A pumping assembly keeps a pneumatic tire from becoming underinflated. The pumping assembly includes an even number of pumps attached to the tire rim, a gravity mass for producing a pumping action, a cam fixed to the gravity mass for maintaining the cam in a fixed position relative to the gravity mass, and rollers for engaging the cam and producing the pumping action as the tire rim rotates and the gravity mass retards rotation of the cam as the tire rim rotates.

A double-headed piston type swash plate compressor includes a rotation shaft, a housing, a swash plate, two cylinder bores, a double-headed piston, and two shoes. The double-headed piston includes two shoe holders, a neck, two heads, and two coupling portions. Each of the coupling portions includes an outer portion and an inner portion. A direction orthogonal to both of an opposing direction of the inner portion and the outer portion and the axial direction of the double-headed piston is referred to as a widthwise direction. The neck is larger in the widthwise direction than in the opposing direction so that the neck is deformable in the opposing direction. Each of the two coupling portions has a width that is less than or equal to a width of the neck. The inner portion includes a narrow portion. The narrow portion is at least partially located closer to the head than the shoe holder in the inner portion. The two coupling portions are deformable in the widthwise direction when the swash plate applies load to the double-headed piston.

A double-headed piston type swash plate compressor includes a rotation shaft, a housing, a swash plate, two cylinder bores, a double-headed piston, and two shoes. The double-headed piston includes two shoe holders, a neck, two heads, and two coupling portions. Each of the coupling portions includes an outer portion and an inner portion. A direction orthogonal to both of an opposing direction of the inner portion and the outer portion and the axial direction of the double-headed piston is referred to as a widthwise direction. The inner portion includes a narrow portion and a wide portion. The wide portion projects out of the narrow portion in the widthwise direction and has a larger width than the narrow portion. An outer surface of the wide portion is slidable on a wall surface of the corresponding cylinder bore when the double-headed piston reciprocates in the cylinder bores.

A variable-pressure air pump includes a first cylinder with a first chamber and a second cylinder with a second chamber movably connected with one another. The second chamber fluidly communicable with the outside of the variable-pressure air pump selectively. A discharge device includes a connecting member and a switch movably connected with one another. The connecting member defines at least one discharge hole fluidly connecting with the second chamber. The switch has at least one flow guide portion and at least one blocking portion. The switch is movable between a first position in which the at least one flow guide portion is adjacent and opens to the at least one discharge hole and a second position in which the at least one blocking portion is adjacent to and blocks the at least one discharge hole.

A natural gas compressor can include a pre-staging chamber that couples with a supply line to receive natural gas from the supply line. The compressor can additionally include a first-stage chamber that couples with the supply line to receive natural gas from the supply line. The first-stage chamber can additionally be coupled with the pre-staging chamber to receive from the pre-staging chamber natural gas that has been compressed by the pre-staging chamber. The compressor can also include a second-stage chamber configured to receive natural gas that has been compressed by the first-stage chamber.

A piston type pump includes a pump housing having a pump inlet, a pump outlet, and a piston arrangement connected to a drive shaft. The drive shaft is configured to drive the piston arrangement, and the drive shaft includes a first eccentric. The piston arrangement has a first primary stage piston connected to a first sliding block guide slidably seated on the first eccentric. The first sliding block guide has a main axis, a minor axis, and an inner surface. A first sliding bush is arranged between the first eccentric and the first sliding block guide. The outer surface of the first sliding bush corresponds to the inner surface of the first sliding block guide. Translational movement of the first sliding bush relative to the first sliding block guide is allowed along the main axis and restricted along the minor axis.

A reciprocating-piston machine, in particular a two-stage or multi-stage piston compressor, includes: a first connecting rod for deflecting a first piston and which has a connecting-rod eye, the first connecting rod being a drive connecting rod; a second connecting rod for deflecting a second piston and which has at least one further connecting-rod eye, the second connecting rod being a follower connecting rod; a coupling element which extends through the connecting-rod eye and the at least one further connecting-rod eye and about which the first connecting rod and the second connecting rod are rotationally movable relative to one another; a coupling bearing element arranged between the coupling element and a connecting-rod eye inner surface of the connecting-rod eye; and a damping element with elastic damping action arranged in a damping annular chamber between the coupling bearing element and the connecting-rod eye inner surface of the connecting-rod eye.

Provided a household electric appliance with a high/low-pressure function, and the household electric appliance with a high/low-pressure function includes a high/low-pressure forming apparatus, where the high/low-pressure forming apparatus includes a movement apparatus, a pressure forming rod, a pressure forming body, a pressure forming shell and a valve, and the valve includes a pressure suction valve and a pressurization valve. A pressure-resistant shell, a build-in groove, a sealing apparatus and a pressure-resistant build-in door are disposed on a device on a high-pressure compartment or a low-pressure compartment of the household electric appliance. The high-pressure compartment or the low-pressure compartment of the household electric appliance with the high/low-pressure function is integrally provided with or coupled with the high/low-pressure forming apparatus through a high/low-pressure control valve and a pipe.

An air compressor includes a compression machine configured to generate compression air, a main tank configured to store therein the compression air, an extension tank configured to store therein the compression air, a connection pipeline provided between the main tank and the extension tank to be removably inserted thereto, and a fastening unit configured to releasably connect the main tank and the extension tank with each other.

A hydraulically operated compressor has a fixed piston and a fixed compression or outer cylinder. A drive or intermediate cylinder is located between the piston and outer cylinder. A compression chamber is formed between the drive cylinder and the outer cylinder. Drive fluid is pumped into and released from an interior chamber in the drive cylinder to reciprocate the drive cylinder. The drive fluid also provides cooling to the interior of the compressor.