In a scroll fluid machine, a thinned section (26) is provided in correspondence with a position at which the wrap height of a spiral wrap (15B, 16B) changes due to a step part. The thinned section (26) is provided on the front-side surface or the rear-side surface of a tooth tip section of at least one of the spiral wraps (15B, 16B) of at least one of partner scrolls (15, 16) respectively engaging with scrolls (15, 16). The thinned section (26) is provided in the direction in which the wrap thickness decreases so as to extend over at least a reduced-machining-accuracy area (27), which is an area where the machining becomes discontinuous due to at least a change in the wrap height. Thus, a contact failure between the spiral wraps (15B, 16B) is avoided in the area where the machining accuracy relatively decreases as a result of increasing the machining speed, thereby achieving both improved productivity and maintained performance.

A screw spindle pump, including a housing and a drive spindle accommodated therein and at least one running spindle which meshes with the latter and which has in each case two terminal end surfaces. A stop surface is provided axially adjacent to at least one end surface of the running spindle, wherein the running spindle is accommodated displaceably with an axial clearance perpendicular to the stop surfaces.

A compression device includes at least: two interleaved scrolls each of which is made of an aluminum alloy, one of the scrolls, being a fixed scroll (3), and is fixed and the other scroll, which is an orbiting scroll and moves eccentrically without rotating. Also included are anti-rotation means made of an aluminum alloy and configured to allow anti-rotation of the orbiting scroll. The compression device also includes one flat thrust bearing configured to axially contain the orbiting scroll and is made of aluminum alloys or grades of cast iron. The compression device also includes coatings for promoting friction between the fixed scroll, the orbiting scroll, the anti-rotation means and the flat thrust bearing.

A vacuum booster assembly includes, but is not limited to, a booster housing defining a booster chamber and including a gas inlet and a gas outlet; a first rotor positioned within the booster chamber and adapted for rotation therein, the first rotor including a first shaft and at least two lobes defining a first lobe profile; and a second rotor positioned within the booster chamber and adapted for rotation therein, the second rotor including a second shaft and at least two lobes defining a second lobe profile, wherein the first and second rotors are formed from a metal having a coefficient of thermal expansion from about 1 (10.sup.−6 in/in*K) to about 13 (10.sup.−6 in/in*K), and wherein at least one of the outer surface of the first rotor, the outer surface of the second rotor, or the booster chamber includes a coating.

A hydraulic tool includes a stator and a rotor rotatably disposed within the stator. At least one of at least an inner portion of the stator and at least an outer portion of the rotor includes an insert comprising a hard material. A method of forming a hydraulic tool includes attaching at least one insert comprising a hard material to a surface of a stator or a surface of a rotor. A downhole motor or pump includes a stator and a rotor. The stator includes at least one insert comprising a hard material disposed over at least a portion of an interior surface thereof and a matrix material at least partially surrounding the at least one insert. The rotor includes at least one insert disposed over at least a portion of an exterior surface thereof and a matrix material at least partially surrounding the at least one insert.

A pump as provided includes an inlet, an outlet, and a scroll pumping element. The scroll pumping element includes a fixed scroll component having one or more fixed scrolls and orbiting scroll component having one or more orbiting scrolls for fluid pumping. The fixed scroll component and the orbiting scroll component are arranged so as to be capable of providing pressurized fluid to a thrust bearing and prevent contact between the fixed scroll component and the orbiting scroll component.

A mud motor and a drill string having the mud motor. The mud motor includes a stator and a rotor. A lining between the stator and the rotor includes fibers forming a fiber pattern. The lining is a coating of at least one of a lobed inner surface of the stator and a lobed outer surface of the rotor.

A compressor includes a cylinder including a cylinder chamber, a piston movably arranged relative to the cylinder in the cylinder chamber, and a sliding member slideable against the cylinder and the piston in the cylinder chamber. The cylinder and the piston are constructed from an Al—Si alloy having a Si content exceeding 12.6 wt %, which is a eutectic point. The sliding member is constructed from steel and has a surface layer including a sliding surface slideable against the cylinder and the piston. The surface layer is treated so as to have greater hardness than hardness of proeutectic Si contained in the Al—Si alloy, and the surface layer has hardness of at least Hv 1000 in the sliding surface.

A gear pump (1) comprises a pump housing (2), wherein a working chamber (6) is formed in the pump housing (2). A first gearwheel (11) and a second gearwheel (12) are arranged meshing with each other in the working chamber (6). The first gearwheel (11) has a number of first teeth (13) and the second gearwheel (12) has a number of second teeth (14). A first tooth flank (13a, 14a) and a second tooth flank (13b, 14b) are formed on each of the teeth (13, 14). When the gearwheels (11, 12) mesh, the first tooth flanks (13a) of the first teeth (13) are meshed with the first tooth flanks (14a) of the second teeth (14). A coating (15) is arranged on each of the first tooth flanks (13a, 14a). The coating (15) and the first tooth flank (13a, 14a) are positively connected to each other.

A device for painting a compressor or vacuum pump housing including a first semi-cylindrical structure adjoined to a second semi-cylindrical structure, a dispersing head including a rotating part having a bell shaped structure and a stationary part; a paint reservoir connected to the stationary part through a conduit; a supporting structure including fixing means. The device further includes a controller for controlling a rotational speed of the rotating part. The controller is provided with means for controlling a rotational direction of the rotating part in a clockwise direction for painting the first semi-cylindrical structure of the compressor or vacuum pump housing and for changing the rotational direction to a counterclockwise direction for painting the second semi-cylindrical structure of the compressor or vacuum pump housing.