Abstract: An oiler pump comprises a housing defining a cylinder and a chamber, a manually displaceable piston received in the cylinder, a spring in the chamber between the housing and the piston, a first one-way check valve on a first end of the piston, a second one-way check valve on the housing, and a fluid displacement member substantially completely filling the chamber when the piston is in a retracted position and to substantially completely open the chamber when the piston is in the first position. The fluid displacement member is formed by an outer skirt member and an inner guide member formed integrally with the piston member. The fluid displacement member increases the priming height and efficiency of the pump by reducing the volume area in the chamber in the fully compressed state which might accumulate gas to zero.

Abstract: A pump for use with a dispensing unit of a liquid hot melt adhesive system, dispensing units including the pump, and a method of operating a pump for pumping a liquid like liquid hot melt adhesive. The pump has a piston movable within a pumping chamber for transferring liquid from an inlet to an outlet. A valve body, which is resiliently biased relative to the piston, is moved out of contact with the inlet when the piston moves in a first direction and into contact with the inlet when the piston moves in a second direction. When the piston is moved in the first direction, the resilient biasing actively lifts the valve body out of contact with the inlet for overcoming any attractive adhesive force acting between the valve body and inlet.

Abstract: A restorable sand or pellet pile is provided for use as an amusement or exercise device. A sand or pellet collection chamber has inclined side walls that converge toward each other in a downward direction and having a bottom surface connected to the side walls. A support deck is positioned above the side walls of the collection chamber and is adapted to support sand or pellets on its upper surface. A safety grating is formed around the perimeter of the support deck to allow sand or pellets to flow downwardly therethrough into the collection chamber as children or adults play or exercise on the pile. A diaphragm pump is positioned in the collection chamber and pumps sand upwardly through a vertically extending conduit to restore the pile. The pump may be operated intermittently or continuously. Other pumping mechanisms may be used. The preferred embodiment utilizes resilient inclined side walls in the collection chamber and a vibrator connected to the side walls to cause the side walls to vibrate.

Abstract: A piston system for a reciprocating compressor is adapted for high speed, high pressure unloading conditions by providing a dual stage piston assembly wherein the piston is adapted for absorbing and redistributing a portion of the load during the high pressure applications or high pressure portion of a cycle without reducing the efficiency of the system during normal loads. Pressure of up to 4000 psi can be handled without damage to the piston or other valve components. The valve plate is held in the closed position by a compression spring which is adapted to be engaged by a finger/driver upon reciprocation of the valve piston. The finger driver moves with the piston against the valve plate to open the valve on the plunger downstroke and move away from the valve on the plunger upstroke. A shock absorbing element is positioned in the plunger/finger assembly to absorb the shock of the driving downstroke, thereby reducing the shock of the finger against the valve plate.

Abstract: In a seal mechanism which constitutes a port switching portion in a pump mechanism of a paste ejection apparatus that ejects paste, and which prevents leakage of the paste from a seal portion between a plunger block rotating with a plunger and a fixed seal block (between a seal surface and a sliding surface), a housing portion is formed by opposing an outer surface provided for the seal block to an inner surface extending axially from the cylinder block, and a ring-shaped external seal member formed by combination of an O-ring and self-lubricant material such as PTFE is attached into the housing portion. Hereby, it is possible to prevent the paste that has leaked from the seal portion from leaking to the outside of the housing portion by the external seal member.

Abstract: An air pumping/extracting duplex pump for use in an inflatable device for selectively pumping air into/out of an air chamber of an inflatable device is constructed to include two connected housing, and an actuating mechanism mounted in the housings and manually rotatable between a first position for drawing air into the inflatable device and a second position for drawing air out of the inflatable device.

Abstract: A pump assembly for mounting a high-pressure oil pump on an internal combustion engine where the pump in the assembly is mounted in a closed chamber and a solenoid controlled valve is mounted outside of the chamber.

Abstract: A fluid compressor controls opening and closing of a fluid intake port in the crankcase with a novel and improved form of gate control member which follows rotation of the crankshaft and times the opening and closing of the intake port to coordinate with the intake and discharge strokes of a piston which is reciprocal through a cylinder bore communicating with the crankcase, the piston having an intake valve, and a cylinder head at the end of the cylinder bore having only a discharge valve.

Abstract: An object of the present invention is to provide a suction-discharge device for fluids capable of sucking fluids continuously and discharging fluids continuously under fixed flow rate and pressure, without substantially bringing about pulsations of even one unit.

Abstract: A fluid pump is provided that produces an outflow of fluid that is not proportional to the speed of the input drive. Thus, the fluid pump can be tuned to provide a substantially constant outflow of fluid irrespective of the speed of the input drive. The fluid pump also provides fluid outflow when the rotational direction of the input drive is reversed.

Abstract: A rotary valve, a piston pump rotary valve assembly and a piston pump rotary valve assembly tank dispenser for use in discharging a metered amount of liquid, gel, or slurry has a valve body having a first channel pathway and a second channel pathway. The first channel pathway has an inlet opening to receive a liquid, gel, or slurry and an outlet opening to provide the same to a pathway of the piston pump assembly. The second channel pathway is segregated from the first channel pathway and includes a plurality of inlet openings, each capable of communicative alignment with the pathway of the piston pump assembly, and at least one outlet opening communicative with such inlet openings. The valve body is capable of rotation with respect to the piston pump assembly to dispose both the first channel pathway and the second channel pathway each to two operative positions to receive the liquid, gel, or slurry and to two inoperative positions blocking fluid communication with the liquid, gel, or slurry.

Abstract: A fluid compressor controls opening and closing of a fluid intake port in the crankcase with a novel and improved form of gate control member which follows rotation of the crankshaft and times the opening and closing of the intake port to coordinate with the intake and discharge strokes of a piston which is reciprocal through a cylinder bore communicating with the crankcase, the piston having an intake valve, and a cylinder head at the end of the cylinder bore having only a discharge valve.

Abstract: A rotary valve, a piston pump rotary valve assembly and a piston pump rotary valve assembly tank dispenser for use in discharging a metered amount of liquid, gel, or slurry has a valve body having a first channel pathway and a second channel pathway. The first channel pathway has an inlet opening to receive a liquid, gel, or slurry and an outlet opening to provide the same to a pathway of the piston pump assembly. The second channel pathway is segregated from the first channel pathway and includes a plurality of inlet openings, each capable of communicative alignment with the pathway of the piston pump assembly, and at least one outlet opening communicative with such inlet openings. The valve body is capable of rotation with respect to the piston pump assembly to dispose both the first channel pathway and the second channel pathway each to two operative positions to receive the liquid, gel, or slurry and to two inoperative positions blocking fluid communication with the liquid, gel, or slurry.

Abstract: Variable valve timing is provided to control compressors and expanders in a fuel cell powering system in order to provide for matching the displaced volume of the compressor and expander over a range of pressure delivery requirements. A movable timing edge is positioned adjacent inlet and/or discharge ports to cooperate with a movable valve element with inlet and outlet slots to adjust the time and time period of open and close operations. Several embodiments are presented.

Abstract: A hand holdable pump spray apparatus is disclosed where the pump mechanism is in the hand holdable wand rather than in a spaced apart liquid container. The wand may be held with one hand while a pump handle is extended with the other hand. This creates a pressure differential which allows liquid to flow from the container, passed a check valve and into the wand. After filling, a biased spring provides a force against the liquid creating a higher pressure in the wand than ambient pressure. This closes the check valve. When an operator depresses an actuator, another valve opens allowing the liquid in the wand to be ejected through a nozzle.

Abstract: A fluid transfer pump wash-out apparatus is provided to facilitate cleaning of fluid transfer pump system components. The wash-out apparatus is adapted for temporary or permanent insertion between at least one pump liquid source pick-up point and a pump intake. The body of the wash-out apparatus is preferably adapted for connection in a pick-up hose assembly. The wash-out apparatus body is joined to a flow valve that is coupled to an intake coupler. The flow valve is operable to control the flow of fluid from the first pick-up hose into the body. The intake coupler is in turn coupled to a first pick-up hose that transports fluid from the liquid source pick-up point to the wash-out apparatus. An output coupler joined to the output end of the body is coupled to a second pick-up hose for connection to the fluid transfer pump assembly. A wash-out hook-up is provided to couple the body of the wash-out apparatus to a source of cleaning fluid.

Abstract: A dual disc pump in which the suction disc is phased to lag by more than 180° behind the pressure disc.

Abstract: A hand holdable pump spray system where the pump mechanism is in the hand holdable wand rather than in the liquid container. The wand may be held with one hand while the pump handle is extended with the other hand. This creates a pressure differential which allows liquid to flow from the container into the wand. A biased spring provides force against the liquid so that when a thumb actuated trigger opens the nozzle, the liquid will be ejected. Should all of the liquid not be ejected, there is a liquid return mechanism which opens a check valve and allows the liquid to return to the container through a supply tube connecting the wand and the container.

Abstract: A piston pump comprising at least one working space, which is surrounded by a cylinder and which is adapted to be varied by a piston arranged in said cylinder, and at least one inlet valve as well as at least one outlet valve, said valves being lifting valves and being adapted to be controlled and driven by a control and drive means. In order to provide a piston pump which can be cleaned more easily and which includes the smallest possible number of dead spots, a first teaching according to the present invention suggests that, when closed, the inlet valve should be located nearer to the working space than when it is open. Alternatively, the underlying technical problem is solved according to a second solution of the present invention by the feature that the valve surface of the inlet and/or outlet valve(s) facing the working space merges without any steps with the inner surface of said working space at the closed position of the valve or of each valve.

Abstract: A piston compressor has a valve support, which closes a compression chamber and has an intake valve. A non-rotatable lamella can be moved between two positions, in one position the lamella lifts up from the valve support, leaving intake openings unblocked and in another position, the lamella closes the intake openings. A device is provided on the piston compressor for interrupting the supply. This device has a plate that is disposed between the lamella and the valve support and can be moved into two positions. The plate has openings, which continue the intake openings of the valve support. In the one position of the plate, its intake openings are covered by the lamella. In another position of the plate, intake openings thereof and the intake openings of the valve support are left unblocked by through openings in the lamella. The piston compressor can be used in compressed air brake systems of commercial vehicles.

Abstract: A pulsating vibration air generator in which wave height, frequency and wave shape of the pulsating vibration air can be optionally modified and such pulsating vibration air can be periodically and continuously emitted. The pulsating vibration air generator has a valve chamber with an inlet port and an outlet port where a valve plug and a valve seat with a control opening are provided and a cam mechanism which moves the valve plug to open or close the opening of the valve seat, whereby positive or negative pulsating vibration air is emitted from the outlet port while pressurized air is supplied into the inlet port or air is sucked from the inlet port.

Abstract: A fluid driven reciprocating engine includes a main body having an inlet for receiving a primary fluid and an outlet for discharging the fluid. A drive piston is sealingly mounted in the main body for reciprocating movement in response to flow of the primary fluid through the body. The drive piston divides the body into first and second chambers. A first valve selectively transmits the primary fluid from the inlet to the first and second chambers and a second valve selectively transmits the primary fluid from the first and second chambers to the outlet. An overcenter linkage mechanism that operably interconnects the drive piston and the first and second valves.

Abstract: A blood pump having a rigid chamber with a central opening is connected to a vacuum source such that the vacuum source applies a vacuum on an elastic tubular membrane through the opening in the rigid chamber. The blood supply to the chamber is controlled by a first pinch valve disposed on the blood input end and a second pinch valve disposed on the blood output end. In order to pump the blood through the chamber, a vacuum source is applied when the first pinch valve is opened and the second pinch valve is closed to suction blood inside the tubular membrane. Then, the vacuum source ceases to apply a vacuum when the first pinch valve is closed and the second pinch valve is open in order to expel the blood from the tubular membrane. This type of blood pump reduces the formation of platelet aggregates and thrombi, and allows for blood to be more efficiently pumped to the patient.

Abstract: A pressure washer is powered by a prime mover, e.g., an electric motor or an internal combustion engine, and has a flow control valve. The valve has a housing containing a piston assembly and the assembly has a mechanism coupled to it for controlling prime mover power. The piston assembly includes a first piston sealing against the housing and dividing the housing interior into two chambers. Such first piston is spring-biased to a first position during periods when no output flow is being demanded from the washer. The assembly also has a second piston spring-biased to seal against the first piston during periods of no flow. When flow is demanded by opening the nozzle, the pressure in the second chamber diminishes. And when the difference between the pressure in the second chamber and that in the first chamber exceeds a predetermined value, the assembly shifts to a second position, causing the mechanism to actuate the prime mover.

Abstract: An IV pump actuates a disposable cassette having two parallel fluid paths that include first and second pumping chambers. The disposable cassette (12) has a housing(14) that includes a back portion (152) in which is defined a fluid path (60) between an inlet port (16) and an outlet port (18). An elastomeric membrane (150) is sealed between the back portion and a front portion (52). The elastomeric membrane is exposed through the front portion at a first pumping chamber (82), a second pumping chamber (84), inlet valves (70, 76), and outlet valves (86, 92). The inlet valves operate in a fully open mode, a fully closed mode, and a cracking mode. The cracking mode of the inlet valve occurs as the elastomeric membrane is initially forced further into the pumping chamber. If the pressure of the fluid in the pumping chamber exceeds a predetermined cracking pressure, the inlet valve is forced open so that the fluid flows from the pumping chamber back toward the inlet port.

Abstract: A hand pump includes a piston slidably engaged in a housing for separating the housing into two chambers. A tube is secured on top of the housing. The piston includes two annular grooves for receiving two sealing rings. A piston rod has one end secured to the piston and has the other end extended outward of the housing. The piston may pump the air in upper chamber into the tube when the piston moves upward, and the air in the lower chamber may be pumped into the tube when the piston moves downward. The tube includes two mouths for engaging with different tire valves.

Abstract: A device is proposed for applying material such as solder paste and glue in discrete points, particularly for applying solder paste on electronic circuit boards. The device comprises a pump house (202-205; 301, 307), a tube or a channel (206) by means of which material is fed to the pump house, a nozzle (111, 205) for feeding material from the pump house (202-205; 301, 307). Suitable upper and lower valve devices are arranged to block, at predetermined times, the feeding of material to and from the pump house (202-205; 301, 307). The lower valve device may possibly be replaced by a restriction device. As is conventional the pump house (202-205; 301, 307) comprises an outer pump cylinder (203; 307) and an inner piston (204; 301). The displacement of the piston (201; 301) is obtained by the fact that the piston is connected to a magnetostrictive rod (202; 308). This rod (202; 308) cooperates with a coil (208) arranged around the rod (202; 308).

Abstract: In a valve assembly exhibiting zero dead volume the port head is mounted on a solenoid and defines an inlet port on one side of the valve seat, and two outlet ports on the opposite side of the valve seat. A flexible diaphragm is seated across the valve seat between the port head and the solenoid, and is sealed along its peripheral edge. A spring-biased valve rod is coupled to the opposite side of the diaphragm relative to the valve seat, and the solenoid is actuated to move the valve rod and diaphragm between open and closed positions. The valve assembly is opened by actuating the solenoid to drive the valve rod and diaphragm away from the valve seat and permit the passage of fluid across the valve seat between the inlet and outlet ports.

Abstract: A pump for the hot chamber die casting of corrosive light alloys including a body (2) wherein a cavity (3) is formed in which a piston (4) vertically reciprocates and on whose side wall (5) an opening (11) for the introduction of the molten alloy (1) and the mouth of a sprue (9) for the connection with the mold (10) are formed. The diameter of the piston (4) is smaller than that of the cavity (3) so that it may move without rubbing on the wall (5) as it is guided by a seal packing (6) detachably constrained to the mouth of the cavity (3), the opening (11) being closed during the compression of the alloy in the cavity (3) by a valve (12) controlled from outside through a lever (13).

Abstract: The pump comprises a cylinder delimiting a pumping chamber in which a piston is mounted to slide between an admission orifice and a delivery orifice, the piston including a pumping orifice which is associated with a closure member mounted to pivot about an axis adjacent to the pumping orifice and including a closure face that is substantially plane and that faces the piston.

Abstract: An ambulatory parenteral fluid infusion pump employs a disposable in-line cassette which provides three independent fluid paths between two flexible plastic sheets. The fluid path extends through a pump chamber having a piston plate secured to the flexible sheet at each pumping chamber. The sealed flexible sheets are housed in a rigid housing which provides an aperture through which a catch member formed on the piston plate extends, and having living hinges overlying the inlet and outlet paths for shutting off those paths. An outlet valve is normally closed, and operates in response to buildup of fluid pressure from advancement of the piston plate into the pump chamber to deliver fluid.

Abstract: An encasement is provided for improving the acoustic characteristics of fluid pumps. The encasement is substantially formed from a material selected from the group consisting of glasses, ceramics, thermoplastic resins and thermosetting resins. Further, the encasement forms a chamber open to one side for receiving and containing a fluid pump. The open side of the encasement includes a lip for mating with a base. The encasement is designed in modular fashion for relatively quick assembly and disassembly.

Abstract: A mechanical drive system for use in driving a disposable cassette containing a reciprocating fluid pump and active valves from a main pump unit is disclosed which utilizes a single power module cam to drive both the reciprocating pump and the valves. By using a unitary power module cam, the system completely eliminates the possibility of a timing error between the operation of the reciprocating pump and the valves. A one-way clutch is used to prevent the system from slipping into a reverse operation, and the operation of the valve actuators prevents the possibility of free flow through a cassette installed onto the main pump unit.

Abstract: A machine for dispensing liquids, especially for filling cartons at a higher rate of speed, is disclosed. The machine includes three bellows arranged in vertical alignment, with upper and lower sleeves interposed between the bellows. The discharge nozzle is located below the lowest bellows. The upper sleeve moves axially relative to the nozzle to control the opening and closing of the discharge valve. The lower sleeve also moves axially to control the filling and recharging of the bellows directly above the discharge nozzle. The method of operating the components in timed relation to achieve effective and efficient carton filling, as well as draining and cleaning, is disclosed.

Abstract: A driver for use in an infusion pumping cassette having an elongated valve actuator which operates a valve controlling the flow of fluid through the cassette, a bracket having a first arm pivotally secured to one end of the valve actuator and a second arm, a cam driveably engaging the second arm, a motor which drives the cam and a positioner which monitors the rotational position of the cam.

Abstract: The liquid pressure capacity of a chemical injector pump is increased substantially by using high pressure gas to drive the gas motor. In one embodiment, the chemical injector pump includes a liquid pump end, a gas motor end, a low pressure position responsive valve, and a high pressure pilot operated valve manipulated by the low pressure valve for delivering high pressure gas to the gas motor. In other embodiments, the chemical injector pump includes a liquid pump end, a gas motor end, and a high pressure position responsive valve for directly delivering high pressure gas to the gas motor.

Abstract: The hydraulic tool of this invention includes a pressure chamber into which a fluid is pumped. A pump chamber has an inlet port and outlet port at opposite ends thereof and a pump plunger extends into the chamber with an annular space around it. An annular shoulder is provided on either the chamber or the plunger and a seal ring or sleeve fits slidably on the other component to seal against the shoulder. A spring biases the seal ring against the shoulder, and when the pump is extended to force fluid out the outlet port, the pressure in the chamber augments the spring force. Then, when the rod is retracted to create a void, fluid in the reservoir forces the seal ring or sleeve away from the seat surface to enter the inlet port.

Abstract: A piston proportioning pump for liquids, with a piston in a cylinder, an uptake and discharge valve and an oscillating drive is improved so that the formation of vapor bubbles or of a low pressure during the suction phase is prevented even when the pump space is filled quickly. The dead space of the piston proportioning pump still remains so small that a largely complete expulsion of the proportioned amount through the discharge valve is guaranteed. To this end, provisions are made so that the discharge communicates with the pump space within an uptake valve.

Abstract: A fluid dispensing apparatus is provided especially designed to minimize the amount of fluid retained in the apparatus during a pumping cycle. The apparatus includes a pair of concentrically aligned inner and outer tubular sleeves shiftable relative to each other for alignment of their respective inlet ports. A piston is received within the inner sleeve, and a nozzle member is axially aligned with and receivable in the inner sleeve.

Abstract: A hydraulic pump comprising at least a reciprocating piston, each piston being associated with one suction valve returned to its closing position by a return spring. The return spring is associated on the one hand with the valve and on the other hand with a push-piece cyclically actuated by a cam driven by the pump driving shaft in such manner that the action of the spring on the suction valve is cancelled during the suction phase and reestablished at the end of the suction phase.

Abstract: A positive displacement machine, particularly an internal combustion engine, comprises an oscillating piston connected to a piston pump. The cylinder of the pump is connected through valves to a pressure accumulator and to a substantially pressureless tank. The piston of the motor is integral with the piston of a pump. The valves of the pump are positively actuated by a separate motor.

Abstract: A metering and/or feeding unit for fluid materials, particularly dry particulate materials and semifluid materials, is disclosed. An elastic-walled tube having an open feed end and an open discharge end is vertically oriented. A power-driven assembly, including tube rollers, are adapted to constrict the elastic tube, beginning at its upper end and progressively moving down the length of the tube. The material being metered or fed is introduced into the elastic tube at its upper end and is progressively moved down the length of the tube as the tube roller of the power-driven assembly moves down the length of the tube. A valve is provided to prevent entry of material into the feed end of the tube at periodic intervals and in coordination with constriction of the tube so that when a tube roller initially engages the tube near the feed end of the tube, that portion of the tube is substantially free of material.

Abstract: A hydraulic pump having spring loaded valves utilizes a spring providing a constant spring force and a spring providing a varying spring force. The varying spring force depending upon the position of the pump piston. The pump suction valve opens after a variable delay relative to the beginning of the piston suction phase when the pressure prevailing in the pump's dead chamber falls below a predetermined value. Abrupt decompression to the dead chamber is therefore avoided resulting in reduced energy consumption and noise level.

Abstract: A fluid processing apparatus for use in conjunction with a disposable fluid processing module of the type which includes an integral housing wherein fluid containers, tubing segments, and other components required in processing a fluid are contained, and wherein fluid communication between the containers, components and tubing segments is provided by a fluid circuit formed by a panel of the housing, and an overlying fluid-impermeable flexible sheet member. The processing apparatus includes an actuator station for receiving the module housing, and pneumatic actuator ports which apply pressures to pump and valve elements in the fluid circuit to circulate fluid through the system.

Abstract: A liquid medication infusion device includes a number of elongate fingers each displaceable in a predetermined sequence by associated cams driven by drive means such as a motor. A feeding tube for liquid medication, when placed between said fingers and a cap, is squeezed by the fingers to infuse liquid medication into a human body. The fingers comprise at least three fingers arranged parallel to one another with a central finger and side fingers arranged on either side of the central finger. The central and side fingers are formed integrally with a support member and are each carried at first ends by the support member in cantilevered fashion. The side fingers are shaped for squeezing the feeding tube at corresponding substantially point locations on the tube to completely collapse the tube, and the central finger is shaped for squeezing the feeding tube over a required length between the point locations for pumping the medication in the tube.

Abstract: A fluid processing apparatus for use in conjunction with a prepackaged disposable fluid processing module of the type which includes an integral housing wherein fluid containers, tubing segments, and other components required in processing a fluid are contained, and wherein fluid communication between the containers, components and tubing segments is provided by a fluid circuit formed within the housing by a first relatively inflexible fluid-impervious sheet member and a second relatively flexible fluid-impermeable sheet member. The fluid circuit includes pump and valve elements which operate in response to pressures applied to the second sheet member. Upon installation of the system in the processing apparatus pneumatic actuator ports apply pressures to the second sheet member through access apertures in the housing to circulate fluid through the fluid circuit.

Abstract: A fuel injection pumping apparatus for supplying fuel to an internal combustion engine comprises a reciprocable plunger, a roller forming part of a tappet assembly and a cam for actuating the roller and plunger. The cam is formed on the outer peripheral surface of a cup-shaped member, which is supported about a spigot. A drive shaft is integral with the cup-shaped part.

Abstract: A device for precise metering of liquids for intravenous delivery to a patient, the device including a pumping chamber with a reciprocable diaphragm positioned therein. The device also includes valves positioned at the pumping chamber inlet and outlet, the valve at the pumping chamber inlet being operated independently of the pressure within the pumping chamber. The device also includes a gas retention chamber having an upper portion providing for the formation of the gas-liquid interface and a lower portion from which liquid free of gas bubbles may be removed.

Abstract: A small, accurate, reliable and economical pump which is particularly useful in intravenous (IV) feeding includes a disposable pump chamber and a pump housing. The disposable pump chamber has an inlet, an outlet, and first and second flexible rolling diaphragm pumping chambers. First and second cylinders in the pump housing are positioned to receive the first and second flexible rolling diaphragms of the disposable pump chamber. First and second pistons are movable in the first and second cylinders, respectively. In addition, first and second valves are provided in the pump housing. The first valve controls fluid flow between the inlet and the first flexible rolling diaphragm pump chamber, while the second valve controls fluid flow between the first flexible rolling diaphragm pumping chamber and the second flexible rolling diaphragm pumping chamber. A motor and cam shaft drive the first and second pistons and the first and second valves.

Abstract: Portable hydraulically operating lifting apparatus including a wheel mounted chassis, a mounting base supported on the chassis and defining first and second pivot mounting locations and a cylinder pivot mounting location, the cylinder pivot mounting location being below the first and second pivot mounting locations, a raisable element defining a planar supporting surface, first and second support elements pivotably coupled to the first and second pivot mounting locations respectively and to the raisable element, a hydraulically operated cylinder pivotably coupled to the cylinder pivot mounting location and to the raisable element and apparatus for providing a pressurized flow of hydraulic fluid to the cylinder. The apparatus is constructed for maintaining the raisable element substantially horizontal throughout its range of dispositions and for maintaining the hydraulic pressure in the cylinder substantially constant throughout the range of dispositions.