Abstract: A radial piston pump includes a plurality of radially arranged cylinder-pger assemblies having suction valves and pressure-regulating valves, with the plungers being controlled by an eccentric disk which eccentrically circulates relative to a housing accommodating the cylinders. In order to provide a radial piston pump of this type with a simple design and to allow a digital operation of the pump for controlling the flow rate, the space between the end faces (12) of the cylinders (9) and the pertaining plungers (7) is connectable with a pressure manifold (19) of the pump by a randomly controllable valve (21, 22), with the plungers (9) of the pump preferably having different diameters.

Abstract: An assembly is disclosed for supplying compressed air to both an engine and an air suspension of a motor vehicle. The assembly comprises a direct current electric motor, a centrifugal air pump, and a piston pump. The motor has a shaft extending outwardly from opposite sides of the motor, with the centrifugal pump being driven by one end of the shaft and the piston pump being driven by the other end of the shaft. The centrifugal pump produces high volumes of air at low pressure required by the engine, while the piston pump produces low volumes of air at high pressure required by the air suspension. Bypass valves are provided to selectively divert the air provided by the pumps to the atmosphere.

Abstract: A pump system is disclosed which operates at high efficency in either a high volume, low pressure mode or a low volume, high pressure mode. First and second internal gear pumps are driven by a common drive shaft. The first pump has a smaller displacment than the second pump and both pumps deliver pressurized fluid to a common discharge passage. An unloading valve is operative to dump the output of the second pump in response to fluid pressure in the discharge passage so that it delivers fluid to the load device only when the pressure is below a predetermined value. The unloading valve also performs the function of a low capacity accumulator. A check valve is provided to prevent back flow in the outlet of the second pump.

Abstract: A constructionally simplified hydraulic pump has two pump elements which discharge from a common suction chamber. The flows can be alternatively fed in common to a pressure outlet or separately to two outlets, one of which outlets leads back into the suction chamber. The pressure-side chambers for the separated flows can be connected, via a unidirectional valve, through which, in the open state, the flow of one pump element can be united with that of the second pump element. The different flow guide modes are switched via control valves whose position depends only on the pressure prevailing at the pressure outlet of the hydraulic pump. The control valves to be switched are a common component of a single control slide valve.

Abstract: The first of two serially arranged electromagnetically operated spool type drain control valves is conditioned to select the drain passage of smaller the pump before the second valve is moved from its closed or communication cut-off position, to its open position wherein hydraulic fluid can be drained therethrough, whereby the spool of the second valve is exposed to a relatively small flow generated force which acts thereon and which tends to move the valve spool toward to its closed position. In another embodiment the hydraulic fluid temperature is monitored and used to modify the control schedule via which the switching of the drain control valves is determined. A further embodiment monitors a parameter which is indicative of the prime mover rotational speed and inhibits the closure of the second of the two valves when the rotational speed is above a predetermined limit.

Abstract: Apparatus for preventing damage to a machine in the event the machine inadvertently goes into reverse rotation. An automatically actuated flow controller is adapted to reroute the flow of lubricant to the primary pump when the machine rotates in a reverse direction thereby assuring that lubricant is supplied to the machine bearings, and the like, to prevent the machine from being damaged. The mechanism also has the ability to deliver a metered amount of lubricant to the main pump from an auxiliary pump to prime the main pump when the main pump is shut down thus allowing the main pump to be quickly brought on-line.

Abstract: In the present fluid system, a variable pressure inlet system is provided and operational to control the operating pressure level of a charge pump in response to various operating parameters of the fluid system. The charge pump provides pressurized fluid to an inlet of a hydraulic pump to insure filling of the pumping chambers therein. By having the operating pressure level of a variable pressure relief valve that is connected to the charge pump controlled between a minimum pressure level and a maximum pressure level responsive to various operating perimeters of the system, the degree of horsepower needed to drive the charge pump is controlled.

Abstract: A loading machine equipped with a first and a second pump for supplying hydraulic oil to at least one hydraulic operated working component, such as a hydraulic piston-cylinder device or a hydraulic motor having a varying oil-pressure and flow requirement, wherein the pumps can be connected together for mutual coaction, when necessary. The second, larger pump is a fixed displacement pump. The first pump is provided with a pump regulator which is influenced by the load pressure prevailing in the hydraulic system and is intended to influence the first pump in a manner to maintain between the outlet of the pump and the load pressure on the pump regulator a pressure difference determined by the pump regulator, wherein the first pump is connected to the working component via a variable restriction. A control device is operative to connect the second and larger pump to the system solely when there is a need for a smooth increase in flow which cannot be achieved solely by the first pump.

Abstract: A fuel pump having a first pumping mechanism for pumping a fuel in a main tank to a subtank and having a second pumping mechanism for pumping the fuel in the subtank to an outside of the main tank. The fuel pump includes a rotatable impeller having a plurality of outer peripheral vanes, and a wall member surrounding the vanes so as to define a fuel flow passage. The wall member has two partition walls for partitioning the fuel flow passage into a first pumping passage and a second pumping passage, a first suction hole for communicating an upstream end of the first pumping passage to the main tank, a first discharge hole for communicating a downstream end of the first pumping passage to the subtank, a second suction hole for communicating an upstream end of the second pumping passage to the subtank, and a second discharge hole for communicating a downstream end of the second pumping passage out of the main tank.

Abstract: An oil pump includes a pair of pump cartridges, one of which can be unloaded. Oil which is discharged from one of the pump cartridges is supplied to an accumulator through a supply passage in which an orifice is provided. The orifice is opened and closed in response to a pressure which prevails in the accumulator. A spool is operated upon by a pressure differential across the orifice to return the discharged oil to the suction side of the pump. A clearance is formed between the outer surface of the spool and the inner surface of the valve opening in which the spool is fitted, permitting the oil in a chamber into which a pressure prevailing downstream of the orifice is introduced to be returned to the return path.

Abstract: An air-hydraulic pump incorporates a primary pumping mechanism for supplying a first level of fluid pressure to a work-performing tool at a first flow rate in response to a supply of pressurized air. An auxiliary pumping mechanism is provided for delivering a second level of hydraulic fluid pressure less than the first level at a flow rate greater than the first flow rate. The auxiliary pumping mechanism provides sufficient pressure to overcome a load on the system up to a predetermined level, after which the auxiliary pumping mechanism ceases operation due to such load and the primary pumping mechanism delivers fluid pressure to the system sufficient to overcome the load. The auxiliary pumping mechanism speeds up operation of the work-performing tool for providing time-saving operation thereof.

Abstract: A power aggregate comprising a two-stroke engine, a piston rigidly linked together by means of a piston rod, a plurality of pump cylinders circumferentially mounted around the piston rod and a corresponding number of pump pistons fixed to the piston rod through the intermediary of radial rods or a flange, for reciprocation within the pump cylinders. Each pump cylinder is provided with hydraulic fluid intake and pressure ducts, and at least two of the pump cylinders have different diameters. The hydraulic duct of one or several pump cylinders operates its own hydraulic motor or actuator cylinder.

Abstract: An hydraulic power generating pack 1 comprises a primary pump 23 of the multi-cylinder, reciprocating ram type with a reciprocable piston 27 located in each cylinder 28 and displaceable by a crank shaft 20 rotatable by a prime mover 2 to provide a primary hydraulic fluid output 32 at a predetermined constant pressure and constant volume, and a power take off 14 to drive a secondary pump 36 of the pressure compensated variable delivery type, the output 40 of which drives a pressure intensifier 42 serving to intensify, to the required secondary pressure and volume, hydraulic fluid supplied to the intensifier 42 at a first pressure and volume.

Abstract: In a compressor having a plurality of banks of cylinders, smaller steps of unloading are achieved by unloading a single cylinder in a bank. When only one cylinder is to be unloaded, gas bypass is used in order to maintain a closer balance of forces in the bank. When the entire bank is unloaded, it is preferably done via the suction cutoff method.

Abstract: A pump system is disclosed which operates at high efficency in either a high volume, low pressure mode or a low volume, high pressure mode. First and second internal gear pumps are driven by a common drive shaft. The first pump has a smaller displacement than the second pump and both pumps deliver pressurized fluid to a common discharge passage. An unloading valve is operative to dump the output of the second pump in response to fluid pressure in the discharge passage so that it delivers fluid to the load device only when the pressure is below a predetermined value. The unloading valve also performs the function of a pressure relief valve. A check valve is provided to prevent back flow in the outlet of the second pump.

Abstract: A plurality of unloading steps for a compressor are achieved by providing the compressor with at least two cylinders having different displacements. By unloading different cylinders, the compressor output is better able to match system demand.

Abstract: A pump system is disclosed for delivering hydraulic fluid to a load device, such as a hydraulic brake system. The system automatically switches from larger displacement to smaller displacement as pressure at the outlet increases. The pump system comprises one or more lower pressure pumps and a high pressure pump with an actuator driving all pumps simultaneously. An unloading valve is coupled with each lower pressure pump for dumping the output thereof in response to pressure of the fluid delivered to the load device. The actuator comprises an electromagnetic linear motor which imparts an intake stroke to the pumps and stresses a spring which releases stored energy for imparting the pressure stroke to the pumps.

Abstract: A hydraulic power pack for supplying hydraulic fluid under pressure for operating apparatus such as hydraulic workover units used in servicing oil and gas wells. The power pack provides substantially constant hydraulic power input to the driven apparatus over a wide range of pressures and flow rates. The power pack includes a constant speed engine, a gear box driven by the engine, a bank of positive fixed displacement pumps of varying sizes driven by the gear box and having discharge ports connected with a common discharge manifold, a hydraulic fluid reservoir, an intake manifold between the reservoir and the pumps, a return line to the reservoir, a recirculating line connected between the discharge from each of the pumps and the return line, and an unloading valve in each of the recirculating lines operable responsive to the pressure in the discharge manifold for recirculating each of the pumps to the reservoir at a predetermined pressure value.

Abstract: In a fluid pumping system in which a fluid is pumped from a fluid supply to a load, two continuously driven fixed displacement pumps are operated in parallel to provide the pumping action. The two pumps are arranged with a common inlet, and with a common outlet, the flow delivered to the load from one of the two pumps passing through a check valve upstream of the common outlet. The fluid flow is regulated to provide a constant pressure by sequentially bypassing fluid around each pump through separate pump bypass ducts. This sequential fluid bypassing or pump unloading is effected by a single control responsive to the flow requirements of the load necessary to maintain that constant pressure. The pump whose delivered flow outlet contains the check valve is the pump whose flow is bypassed initially when less than full pumping capacity is desired. During maximum flow demand operation, both pumps are delivering against full delivery pressure.

Abstract: A vane-type double lobe hydraulic pump having a casing with a rotor having a plurality of slots with each slot mounting a vane for tracking of a surrounding cam ring and porting for pumping from both undervane and intervane pumping chambers. The cam ring has two generally elliptical sections of different contour whereby the volumes of fluid pumped by the vanes in coacting with one of said sections differ from the pumped volumes of the vanes when coacting with the other section. In one embodiment, there are four independent volume outputs while, in other embodiments, valve elements control the output of the pump whereby it may be the total of the pumped fluid or lesser amounts including only the volume pumped by the vanes in coacting with one of said cam ring sections or only part thereof.

Abstract: A multiple displacement pump system utilizing a single fixed displacement pump having pumping elements providing both first and second sets of pumping chambers. Circuit means having a fluid utilization conduit provides for delivery of fluid to said fluid utilization conduit which is either the sum of fluid delivered from both sets of pumping chambers or from only one set of pumping chambers. Additionally, the circuit means includes various alternate forms of control dependent upon pressure in a part of the system or on speed of a mechanism utilizing the pumped fluid to establish conditions wherein fluid delivered by the system is at either a desired flow rate or within a range of flow rates at different pressures.

Abstract: A hydraulic pump arrangement and control circuit for supplying fluid at high volume and a high pressure to a work circuit. The system utilizes a fixed displacement pump, a variable displacement pump, a dual pressure compensator, and an unloading valve working together to provide high pressure fluid delivery while reducing the horsepower requirements of the fixed displacement pump and the variable displacement pump. High flow is provided through the utilization of the combined pumps and high pressure is attained through the unloading of the fixed displacement pump through the unloading valve and destroking of the variable displacement pump in response to signals provided by the dual pressure compensator.

Abstract: A high pressure positive displacement gradient pump for two flowable materials utilizing two reciprocating pistons with the pair of pistons pumping in an overlapping reasonably pulse free manner. The gradient of the two flowable materials is created by adjustment of the stroke of each piston. Streams for the pair of pistons are combined and mixed in a mixing chamber. A third pair of pistons may deliver the mixed stream at high pressure to the desired location.

Abstract: A multiple displacement pump system and method utilizing a single fixed displacement pump having pumping elements providing both first and second sets of pumping chambers. Circuit means having a fluid utilization conduit provides for delivery of fluid to said fluid utilization conduit which is either the sum of fluid delivered from both sets of pumping chambers or from only one set of pumping chambers. Additionally, the circuit means includes various alternate forms of control dependent upon pressure in a part of the system or on speed of a mechanism utilizing the pumped fluid to establish conditions wherein fluid delivered by the system is at either a desired flow rate or within a range of flow rates at different pressures.