Abstract: An apparatus and method for pressure processing a pumpable substance, such as a pumpable food product or slurry. In one embodiment, the apparatus includes a pressure vessel having an inlet valve toward one end and outlet valve toward the other end. A flexible bladder is coupled between the inlet and outlet valves for receiving the pumpable substance. The pressure vessel can further include a high-pressure inlet port for receiving high-pressure fluid that biases the membrane inwardly to pressure process the pumpable substance. The pumpable substance is then removed from the vessel through the outlet valve.

Abstract: A drywall taping and texture system for pumping drywall mastic material from a container filled with the drywall mastic material to a work surface includes a pump housing, an air compressor, a tool for applying the drywall mastic material to the work surface, material and control lines, an inflatable bladder, an air release mechanism, and an airway. The pump housing is immersed in the container filled with the drywall mastic material, and the air compressor is connected to the pump housing. The material and control lines are connected between the pump housing and the tool such that there is material and air flow communication, respectively, therebetween. The bladder is mounted within the pump housing between upper and lower valves for controlling the flow of the drywall mastic material. The airway connects the air compressor, the control line, the bladder, and the air release mechanism, such that there is air flow communication therebetween.

Abstract: A flexible actuator assembly (20) including a flexible bladder device (22) having an expandable sealed chamber (23) adapted to substantially directionally displace between a deflated condition and an inflated condition, displacing a proximal portion (25) of the bladder device (22) away from a distal portion (26) thereof. An elongated tendon member (27) includes a distal portion (28) oriented outside the chamber (23), while an anchor portion (30) extends into the chamber (23) through a distal opening (31) in the bladder device (22).

Abstract: In a worm-like operating mechanism including hydraulic or pneumatic actuators arranged around a central axis, the actuators include serially arranged bags disposed in communication with one another and folded meander-like and having fluid passages for supplying fluid under pressure to, or evacuating, the actuators individually, so that the operating mechanism can be lengthened or shortened or bent in any direction.

Abstract: A system for deforming or actuating an elastomeric structure is described. he system includes a plurality of tubes joined to the elastomeric structure. The tubes extend in the direction of a desired strain to be applied to the elastomeric structure and are constrained from circumferential expansion. When a pressurized fluid is applied to the tubes, the tubes deform causing a like deformation of the elastomeric structure.

Abstract: A flexible actuator assembly (20) including a flexible bladder device (22) having an expandable sealed chamber (23) adapted to substantially directionally displace between a deflated condition and an inflated condition, displacing a proximal portion (25) of the bladder device (22) away from a distal portion (26) thereof. An elongated tendon member (27) includes a distal portion (28) oriented outside the chamber (23), while an anchor portion (30) extends into the chamber (23) through a distal opening (31) in the bladder device (22).

Abstract: A positive displacement pump includes a deformable hollow member for delivering a subject liquid by a cycle of contraction and restoration of its volume, a casing which contains the hollow member, and a pressurizing device for supplying and evacuating a hydraulic liquid in an annular space between the casing and the hollow member. The supplying of hydraulic fluid causes the contraction of the hollow member, and the evacuating of the hydraulic fluid causes the restoration (expansion) of the hollow member. A guide structure contacts and deforms the outer circumferential portions of the hollow member as the hollow member continues to expand to determine an initial contraction position of the hollow member. That is, a particular direction of contraction of the hollow member is set by the guide structure. Drive means periodically vary the circumferential position of the guide means relative to the hollow member to vary the initial contraction position of the hollow member.

Abstract: An actuator for converting fluid energy into a mechanical force comprises an inner expansion chamber and an outer power transmission envelope which surrounds the expansion chamber and comprises a flexible but non-stretchable endless filament or multifilament which is redirected with a back-and-forth motion between two tie rod members for surrounding the expansion chamber with multiple layers, the two tie rod members being connected with the two axial ends of the inner expansion chamber. By admitting a fluid into the expansion chamber for obtaining its radially outward directed expansion the two tie rod members will be approached with respect to each other by means of the power transmission envelope to thereby produce axially directed tension forces.

Abstract: A gas transfer system is provided for establishing or maintaining a predetermined gas pressure within a plenum, such as a tire. In an exemplary embodiment, the gas transfer system includes a power source, a pressure sensor, a control unit, and a gas transfer mechanism. Preferably, a gas transfer mechanism includes a micromechanical device, comprising one or more pumping units that transfer gas from one pressure zone to another. In one embodiment, pumping is accomplished, in part, by heating the gas within a sealable chamber of a pumping unit to cause the pressure of the gas to increase. In another embodiment, the change in pressure of the gas caused by compression of a tire provides a pumping force. Valves are provided for regulating movement of the gas through the gas transfer mechanism and can include electromechanical valves responsive to signals from the control unit, or passively biased valves responsive to applied gas pressure.

Abstract: A system for characterizing contamination or integrity information from within a pipe, including a flexible tubular membrane which is extendable within the pipe and inflatable to a diameter effective to urge the tubular membrane against the rigid wall. The tubular membrane has a first end and a second end, and is initially rolled up and connected to a reel inside of a deployment system. A tether connects the deployment system to a characterization tool retained within the tubular membrane, which is attached adjacent to the second end of the tubular membrane. When the system is engaged, pressurized fluid enters the tubular membrane causing the membrane to invert and distend into and through the pipe's interior.

Abstract: A hose piston is disposed inside a flexible hose which is filled with fluid and movable in any direction upon hydraulic pressure. The rollers of an external device are engaged on the exterior surface of the flexible hose and are located adjacent to the midsection of the hose piston. The fluid pressure inside the flexible hose forces the hose piston to move along a given direction within the flexible hose, which in turn forces the rollers to travel in the same direction. This mechanism can transport the external device along the flexible hose.

Abstract: The invention provides a vibrator which may be used to vibrate industrial apparatus such as a conveyor, hopper, bin, screen, shaker table, or to agitate a fluid. The vibrator has a element comprising a concave outer skin on one side and a convex outer skin on the other side which define between them a cavity. The cavity is connected to a hydraulic driving circuit which provides a continuous series of high pressure pulses. Each pulse causes the deformable element to change shape. The continuous application of a series of pulses causes the deformable element to continuously vibrate. The high pressure pulses are generated by creating a water hammer within a conduit by means of a valve which can be rapidly opened and closed to allow fluid to flow through the conduit and then suddenly block the fluid flow. The vibrating apparatus may be used to shake industrial structures such as shaking screens, shaking tables, hoppers, bins or the like.

Abstract: The lifting apparatus employs a plurality of stacked annular discs, each of which is secured at the inner and outer periphery to an adjacent disc to define a hollow space. Circular discs are secured at the opposite ends of the stacked annular discs to enclose the hollow space. The lifting apparatus is collapsible from an extended elongated position to a collapsed position. A nipple is provided to permit the entry of compressed air into the hollow space when the lifting apparatus is in the elongated extended position to allow the hollow space to be radially expanded while being longitudinally contracted in order to effect lifting of an object secured to the lower end of the listing apparatus.

Abstract: A lift bag includes a plurality of independently inflatable chambers for controlling lifting of objects. Each chamber is defined by an upper surface sheet and a lower surface sheet, the upper surface sheet of one chamber positioned below an adjacent chamber being securely attached to the lower surface sheet of an adjacent chamber. The lift bag can be operated at pressures of about 15 psig at specified heights which allows greater flexibility compared to conventional, single-chambered lift bag which operate at pressures of about 7 psig. Preferably, all seams, reinforcements, and fittings are vulcanized in place using uncured rubber coated fabric. Grommets or other securing means may provide further stability to the lift bag.

Abstract: Each end of a lifting hose (10) is sealed pressure-tight by means of two clamping strips (12, 14) , one strip (12) having a row of projecting pegs (20) , and the other strip (14) having holes (30) in a corresponding arrangement. The pegs (20) have thickened heads (24), and the holes (30) are stepped, thus giving rise to annular supporting surfaces into which the heads (24) latch in the clamped position of the two flatly folded layers (40, 42) of the hose (10). FIG.

Abstract: A device for providing rotational movement. The device includes two body sections, each rotatably associated with respect to the other and two collapsible chambers having the configuration of a segment of a circle, the chambers being mounted such that the inflation of one causes the other chamber to collapse and the inflation of either chamber causing the body segments to rotate with respect to each other.

Abstract: A gas actuator (21) and a pop-up target (10) incorporating the gas actuator (21) are disclosed. The gas actuator (21) comprises support surfaces (24, 26), pivoting surfaces 5 (64,66) pivotably coupled upon the support surfaces (24, 26), respectively, and flexible and inflatable members (18, 20) disposed for pivoting the pivoting surfaces (64, 66) with respect to the support surfaces (24, 26) between a first and a second position. The members (18, 20) act over a relatively large area between the support surfaces (24, 26) and the pivoting surfaces (64, 66). The magnitude of the pivoting force produced by the members (18, 20) increases to a maximum and thereafter decreases as the pivoting surface (64) pivots upwards. An accumulator (104) allows for relatively low flow rates of as from a source of compressed as (102) and provides relatively high flow rates of compressed as to the members (18, 20).

Abstract: A pneumatic rotary drive includes a housing which is connectable to a pressure medium source and is closed in a pressure medium-tight manner by plane covers. A rotatable shaft extends out of the housing through at least one of the covers. A belt which is in engagement with the shaft is arranged within the housing so as to form moveable pressure chambers. At least one guide body arranged within the housing is surrounded by the belt. At least one of the guide bodies is provided with a spring element for resiliently adjusting the effective circumference of the at least one guide body.

Abstract: A split tube for use in a fluid friction assembly, such as a clutch or brake, includes a tube body with end caps disposed at each end. The end caps seal the ends of the tube, and further provide a device to connect the two end caps. This arrangement allows the tube to be placed about the shaft of a friction assembly, and then formed into a continuous ring. The ends of the tube are connected, and will not be flung radially outwardly at high rotational speeds.

Abstract: The present invention relates to an apparatus for handling a workpiece comprising a vessel that is longitudinally extensible and pressurizable, and a nonextensible and laterally flexible member on the vessel. The member constrains one side of the vessel to be nonextensible, causing the vessel to bend in the direction of the nonextensible member when pressurized.

Abstract: A robotic joint wherein an elongated support member attached at one end to a base has the other end thereof pivotally attached to one end of a lever, the other end of the lever extending away from the support member. A tension strip extends along the support member and over the other end of the lever, the ends of the tension strip being attached to the base on opposite sides of the support member. A pair of bladders positioned between the tension strip and the support member on opposite sides thereof can be inflated to apply a tensile force to the strip and cause the lever to pivot, carring with it a finger which is attached to the lever.

Abstract: A belt-driven rotary drive having a belt closed upon itself which is connected, within a pressure fluid-tight housing over roller-shaped bodies with the formation of movable pressure chambers, to a rotatable shaft which is extended out of the housing and the movable pressure chambers can be acted on by pressure fluid. In order further to develop a belt-driven rotary drive of this type in such a manner that the sealing action and the friction caused thereby can always be adjusted in simple manner from the outside, it is proposed that the closed belt (1) be adapted to be pressed on itself over a part of its length, with the formation of two pressure chambers which are pressure fluid-tight from each other, by a static pressing member which acts in the direction towards one of the roller-shaped bodies and that the pressing member be functionally connected for the adjustment of the pressing force with an adjusting device which is adjustable from the outside.

Abstract: An actuator includes an elastic member extensible in axial directions when a pressurized fluid is supplied into the elastic member, and guiding device arranged inwardly of the elastic member and permitting the elastic member to move in the axial directions, but restraining the elastic member from moving in directions intersecting the axial directions. As the actuator is of an air-bag type so that energy of the pressurized fluid can be converted into mechanical movement with high efficiency. The actuator moves only in radial directions without expanding in radial directions, so that a space occupied by the actuator in operation is little.

Abstract: A variable focus camera system for a borescope or endoscope has a camera or imager disposed within an imager sleeve and a braid and bladder assembly attached between the distal end of the imager sleeve and a lens assembly. A controlled pressure is applied through a pressure conduit into a confined volume defined by the imager sleeve, the braid and bladder assembly, and the lens assembly. The braid and bladder assembly expands axially but not radially, when pressure is applied, and changes the relative position of the imager and lens between a far focus and a near focus position.

Abstract: A bellows actuator has at least one bellows chamber comprising at least three chamber segments arranged around an axis. Each of the chamber segments forms a radially outwardly extending protrusion comprising four chamber wall portions, which merge with one another along fold lines which extend peripherally and radially of the bellows chamber and converge radially outwardly to meet at radially outermost apexes of the chamber segments. The bellows actuator is expansible and contractible along the axis by flexure of the wall portions relative to one another about the fold lines in response to pressure changes within the bellows chamber.

Abstract: A pneumatic actuator includes an elongate tubular body of a rubber-like elastic material, a braided reinforcing structure arranged on outer circumferential wall of the tubular body and composed of high tensile strength fibers oriented at a predetermined initial braiding angle with reference to longitudinal axis of the tubular body, and two closure members tightly closing the axial ends of the tubular body, respectively. At least one closure member has a connection hole for supplying pressurized fluid into a pressure chamber inside of the tubular body so that axial length of the actuator changes depending upon the initial braided angle of the reinforcing structure. Two hollow cylindrical fitting members are connected to the closure members and relatively slidably fitted with each other inside of the pressure chamber.

Abstract: An actuator includes an elastic member extensible in axial directions when a pressurized fluid is supplied into the elastic member, and guiding device arranged outwardly of the elastic member and permitting the elastic member to move in the axial directions, but restraining the elastic member from moving in directions intersecting the axial directions. As the actuator is of an air-bag type so that energy of the pressurized fluid can be converted into mechanical movement with high efficiency. The actuator moves only in axial directions without expanding in radial directions, so that the actuator takes up little space in operation.

Abstract: A gripping actuator comprises a plurality of flexible cylinders arranged adjacent to one another. The inside of each of the flexible cylinder is divided into a plurality of pressure chambers with partition walls that extend axially inside the flexible cylinder. The actuator has a pressure adjuster for adjusting pressures in the respective pressure chambers of the flexible cylinders so that the flexible cylinders may operate at individual degrees of freedom in achieving cooperative motions.

Abstract: A low pressure air pump includes an outer flexible envelope which encloses an articulate frame. When the envelope is manually compressed against a smooth surface, an intake aperture on the bottom side of the envelope is sealed and air is forced out of the pump. When pressure is released from the pump, the frame returns the envelope to its uncompressed state and, in so doing, opens the intake aperture to take in more air.

Abstract: An air-seal, air-cell rotary-ring-type log debarker which is capable of operating in two different operating modes. In one operating mode, the air seal is nonpressurized, and debarking tools in the debarker are under the actuation control solely of pressure-isolated charged air cells which are carried on the rotary ring in the debarker. In another operating mode, the seal between the rotor and stator is pressurized to allow fluid communication between the two, and tool actuation is under the combined control of the ring-carried air cells and of an external source of selectively variable fluid pressure.

Abstract: In a method for displacing forces, particularly loads (P), either a force (P) acting on a guide surface (23) is reduced by an opposing force and simultaneously displaced, or a pressing force (P) is caused to act on a guide surface (23) in order to produce a displacing force (P2). In order to reduce the frictional resistance of the force (P) on the base (A, B) on which it acts, this force can be reduced by an opposing force and the force then displaced. The opposing force is produced, for example, by a known self-guided membrane cell (20) or a piston. Part of the force is supported displaceably on a wedge surface (23). This method permits advantageous displacement of forces, particularly loads, in opposition to friction forces.

Abstract: All-elastomer fluid-pressure-actuatable twistors have an elongated tubular wall of resilient elastomeric material extending between first and second mounting ends spaced from each other along a twist axis extending longitudinally within the twistor. The tubular wall encircles its twist axis and surrounds an elongated interior chamber. Interior reinforcing webs of resilient elastomeric material are joined to the wall. These web-partitions extend longitudinally within the chamber, separating the chamber into longitudinally extending compartments. By applying torque or other preform means in a first sense to the first mounting end relative to the second mounting end, the tubular wall and interior webs become twisted in the same sense around the twist axis into a generally helically-twisted configuration.

Abstract: A bendable actuator includes a tubular body made of an elastic material, a reinforcing braided structure surrounding the tubular body, and closure members closing both open ends of the tubular body and the reinforcing braided structure, respectively. At least one closure member is formed with a connecting aperture communicating with an internal space of the tubular body. A restraining device is provided at least partially between the closure members for partially restraining extension of the actuator in the axial direction. When the tubular body is supplied with a pressurized fluid, the actuator is extended in the axial direction while being curved at the same time.

Abstract: A bendable actuator includes a plurality of elastic extensible members arranged in parallel and extensible in axial directions when a pressurized fluid is supplied into the elastic extensible members. The actuator further includes connecting members arranged in a manner embracing the elastic extensible members and connecting respective ends of the elastic extensible members. The actuator includes an elastic member arranged between the connecting members and surrounding the elastic extensible members to resist extending forces of the elastic extensible members and to restrain bending of the elastic extensible members. With this arrangement, linear extension and bending of the actuator are realized by adjusting supply and exhaust of the pressurized fluid into and from the elastic extensible members.

Abstract: Single or multiple flexible robotic manipulator trunks can be made from individually activated, three degree-of-freedom, flexible robotic links. Three dimensional positioning and orientation of the distal end of each link is achieved exclusively by elastic deformation of the flexible link assembly without revolute or prismatic joints. The activating bending and torsional moments required for such a positioning are generated by the antagonistic action of a plurality of prestressed, inflatable, laterally bendable and axially extensible tubular actuators with the anisotropic, circumferentially reinforced walls. The positioning motion, working forces and manipulator arm stiffness are all controlled by asynchronously modulated pulse streams which regulate the distribution of energy from a common source of fluid under constant pressure.

Abstract: A pneumatic driver is disclosed. The pneumatic driver includes a frame and a shaft movable between an extended driving position and a retracted position relative to the frame. A first inflatable air bladder is supported by the frame. The first inflatable air bladder is operatively connected to the shaft so that when the first air bladder is inflated, the shaft is moved into an extended driving position. A second inflatable air bladder is supported by the frame and operatively connected to the shaft. When the second air bladder is inflated, the shaft is moved to a retracted position. A valve manifold operatively connects first and second air bladders for controlling inflation and deflation of the air bladders. The frame includes longitudinal guide rods and transverse frame members fixed to the guide rods. A shaft support member having the shaft mounted thereto is slidably mounted on the guiderods. Support rods are mounted to the shaft support member by bolts received in orifices to provide a clearance fit.

Abstract: The present invention discloses an engine primer bulb assembly having a base, a primer bulb and a retaining ring for securing the primer bulb to the base. The retaining ring is self-locking and provides a circumferential force against the bulb to seal it with the base to provide a primer chamber.

Abstract: A double-acting actuator includes a first tubular body made of an elastic material, a first reinforcing braided structure surrounding the first tubular body, a second tubular body made of an elastic material surrounding the first reinforcing braided structure to form a space outwardly thereof, and a second reinforcing braided structure surrounding the second tubular body. The actuator further includes closure members for closing and joining ends of the first and second tubular bodies and reinforcing braided structures, and guiding device for permitting axial movements of the first and second tubular bodies but restraining lateral movements thereof. The first and second reinforcing braided structures are so constructed that initial braided angles thereof permit of the first braided structure elongating and permit of the second braided structure contracting when the pressurized fluid is supplied into the first and second tubular bodies.

Abstract: A pneumatic stepper motor weight actuator captures the advantages of polymeric harmonic gears while occupying less space and eliminating the problems associated with air entrapment in the stator grooves. Air entrapment is eliminated by providing orificed air passages from the bottom of the longitudinal stator grooves to the center stator hole. Advantageously, the actuator includes a rigid gear comprising a toothed polymeric sleeve adhesively bonded inside a metal cup.

Abstract: A pressure vessel contains a flexible separator comprising three layers, an outer layer, an inner layer and an intermediate layer which is at least partly impermeable to gases. The intermediate layer comprises a metal film. A particular application of the pressure vessel is to braking circuits.

Abstract: A fluid actuator including a pair of hingedly interconnected members between which is located a fluid expansible element such as a bellows which may be expanded upon application of fluid pressure to cause pivotal movement of the hingedly interconnected members. The actuator may also include a further pair of hingedly interconnected members which are themselves hinged to the first pair of members and which define with the first pair of members a space for receipt of the fluid expansible element.

Abstract: A hydraulically or pneumatically actuated muscle has an elongated elastomeric bladder that is covered by a tubular sheath. A fluid conduit is coupled to the bladder to supply hydraulic or pneumatic pressure. A coil tension spring is attached to a distal terminator of the muscle and extends to the distal end of a compression tube covering the bladder and braid. The evacuation spring draws the braid and bladder towards their fully extended state when fluid pressure is relieved and ellshaped retaining pin in the muscle terminator has one end that extends radially outward to lodge between turns of the evacuation spring. Split shoulder washers secure the proximal and distal ends of the compression tube.

Abstract: An electronically controlled actuator which compresses a fluid thereby storing potential energy as it transitions from a first to a second position is disclosed. The compressed fluid exerts a high force on the actuator and the potential energy is recovered in returning the actuator to the first position. A latching arrangement automatically locks the actuator shaft as it reaches the second position. The latching arrangement is selectively unlocked at the prescribed time to allow the stored potential energy to return the actuator to the first position.

Abstract: Fluid cell arrangement for compressed air radial motors, comprising a plurality of fluid cells arranged rosette-shaped to one another in a pressureless state and approximately plane for the alternate inflation of fluid cells, which are provided with air connector means and which are formed by welding two leaves of film or foil made of synthetic resin along the peripheries of the cells. In this connection, an endless elastic rubber cord or ring inserted between the two film leaves extends along the peripheries of the cells and is disposed in radial arrangement near the center of rotation, the two film leaves made of synthetic resin being disposed on both sides of the ring and completely enclosing the latter are welded together.

Abstract: A hydraulically or pneumatically actuated fluid-dynamic motor has an elongated elastomeric bladder, a braid disposed over the bladder, and a flexible but substantially incompressible spine disposed between the braid and the bladder. The muscle or motor is configured in a helix with the spine arranged on the inside of the helix. Application of fluid under pressure to the bladder causes one end of the helical motor to untwist or rotate relative to the other end. Upon deflation of the bladder, the spine causes the bladder to deflate and rotate the other end in the opposite direction. This fluid dynamic motor provides an azimuthal motion that can be employed for the steering section of an elongated flexible probe, such as a borescope or endoscope.

Abstract: A hydraulic or pneumatically actuated muscle has an elongated elastomeric tubular bladder covered by a tubular braid. A fluid conduit supplies hydraulic or pneumatic pressure to the bladder to expand it and thereby shorten the braid. When pressure is relieved, the braid is permitted to elongate, and the bladder constricts radially. To ensure that the bladder has its cross section at a minimum when elongated, the bladder has a fold or invagination along its length. The process for forming this bladder can employ a fixture in the form of a threaded rod.

Abstract: A tubular, fluid-controlled bending neck is provided for an elongated flexible probe, such as a video borescope. An elongated tubular elastomeric bladder is fitted to a proximal connector that fits onto a distal end of the probe insertion tube, and a distal fitting seals the distal end of the bladder. A tubular braid is disposed over the bladder to confine the same and is mechanically attached to the distal fitting and to the proximal connector. The connector provides communication of fluid presure from a controlled fluid pressure source to be interior of the bladder. An elastically bendable, by axially substantially incompressible spine is disposed at the interface between the bladder and the braid. This spine is preferably set or biased to be curved into one bending direction. As fluid pressure is applied to the bladder, the bladder inflates laterally. This shortens the braid on the side away from the spine, thereby bending the neck in the opposite direction.

Abstract: This invention comprises four hydraulic muscle pumps connected to four hydraulic dynamic muscles in hermetically sealed pairs to transfer tensive forces from a local to a remote location for use in actuating the articulation section of a borescope or endoscope.

Abstract: A terminator for a hydraulic or pneumatic muscle seals the end of the internal elastomeric bladder and provides direct transfer of force between the external braid and a mechanical device to which the terminator is connected. The terminator is provided with an annular land or step at the end that is inserted into the corresponding end of the muscle, a first valley or recess after the first annular land, a second annular land or step adjacent the first recess, a second annular valley or recess adjacent the second land and axially separated from the first recess, and an anchor or attachment portion beyond the second valley or recess which provides a point of attachment for the end of a cable or for a tubular sheath or the like. The bladder is attached to the first recess to form a fluid-tight seal, and the end of the braid continues over this and over the second land, and is attached to the second valley or recess. The attachments can be made using coils or wraps of fishline or equivalent.

Abstract: A fluid motor is disclosed that has a housing with a body portion formed as a hollow circular cylinder. A series of peristaltic tubes are disposed in the housing with one end of each tube leading from an inlet manifold on the housing and with the other end of the tubes open to the hollow interior of the housing. The tubes are disposed about the inner perimeter of the cylindrical body. A pair of rollers engage with each tube. The rollers for each tube are mounted on the ends of arms that extend in diametrically opposite directions from a motor shaft journaled in the housing. The rollers for each tube are angularly displaced with respect to the rollers for the other tubes about the axis of the motor shaft. Fluid under pressure entering the inlet will cause the rollers to advance along the length of the tubes and thereby rotate the motor shaft.