Abstract: An inner cylinder, a pin, and a valve body are movable in a reciprocating manner in a direction along the rotational axis in relation to an oil supply pipe. At a proximate position, where a cutter attaching portion is close to the oil supply pipe, a rod portion of the valve body is supported by a pressure receiving portion of the holder inner cylinder due to the elastic force of a compression coil spring, such that an opening-closing portion of the valve body closes a valve port of the oil supply pipe. At a separated position, where the cutter attaching portion is separated from the oil supply pipe, the rod portion of the valve body is supported by the upper end of the pin due to the elastic force of the compression coil spring, instead of the pressure receiving portion, such that the opening-closing portion opens the valve port.

Abstract: In a state where a rail drilling machine is attached to a rail, a drive source, a cutter support mechanism, and a support base are arranged on one side of the rail. A support plate having an upper support surface and a lower support surface is provided on either end of the support base in the longitudinal direction. The upper support surface and the lower support surface of each support plate contact a lower surface of the rail head and an upper surface of the rail foot, respectively, so that the support base is prevented from moving vertically with respect to the rail. The support base has a magnetic sticking portion located between the support plates. The magnetic sticking portion has a sticking surface that is stuck to a side surface of the rail web.

Abstract: An inner cylinder, a pin, and a valve body are movable in a reciprocating manner in a direction along the rotational axis in relation to an oil supply pipe. At a proximate position, where a cutter attaching portion is close to the oil supply pipe, a rod portion of the valve body is supported by a pressure receiving portion of the holder inner cylinder due to the elastic force of a compression coil spring, such that an opening-closing portion of the valve body closes a valve port of the oil supply pipe. At a separated position, where the cutter attaching portion is separated from the oil supply pipe, the rod portion of the valve body is supported by the upper end of the pin due to the elastic force of the compression coil spring, instead of the pressure receiving portion, such that the opening-closing portion opens the valve port.

Abstract: In a state where a rail drilling machine is attached to a rail, a drive source, a cutter support mechanism, and a support base are arranged on one side of the rail. A support plate having an upper support surface and a lower support surface is provided on either end of the support base in the longitudinal direction. The upper support surface and the lower support surface of each support plate contact a lower surface of the rail head and an upper surface of the rail foot, respectively, so that the support base is prevented from moving vertically with respect to the rail. The support base has a magnetic sticking portion located between the support plates. The magnetic sticking portion has a sticking surface that is stuck to a side surface of the rail web.

Abstract: A lock body in a locked state is inserted radially inward of an outer surface. A stopper body in a contact state holds the lock body in an unlocked state. The stopper body in a non-contact state is retracted from the lock body. A pressing body is switchable between a standby state and a retracted state. The pressing body in the standby state selectively contacts a central shaft when an insertion portion is inserted in a support cylinder. The pressing body in the retracted state is retracted from the stopper body. An urging member urges the pressing body into the standby state, and urges the stopper body into the contact state. The urging member detachably engages the pressing body to the stopper body. Thus, the structure of the cutter holder is simple.

Abstract: The front cutting edge is provided with an inner front cutting edge connected with an inner lateral cutting edge and an outer front cutting edge connected with an outer lateral cutting edge. A front flank corresponding to the front cutting edge is provided with an inner front flank corresponding to the inner front cutting edge and an outer front flank corresponding to the outer front cutting edge. An inner front clearance angle of the inner front flank is set at a larger value than an outer front clearance angle of the outer front flank. Therefore, it is difficult for the hole cutter to be chipped, and its cutting performance is also good.

Abstract: A lock body in a locked state is inserted radially inward of an outer surface. A stopper body in a contact state holds the lock body in an unlocked state. The stopper body in a non-contact state is retracted from the lock body. A pressing body is switchable between a standby state and a retracted state. The pressing body in the standby state selectively contacts a central shaft when an insertion portion is inserted in a support cylinder. The pressing body in the retracted state is retracted from the stopper body. An urging member urges the pressing body into the standby state, and urges the stopper body into the contact state. The urging member detachably engages the pressing body to the stopper body. Thus, the structure of the cutter holder is simple.

Abstract: The front cutting edge is provided with an inner front cutting edge connected with an inner lateral cutting edge and an outer front cutting edge connected with an outer lateral cutting edge. A front flank corresponding to the front cutting edge is provided with an inner front flank corresponding to the inner front cutting edge and an outer front flank corresponding to the outer front cutting edge. An inner front clearance angle of the inner front flank is set at a larger value than an outer front clearance angle of the outer front flank. Therefore, it is difficult for the hole cutter to be chipped, and its cutting performance is also good.

Abstract: A cutting apparatus for cutting a rail or other elongated workpiece includes a rotatable blade for cutting the rail, a blade cover for covering the blade, an engine (or motor) for driving the blade, and a frame for supporting the blade, the blade cover and the driver. The cutting apparatus further includes link mechanisms. One link mechanism supports the blade and the blade cover relative to the frame and permits the blade cover to move while maintaining a predetermined attitude during cutting. Therefore, the blade cover moves vertically and avoids hitting obstacles. Another link mechanism moves the driver while maintaining a predetermined attitude of the driver. Therefore, the driver remains level during cutting.