Abstract: A fuel pump assembly includes a pump bushing defining a dual-chambered pumping cavity, a fluid channel for shuttling fuel between the chambers, a plunger, and a plurality of fluid control valves. A first check valve is a pressure relief valve in fluid communication with an outlet of the pump bushing and with either an inlet of a second check valve or an inlet of the pump bushing. Another check valve or a control orifice may be used in parallel with the second check valve, with the third check valve or control orifice being positioned at least partially external to the fuel pump assembly. A vehicle includes a transmission, engine, a returnless high-pressure fuel pump assembly, and a low-pressure fuel line in fluid communication with an inlet side of an inlet control valve. The high-pressure fuel pump assembly inhibits a pressure pulsation from propagating through the low-pressure fuel line.

Abstract: An improved high-pressure pump (1) for an accurate, largely pulsation-free flow of the working medium, more particularly an HPLC pump, includes one or a plurality of the following measures: reduced dead space due to adapted seals (48, 70); reduced dead space thanks to a device (15, 16; 32; 36, 38) for adjusting the length of the displacement piston; adjustable dead space and therefore adjusting capability of the pulsation freedom through a displacement chamber provided with an adjustable opposed piston (58); and seals compensating construction tolerances by a combination of a cambered sealing surface and a conical sealing surface.

Abstract: A pump assembly with a first pump which draws liquid from a reservoir and dispenses it to a second pump. The second pump receives the discharge from the first pump and air such that the second pump discharges both liquid and air. The first pump preferably has a piston movable in a first inner chamber and the second pump utilizes the same piston movable in a second outer chamber. Preferably, the second pump discharges in the withdrawal stroke, that is while moving from a retracted position to a withdrawn position.

Abstract: Pump, comprising a casing that is generally cup-shaped intended to be fixed to a driving motor (3), and containing a drive shaft (6) suitable for being coupled with said motor, and having a tilted surface for the actuation of one or more pistons (7) that move parallel to the axis of said drive shaft, where said casing consists of a monolithic body (2) that comprises means (4) for its attachment to said motor, a system for supporting and holding said drive shaft, and the guide and sliding seats of the quoted pistons.

Abstract: A piston pump having at least one piston drivable by a drive unit and is longitudinally movable in a housing and having a first pressure chamber delimited by the piston element and at least one component affixed to the housing. The first pressure chamber is connectable to a suction region via an inlet valve and is operationally connectable to a delivery side via an outlet valve. A compensation piston unit drivable by the drive unit has a working piston chamber connected to the delivery side. A stroke volume of the first pressure chamber is twice the size of a stroke volume of the working piston chamber.

Abstract: A multistage ultra high pressure multichamber, have among which stages can be included pumps. A chamber has another chamber inside which also contain a pump or a pumping system towards the inside, where a third chamber is considered with its pumping system towards its interior successively the device is useful in making of ultra high pressure sinterized material parts, manufacture of parts made of new materials like synthetic diamond, manufacture of material for pharmaceutical products and hydrowasher using this new technique to increase its pressure.

Abstract: A reciprocating-piston compressor having at least two working cylinders arranged in series, along a cylinder axis is described. The compressor includes a piston in each of the cylinders, guided in an axially movable manner, and a common axially actuated piston rod of the pistons, extending through a passage opening in a partition between the at least two working cylinders. The at least two working cylinders are sealed off with respect to one another in a region of the common axially actuated piston rod, exclusively by a non-contact seal. The axial seal has an axial gap seal formed between a radially outer circumferential surface of the common axially actuated piston rod and a radially inner circumferential surface of the passage opening.

Abstract: A high pressure radial piston fuel pump is featured having an hydraulic head with two individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where a rotating eccentric drive member with associated actuation ring are situated. A rolling interaction is provided between the actuation ring and the inner ends of the pistons for intermittent actuation. Relative rotation is provided between the actuation ring and the drive member. Each piston has a piston bore that has a centerline that intersects the actuation ring but is offset (X) from the drive axis as viewed in cross section perpendicularly to the drive axis and the piston bore centerlines are parallel to each other but offset (Y) from each other as viewed in longitudinal section along the drive axis.

Abstract: A pump having adjustable pumping pressures comprises a tube, a first and a second chamber and a channel extending from the first end to the second end of the tube, and an orifice extending through the tube and opening to the channel. A base connected to the second end of the tube includes a first passage opening to the first and second chambers and a second passage opening to the first passage and the channel. A switching device includes a rod disposed in the channel and a shaft received in the orifice for selectively moving the rod to a first position for permitting air through the second passage to the channel and a second position for preventing air through the second passage to the channel.

Abstract: A high pressure radial piston fuel pump is featured having an hydraulic head with two or three individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where a rotating eccentric drive member with associated actuation ring are situated. A rolling interaction is provided between the actuation ring and the inner ends of the pistons for intermittent actuation. Relative rotation is provided between the actuation ring and the drive member. Respective inlet and outlet valve trains are situated in the head. The head is attachable to a removable mounting plate, and the drive member is rigidly carried by a drive shaft that is supported by two bushings, one located in the mounting plate and the other in the hydraulic head.

Abstract: A condensate pump includes a condensate reservoir, a liquid level float sensor operable to sense a liquid level within the condensate reservoir, and a pressure/vent valve including a pressure source, a pressure vent, and a primary piston slidably supported in a primary cylinder and sliding in the primary cylinder responsive to the liquid level sensor. A secondary piston is slidably supported in a secondary cylinder and moves responsive to a movement of the primary piston between a first secondary-piston position wherein the pressure source is in communication with a gas space of the condensate reservoir and the pressure vent is isolated from the gas space, and a second secondary-piston position wherein the pressure source is isolated from the gas space and the pressure vent is in communication with the gas space. An aperture in the primary piston and passages may also be provided to prevent build-up of gas pressures and maintain pressures in preselected regions within the pump at atmospheric pressures.

Abstract: An hydraulic head features two, three, or four individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where an eccentric drive member with associated outer rolling actuation ring are situated. The piston shoe or foot smoothly enlarges from the piston stem, thereby avoiding the concentration of stress at the interface. Another improvement is in the capture of the piston foot through beveled holes at the ends of a C-band spring such that the bevel substantially conforms to the contour of the foot and thereby reduces stresses and wear. Yet another improvement is that the C-band spring is retained within a guide channel of the cavity wall thereby permitting apparent reciprocating displacement of the spring in parallel with the reciprocation of the pistons, while avoiding axial movement or tilting within the cavity.

Abstract: A quintuplex mud pump has a crankshaft supported in the pump by external main bearings. The crankshaft has five eccentric sheaves, two internal main bearing sheaves, and two bull gears. Each of the main bearing sheaves supports the crankshaft by a main bearing. One main bearing sheave is disposed between second and third eccentric sheaves, while the other main bearing sheave disposed between third and fourth eccentric sheaves. One bull gear is disposed between the first and second eccentric sheaves, while the second bull gear is disposed between fourth and fifth eccentric sheaves. A pinion shaft has pinion gears interfacing with the crankshaft's bull gears. Connecting rods on the eccentric sheaves use roller bearings and transfer rotational movement of the crankshaft to pistons of the pump's fluid assembly.

Abstract: There are a number of applications today where the pumping of abrasive slurries is necessary. The pumping mechanisms, though, can be complex, employing multiple transfer cylinders and movable pipes. These designs have their problems, specifically wear between poorly sealing surfaces. To reduce this problem, seals are provided that have multiple wear surfaces which include harder tiles secured over a softer core to benefit from the relative hardness or flexibility of each of the respective materials.

Abstract: The invention is a 180° reciprocating piston compressor comprising additional eccentric disc linkage between the crankpin and the connecting rod. The additional linkage lessens the compression above the piston during start-up and limits the electrical motor shaft load at design operating conditions lowering the starting current surge when bringing the system up to starting speeds. The additional disc eccentric linkage also lessens the torque load on the motor during motor normal operating speed.

Abstract: A hydraulic machine includes a valve plate, with first and second fluid ports in a surface thereof. A cylinder barrel is rotatably coupled to the valve plate. A plurality of cylinders is formed in the cylinder barrel, such that, as the barrel rotates, each cylinder is coupled to the first and second fluid ports, sequentially. First and second pressure relief ports are formed in the surface of the valve plate between the first and second fluid ports at top- and bottom-dead-center, respectively. A cross-port bore is formed in the valve plate, placing the first and second pressure relief ports in fluid communication with each other. As each cylinder rotates to top-dead-center, an opposite cylinder rotates to bottom-dead-center. The respective cylinders are coupled to the first and second pressure relief ports, such that differential pressure in the cylinders is equalized.

Abstract: A compressed gas compressed by the first gas compressor is further compressed by the second gas compressor. The compressed gas from the first gas compressor is sent to a crank case of the second gas compressor in which the gas is further compressed. The gas is sent to a cylinder of the second gas compressor and compressed by a piston in the cylinder.

Abstract: A pressurizing device comprising a control mechanism (7) which maintains the opening of a communication passage (22a) which allows the fluid pressure mechanism (6) to communicate with the outside when the fluid pressure mechanism is connected by a connection mechanism (5) and closing the communication passage (22a) by detecting the flow of a fluid in the fluid pressure mechanism (6) when the fluid is pushed to the outside by the energization of an input shaft (3) when the connection by the connection mechanism (5) is released so as to isolate the fluid pressure mechanism (6) from the outside.

Abstract: Piston assemblies for rocking piston compressors, diaphragm compressors and vacuum pumps are provided wherein the overall mass of each piston assembly is identical to that of the other assembly despite having rod tops, retainers and diaphragms of different diameters and therefore different capacities. Each piston assembly includes a connecting rod connected to a rod top that supports a cup seal and a retainer or retainer plate. The mass of each rod is equal to that of the other rod despite the differing geometries. The mass of each retainer is the same as that of the other retainer despite the differing geometries. The overall length and stroke length of each piston assembly is the same. As a result, centers of gravity of the piston assemblies are continuously balanced on either side of the drive shaft in terms of distance from the drive shaft and in absolute value.

Abstract: A dual rocking piston pump is disclosed which includes a first piston with a first connecting rod eccentrically mounted to a rotor shaft and a second piston with a second connecting rod eccentrically mounted to the rotor shaft. The rotor shaft passes through a first bearing and a second bearing before being connected to a rotor body. The rotor body is disposed within a stator. The first and second bearings and stator are supported by a bracket. The bracket includes a hub which, in turn includes a first end connected to a wall at an opening in the wall. The hub also includes a second end. The first end of the hub supports the first bearing at the wall and the second end of the hub supports the second bearing. Both the first and second bearings are disposed to “in front” of the motor or in front of both the rotor and stator.

Abstract: The exposure of components to high-pressure fluids can result in the application of high tensile stresses to those components, which may lead to reduced life. The preload system described herein helps to reduce the magnitude of those tensile stresses by providing a body and a plug. The body includes a first bore and a second bore. The first bore is configured to be exposed to high tensile stresses. The second bore includes a first engagement structure and a bottom surface near a first portion of the first bore. The plug includes a second engagement structure and a first end. The second engagement structure engages the first engagement structure to force the first end of the plug against the bottom surface of the bore. The force of the plug against the bottom surface of the bore applies a compressive preload to the first portion of the first bore.

Abstract: A pump (60, 160) has a pair of working members (preferably diaphragms 1, 2, 101, 102) and a pump chamber (3, 4, 103, 104) associated with each working member is communicated via check valves (32-35, 132-135) to a suction manifold (30, 130) and to an outlet manifold (31, 131). A drive mechanism (10, 110) couples the working members so that they reciprocate together and a first of the working members performs an outlet stroke while a second of the working members performs a suction stroke. The suction and outlet manifolds (30, 130, 31, 131) are incorporated in a manifold assembly that connects the pair of diaphragms (1, 2, 101, 102) for coordinated reciprocation. A pair of manually-operated levers (J, 8, 107, 108) are connected together for opposite reciprocation and are drivingly connected to the working members (1, 2, 101, 102).

Abstract: A pump comprising a guide (1) forming a closed loop of variable radius and at least one piston assembly (2). The piston assembly (2) comprises a chamber (4) and a piston (5) slidably mounted within the chamber (4). A first end of the piston assembly (T) is arranged to follow the guide (1) and a second distant end of the piston assembly (2) is mounted proximate the radial centre axis of the loop. At least one of the guide (1) and the piston assembly (2) are arranged to rotate causing relative rotational movement between the guide (1) and the piston assembly (2). The relative rotational movement causes the piston (5) to reciprocally displace within the chamber (4) for pumping a fluid from an inlet (22) to an outlet (20) of the pump.

Abstract: A flexible impeller pump includes first and second component housings. The first component housing includes a first flexible impeller and the second component housing includes a second flexible impeller. As these impellers rotate within their respective housings, they draw in and expel individual components into a common receiving chamber. In a particular application, one component is a foamable liquid, and the other component is air, and a mixture of foamable liquid and air is thus created in the common receiving chamber.

Abstract: The high pressure lubricant pump for steelworks comprises a body provided with at least one cylinder provided with a lubricant intake port and a lubricant delivery port. Within the cylinder a piston is movable to pressurize the lubricant. The cylinder and the piston define a pre-assembled pumping unit removably fixed into a seat of the body.

Abstract: A reciprocating compressor is provided. In one embodiment, the reciprocating compressor includes a frame having a central body and a crosshead guide extending from the central body. The compressor may also include a crosshead disposed within the crosshead guide and coupled to a crankshaft disposed within the central body of the frame. Additionally, the compressor may include at least one support structure extending from the crosshead guide to the central body, comprising an oblique support structure formed at an angle with respect to the horizontal and vertical dimensions of the crosshead. Other embodiments of compression systems, devices, and frames of such systems are also provided.

Abstract: A piston type compressor comprises a cylinder block having a plurality of cylinder bores, a plurality of pistons disposed in the respective cylinder bores for defining compression chambers in the respective cylinder bores, a housing for defining a suction-pressure region and a discharge-pressure region therein, a valve-port assembly provided between the cylinder block and the housing, and a seal member provided between the cylinder block and the housing. The seal member has a first seal portion for preventing the refrigerant from leaking out of the compressor and a second seal portion for preventing the refrigerant from leaking between adjacent refrigerant passages. Each of the first and second seal portions has a bead. The bead of the second seal portion has a height which is smaller than that of the first seal portion.

Abstract: A multi-directional pump is disclosed generally comprising a housing with inlet and outlet ports, a pumping device disposed therein, a first chamber in fluid communication with the inlet port, and a second chamber in fluid communication with the first chamber. The first and second chambers are both in direct fluid communication with the outlet port, such that a double pumping effect is achieved while some of the fluid is compressed in multiple stages. In certain embodiments, one or more sealing mechanisms can be activated when particular conditions are desired in order to seal the first conduit by which the first and second fluid chambers communicate, or by which the second fluid chamber communicates with the inlet port, such that a standard double or single pumping effect is achieved.

Abstract: A compressor for a fuel canister. The compressor includes a handle or other device for rotating a shaft. Rotation of the shaft causes the operation of pistons, which drive air into the fuel canister, thus pressurizing the fuel canister. In an embodiment, the compressor is a rotary style compressor. In another embodiment, the compressor is a horizontally opposed compressor system. Other compressor configurations may be used.

Abstract: A hand-operated inflator with dual cylinder is provided. Once the cylinders are pulled out on two sides of the central block to form a line axially, and a clamp plate at mid point in between the two cylinders is turned to the transversal position to lock the cylinders in place, the inflator is set for refilling operation. The two cylinders can be folded back when the clamp plate is released, making it easy for carrying and storage with the length reduced by half. The inflator is able to inflate an object with faster rate as compared with the conventional inflators with only one air cylinder. Moreover, the central block can be attached with a pressure meter. If the measured air pressure inside the object gets excessively high, air can be safely released through an over pressure valve.

Abstract: An hydraulic head features two or three individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where an eccentric drive member with associated outer rolling actuation ring are situated, whereby a rolling interaction is provided between the actuating ring and the inner ends of the pistons for intermittent actuation, and a sliding interaction is provided between the actuation ring and the drive member. The respective inlet and outlet valve trains are also situated in the head, and the head is attachable to an application and/or customer specific mounting plate. The outside diameter of the rolling element is barrel shaped, to compensate for any misalignment of the pistons relative to the drive shaft due, for example, to either tolerance stack up or deflection.

Abstract: A positive displacement pump includes a magnetostrictive actuator. A single actuator drives multiple pumping chambers. The pump may include two pumping chambers driven in phase by the linear expansion of the actuator at both its ends. The pump may include a third pumping cavity, driven by the transverse expansion and contraction of the actuator, out of phase with either cavity driven by the lengthwise extension of the actuator. A pump assembly having multiple pumps each including a magnetostrictive element is also disclosed.

Abstract: A compact 180° opposed piston pump/compressor minimizes axial spacing between its pistons on the drive shaft and thereby reduces the shaking couple and noise from reciprocation. Each piston has its own eccentric element press-fit into the connecting rods so as not to occupy space between the pistons. The shaking couple can be further reduced for pistons of different masses by selecting the mass of the cup retainers to compensate for the difference in overall piston masses. The pump also includes an improved cylinder sealing arrangement having a circumferential groove in an angled surface at the end of the cylinder. The pump also has a special cover and seal for closing the open neck of the pump crankcase and an improved multi-lobed valve stop. The pump further uses tubular transfer members for transferring intake and/or exhaust air into the crankcase and/or between valve heads.

Abstract: An electromagnetic micropump for pumping small volumes of liquids and gases comprises a magnetic actuator assembly, a flexible membrane and a housing defining a chamber and a plurality of valves. The magnetic actuator assembly comprises a coil and a permanent magnet for deflecting the membrane to effect pumping of the fluid. A plurality of micropumps may be stacked together to increase pumping capacity.

Abstract: A first piston connected to a first shaft and a second piston connected to a second shaft are supported within a housing by using a first leaf-spring unit and a second leaf-spring unit, respectively. Therefore, axial movement of the first shaft or the second shaft can be allowed, while circumferential rotational movement and radial movement can be restricted. The first leaf-spring unit includes two leaf-spring groups that are disposed in a row around the first shaft in the direction of the axis of the first shaft; similarly, the second leaf-spring unit includes two leaf-spring groups that are disposed in a row around the second shaft in the direction of the axis of the second shaft. Therefore, inclinations of the first shaft and the second shaft can be decreased. This results in reduction in contact between the first and second shafts and a cylinder within the housing and friction due to the contact.

Abstract: A dual-direction pump includes two cylinders arranged on opposite sides of a head portion and an inlet return-flow prevention device and a leakproof device mounted between the cylinder and the head portion for avoiding leakage at the juncture between the cylinder and the head portion or leakage induced by reverse flow in one of the cylinders in the case of a single-sided pumping operation in the other cylinder. The head portion has an outlet port to which an outlet return-flow prevention device is mounted. A knob is rotatably mounted to the outlet pot and a nut is fixed to the knob for selectively engaging an inflation valve to avert detachment. The outlet return-flow prevention device prevents reverse or return flow induced in the outlet port in order to reduce resistance caused thereby and enhances pumping efficiency.

Abstract: A pump has a flexible liner which is expanded and contracted by application of positive and negative fluid pressure for receiving and discharging fluent material. The liner is received in a rigid shell which defines the maximum volume received. In discharging fluent material, a vacuum is applied to one side of the liner, while applying pressure to the other side so the liner is collapsed against the rigid shell. The liner is arranged so as to be the only part of the pump which contacts the fluent material, and is replaceable to effect rapid and easy cleaning of the pump. The liner has multiple pump cells which can expand and contract for moving fluent material through the pump cell. The pump cells can be sized and arranged so that by selection of particular pump cells which receive the fluent material, precise volumes can be metered by the pump.

Abstract: The invention relates to a hydraulic device provided with a housing having at least a first line connection and a second line connection and, if appropriate, further line connections, a rotor which can rotate in the housing and chambers which are alternately connected to one of the line connections as a result of the rotation of the rotor. According to the invention, chambers are connected by connecting lines in which there are means for closing a connecting line after a limited volume of fluid has flowed through the connecting line in one direction.

Abstract: A compact 180° opposed piston pump/compressor minimizes axial spacing between its pistons on the drive shaft and thereby reduces the shaking couple and noise from reciprocation. Each piston has its own eccentric element press-fit into the connecting rods so as not to occupy space between the pistons. The shaking couple can be further reduced for pistons of different masses by selecting the mass of the cup retainers to compensate for the difference in overall piston masses. The pump also includes an improved cylinder sealing arrangement having a circumferential groove in an angled surface at the end of the cylinder. The pump also has a special cover and seal for closing the open neck of the pump crankcase and an improved multi-lobed valve stop. The pump further uses tubular transfer members for transferring intake and/or exhaust air into the crankcase and/or between valve heads.

Abstract: Described herein is an engine/pump of a pneumatic type, having a stator with radial cylinders, within which there can slide respective pistons, each carrying a roller that engages an annular cam carried by a rotor. A guide system forces each piston to move, maintaining its axis rigorously aligned with the axis of the respective cylinder. The propulsion system that uses said engine includes high-pressure, medium-pressure and low-pressure tanks, and an auxiliary engine, which controls one or more compressors. A motor vehicle which uses the aforesaid system presents innovative peculiarities as regards construction and location of the tanks of pressurized air or gas, which are filled with spongy material, and also as regards construction of the accelerator and brake controls.

Abstract: An improved roller pump having a rotor formed of a plastic material that provides improved performance and longevity as compared to roller pumps having metal rotors.

Abstract: The invention relates to an internal gear pump for delivering fuel in an internal combustion engine, with an internally toothed annular gear and an externally toothed pinion that cooperates with the annular gear to produce a pumping action. In order to increase both the delivery capacity at starting speed and the service life of the internal gear pump, the pinion is supported on a supporting stub in a radially mobile fashion, eccentric to the annular gear. In addition, a device is provided to compensate for the radial play between the pinion and the annular gear. The drive is transmitted by a spring-loaded Oldham coupling, which adjusts the axial play of the pump according to the invention.

Abstract: This invention relates to a device for pumping high delivery volumes of a liquid, with at least two pumps each forming a single structural unit, which are jointly hooked up to a pressure line on the delivery side, and coupled to a single drive. The device according to the invention further develops the known device described in greater detail above in such a way as to provide an easily transported and space-saving device. This is achieved by virtue of the fact that at least one pump (4) is positioned in a plane spaced vertically apart from the plane in which the respective other pump (5, 6) is located.

Abstract: The invention relates to a hydraulic pump unit having a plurality of pump elements, disposed in one plane, each of which has one pump cylinder and one pump piston longitudinally displaceable in the pump cylinder, and whose longitudinal axes intersect at a common intersection point, and having a cam drive with cams, which upon a rotation of the cam drive relative to the pump elements act upon the pump pistons with an actuating motion. To enable a uniform pumping of the hydraulic fluid and to make a high degree of smoothness of the hydraulic pump unit possible, it is proposed that the number and the angular spacing of the cams is adapted to the number and angular spacing of the pump elements in such a way that when a certain number of pump pistons are located at top dead center, the same number of pump pistons are at bottom dead center.

Abstract: A cover apparatus has a cover main body held to a compressor by using a clip to cover a terminal and electrical parts connected to the terminal, the clip having an elasticity. The cover main body has a an internal passageway or pass portion formed in an inner portion of the main body, and the clip has a press portion, an insertion portion extended from the press portion, and an engagement portion formed in the insertion portion. The insertion portion is inserted within the pass portion and the engagement portion is detachably engaged with a fence provided in the compressor in adjacent to the terminal by its elasticity, and the press portion contacts an outer surface of the cover main body.

Abstract: The invention relates to a device for producing consumables, especially filled chocolates that consist of a coated filling. The aim of the invention is to provide a device for feeding substances of the consumables to nozzles in a controlled manner. To this end, the device is provided with pumps that comprise pump pistons in a pump chamber and at least two pump chambers are located in a pump housing one on top of the other.

Abstract: In a pump, a plurality of pump chambers are defined by a plurality of diaphragms. A pivotable member is attached to the diaphragms. A rotator is formed with a first hole having a first diameter, which is arranged eccentrically from a rotation center of the rotator, and a second hole having a second diameter smaller than the first diameter, which is formed in a bottom of the first hole. A shaft member connects the rotator and the pivotable member so as to convert a rotation of the rotator into a pivotal movement of the pivotable member for sequentially deforming each diaphragm to vary a volume of each pressure chamber. One end of the shaft member is fitted into the second hole.

Abstract: A reciprocating compressor of un-lubricating type, equipped with a cooling device including a cooling fan beneath a motor and provided with four gas compressors, each having a cylinder and a piston. The pistons of each gas compressor cooperate by converting a rotating motion of a crankpin of a crankshaft provided on an electric drive source via two yokes having a phase difference of 90 degrees therebetween to a reciprocating motion by a scotch yoke mechanism. The flows of compressed gases from each gas compressor are joined to one place by connecting tubes to be discharged. The lengths of each connecting tube are selected such that pressure waves of the compressed gases compete with each other at the joining point for a time period encompassing one rotation of the crankpin, whereby a pulsation resulting from gas flow discharged in concentration is decreased.

Abstract: The two cylinder and piston systems (1, 3), operating in series, are driven by a crankshaft, with a minimum or even zero phase difference.

Abstract: A manual air pump with a handle includes a base member, a foot switch, an outlet cylinder, an inner cylinder and a pumping assembly. The foot switch is mounted on the base member. The outlet cylinder is mounted vertically on the base member. The inner cylinder is mounted vertically on the base member in the outer cylinder. The pumping assembly is moveably mounted in the outer cylinder and securely attached to the inner cylinder. Multiple check valves are mounted in the cylinders and the base member to form two stages to pump the air into the object to be inflated in a great quantity when the object to be inflated is in a low-pressure condition and easily pump compressed air into the object to be inflated when the object to be inflated is in a high-pressure condition.