A tapered roller bearing (31a) has a plurality of retainer segments (11a, 11d) each having a pocket to house a tapered roller (34a), and arranged so as to be continuously lined with each other in a circumferential direction between an outer ring (32a) and an inner ring (33a). The retainer segment (11a, 11d) is formed of a resin containing a filler material to lower a thermal linear expansion coefficient. In addition, a clearance (39a) is provided between the first retainer segment (11a) and the last retainer segment (11d) after the plurality of retainer segments (11a, 11d) have been arranged in the circumferential direction without providing any clearance. Here a circumferential range (R) of the clearance (39a) is larger than 0.075% of a circumference of a circle passing through a center of the retainer segment (11a, 11d) and smaller than 0.12% thereof at room temperature.

A twin-shaft pump comprising: a pumping chamber; two rotatable shafts each mounted on bearings is disclosed. Each of the two rotatable shafts comprises at least one rotor element, the rotor elements being within the pumping chamber and the two rotatable shafts extending beyond the pumping chamber to a support member. The support member comprises mounting means for mounting the bearings at a predetermined distance from each other, the predetermined distance defining a distance between the two shafts. A thermal break between the pumping chamber and the support member is provided for impeding thermal conductivity between the pumping chamber and the support member, such that the pumping chamber and support member can be maintained at different temperatures. The support member and the rotor elements are formed of different materials, a coefficient of thermal expansion of a material forming the support member being higher than a coefficient of thermal expansion of a material forming the rotor elements.

A screw rotor which is hollow has improved performance against heat, pressure, rust, and the like. A screw rotor includes a screw portion of which an outer periphery has teeth and grooves having a helical shape and extending by a predetermined length in an axial direction. A radial cross section of at least a part of the screw portion includes a cross section of an outer surface portion forming the teeth and the grooves, a cross section of an axial center portion, a cross section of a support portion that connects an axial center side of the outer surface portion and an outer diameter side of the axial center portion, and a cross section of a hollow portion formed by the support portions adjacent to each other in a rotational direction and an axial center side inner surface of a tooth bottom or a tooth tip. In at least the radial cross section of the screw portion, different members are continuously joined as an integral structure in a cross section of at least one of the axial center portion and the support portion and the outer surface portion.

A bearing cap (1) is attached to a bulkhead (22) of a cylinder block (21) made of a light metal through a pair of bolts (24). The bearing cap (1) has a frame (2) made of an iron-based metal and a cast light-alloy part (3). The frame (2) has a pair of pillar parts (9) through which the bolts (24) extend and a circular-arc-shaped arch section (10). At high temperatures, the span of the pair of the bolts (24) increases due to thermal expansion of the light-alloy material, and the pair of the pillar parts (9) expand. This causes the middle part of the arch section (10) to shift upward, thereby suppressing an increase in bearing clearance.

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 galleryless steel piston designed to improve thermal efficiency, fuel consumption, and performance of an engine is provided. The piston includes a steel body portion and a thermal barrier layer applied to an upper combustion surface and/or a ring belt to reduce the amount of heat transferred from a combustion chamber to the body portion. The thermal barrier layer has a thermal conductivity which is lower than a thermal conductivity of the steel body portion. The thermal barrier layer typically includes a ceramic material, for example ceria, ceria stabilized zirconia, and/or a mixture of ceria stabilized zirconia and yttria stabilized zirconia in an amount of 90 to 100 wt. %, based on the total weight of the ceramic material. The thermal barrier layer can also have a gradient structure which gradually transitions from 100 wt. % of a metal bond material to 100 wt. % of the ceramic material.

A thermal barrier coating for an internal combustion engine includes an insulating thermal spray coating, where a chosen material of the insulating thermal spray coating has a thermal conductivity lower than 2 W/mK in fully dense form and the chosen material includes a coefficient of thermal expansion within 5 ppm/K of a coefficient of thermal expansion of a material of a component of the internal combustion engine upon which the coating is placed.

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 blower assembly includes, but is not limited to, a blower housing defining a blower chamber and including a gas inlet and a gas outlet; a first rotor positioned within the blower 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 blower 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 blower chamber includes a coating.

A blower assembly includes, but is not limited to, a blower housing defining a blower chamber and including a gas inlet and a gas outlet; a first rotor positioned within the blower 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 blower 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 blower chamber includes a coating.