Abstract: A method for controlling the RPM of an engine in a hydraulic construction machine. A reference throttle lever position value and a reference engine RPM value are set to allow the engine to have a target output characteristic. A first control arithmetic operation is performed in response to a present throttle lever position value and the set reference throttle lever position value to allow a difference between the present throttle lever position value and the set reference throttle lever position value to be within the range of a mechanical error of an engine throttle control mechanism. A first control signal is generated as a result of the first control arithmetic operation to control the RPM of the engine.

Abstract: A straight travelling apparatus for heavy construction equipment, equipped with a travel supplement circuit, including a variable orifice disposed in a fluid line connected to the supply-side of the control valve of a bucket and controlled to vary an opening degree thereof by a predetermined pilot signal that is applied to the variable orifice in response to an operation of at least one of right and left travel motors in order to keep the variable orifice at a relatively closed state while being released in response to the travel motors not operating in order to keep the variable orifice in a relatively opened state, thereby capable of supplementing a sufficient amount of fluid to a travelling system when the bucket is operated during, thereby preventing an abrupt reduction in travelling speed caused by operatings the straight travelling apparatus.

Abstract: A motor cavitation prevention device for hydraulic systems is disclosed. The device exerts no influence upon return fluid of any actuators other than the hydraulic motor thereby preventing undesired pressure loss of the return line. The device has valve means installed in a given position of the return line such that the return fluid of the motor necessarily passes the check valve prior to returning to a return tank but the return fluid of the other actuators does not pass the check valve, and a feedback line for feeding the return fluid of the motor back to the motor in the ease of generation of the pressure above tank in the return line, one end of which feedback line is connected to the return line at the front of the check valve but the other end of which feedback line is connected to the motor.

Abstract: Disclosed is an improvement of the spline used for a mechanical apparatus for transmitting/cutting-off power by using friction discs. The spline includes an internal spline in the form of a semi-circular groove and an external spline with both edges thereof having the same arc, at a predetermined length as that of the internal spline.

Abstract: A method of and an apparatus for controlling noise generated in a confined space, being capable of reducing a radiating sound pressure generated from a main noise source to that of an optimal state. The method includes the steps of measuring the radiating sound pressure generated from the noise source, and generating, from an additional sound source, a radiating sound pressure having the same magnitude as the radiating sound pressure generated from the noise source while having a phase 180.degree.-shifted from that of the noise source's radiating sound pressure so that the radiating sound pressures can offset each other when they are mixed.

Abstract: A discharge flow control system and method of a hydraulic pump driven by an engine for the minimization of the difference between a discharge mount of flow in the pump and total mount of operating oil necessary to operate each actuator in hydraulic equipment. The control system is provided with a detector which detects the number of rotation of the engine, generates equal number of pulses to the number of rotation, a detector which detects the tilt angle of a swash plate of the pump, a detector which detects the operating displacement of the actuator, a detector which detects the load pressure acting on the pump, and a controll unit which controls a target discharge flow mount of the pump which is suitable for performing a predetermined work based on the number of rotation, the tilt angle, the displacement and the load pressure.

Abstract: A device for draining oil out of a valve spool cap is disclosed. The device makes the oil start to drain out of the spool cap just after the valve spool starts to move thereby remarkably improving the responsibility of the spool. The valve body has either an enlarged inner diameter portion formed in the bore or a drain hole extending in the body for making the drain core communicate with the inside of the spool cap. The enlarged inner diameter portion is formed by partially enlarging the inner diameter of the bore between the drain core and the end wall of the valve body. The drain hole extends in the valve body from the drain core to the end wall of the valve body.

Abstract: The invention is made to provide a reliable driving system by solving the problem of the conventional apparatus caused by unstable current in the chopper transistor located at the low end of the field winding and armature winding. The over drive control apparatus of the direct current series motor of the present invention, including the field winding and armature winding and driven by power from the battery, comprises a chopper transistor to which the battery is applied, and an over drive contactor connected between the chopper transistor and the field windings to switch the battery power from the chopper transistor to the field winding.

Abstract: Disclosed is a manufacture and coating method of mechanical products using ferrous alloy in order to improve wear, corrosion, and heat resistances of the mechanical products which are exposed to friction and wear environments with or without lubricating conditions. The mechanical products of the invention include rotation contact parts such as bush and shaft in the inside of caterpillar roller, mechanical seal under high surface pressure, and drawing dice and plug under sliding friction stress. A ferrous alloy composition used for coating in the invention comprises Cr:18.0-42.0 wt %, Mn: 1.0-3.2 wt %, B:3.0-4.5 wt %, Si: 1.0-3.0 wt %, C: less than 0.3 wt %, inevitably incorporated impurities, and Fe for the rest of content. A ferrous alloy composition used for manufacturing bush type product comprises C: less than 4.5%, Si:2.5%, Mn:less than 2%, Cr:0.5-35%, and Fe for the rest of content.

Abstract: This invention is concerned with an amplifying system with a microprocessor which makes it possible to adjust parameters easily with a simple construction and to perform automatically a simple repeating work without manual operation. The system is also provided with a safety mechanism to prevent system errors, an alarm unit and a display unit to indicate errorneous operations and a failure diagnosis means to detect failure. The microprocessor of the amplifying system operates at least one solenoid proportion valve by producing a control signal consisting either of dither signals of a triangular wave or of pulse signals of a variable duty cycle.

Abstract: Disclosed is a regeneration device used for industrial electric vehicle including a main controller having a microcomputer, a contactor circuit having forward and reverse current paths comprised of a DC choke coil, a battery, and an acceleration switch connected to the batter.

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: The present invention relates to a method for automatically controlling prescribed work to be repeatedly done by the excavator. An electronic control using a processor and sensors is used to precisely control the work under program control regardless of the hardness of the ground. The controlling method according to the present invention utilizes stored data of the position of each of the joints of the actuators when the prescribed work is performed. During the repeated work, each joint is able to maintain its desired position regardless of the hardness of the ground. Further, because the operational mode can be stored at the same time as storing of the data for the prescribed work, the invention compares the operational mode with the repeated work. The performance speed of the repeated work can be controlled as much as intended by the operator. The repeated work can be performed with high speed when an unskilled operator stores the operation of the prescribed work with a slow speed.

Abstract: A delivery control device for hydraulic pumps suitable for controlling the pump delivery such that the pump's delivery characteristics are not influenced by load acting on actuators is disclosed. The device also reduces the pump delivery in cases where no actuator is being operated but instantly increases the pump delivery in the event either actuator is operated. The device has a branch line branched from a pilot line and adapted for draining the swash plate's regulating pilot oil from the pilot line to a return tank, and a relief valve provided in the branch line, selectively opened in response to a preset pressure applied thereto. The preset pressure for opening the relief valve is the delivery pressure of the hydraulic pump.

Abstract: A device for sensing the displacement of working members in industrial equipment is disclosed. The above sensing device includes cheap analog inductive sensors capable of maintaining the sensing characteristics irrespective of moisture and leaking water, thereby precisely sensing the displacements of the working members. The sensor housing of the device easily fixes the analog inductive sensor by simply fitting the sensor into a mount hole formed in the housing, thereby easily changing the troubled sensor with a new one and easily focusing the sensor when initially mounting the sensor to the housing. As a pair of analog inductive sensors are mounted to both side surfaces of the working member, the sensing device of this invention also prevents the operational errors to the sensors caused by the operational vibrations of the working members while sensing the displacements of the working members.

Abstract: A variable priority device for heavy construction equipment for establishing a priority of the boom over the bucket by limiting an amount of fluid passing through a bucket-side parallel fluid line when the boom operates alone and thereby decreasing the amount of fluid supplied to the bucket actuator. The device is installed in the bucket-side parallel fluid line and adapted to be switched between an orifice state and an orifice release state, the priority control valve being initially maintained at the orifice release state by a resilience device while being switched from the orifice release state to the orifice state against a resilience of the resilience device in response to a pilot pressure for moving the spool of a boom-side switching valve communicating with the boom actuator.

Abstract: An apparatus and a method for monitoring the state of a battery are disclosed in which a micro-processor is used to accurately measure the current state of a battery used for supplying electric power in electric automobiles and the like. The present invention includes: a plurality of passive modules with a micro-processor installed thereon for measuring the charge state of respective batteries; an active module for measuring the overall state of the batteries and for supervising the respective passive modules; and serial lines for connecting the passive modules and the active module. The passive modules compute the charge/discharge states of the respective batteries within certain time intervals to record the data into an internal RAM. The active module measures the overall charge/discharge state of the total batteries within certain time intervals, and receives the data on the charge/discharge states of the individual batteries through the serial communications.

Abstract: A hydraulic system controls a brake system and a suspension system of a wheel-type excavator. The system has a switching section for electrically controlling various systems such as a brake system and a suspension system of the excavator. The system performs various brake functions according to the switching of the switching section. By the system, convenience is provided in handling the switch or operating the systems, and breakage of components which can be happened due to the mis-operation is prevented.

Abstract: A system for monitoring the energy performance of a secondary battery, and a method therefor, are disclosed. A micro-processor (32) is used to compute the energy capacity during the use of the battery by charging and discharging, thereby determining the decrease in the battery capacity. This data is provided to the user and is transmitted to a battery residue capacity measuring means, so that the battery may be charged if needed. The total discharged energy amount is stored in a ROM, and analog signals obtained from a power supply means are converted to digital signals, while an actually used total energy amount is stored in a non-volatile RAM (35). The value stored in the RAM (35) is compared with the value stored in the ROM 33, thereby computing the decrease of the battery capacity.

Abstract: In a hydraulic device including at least two actuators both adapted to be operated by a single pump, one of the actuators having priority over the other actuator, a control valve for the one actuator including a load hold check valve adapted to assign a variable priority function to the one actuator over the other actuator, the load hold check valve including a valve body provided with a pair of ports respectively communicating with the actuators and a parallel fluid passage communicating with the pump, the parallel fluid passage also communicating with a selected actuator port in an opened state thereof, a poppet disposed in the valve body and adapted to fully open the parallel fluid passage at a full stroke thereof and partially opening the parallel fluid passage at a limited stroke thereof, and a pressure setting spring adapted to always urge the poppet toward the initial position for closing the parallel fluid passage.