Abstract: A torque transmission device is provided wherein a rotary housing is connected to one of front and rear drive shafts which respectively drive front and rear axles of a four-wheel drive vehicle, while a rotary shaft coaxially carried by the rotary housing is connected to the other of the front and rear drive shafts. The housing receives therein a multiple disc clutch device for transmitting rotational power between the housing and the shaft through friction engagement between alternately arranged outer and inner clutch discs which are respectively rotatable bodily with the housing and the shaft. The housing also receives an axially movable piston to press the clutch discs for friction engagement. An end wall of the housing or an end cap secured thereto and a facing end surface of the piston define an axially narrow circuit chamber, within which a rotary with several radially extending blade portions is received to be rotated by the shaft.

Abstract: In a machine tool with an automatic tool change function, a rotatable tool spindle carries a key engageable with a key-way formed on a tool. A tool change arm, serving as a tool support device, rotatably supports at least one tool to selectively insert and remove the same into and from said tool spindle. When a tool change operation is to be performed, the rotation of the spindle is changed into a predetermined speed suitable for the key-way engagement. An operating device is provided for causing relative movement between the tool change arm and the spindle to insert a tool into the spindle. However, the relative movement thereof is stopped by a stopping device just before the engagement of the key with the key-way. Subsequently, when a first detecting device detects that the key has reached a predetermined angular position, the relative movement of the tool change arm is permitted to thereby make engagement of the key with the key-way.

Abstract: A machine tool with an automatic tool change function wherein a rotatable tool spindle carries a movable key engageable with either of a pair of key-ways formed on a tool. A tool changing arm, serving as a tool support device, friction-rotatably supports at least one tool for being selectively inserted within and removed from the tool spindle. When tool changing operation is to be performed, rotation of the spindle is changed to a predetermined speed permitting key-engagement. A first confirming device is provided for confirming the fact that the spindle has reached a first predetermined position during rotation thereof. The tool change arm is then operated to remove the tool from the spindle in response to the first confirming device. A second confirming device is provided for confirming that the spindle has reached a second predetermined position during rotation thereof.

Abstract: A contact detecting apparatus for detecting the contact of a workpiece with a tool in a machine tool which includes a magnetic coil mounted on the periphery of a spindle head and connected to an AC power source for generating an induced current in a looped secondary circuit including the workpiece, a work table, a machine body, a spindle head, a tool spindle and the tool, when the workpiece and the tool are moved relatively into contact with each other. A first conductive wire forming a secondary winding of one turn is arranged in a parallel relationship with the looped secondary circuit and a current induced therein by energization of the magnetic coil. A second conductive wire is connected at one end thereof to the looped secondary circuit. A detecting device is connected to the first and second conductive wires for detecting contact between the workpiece and the tool based on the voltage induced across the first and second conductive wires.

Abstract: A resinoid-bonded grinding wheel employing the ultra-hard abrasives such as cubic boron nitride or diamond are formed with a support member which is made of a heat insulating material such as ceramics for preventing a thermal expansion of the grinding wheel and maintaining a precision grinding operation.

Abstract: In a machine tool with an automatic tool change function, a rotatable tool spindle carries a movable key engageable with a key-way formed on a tool. A tool changing arm, serving as a tool support device, friction-rotatably supports at least one tool for selectively inserting and removing same into and from the tool spindle. When a tool change operation is to be performed, rotation of the spindle is changed into a predetermined speed permitting key-engagement. A detecting device is provided for detecting movement of the movable key to confirm engagement of the movable key with the key-way of the tool. A clamp device clamps the tool inserted into the spindle in response to the detecting device. After the tool is clamped on the spindle, rotation of the spindle is changed into a machining speed. A confirming device is provided for confirming that the spindle is reached at a predetermined angular position during rotation thereof.

Abstract: A machine tool includes an indexing device for indexing a spindle to a predetermined angular position for engagement between a key member disposed upon the spindle and a key-way disposed upon a tool to be used. When either the tool, to be used next, upon a tool storage magazine, or a used tool, held upon the spindle, is a tool utilized for heavy cutting, the indexing device is operated before the tool change operation is performed. On the other hand, when the tool to be used next, and the used tool, are both tools utilized for light cutting, the tool change operation is performed without operation of the indexing device.

Abstract: A machine tool is provided with a transfer arm for interchanging a first tool, inserted into a rotary spindle and positioned at a predetermined angular position, with another tool stored within a storage magazine, the spindle and each of the tools being respectively provided with drive and driven protrusions, which are engaged with each other for a positive drive operation by inching the spindle in a tool exchange operation. Interference preventers, which are provided upon the magazine in order to respectively cooperate with the driven protrusions, angularly correspond to the drive protrusion positioned at the predetermined angular position, such that each of the tools may be inserted into the spindle without interference between the drive and driven protrusions.

Abstract: A grinding machine provided with an apparatus for changing a feed rate of a grinding wheel relative to a workpiece just before the grinding wheel comes into contact with the workpiece. An electrode device is mounted adjacent to the grinding wheel and connected to an electric power source for applying a potential to the surface of the grinding wheel. A detecting device detects a difference of potential between the grinding wheel and the workpiece to generate an output voltage. A memory device memorizes the output voltage detected when the grinding wheel is distant from the workpiece. A setting device reduces the memorized output voltage at a predetermined rate to provide a reference voltage corresponding to a predetermined gap between the grinding wheel and the workpiece. A comparator circuit compares the output voltage with the reference voltage to generate a feed rate changing signal when the output voltage attains the reference voltage.