Abstract: Erosion and wear resistant iron alloy, comprising: Cr 20.0-36.0% by weight, B 2.5-5.0% by weight, Mn 0.5-3.2% by weight, Si 0.05-0.6% by weight, Mo 0.3-2.5% by weight, V 0.05-0.3% by weight, Nb 0.03-0.3% by weight, P 0.5% by weight or less, C 0.05-0.3% by weight, and a trace of unavoidable impurities, which confers superior corrosion and wear resistance upon abraded or corroded portions by coating or molding.

Abstract: A method for controlling the operation of a power excavator during a land finishing work is disclosed. In the above method, the bucket, arm and swing unit are controlled in response to output signals from a handling signal input means. Meanwhile, the boom is controlled as follows. That is, when a boom handling signal is output from the handling signal input means, the boom is controlled in response to the boom handling signal. However, when the handling signal input means does not output a boom handling signal, the boom is controlled by a geometrical operation of signals output from the boom, arm and bucket sensors and a land finishing angle for calculating reference boom angle data. The reference boom angle data is control-operated to output an automatic boom control signal, thus controlling the boom in order to move the bucket tip on a land with the land finishing angle in response to an arm handling signal output from the handling signal input means.

Abstract: A device for controlling a breaker in construction vehicles is disclosed. The device includes a control circuit provided with a power supply, a first solenoid valve used for controlling the breaker, and a second solenoid valve used for boosting the relief pressure of the circuit. The device also includes a control switch and a select switch. The control switch is installed in a control lever and is handled by an operator in order to selectively open or close the control circuit. Meanwhile, the select switch is connected between the control switch, power supply and first and second solenoid valves. The select switch selectively connects the power supply to the first or second solenoid valve in order to select either of the breaker and pressure boosting operations, which are commonly controlled by the control switch.

Abstract: A device and process for controlling the automatic operations of a power excavator are disclosed. The device has a plurality of sensors for sensing the motions of the excavator's moving parts. The device also has a controller with discriminating means. The discriminating means operates the sensed data of the sensors and discriminates the automatic operation to be performed. The controller outputs the control signals to the excavator's moving parts for automatically performed the automatic operation. The control device further includes recognizable signal output means for converting the discriminated results into recognizable signals prior to outputting the discriminated results, and confirmation signal input means for confirming the discriminated results outputted from the recognizable signal output means.

Abstract: A control device for a travelling system in construction vehicles is disclosed. The control device applies the pilot pressure of the pilot pump to the spool of the directional control valve separately from the travelling control pedal, thus automatically controlling operation of the directional control valve. However, the manual control mode performed by the travelling control pedals has priority over the automatic control mode. The control device has a proportional control valve, which applies the pilot pressure of the pilot pump to the spool in response to an input current signal. A pressure sensor checks the pilot pressures, which are generated by both the travelling control pedals and the proportional control valves and act on the spool. A controller receives a signal indicative of the pilot pressures checked by the pressure sensor and outputs the current signal to the proportional control valve.

Abstract: A return fluid regeneration device for construction vehicles is provided. The regeneration device includes an orifice disposed on a return-side internal line of a directional control valve of an actuator. A regeneration line is arranged between the return-side internal line and a return line extending to a return tank and is further selectively connected to the return-side internal line during a weight operation of the actuator. A regeneration branch line is branched from the return-side internal line and is connected to a supply-side internal line of the valve, thus selectively feeding the return fluid from the return-side internal line to the supply-side internal line and thereby regenerating the return fluid. First and second check valve are also provided on the regeneration line and branch line, respectively. The regeneration device regulates the moving speed of the actuator while simultaneously preventing the generation of high pressure in a fluid supply line.

Abstract: An engine/pump control device for loaders is disclosed. The control device controllably distributes the output power (rotating force) of an engine to the travelling and working units of a loader in accordance with operational conditions of the loader, thus remarkably improving work efficiency of the loader. When the loader performs an operation requiring a high tractive force prior to the driving force of the working members, the control device opens the unloading valve thereby partially returning the output fluid of a hydraulic pump to a return tank while transmitting the surplus output power of the engine to the traveling unit. Meanwhile, when the loader performs an operation requiring a high driving force of the working members prior to the tractive force, the control device closes the unloading valve, thereby totally supplying the output fluid of the hydraulic pump to the actuators in order to generate a high moving speed of the working members.

Abstract: A method for carrying out a surface finishing work with an electronically controlled hydraulic excavator is disclosed.

Abstract: An automatic rear wheel self-centering device for four-wheel steering vehicles automatically performs the rear wheel self-centering operation when the steering mode of the vehicle returns from another steering mode to the standard steering mode. The device has a branch conduit branched from a conduit leading from the steering unit to the steering mode selection valve. A conduit control valve is mounted to the branch conduit and is changeable between a neutral position blocking the branch conduit, a first position connecting the branch conduit to one side chamber of the rear wheel steering cylinder and a second position connecting the branch conduit to the other side chamber of the cylinder. The spool of the conduit control valve moves synchronous with a linear movement of the piston of the rear wheel steering cylinder, thereby changing the position of the conduit control valve between the above three positions.

Abstract: A mono-block control valve having a regeneration conduit is disclosed. The regeneration conduit does not enlarge the valve body. The control valve has a bypass conduit formed in either side of the valve body. The bypass conduit is opened to return the pressurized oil of the hydraulic pump to a return tank if the spool is in a neutral position, but closed if the spool moves. Two actuator ports are formed in each section of the body. The ports supply the pressurized oil of the pump to a supply side of each actuator and for returning the oil coming out of the return side of each actuator to the return tank respectively. A regeneration conduit is formed in a bottom portion of the body and connects the two actuator ports to each other. The control valve further includes a check valve and a pilot conduit.

Abstract: An unmanned operating method for a crane for moving containers in use in a harbor and the apparatus therefor compensates the influence due to a disturbance such as the wind in driving the crane, detects the position and posture of the spreader and crane, thereby allowing the container to be attached and detached automatically. Accordingly, a crane automation for moving containers is achieved.

Abstract: Electron beam irradiation step is followed by alkaline material atomizing step in the present invention. Since irradiation step and alkaline material atomizing step is conducted in different time and in different reactors, the construction cost of X-ray shielding concrete is decreased remarkably. If the humidity of incinerator effluent gas is more than 100 g/Nm.sup.3 in dry basis by adding a steam of 110.degree..about.200.degree. C., harmful substances are efficiently removed by electron beam irradiation. As a result, it is possible to realize a space-saving equipment, a reduction of required energy, a simple operation controlling, and a prevention of occurrence of secondary environment pollution.

Abstract: A Stiffener manufacturing method and apparatus appropriate for manufacturing a stiffener such as a flat bar is disclosed. The stiffener manufacturing method is composed of a steel plate arrangement step, a strip-cutting step and a pattern cutting step, which are performed in a predetermined interval of time at a position.

Abstract: A control system of an excavator. The excavator includes a lower running body, an upper pivoting body, a working device having a plurality of links attached to the upper pivoting body, a pivoting device, and a running device, actuators for actuating the working device, the pivoting device, and the running device, hydraulic control valves for controlling quantities of hydraulic fluid supplied to the actuators, sensors for detecting relative angular positions of the links, and a control system.

Abstract: A working unit of construction equipment with an attachment self leveling function is disclosed. The working unit includes an attachment self leveling linkage. The linkage automatically maintains the desired angle of the attachment relative to the reference or ground surface, thereby maintaining the horizontal position of the attachment without any motion for controlling the bucket cylinder while lifting up the attachment from the initial position to the uppermost position by the arm-up motion during the operations of construction equipment. The attachment self leveling linkage has a simplified construction, thereby being easily produced and installed at a lower cost and lightening the weight of the working unit. The linkage thus improves the operational efficiency of the working unit.