Abstract: The invention relates to an injection screw drive for a plastic injection molding machine comprising axes (A1, A2) respectively provided for the rotative and for the axial motion of the injection screw (4). According to the invention, the injection screw drive has at least one double rack rail overdrive for effecting the axial motion. The injection worm drive is configured as a gear combination having at least two drive motors (18, 44) and an output axle. The gear combination has, as a core, a gear block with a gear casing (42), to which at least two reducing gears are connected that effect the rotative and the axial motion of the injection screw (4). This enables the entire machine to be provided with a short and compact structure insofar as this concerns the injection aggregate. According to a second embodiment, both drives have separate housings. The entire injection unit rests, in a known manner, on the machine stand (33) via guide rails (32) such that it can be displaced.

Abstract: A hammer drill has a cylinder within a housing with the cylinder forming a piston chamber. A drive piston is reciprocally mounted within the piston chamber and is displaced by a motor. A percussion piston is located within the piston chamber with an air cushion space located between the two pistons. As the drive piston reciprocates, it moves the percussion piston back and forth by way of the air cushion located between them. One of the pistons has a conduit open at one end to the air cushion space and at the other end to the exterior of the cylinder. A closure plug is located in the one end of the conduit and closes off air flow from the air cushion space into the conduit at regular operating temperatures. If the temperature in the air cushion space rises due to air leakage from the space, the closure plug melts and connects the conduit with the air space so that the reciprocation of the percussion piston stops before the pistons strike against one another and cause damage.

Abstract: In a motor driven drilling or chipping device, a housing forms a sealed housing space containing a gear arrangement and an air cushion propulsion mechanism driven by the gear arrangement. The housing space is partially filled with lubricating oil. A pressure equalizing nozzle has a bore connecting the interior of the housing space to the ambient atmosphere outside the housing. The port at the end of the nozzle bore communicating with the housing space is enclosed by wall members forming a stilling chamber. The stilling chamber is in communication with the sealed housing space and is arranged so that regardless of the position of the drilling or chipping device, it is not flooded by the lubricating oil and the lubricating oil does not flow out of the stilling chamber through the nozzle bore.

Abstract: A hammer drill is arranged to rotate and also apply percussive force to a tool receptacle. The percussive force is transmitted from a shaft to a drive piston which, in turn, reciprocates a percussion piston which drives the tool receptacle. The hammer drill includes a housing and a bearing rotatably mounted in the housing. The shaft is rotatably mounted in the bearing and its axis extends perpendicularly of the axis of rotation of the bearing. The bearing supports a contact rim which is in meshed engagement with the shaft. The contact rim is displaceably into frictional contact with a brake member for holding the contact rim against rotation while the bearing rotates carrying with it the shaft. Due to its meshed engagement with the contact rim, the shaft rotates about its own axis causing the drive piston to reciprocate.

Abstract: In a hammer drill, a drive piston is reciprocated by a motor, and, over a pneumatic buffer, the reciprocating motion is transmitted to a percussion piston. A throttle valve regulates the flow of a fuel mixture to the motor for controlling its operation. A membrane switch connected to and operated by the pressure conditions within the pneumatic buffer controls the throttle valve.

Abstract: In an electropneumatic hammer including an exciter piston and a percussion piston reciprocally displaceable within the bore of a guide cylinder, a sleeve-like clamping member is secured in an axially stationary position within the bore of the guide cylinder with the percussion piston passing through the clamping member. If there is no tool in the hammer and under certain other operating conditions, an axially displaceable tubular member located within the bore and laterally enclosing the clamping member, presses the clamping member inwardly into gripping contact with the percussion piston.

Abstract: For securing an expansion anchor formed of an anchor sleeve and an expansion element into a prepared hole in a receiving material, a conventional piston type explosive powder charge driven setting gun is adapted to hold individual anchors in a guide member mounted on the gun and then by means of a combined sleeve-like piston guide and piston mounted within the guide member to insert the anchor from the guide member into the prepared hole and to drive the expansion element into the anchor sleeve for firmly securing the anchor within the hole.

Abstract: An expansion anchor includes an expansion sleeve with a slot formed through the sleeve wall and extending for its axial length and an expansion body which is displaceably positionable through the slot for expanding the sleeve into contact with the wall of a hole formed to receive the sleeve. The slot is in parallel relation with the axis of the sleeve. The expanding body is a cylindrical pin which has a diameter greater than the dimension of the slot measured in the circumferential direction of the sleeve. An insert is secured within the sleeve and has a threaded bore into which a member can be secured and held within the expansion anchor.

Abstract: A straddling dowel includes at least a pair of shell members each having a first contact surface and a second contact surface. The first contact surfaces are disposed in contact with one another and extend in parallel with the axis of the dowel and the second contact surfaces are disposed in contact with one another and extend helically relative to the axis of the dowel. The first and second contact surfaces extend for substantially the entire axial length of the shell members.