Abstract: A charging circuit generates a charging current from an ac supply which is supplied to a secondary battery in a battery package through first terminals. A second terminal receives a temperature detection signal from a thermistor on the secondary battery. A value of the temperature detection signal is sampled every predetermined interval. A memory stores the sampled value. A difference between the sampled value and the value from the memory is obtained, as well as the temperature decrease value between the sampled value and the value stored, when it applies. An error signal is generated when the difference is higher than a predetermined value and the operator is alarmed and informed of the error. The difference may be obtained between the sampled value and the value one-cycle-previously-sampled value from the memory, between the sampled value and a minimum of the sampled values, or between the sampled value and a charging start value of the sampled value.

Abstract: A hydraulic ramming apparatus including an apparatus body (14) having a cylinder bore (23) and a guide bore (24) that are successively formed to each other in the apparatus body (14). A piston (30) is slidably inserted into the cylinder bore (23) so as to be reciprocable within the cylinder bore (23). An upper pressure-receiving chamber (31) is defined at an upper end portion side of the piston (30), and a lower pressure-receiving chamber (32) is defined at a lower end portion side of the piston (30). A ramming tool (19), having a rod body (35), can be detachably inserted into the guide bore (24). Also, a mechanism for moving the rod body (35) is provided so as to follow upward movement of the piston (30).

Abstract: A vibration generating apparatus comprises a cylinder assembly (6) having a cylinder and a piston (3) slidably inserted in a cylindrical bore (2) of the cylinder for defining a first pressure receiving chamber (4) with a small pressure receiving area and a second pressure receiving chamber (5) with a large pressure receiving area. The piston (5) is selectively movable in one direction and in the other direction responsive to pressures in the pressure receiving chambers. A switching valve (9) has a first pressure chamber (13) with a large diameter, a second pressure chamber (14) with a small diameter, a pump port (10), an auxiliary port (23), a principal port (11) and a tank port (12). The switching valve (9) takes a first position under a pressure within the first pressure chamber and takes a second position under a pressure within the second pressure chamber.

Abstract: Re-powering an electrical equipment after recovery of service interruption is prevented if the power switch of the electrical equipment stays in ON position. During a transit period of time just after recovery of service interruption, the detection voltage from a post-voltage detection circuit is set to exceed the detection voltage from a pre-voltage detection circuit. In this condition, a photo triac connected in series to the power switch is rendered non-conductive so that the electrical equipment will not be energized.

Abstract: To discriminate that a rechargeable battery has reached an end of life, the maximum battery voltage detected during a preliminary charge time is compared with a predetermined reference voltage. When the comparison results indicate that the battery voltage is above the predetermined reference voltage, it is determined that the battery has reached the end of life.

Abstract: A charge current to be supplied to a battery is selected depending on a remaining capacity of the battery to be charged and/or an initial temperature of the battery to be charged. A battery voltage or a battery temperature is being monitored and sampled at a relevant sampling interval determined depending on the selected charge current. A difference between two battery voltages or between two battery temperatures at two sampling points is sequentially computed and whether or not the battery has reached a fully charged condition is determined based on the computed results.

Abstract: To charge a battery having a different number of cells connected in series with a relevant charge current, the number of cells of the battery is firstly determined and a current level corresponding to the number of cells is determined in view of the potential of the charger. The charge current having a level substantially equal to the thus determined current level is flowed in the battery.

Abstract: An automatic drilling machine has an electric drilling unit on which a cylindrical cutter is rotatably mounted. The drilling machine includes a drill motor for rotating the cutter and a feed motor for linearly moving the cutter for the purpose of drilling into materials such as concrete. The current flowing through the drill motor before a drilling load is imposed thereon is detected for a microprocessor to determine the type of the cutter being used. The drill motor is driven at a rotation speed suitable for the cutter being used and the feed motor is driven at a speed such that the rotation speed of the drill motor thus set is maintained unchanged. Particularly, the drill motor is driven at a reduced rotation speed from the start of drilling until a predetermined drilling depth is reached to reduce chatter vibration which may otherwise be generated if the drill motor is driven at a regular constant speed from the beginning of drilling until the end.

Abstract: In a hydraulic circuit system, when pressurized oil discharged from a single hydraulic pump is supplied to a plurality of actuators: the pressurized oil is supplied to heavily-loaded ones of the actuators at gradually reducing flow rates to reduce a shock, while supplied to lightly-loaded ones of the actuators at gradually increasing flow rates to increase working speeds of these lightly-loaded actuators. The hydraulic circuit system comprises a plurality of directional control valves (2) one of which is provided with pressure-compensated flow control valves (18) each of which is provided with a load lead-in passage having a restriction means (R). In addition, further comprised in the system are: relief valves (22, 22) for relieving the pressurized oil under the influence of load pressure of the actuators (3) operated by the directional control valves (2); a restriction orifice (24) provided in a drain side of each of the relief valves so as to produce pressure therein.

Abstract: A status of a battery is detected to determine whether an amount of residual charge is large or not. Detection of the status of the battery is performed on the basis of a change in the voltage level over a preliminary charge time. If the battery is determined to at low charge, then a sleep time is set. The full charge condition of the battery is, for example, detected when a second order differential of the voltage across the battery becomes negative. However, the computation of the second order differential is not performed during the sleep time. Further, to accurately determine the status of the battery, the duration of the preliminary charge time is prolonged if the battery is detected to have been deeply discharged.

Abstract: To enable recharging of a battery under a low temperature circumstance, a rapid battery charger is provided with a rapid charge mode and a slow charge mode which are selectively used depending upon the temperature of the battery. The rapid charge mode is selected when the temperature is above a predetermined value, wherein the battery charger charges the battery with a charging current of more than 5 C, whereas the slow charge mode is selected when the temperature is below the predetermined value, wherein the battery charger charges the battery with a charging current of less than 1 C.

Abstract: A management system for use in a centrifuge equipped with a detachable rotor which is rotatable so as to separate density-different samples by a centrifugal force due to the rotation. The management system is for managing the lifetime of the rotor on the basis of the detection results of an operated-condition detector for detecting operated conditions such as the number of times of rotation, running time and rotational speed of the rotor. The management system includes a data storing device which is provided on the rotor to be rotatable therewith and is composed of a magnetic recording medium to allow keeping data relating to the operated conditions of the rotor. Also included in the management system is a data processing unit coupled through a data reading and writing device such as a magnetic head to the data keeping device and also coupled to the operated-condition detector to be responsive to the operated conditions.

Abstract: This invention aims at providing a hydraulic circuit apparatus for supplying pressurized fluid into cylinders for a work implement arranged such that during normal operation of the work implement the flow rate of fluid discharged by a pump is controlled such that the difference between the discharge pressure of the pump and the load pressure is always kept constant, whilst during inching operation of the work implement the flow rate of fluid discharged by the pump is reduced.

Abstract: This invention provides a hydraulic circuit apparatus for operating a work-implement actuating cylinder arranged such that, during an earth compacting operation using a bucket, a work implement or boom is lowered by its own weight, and during other operations, a part of the fluid under pressure in a lifting chamber of the actuating cylinder is supplied together with pressurized fluid discharged by a pump into a lowering chamber to increase the retracting speed of a piston rod in the work-implement actuating cylinder. The apparatus comprises a spool slidably inserted in a valve bore formed in an operating valve body so that it may be moved between a first actuating position, where a second port connected to the lowering chamber is communicated with a second tank port and a first port connected to the lifting chamber is communicated with a first pump port; and a second actuating position, where the second port is communicated with a second pump port and the first port is communicated with a first tank port.

Abstract: This invention provides a hydraulic circuit apparatus arranged such that when each of operating valves is operated suddenly, the stability of each of actuators is improved, and when the operating valves are kept at their neutral positions, the flow rate of fluid discharged by a variable displacement pump is increased to improve the response of the hydraulic circuit, and when the actuators are supplied with pressurized fluid, pressure compensation is made by pressure compensating valves.

Abstract: A hydraulic circuit arranged to prevent the load pressure in one of the hydraulic actuators at the time of starting from becoming abnormally high thereby preventing fluid under pressure from being relieved by the safety valve when a plurality of hydraulic actuators are operated at the same time, wherein the function of one of the pressure compensating valves is temporarily enhanced by introducing the load pressure in the hydraulic actuator so as to supply a large quantity of fluid under pressure to the hydraulic actuator connected to the pressure compensating valve so that the operating speed of the hydraulic actuator can be increased.

Abstract: A quick-return motion mechanism for use in an automatic magnetic drilling machine including a feed motor for generating power transferred through a worm wheel and a high-ratio reduction gear to a handle shaft to drive an electric drill. A one-way clutch is provided inside the worm wheel so that the handle shaft races on feed and is locked on return. The high-ration reduction gear is composed of elements which are arranged to cause the input and output sides of the high-ratio reduction gear to rotate in the same direction. The quick-return motion mechanism consists of an arrangement for restraining the input side element of the high-ratio reduction gear on feed and for releasing it on return to race the high-ratio reduction gear.

Abstract: In a battery charging method and apparatus, a plurality of voltage-division resistors serving as a battery voltage detecting means are connected between the battery and a microcomputer so that a voltage-division ratio can be automatically selected corresponding to the detected battery voltage. Thus, the detected battery voltage applied to the microcomputer is kept substantially constant irrespective of the value of the battery voltage.

Abstract: A drive motor connected to a drill bit serves to actuate the drill bit. An electric current is allowed to flow through the drive motor to activate the drive motor. A mechanism serves to feed the drill bit with respect to a workpiece. The current flowing through the drive motor is sensed. A device stores a value of the current which is sensed when the drill bit is out of engagement with the workpiece. A determination is made as to whether or not a drilling process is completed in accordance with a value of the present sensed current and the stored value of the sensed current.

Abstract: A speed controller for a DC motor includes a semiconductor switching device connected in series with it in a DC power circuit. The switching circuit is turned on and off with a duty ratio variable as a function of motor load. A time constant circuit including a capacitor is connected in parallel with the switching device to develop a voltage which is compared with a reference variable between high and low levels in response to the exceedance of the varaible reference. The switching device is turned on when the voltage developed by the capacitor is higher than the lower reference voltage to energize the motor, and is turned off when the capacitor voltage is lower than the higher reference voltage to de-energize the motor.