Control and hydraulic system for liftcrane

A control system for operation of liftcrane having mechanical subsystems powered by a engine, each mechanical subsystem connected thereto by an individual closed hydraulic loop, comprising:

• a first mechanical subsystem powered by the engine and connected thereto by a closed hydraulic loop,
• a first set of controls for outputting signals for operation of said first mechanical subsystem,
• a first sensor operable to sense the pressure in the closed hydraulic loop connected to said first mechanical subsystem and to provide an output signal indicative thereof, and
• a programmable controller connected to said first set of controls, said first sensor, and said first mechanical subsystem,
• a mode selector for selecting a desired mode of operation of the first mechanical subsystem, and
• an operating routine adapted to run on said programmable controller, said operating routine comprising:
• first information corresponding to a range of possible signals that can be received from said first set of controls, and
• at least two sets of second information each set corresponding to a range of possible operations of said first mechanical subsystem, said first information being related to each of said sets of second information, and further wherein one of said sets of second information is related to the first information based upon an input from the mode selector,
• whereby said first mechanical subsystem can be operated in accordance with an operating routine run on said programmable controller based upon the output signals of said first set of controls and said first sensor.

An improved control system for a liftcrane having a plurality of mechanical subsystems powered by an engine and each connected thereto by an individual closed hydraulic loop, the system comprising:

• a set of controls for outputting signals for operation of the mechanical subsystems of the liftcrane,
• a set of sensors operable to sense the pressure in at least some of the closed hydraulic loops and for outputting signals indicative thereof,
• a mode selector for providing an operator with a selection of alternative modes of liftcrane mechanical subsystem operation and adapted to output a signal representative of said selection and wherein at last two of the alternative modes of liftcrane mechanical subsystem operation are fully operational modes;
• and
• a programmable controller connected to said set of controls, said mode selector, and said set of sensors, said programmable controller adapted to run a routine operable to output signals to the mechanical subsystems for the control thereof based upon the signals output by said set of controls, said mode selector, and said first set of sensors.

An improved method for controlling operation of a liftcrane having and engine and mechanical subsystems each powered by a closed hydraulic loop driven by the engine, comprising the steps of:

• lifting a load with a hoist and a boom;
• applying a brake to the hoist to prevent the load from slipping,
• sensing with a sensor associated with the hoist the application of the brake to the hoist;
• storing data in a memory indicative of the pressure sensed by the sensor associated with the hoist at the time when the brake is applied to said hoist;
• applying pressure to the hoist equal to the pressure indicated by the data stored in the memory;
• and
• releasing the brake.

An improved method for performing clamshell work with a liftcrane having an engine and mechanical subsystems each powered by a closed hydraulic loop driven by the engine, comprising the steps of:

• supporting a the load in a clamshell with a first line connected to a hoist drum;
• sensing the pressure in a first closed hydraulic loop connected to a first pump associated with the hoist drum,
• outputting a signal indicative of the pressure sensed in the first closed hydraulic loop to a programmable controller, and
• commanding with the programmable controller a second pump associated with a second hoist drum to maintain a force on a second line connected to the clamshell said force related to the pressure sensed in the first closed hydraulic loop.

An improved method for performing swing operation in a liftcrane having an engine and mechanical subsystems each powered by a closed hydraulic loop driven by the engine, comprising the steps of:

• outputting a signal from a control handle to a programmable controller to indicate the desired operation of the swing in a first mode;
• sensing the pressures in a first hydraulic line associated with the swing motor with a first pressure sensor and in a second hydraulic line associated with the swing motor with a second pressure sensor, the first and second hydraulic lines forming a closed hydraulic loop connected to a pump driven by the engine;
• outputting signals to a programmable controller from the first and second pressure sensors;
• and
• outputting a signal from the programmable controller to the pump to operate the swing based upon a comparison of the signals received from the first pressure sensor, the second pressure sensor, and the control handle.

An improved method for controlling operation of a liftcrane having an engine and a hose powered by a closed hydraulic loop driven by the engine, comprising the steps of:

• lifting a load with the hoist;
• applying a brake to the hoist to prevent the load from slipping,
• storing data in a computer memory indicative of the pressure in the closed hydraulic loop that powers the hoist when the brake is applied to said hoist;
• applying pressure to the hoist at least equal to the pressure indicated by the data stored in the computer memory;
• and
• releasing the brake.

A method of operating a liftcrane having a mechanical subsystem powered by an engine and connected thereto by a closed hydraulic loop, controls in an operator's cab for outputting signals for operation of said mechanical subsystem, a sensor operable to sense the pressure in the closed hydraulic loop and for outputting signals indicative thereof, and a programmable controller connected to said controls and said sensor, said programmable controller adapted to run a routine operable to output signals from said controller to said first mechanical subsystem for the operation thereof based upon the signals output by said controls and said sensor, the method comprising the steps of:

• operating the controls to produce signals indicative of the desired liftcrane subsystem operation;
• outputting said signals to the programmable controller;
• running an operating routine on said programmable controller, said operating routine having:
• first information corresponding to a range of possible signals that can be received from said controls, and
• at least two sets of second information corresponding to a range of possible operation of said liftcrane subsystem,
• said first information being related to each of said sets of second information,
• relating said first information with said second information,
• outputting a signal from said programmable controller to said mechanical subsystem representative of said second information, and
• operating said mechanical subsystem based upon said signal output from said programmable controller.