Abstract: A machine has a boom, that is pivotally raised and lowered by a first cylinder, and has a load carrier that is pivoted at the end of the boom by a second cylinder. As a machine operator commands movement of the boom, the position of the load carrier is automatically altered by a controller to prevent a load from falling off the load carrier. The load carrier position with respect to the boom is altered in response to the amount of boom motion to maintain a constant position relationship between the load carrier and a chassis of the machine. Although the boom and load carrier move through different angular positions, the machine control is expressed in terms of the linear motion of the first and second cylinders.

Abstract: An apparatus is provided which has sensors that detect pressure on opposite sides of a control valve which controls the flow of hydraulic fluid from a source to a hydraulic actuator. The sensors produce electrical signals indicating those pressures. In response to the sensor signals, a controller produces an output signal the operates a proportional control valve to thereby regulate pressure at a node of the hydraulic circuit. Several mechanisms are described that react to the pressure at the node by varying the pressure of the fluid being supplied to the main valve so that a controlled pressure level is achieved.

Abstract: A plurality of hydraulic actuators are connected by valve assemblies to fluid supply and return conduits. Desired operating velocities are specified for the hydraulic actuators and used to define the amounts of fluid flow required by each actuator to move at the respective velocity. Provide the requisite flow amounts, fluid at related pressures must be provided at the different hydraulic actuators. In order for those pressures to occur, a pump has to furnish fluid at a greater pressure to allow for supply conduit losses. A process is provided for determining the pressure that the pump must provide to satisfy the greatest pressure that is necessary for the desired operation of all the hydraulic actuators.

Abstract: The flow of fluid to a hydraulic actuator is controlled by a valve assembly which operates in different metering modes at various points in time. The metering mode to use in selected in response to the hydraulic load that acts on the valve associated with the hydraulic actuator. Specifically the load is determined and then compared to threshold levels associated with the different metering modes to choose the metering mode for use a given point in time.

Abstract: A plurality of hydraulic actuators are connected between a supply line and a tank return line. A separate desired velocity is requested for each hydraulic actuator. In response to a respective metering mode and the desired velocity for each hydraulic actuator, the flow requirements that each hydraulic actuator has from the supply and return lines are derived. A determination is made as to what fractions of the required flows can be provided by the flow levels that are available from the supply and return lines. Those fractions are used to convert the desired velocity for the given hydraulic actuator into a velocity command which indicates the velocity of the given hydraulic actuator that can be achieved with the available fluid flows. The respective velocity command is used to control the flow of fluid to each hydraulic actuator.

Abstract: An apparatus and method for creating vibration of an appendage of a work vehicle is disclosed. The apparatus includes a hydraulic cylinder, first and second valve assemblies, and a control element. The hydraulic cylinder is coupled between a first portion of the work vehicle and the appendage and includes a first chamber, a second chamber, and a piston. The first and second valve assemblies respectively govern whether hydraulic fluid is provided from a pump to, or to a tank from, the first and second chambers. The control element automatically causes a status of the second valve assembly to repeatedly alternate with time so that the vibration occurs at the piston and is in turn provided to the appendage.

Abstract: A pilot operated valve has a main poppet that selectively controls bidirectional flow of fluid between two ports in response to pressure in a control chamber on one side of the main poppet. The main poppet has a pilot orifice that is opened and closed by a pilot poppet. A unique mechanism is provided to compensate for variation of a pressure differential on opposite sides of the pilot orifice. This mechanism has a pair of annular end members between which extends a spring formed by a plurality of helices. Multiple passages with check valves extend through the main poppet to communicate the greatest pressure among the two ports to the control chamber and the lowest pressure among the two ports to the side of the pilot orifice that is opposite the control chamber.

Abstract: A control system for operating a hydraulic system includes a user input device which generates an input signal indicating desired movement of a hydraulic actuator. A mapping routine converts the input signal into a velocity command indicating desired actuator velocity. A valve opening routine transforms the velocity command into a flow coefficient which characterizes fluid flow through the valve assembly and from the flow coefficient produces a set of control signals designating levels of electric current to apply to valves within the valve assembly. A pressure controller regulates pressure in the supply line in response to the velocity command. When the hydraulic system has a plurality of functions, the control system adjusts each velocity command to equitably apportion fluid to each function when the aggregate flow being demanded by the functions exceeds the total flow available from a source.

Abstract: A system for simultaneously operating first and second hydraulic cylinders has an inlet node for connection to a source of pressurized fluid and an outlet node for connection to a tank. A two-position, three-way primary control valve has a first port connected to the inlet node, a second port connected to the outlet node, and a common port. A first electrohydraulic proportional valve connects the common port to a first port of the first cylinder, and a second electrohydraulic proportional valve connects the common port to a first port of the second cylinder. A third electrohydraulic proportional valve connects the inlet node to a second port of the first cylinder and a second port of the second cylinder. Selectively operating the primary control valve and one of the third and fourth electrohydraulic proportional valves determines the direction in which the first and second cylinders move.

Abstract: A control system for operating a hydraulic system includes a user input device which generates an input signal indicating desired movement of a hydraulic actuator. A mapping routine converts the input signal into a velocity command indicating a desired actuator velocity. A valve opening routine transforms the velocity command into a flow coefficient which characterizes fluid flow through the valve assembly and from the flow coefficient produces a set of control signals designating levels of electric current to apply to valves within the valve assembly. A pressure controller regulates pressure in the supply line in response to the velocity command. When the hydraulic system has a plurality of functions, the control system adjusts each velocity command to equitably apportion fluid to each function, when the aggregate flow being demanded by the functions exceeds the total flow available from a source.

Abstract: The flow of fluid to a hydraulic actuator is controlled by a valve assembly which operates in different metering modes at various points in time. The metering mode to use in selected in response to the hydraulic load that acts on the valve associated with the hydraulic actuator. Specifically the load is determined and then compared to threshold levels associated with the different metering modes to choose the metering mode for use a given point in time.

Abstract: A plurality of hydraulic actuators are connected between a supply line and a tank return line. A separate desired velocity is requested for each hydraulic actuator. In response to a respective metering mode and the desired velocity for each hydraulic actuator, the flow requirements that each hydraulic actuator has from the supply and return lines are derived. A determination is made as to what fractions of the required flows can be provided by the flow levels that are available from the supply and return lines. Those fractions are used to convert the desired velocity for the given hydraulic actuator into a velocity command which indicates the velocity of the given hydraulic actuator that can be achieved with the available fluid flows. The respective velocity command is used to control the flow of fluid to each hydraulic actuator.

Abstract: When a swinging boom driven by a hydraulic cylinder stops, inertia causes continued motion of the boom which increases pressure in a chamber of the hydraulic cylinder. Eventually that pressure reaches a level which causes the boom to reverse direction. Then pressure in an opposite cylinder chamber increases until reaching a level that causes the boom movement to reverse again. This oscillation continues until the motion is dampened by other forces acting on the boom. As a result, an operator has difficulty in properly positioning the boom. To reduce this oscillating effect, a sensor detects when the cylinder chamber pressure increases above a given magnitude and then a determination is made when the rate of change of that pressure is less than a defined threshold. Upon that occurrence, a control value is opened to relieve the pressure in that cylinder chamber.

Abstract: When a swinging boom driven by a hydraulic cylinder stops, inertia causes continued motion of the boom which increases pressure in a chamber of the hydraulic cylinder. Eventually that pressure reaches a level which causes the boom to reverse direction. Then pressure in an opposite cylinder chamber increases until reaching a level that causes the boom movement to reverse again. This oscillation continues until the motion is dampened by other forces acting on the boom. As a result, an operator has difficulty in properly positioning the boom. To reduce this oscillating effect, a sensor detects when the cylinder chamber pressure increases above a given magnitude and then a determination is made when the rate of change of that pressure is less than a defined threshold. Upon that occurrence, a control value is opened to relieve the pressure in that cylinder chamber.

Abstract: A pilot operated valve has a main poppet that selectively controls bidirectional flow of fluid between two ports in response to pressure in a control chamber on one side of the main poppet. The main poppet has a pilot orifice that is opened and closed by a pilot poppet. A unique mechanism is provided to compensate for variation of a pressure differential on opposite sides of the pilot orifice. This mechanism has a pair of annular end members between which extends a spring formed by a plurality of helices. Multiple passages with check valves extend through the main poppet to communicate the greatest pressure among the two ports to the control chamber and the lowest pressure among the two ports to the side of the pilot orifice that is opposite the control chamber.

Abstract: An apparatus and method for creating vibration of an appendage of a work vehicle is disclosed. The apparatus includes a hydraulic cylinder, first and second valve assemblies, and a control element. The hydraulic cylinder is coupled between a first portion of the work vehicle and the appendage and includes a first chamber, a second chamber, and a piston. The first and second valve assemblies respectively govern whether hydraulic fluid is provided from a pump to, or to a tank from, the first and second chambers. The control element automatically causes a status of the second valve assembly to repeatedly alternate with time so that the vibration occurs at the piston and is in turn provided to the appendage.

Abstract: A programmable controller, for operating a machine such as one having a hydraulic system, includes a memory that stores a plurality of software function routines. A memory contains a first data file with address pointers to the function routines where the address pointers are listed in the order that the function routines may be executed. A second data file has a separate record associated with each of the address pointers and each record identifies the data variables required by the corresponding function routine. A third data file contains information about each of the variables. A code sequencer accesses the first data file and directs execution of the function routine in the order designated by the pointers. As each function routine executes, the respective record in the second data file is used to access the required variable information.

Abstract: A system for simultaneously operating first and second hydraulic cylinders has an inlet node for connection to a source of pressurized fluid and an outlet node for connection to a tank. A two-position, three-way primary control valve has a first port connected to the inlet node, a second port connected to the outlet node, and a common port. A first electrohydraulic proportional valve connects the common port to a first port of the first cylinder, and a second electrohydraulic proportional valve connects the common port to a first port of the second cylinder. A third electrohydraulic proportional valve connects the inlet node to a second port of the first cylinder and a second port of the second cylinder. Selectively operating the primary control valve and one of the third and fourth electrohydraulic proportional valves determines the direction in which the first and second cylinders move.

Abstract: A solid motor controller for controlling the current in an electrical motor. The motor controller includes a processing unit, and a solid state switch operatively connected to the electrical motor. The motor controller senses the current through the motor, compares the current with a reference current level, and limits the current in the motor by rapidly switching the switch between an ON and an OFF state when the current exceeds the reference current level. The controller de-energizes the motor by placing the switch in the OFF state when the current exceeds the reference current for a predetermined period of time. The controller also includes a second solid state switch which is controlled to rapidly stop the rotation of the motor. The motor controller also activates a high current warning when the current exceeds a high current limit.

Abstract: The improved battery-powered lawnmower includes a safety key that is automatically removed when the removable battery is removed, while at the same time blocking the battery recharger receptacle. The lawnmower also includes a control circuit that shuts off the lawnmower upon the occurrence of one or more of several predetermined conditions, including low battery voltage, the encountering of heavy grass for a period of 3 seconds or more, and high motor current that may occur when the cutting blade is jammed. The cutting blade is designed to move through any debris accumulated between the blade ends and the housing sidewall without sacrificing the lift for needed cutting and mulching. The invention also includes a unique height adjustment assembly for adjusting the height of the chassis, a handle attachment that allows the handle to be positively tightened to the lawnmower chassis, and a telescoping groove for the battery's quick connect/disconnect terminals.