Universal control system for hydraulic cylinders

A lift control system operable to raise or lower a load while maintaining the load substantially level, comprising:

• first and second means cooperating with the load at first and second lift positions thereon for raising the load;
• first and second means for sensing the elevation of the load at the first and second lift positions, respectively;
• and
• control means coupled to said first and second raising means and said first and second sensing means for providing a selective plurality of equal and incremental movements of each of said first and second raising means responsive to the elevations sensed by said first and second sensing means, respectively, to maintain the load substantially level during a lifting operation.

A lift control system operable to selectively raise or lower a load while maintaining the load substantially level relative to a reference level, comprising:

• a plurality of double-acting rams for engaging the load at a plurality of different lift positions to controlably raise or lower the load;
• a plurality of hydraulic pumps, one for each ram;
• means for hydraulically coupling each pump to one of said rams;
• a plurality of sensing means one at each lift position for sensing the elevation of the load at each of said lift positions;
• and
• control means coupled to said pumps and to said sensing means for commanding operation of said pumps to provide a selective plurality of equal and incremental movements of each of said ram, and thus said load, responsive to the elevation sensed by said sensing means to maintain the load substantially level relative to the reference during a raising or lowering operation.

A method of lifting a load while maintaining the load substantially level relative to a reference, comprising the steps of:

• engaging the load at a plurality of lifting points with a plurality of controllable lifting devices;
• automatically operating each lifting device until each lifting device raises the load a preselected incremental distance;
• waiting a preselected maximum amount of time for each lifting element to raise the load said preselected increment;
• automatically repeating the controlled incremental movement of the lifting devices until the load has been raised a preselected distance.

A method for exerting successive increments of force on a member at spaced locations comprising the steps of:

• engaging the member at spaced locations with a plurality of double-acting hydraulic rams;
• simultaneously starting a plurality of pumps hydraulically coupled to said double-acting rams for simultaneously extending the ram pistons;
• sensing incremental movement of the member at the position of each ram;
• stopping each pump when a ram has achieved a preselected amount of incremental movement;
• waiting for each ram to complete the preselected increment of movement;
• and
• automatically operating the pumps on a cyclical basis to repeat the incremental movement of each ram after all rams have completed an increment of movement.