler sprocket and below said rollers, said drive chain being entrained over said second idler sprocket and extending downwardly from said second idler sprocket to said first mentioned idler sprocket, said drive chain extending upwardly from said first mentioned idler sprocket to said hydraulic motor and extending downwardly from said hydraulic motor to said roller sprockets.

Claim 10

The sheet stacker defined in claim 4 wherein said hydraulic valve means includes a first valve coupled in series with said high capacity pump buT not said low capacity pump, a second valve coupled in series with said low capacity pump but not said high capacity pump, a third valve coupled in series with both said first and second valves between said first and second valves and said hydraulic cylinder for raising said lift table, and a fourth valve coupled in series with both said first and second valves between said first and second valves and said hydraulic motor, whereby said high capacity pump and low capacity pump can be selectively coupled to said hydraulic cylinder for raising said lift table at a selected one of two speeds and can be selectively coupled to said hydraulic motor for rotating said rollers at a selected one of two speeds.