Abstract: The stem of the cephalic femoral component of a hip prosthesis is bounded by two pairs of longitudinally extending surfaces including two relatively wide and two relatively narrow surfaces. At least one of the narrow surfaces is convex, all of the surfaces taper in a direction toward a rounded tip of the stem, the radius of curvature of the convex surface or surfaces decreases in a direction toward the tip, and the wider surfaces taper toward each other in a direction from the one toward the other narrower surface. This reduces the likelihood of loosening of the stem in the medullar canal of the femur wherein the stem is implanted without cement, and the bone around the stem is less likely to be subjected to excessive localized stresses.

Abstract: A pneumatic impact tool wherein a two-stage piston is reciprocable in the two-stage chamber of a cylinder. The tool which is to penetrate into a bone is mounted in the front portion of the cylinder and the piston strikes against such front portion in response to admission of compressed air against its rear end face. A relatively small annular shoulder of the piston faces forwardly and is continuously acted upon by compressed air. When the piston approaches or reaches the end of its forward stroke and rebounds from the front end portion of the cylinder, it seals the source of compressed air from its rear end face so that the action of compressed air upon the shoulder suffices to propel the piston rearwardly against the rear end portion of the cylinder at which time the piston reestablishes a path for the flow of compressed air against its rear end face so that it is propelled forwardly against the front end portion of the cylinder.

Abstract: A prefabricated kit for the assembly of a composite slat which can be used in a venetian blind has two or more elongated first slat sections which can be separably coupled to each other by one or more connecting slat sections. The end portions of the connecting slat sections can be slidably telescoped into the adjacent end portions of neighboring first slat sections or vice versa. At least one outer slat section, which is one of the first slat sections, can be assembled of two shorter sections one of which carries a longitudinally outwardly extending guide pin for reception in a guide rail in the door or window opening wherein the venetian blind utilizing the slat is installed with its slats in vertical or horizontal positions. The connecting slat sections have apertures for the gathering tape or cord which is used to move the neighboring slats of a blind nearer to each other or to permit their movement away from one another.

Abstract: A blind or shutter which is or can be assembled of prefabricated components and of yard goods cut to size at the locale of use has two hollow upright guide rails for the end portions of a curtain of interconnected upwardly and downwardly movable as well as tiltable slats, and combined lifting and tilting mechanisms for the slats. Such mechanisms have lifting bands which are disposed in the guide rails and are connected with the end portions of the slats to effect upward or downward movements of the slats in response to rotation of a main shaft in one or the other direction, and tilting bands which are disposed in the guide rails and change the angular positions of the slats in response to rotation of the main shaft. Blocking levers in the guide rails are connected with the ends of the lowermost slat by vertically movable carriages and engage the respective guide rails by gravity to hold the lowermost slat against unauthorized lifting when the lifting bands are slack.

Abstract: A shutter which can be assembled of prefabricated components and yard goods cut to size at the locale of use has two upright guide rails for the end portions of a curtain of upwardly and downwardly movable as well as tiltable horizontal slats. The shutter further includes a horizontal main shaft between the upper end portions of the guide rails, a housing mounted on top of each guide rail, a motor or a crank drive for rotating the main shaft clockwise or counterclockwise, and combined lifting and tilting mechanisms in the housings. Such mechanisms have lifting bands which are connected with the end portions of the slats to effect upward or downward movements of the slats in response to rotation of the main shaft, and tilting bands which change the angular positions of the slats in response to rotation of the main shaft.

Abstract: A modular shutter is assembled of prefabricated components and of yard goods or piece goods which are cut to size at the locale of use. The components of the shutter include two upright guide rails for the end portions of a curtain of upwardly and downwardly movable as well as tiltable slats, a horizontal main shaft between the upper end portions of the guide rails, a housing mounted on top of each guide rail and having bearings for the corresponding end portions of the main shaft, a motor or a crank drive for rotating the main shaft clockwise or counterclockwise, and combined lifting and tilting mechanisms in the housings. Such mechanisms have lifting bands which are connected with the end portions of the slats to effect upward or downward movements of the slats in response to rotation of the main shaft in one or the other direction, and tilting bands which change the angular positions of the slats in response to selected rotation of the main shaft.

Abstract: A venetian blind wherein the slats have channel-shaped marginal portions and the flexible strip- or cord-shaped carriers for the slats have equally spaced eyelets for the webs of metallic staples whose legs are driven through the adjacent marginal portions of the slats and are bent over behind the marginal portions to establish a permanent connection between the staples and the slats.

Abstract: A venetian blind wherein the slats are moved up and down by means of cords or strips in response to rotation of a shaft in clockwise and anticlockwise directions. The shaft actuates a mechanism serving to turn the slats between open and closed positions and through intermediate positions in which the slats are partly open. The mechanism is caused to automatically maintain the slats in the open positions during upward movement of slats and in the intermediate positions when the slats move downwardly. The slats can turn between the open and closed positions when the venetian blind is fully extended. Yieldable detents are provided to releasably hold the slats in the open, closed or intermediate positions.