382:
from the pump and the motor, for increased cooling and filtering. The flush valve is normally integrated in the motor housing to get a cooling effect for the oil that is rotating in the motor housing itself. The losses in the motor housing from rotating effects and losses in the ball bearings can be considerable as motor speeds will reach 4000-5000 rev/min or even more at maximum vehicle speed. The leakage flow as well as the extra flush flow must be supplied by the charge pump. A large charge pump is thus very important if the transmission is designed for high pressures and high motor speeds. High oil temperature is usually a major problem when using hydrostatic transmissions at high vehicle speeds for longer periods, for instance when transporting the machine from one work place to the other. High oil temperatures for long periods will drastically reduce the lifetime of the transmission. To keep down the oil temperature, the system pressure during transport must be lowered, meaning that the minimum displacement for the motor must be limited to a reasonable value. Circuit pressure during transport around 200-250 bar is recommended.
386:
and operating conditions. The hydrostatic transmission is generally limited to around 200 kW maximum power, as the total cost gets too high at higher power compared to a hydrodynamic transmission. Large wheel loaders for instance and heavy machines are therefore usually equipped with converter transmissions. Recent technical achievements for the converter transmissions have improved the efficiency and developments in the software have also improved the characteristics, for example selectable gear shifting programs during operation and more gear steps, giving them characteristics close to the hydrostatic transmission.
361:
valve's open center; that is, when the control valve is centered, it provides an open return path to the tank and the fluid is not pumped to a high pressure. Otherwise, if the control valve is actuated it routes fluid to and from an actuator and tank. The fluid's pressure will rise to meet any resistance, since the pump has a constant output. If the pressure rises too high, fluid returns to the tank through a pressure relief valve. Multiple control valves may be stacked in series. This type of circuit can use inexpensive, constant displacement pumps.
417:. Pump pressure always equals the pressure setting for the pump regulator. This setting must cover the maximum required load pressure. Pump delivers flow according to required sum of flow to the consumers. The CP system generates large power losses if the machine works with large variations in load pressure and the average system pressure is much lower than the pressure setting for the pump regulator. CP is simple in design, and works like a pneumatic system. New hydraulic functions can easily be added and the system is quick in response.
682:
439:(LS) generate less power losses as the pump can reduce both flow and pressure to match the load requirements, but require more tuning than the CP system with respect to system stability. The LS system also requires additional logical valves and compensator valves in the directional valves, thus it is technically more complex and more expensive than the CP system. The LS system generates a constant power loss related to the regulating pressure drop for the pump regulator :
69:
45:
398:' that is used to temporarily increase the diesel engine rpm while reducing the vehicle speed in order to increase the available hydraulic power output for the working hydraulics at low speeds and increase the tractive effort. The function is similar to stalling a converter gearbox at high engine rpm. The inch function affects the preset characteristics for the 'hydrostatic' gear ratio versus diesel engine rpm.
604:
57:
326:; that is, when the control valve is centered, it provides an open return path to the tank and the fluid is not pumped to high pressure. Otherwise, if the control valve is actuated it routes fluid to and from an actuator and tank. The fluid's pressure will rise to meet any resistance, since the pump has a constant output. If the pressure rises too high, fluid returns to the tank through a
929:
location is just before the return line enters the reservoir. This location is relatively insensitive to blockage and does not require a pressurized housing, but contaminants that enter the reservoir from external sources are not filtered until passing through the system at least once. Filters are used from 7 micron to 15 micron depends upon the viscosity grade of hydraulic oil.
902:, hydraulic fluid is the life of the hydraulic circuit. It is usually petroleum oil with various additives. Some hydraulic machines require fire resistant fluids, depending on their applications. In some factories where food is prepared, either an edible oil or water is used as a working fluid for health and safety reasons.
651:: many designed with a variable displacement mechanism, to vary output flow for automatic control of pressure. There are various axial piston pump designs, including swashplate (sometimes referred to as a valveplate pump) and checkball (sometimes referred to as a wobble plate pump). The most common is the
944:
different types of flanges (especially for the larger sizes and pressures), welding cones/nipples (with o-ring seal), several types of flare connection and by cut-rings. In larger sizes, hydraulic pipes are used. Direct joining of tubes by welding is not acceptable since the interior cannot be inspected.
886:
are a common part of hydraulic machinery. Their function is to store energy by using pressurized gas. One type is a tube with a floating piston. On the one side of the piston there is a charge of pressurized gas, and on the other side is the fluid. Bladders are used in other designs. Reservoirs store
339:
supply full pressure to the control valves, whether any valves are actuated or not. The pumps vary their flow rate, pumping very little hydraulic fluid until the operator actuates a valve. The valve's spool therefore doesn't need an open center return path to tank. Multiple valves can be connected in
219:
If a hydraulic rotary pump with the displacement 10 cc/rev is connected to a hydraulic rotary motor with 100 cc/rev, the shaft torque required to drive the pump is one-tenth of the torque then available at the motor shaft, but the shaft speed (rev/min) for the motor is also only one-tenth of the pump
999:
Components of a hydraulic system need connections that will contain and direct the hydraulic fluid without leaking or losing the pressure that makes them work. In some cases, the components can be made to bolt together with fluid paths built-in. In more cases, though, rigid tubing or flexible hoses
871:
The hydraulic fluid reservoir holds excess hydraulic fluid to accommodate volume changes from: cylinder extension and contraction, temperature driven expansion and contraction, and leaks. The reservoir is also designed to aid in separation of air from the fluid and also work as a heat accumulator to
708:
The spool has a central (neutral) position maintained with springs; in this position the supply fluid is blocked, or returned to tank. Sliding the spool to one side routes the hydraulic fluid to an actuator and provides a return path from the actuator to tank. When the spool is moved to the opposite
580:
System type (3) gives the advantage that activated functions are synchronized independent of pump flow capacity. The flow relation between two or more activated functions remains independent of load pressures, even if the pump reaches the maximum swivel angle. This feature is important for machines
527:
is around 2 MPa (290 psi). If the pump flow is high the extra loss can be considerable. The power loss also increases if the load pressures vary a lot. The cylinder areas, motor displacements and mechanical torque arms must be designed to match load pressure in order to bring down the power losses.
385:
Closed loop systems in mobile equipment are generally used for the transmission as an alternative to mechanical and hydrodynamic (converter) transmissions. The advantage is a stepless gear ratio (continuously variable speed/torque) and a more flexible control of the gear ratio depending on the load
975:
is graded by pressure, temperature, and fluid compatibility. Hoses are used when pipes or tubes can not be used, usually to provide flexibility for machine operation or maintenance. The hose is built up with rubber and steel layers. A rubber interior is surrounded by multiple layers of woven wire
360:
Pump-inlet and motor-return (via the directional valve) are connected to the hydraulic tank. The term loop applies to feedback; the more correct term is open versus closed "circuit". Open center circuits use pumps which supply a continuous flow. The flow is returned to the tank through the control
943:
are seamless steel precision pipes, specially manufactured for hydraulics. The tubes have standard sizes for different pressure ranges, with standard diameters up to 100 mm. The tubes are supplied by manufacturers in lengths of 6 m, cleaned, oiled and plugged. The tubes are interconnected by
833:
in complex hydraulic systems may have auxiliary valve blocks to handle various duties unseen to the operator, such as accumulator charging, cooling fan operation, air conditioning power, etc. They are usually custom valves designed for the particular machine, and may consist of a metal block with
381:
The pump cannot be utilized for any other hydraulic function in an easy way and cooling can be a problem due to limited exchange of oil flow. High power closed loop systems generally must have a 'flush-valve' assembled in the circuit in order to exchange much more flow than the basic leakage flow
158:
To supply large-scale power that was impractical for individual steam engines, central station hydraulic systems were developed. Hydraulic power was used to operate cranes and other machinery in
British ports and elsewhere in Europe. The largest hydraulic system was in London. Hydraulic power was
1003:
There are a number of standardized methods in use to attach the hose or tube to the component. Some are intended for ease of use and service, others are better for higher system pressures or control of leakage. The most common method, in general, is to provide in each component a female-threaded
755:
are used in several places in hydraulic machinery; on the return circuit to maintain a small amount of pressure for brakes, pilot lines, etc... On hydraulic cylinders, to prevent overloading and hydraulic line/seal rupture. On the hydraulic reservoir, to maintain a small positive pressure which
372:
Motor-return is connected directly to the pump-inlet. To keep up pressure on the low pressure side, the circuits have a charge pump (a small gear pump) that supplies cooled and filtered oil to the low pressure side. Closed-loop circuits are generally used for hydrostatic transmissions in mobile
928:
and possibly failure of the pump. Sometimes the filter is located between the pump and the control valves. This arrangement is more expensive, since the filter housing is pressurized, but eliminates cavitation problems and protects the control valve from pump failures. The third common filter
181:
A fundamental feature of hydraulic systems is the ability to apply force or torque multiplication in an easy way, independent of the distance between the input and output, without the need for mechanical gears or levers, either by altering the effective areas in two connected cylinders or the
770:
control the sequence of hydraulic circuits; to ensure that one hydraulic cylinder is fully extended before another starts its stroke, for example. Hydraulic circuits can perform a sequence of operations automatically, such as trip-and-reclose three times, then lockout, of an oil-interrupting
984:
Tubes and pipes for hydraulic n applications are internally oiled before the system is commissioned. Usually steel piping is painted outside. Where flare and other couplings are used, the paint is removed under the nut, and is a location where corrosion can begin. For this reason, in marine
818:
components with a standardized envelope, making them easy to populate a proprietary valve block. They are available in many configurations; on/off, proportional, pressure relief, etc. They generally screw into a valve block and are electrically controlled to provide logic and automated
976:
and rubber. The exterior is designed for abrasion resistance. The bend radius of hydraulic hose is carefully designed into the machine, since hose failures can be deadly, and violating the hose's minimum bend radius will cause failure. Hydraulic hoses generally have steel fittings
745:
directional control valves chosen by flow capacity and performance. Some valves are designed to be proportional (flow rate proportional to valve position), while others may be simply on-off. The control valve is one of the most expensive and sensitive parts of a hydraulic circuit.
345:
852:(a pump plumbed in reverse); hydraulic motors with axial configuration use swashplates for highly accurate control and also in 'no stop' continuous (360°) precision positioning mechanisms. These are frequently driven by several hydraulic pistons acting in sequence.
953:
is used in case standard hydraulic tubes are not available. Generally these are used for low pressure. They can be connected by threaded connections, but usually by welds. Because of the larger diameters the pipe can usually be inspected internally after welding.
585:
compensators have priority, for example the steering function for a wheel loader. The system type with down-stream compensators usually have a unique trademark depending on the manufacturer of the valves, for example "LSC" (Linde
Hydraulics), "LUDV"
1370:
801:
are one-way valve that can be opened (for both directions) by a foreign pressure signal. For instance if the load should not be held by the check valve anymore. Often the foreign pressure comes from the other pipe that is connected to the motor or
655:
pump. A variable-angle swashplate causes the pistons to reciprocate a greater or lesser distance per rotation, allowing output flow rate and pressure to be varied (greater displacement angle causes higher flow rate, lower pressure, and vice
980:
on the ends. The weakest part of the high pressure hose is the connection of the hose to the fitting. Another disadvantage of hoses is the shorter life of rubber which requires periodic replacement, usually at five to seven year intervals.
263:. Just as electric circuit theory works when elements are discrete and linear, hydraulic circuit theory works best when the elements (passive components such as pipes or transmission lines or active components such as power packs or
182:
effective displacement (cc/rev) between a pump and motor. In normal cases, hydraulic ratios are combined with a mechanical force or torque ratio for optimum machine designs such as boom movements and track drives for an excavator.
572:
Load sensing with synchronized, both electric controlled pump displacement and electric controlled valve flow area for faster response, increased stability and fewer system losses. This is a new type of LS-system, not yet fully
490:
427:. Same basic configuration as 'standard' CP system but the pump is unloaded to a low stand-by pressure when all valves are in neutral position. Not so fast response as standard CP but pump lifetime is prolonged.
1004:
port, on each hose or tube a female-threaded captive nut, and use a separate adapter fitting with matching male threads to connect the two. This is functional, economical to manufacture, and easy to service.
1367:
1000:
are used to direct the flow from one component to the next. Each component has entry and exit points for the fluid involved (called ports) sized according to how much fluid is expected to pass through it.
666:
Piston pumps are more expensive than gear or vane pumps, but provide longer life operating at higher pressure, with difficult fluids and longer continuous duty cycles. Piston pumps make up one half of a
618:
supply fluid to the components in the system. Pressure in the system develops in reaction to the load. Hence, a pump rated for 5,000 psi is capable of maintaining flow against a load of 5,000 psi.
581:
that often run with the pump at maximum swivel angle and with several activated functions that must be synchronized in speed, such as with excavators. With the type (4) system, the functions with
267:) are discrete and linear. This usually means that hydraulic circuit analysis works best for long, thin tubes with discrete pumps, as found in chemical process flow systems or microscale devices.
872:
cover losses in the system when peak power is used. Reservoirs can also help separate dirt and other particulate from the oil, as the particulate will generally settle to the bottom of the tank.
163:
steel production. Hydraulic power was also used for elevators, to operate canal locks and rotating sections of bridges. Some of these systems remained in use well into the twentieth century.
1033:
To allow proper orientation of components, a 90°, 45°, straight, or swivel fitting is chosen as needed. They are designed to be positioned in the correct orientation and then tightened.
117:
which states that any pressure applied to a fluid inside a closed system will transmit that pressure equally everywhere and in all directions. A hydraulic system uses an incompressible
220:
shaft speed. This combination is actually the same type of force multiplication as the cylinder example, just that the linear force in this case is a rotary force, defined as torque.
124:
The popularity of hydraulic machinery is due to the large amount of power that can be transferred through small tubes and flexible hoses, the high power density and a wide array of
709:
direction the supply and return paths are switched. When the spool is allowed to return to neutral (center) position the actuator fluid paths are blocked, locking it in position.
639:: cheap, durable (especially in g-rotor form), simple. Less efficient, because they are constant (fixed) displacement, and mainly suitable for pressures below 20 MPa (3000 psi).
808:
are in fact a special type of pilot controlled check valve. Whereas the check valve is open or closed, the counterbalance valve acts a bit like a pilot controlled flow control.
834:
ports and channels drilled. Cartridge valves are threaded into the ports and may be electrically controlled by switches or a microprocessor to route fluid power as needed.
525:
590:
Hydraulics) and "Flowsharing" (Parker
Hydraulics) etc. No official standardized name for this type of system has been established but flowsharing is a common name for it.
921:
which removes the unwanted particles from fluid. Metal particles are continually produced by mechanical components and need to be removed along with other contaminants.
128:
that can make use of this power, and the huge multiplication of forces that can be achieved by applying pressures over relatively large areas. One drawback, compared to
712:
Directional control valves are usually designed to be stackable, with one valve for each hydraulic cylinder, and one fluid input supplying all the valves in the stack.
528:
Pump pressure always equals the maximum load pressure when several functions are run simultaneously and the power input to the pump equals the (max. load pressure + Δ
1316:
827:
are in-line safety devices designed to automatically seal off a hydraulic line if pressure becomes too low, or safely vent fluid if pressure becomes too high.
625:
about ten times greater than an electric motor (by volume). They are powered by an electric motor or an engine, connected through gears, belts, or a flexible
1086:
Elastomeric seals (O-ring boss and face seal) are the most common types of seals in heavy equipment and are capable of reliably sealing more than 6,000
377:
No directional valve and better response, the circuit can work with higher pressure. The pump swivel angle covers both positive and negative flow direction.
909:
components, suspend contaminants and metal filings for transport to the filter, and to function well to several hundred degrees
Fahrenheit or Celsius.
705:
housing. The spool slides to different positions in the housing, and intersecting grooves and channels route the fluid based on the spool's position.
924:
Filters may be positioned in many locations. The filter may be located between the reservoir and the pump intake. Blockage of the filter will cause
259:, and so on) to move heavy loads. The approach of describing a fluid system in terms of discrete components is inspired by the success of electrical
239:. The purpose of this system may be to control where fluid flows (as in a network of tubes of coolant in a thermodynamic system) or to control fluid
444:
577:
Technically the down-stream mounted compensator in a valve block can physically be mounted "up-stream", but work as a down-stream compensator.
207:²) as C1. The downside to this is that you have to move C1 a hundred inches to move C2 one inch. The most common use for this is the classical
1326:
1284:
1237:
1205:
406:
The closed center circuits exist in two basic configurations, normally related to the regulator for the variable pump that supplies the oil:
1490:
1411:
102:
throughout the machine and becomes pressurized according to the resistance present. The fluid is controlled directly or automatically by
1387:
132:
using gears and shafts, is that any transmission of power results in some losses due to resistance of fluid flow through the piping.
1676:
1438:
719:
with the housing of less than a thousandth of an inch (25 ÎĽm). The valve block will be mounted to the machine's frame with a
1150:
890:
Examples of accumulator uses are backup power for steering or brakes, or to act as a shock absorber for the hydraulic circuit.
303:
For the hydraulic fluid to do work, it must flow to the actuator and/or motors, then return to a reservoir. The fluid is then
1681:
1229:
1057:
O-ring boss, the fitting is screwed into a boss and orientated as needed, an additional nut tightens the fitting, washer and
795:
are one-way valves, allowing an accumulator to charge and maintain its pressure after the machine is turned off, for example.
1118:
1047:
A typical piece of machinery or heavy equipment may have thousands of sealed connection points and several different types:
1712:
1054:, the fitting is screwed in until tight, difficult to orient an angled fitting correctly without over or under tightening.
1332:
1707:
1226:
From the
American System to Mass Production, 1800–1932: The Development of Manufacturing Technology in the United States
72:
Fundamental features of using hydraulics compared to mechanics for force and torque increase/decrease in a transmission.
1559:
1549:
394:
Hydrostatic transmissions for earth moving machines, such as for track loaders, are often equipped with a separate '
151:
suggested a cup leather packing. Because it produced superior results, the hydraulic press eventually displaced the
1686:
1564:
1554:
1483:
1123:
855:
693:
668:
1544:
1318:
Micro- and
Nanoscale Fluid Mechanics: Transport in Microfluidic Devices: Chapter 3: Hydraulic Circuit Analysis
1433:
Hydraulic Power System
Analysis, A. Akers, M. Gassman, & R. Smith, Taylor & Francis, New York, 2006,
195:
Cylinder C1 is one inch in radius, and cylinder C2 is ten inches in radius. If the force exerted on C1 is 10
1717:
1635:
211:
where a pumping cylinder with a small diameter is connected to the lifting cylinder with a large diameter.
44:
37:"Hydraulic equipment" redirects here. For exercise equipment using hydraulic cylinders for resistance, see
1655:
1620:
1464:
Information about Fluid Power is also available on the
National Fluid *Power Association web-site nfpa.com
1138:
1103:
1082:
seals, tubes are connected with fittings that are swaged permanently in place. Primarily used in aircraft.
875:
Some designs include dynamic flow channels on the fluid's return path that allow for a smaller reservoir.
715:
Tolerances are very tight in order to handle the high pressure and avoid leaking, spools typically have a
277:
224:
166:
1600:
1579:
1528:
1087:
883:
751:
327:
235:
A hydraulic circuit is a system comprising an interconnected set of discrete components that transport
681:
686:
1722:
1476:
784:
716:
497:
38:
738:
allows part of the spool to protrude outside the housing, where it is accessible to the actuator.
1625:
1615:
1221:
844:
760:
659:
295:
256:
243:(as in hydraulic amplifiers). For example, hydraulic machinery uses hydraulic circuits (in which
99:
1275:
A History of
Industrial Power in the United States, 1730-1930, Vol. 3: The Transmission of Power
1067:, are metal to metal compression seals deformed with a cone nut and pressed into a flare mating.
955:
68:
1610:
1569:
1434:
1322:
1280:
1251:
1243:
1233:
1201:
1145:
994:
939:
735:
648:
308:
30:
This article is about power machinery. For civil engineering concerning water management, see
331:
1015:
918:
823:
642:
160:
1640:
1630:
1605:
1573:
1518:
1374:
1197:
1160:
1133:
949:
849:
723:
pattern to avoid distorting the valve block and jamming the valve's sensitive components.
344:
252:
244:
144:
95:
91:
87:
1165:
199:, the force exerted by C2 is 1000 lbf because C2 is a hundred times larger in area (
114:
1660:
1645:
615:
260:
248:
208:
148:
17:
1701:
1650:
1450:
1273:
1091:
1064:
1051:
1023:
971:
959:
779:
622:
608:
587:
140:
103:
697:
route the fluid to the desired actuator. They usually consist of a spool inside a
304:
152:
56:
603:
1190:
1523:
1108:
1019:
906:
791:
83:
1036:
To incorporate bulkhead hardware to pass the fluid through an obstructing wall.
1513:
1499:
1255:
1155:
1128:
925:
764:
reduce the supply pressure of hydraulic fluids as needed for various circuits.
652:
395:
110:
31:
1070:
1027:
636:
626:
485:{\displaystyle {\text{Power loss}}=\Delta p_{\text{LS}}\cdot Q_{\text{tot}}}
61:
64:; main hydraulics: Boom cylinders, swing drive, cooler fan, and trackdrive
1113:
1043:
fitting may be added to a machine without modification of hoses or valves
772:
731:
632:
Common types of hydraulic pumps to hydraulic machinery applications are:
240:
125:
1458:
227:
or hydrostatic transmission involving a certain hydraulic "gear ratio".
1076:
Beam seals are costly metal to metal seals used primarily in aircraft.
977:
963:
645:: cheap and simple, reliable. Good for higher-flow low-pressure output.
562:
for each connected directional valve. Hydraulically controlled LS pump.
555:
for each connected directional valve. Hydraulically controlled LS pump.
129:
333:
This type of circuit can use inexpensive, constant displacement pumps.
1058:
860:
236:
118:
80:
1073:, metal flanges with a groove and o-ring seal are fastened together.
726:
The spool position may be actuated by mechanical levers, hydraulic
340:
a parallel arrangement and system pressure is equal for all valves.
1079:
702:
680:
602:
343:
264:
67:
55:
43:
318:
use pumps that supply a continuous flow. The flow is returned to
1247:
698:
170:
1472:
196:
1468:
905:
In addition to transferring energy, hydraulic fluid needs to
307:
and re-pumped. The path taken by hydraulic fluid is called a
567:
with a combination of up-stream and down-stream compensators
548:
in the directional valves. Hydraulically controlled LS pump.
27:
Type of machine that uses liquid fluid power to perform work
1388:"What Do Hydraulic Filters Do and Why Are They Important?"
1463:
814:
are in fact the inner part of a check valve; they are
662:: normally used for very high pressure at small flows.
1266:
1264:
500:
447:
169:
was called the "Father of
Industrial Hydraulics" by
1669:
1588:
1537:
1506:
330:. Multiple control valves may be stacked in series.
1272:
1189:
519:
484:
1011:To join components with ports of different sizes.
223:Both these examples are usually referred to as a
1459:On-line re-print of U.S. Army Field Manual 5-499
270:The circuit comprises the following components:
106:and distributed through hoses, tubes, or pipes.
1279:. Cambridge, Massachusetts, London: MIT Press.
90:are a common example. In this type of machine,
121:as its fluid, rather than a compressible gas.
1484:
985:applications most piping is stainless steel.
8:
1192:An Encyclopedia of the History of Technology
1183:
1181:
741:The main valve block is usually a stack of
1491:
1477:
1469:
1271:Hunter, Louis C.; Bryant, Lynwood (1991).
390:Constant pressure and load-sensing systems
1454:, Danfoss Hydraulics, brouwsable pdf file
1412:"Proportional Directional Control Valves"
508:
499:
476:
463:
448:
446:
147:in 1795. While working at Bramah's shop,
1377:. Section ""Recloser operation". p. 3-4.
539:Five basic types of load sensing systems
1177:
734:which push the spool left or right. A
191:Two hydraulic cylinders interconnected
1368:"Reclosers: maintenance instructions"
7:
1452:Facts worth knowing about hydraulics
1355:Chemical Reactor Analysis and Design
756:excludes moisture and contamination.
569:. Hydraulically controlled LS pump.
247:is pushed, under pressure, through
501:
456:
348:Open loop and closed loop circuits
311:of which there are several types.
25:
1007:Fittings serve several purposes;
917:Filters are an important part of
1151:National Fluid Power Association
1014:To bridge different standards;
989:Seals, fittings and connections
177:Force and torque multiplication
1321:. Cambridge University Press.
1230:Johns Hopkins University Press
1196:. London: Routledge. pp.
629:coupling to reduce vibration.
1:
1353:Froment and Bischoff (1990).
799:Pilot controlled check valves
520:{\displaystyle \Delta p_{LS}}
560:with down-stream compensator
322:through the control valve's
88:Heavy construction vehicles
1741:
992:
694:Directional control valves
553:with up-stream compensator
36:
29:
1565:Hydrological optimization
1555:Groundwater flow equation
1302:Theoretical Microfluidics
1119:Hagen–Poiseuille equation
611:of an external gear pump.
421:Constant pressure systems
411:Constant pressure systems
402:Constant pressure systems
1124:High-density solids pump
856:Hydrostatic transmission
669:hydrostatic transmission
109:Hydraulic systems, like
1560:Hazen–Williams equation
1550:Darcy–Weisbach equation
1228:, Baltimore, Maryland:
251:, pipes, tubes, hoses,
1139:Hydraulic drive system
1104:Automatic transmission
933:Tubes, pipes and hoses
752:Pressure relief valves
689:
612:
521:
486:
349:
337:Closed center circuits
225:hydraulic transmission
167:Harry Franklin Vickers
73:
65:
53:
18:Hydraulic drive system
1580:Pipe network analysis
1545:Bernoulli's principle
1529:Hydraulic engineering
1416:hydraulicpartsusa.com
1094:) of fluid pressure.
806:Counterbalance valves
684:
606:
522:
487:
347:
328:pressure relief valve
94:is pumped to various
71:
59:
47:
1713:Engineering vehicles
1315:Kirby, B.J. (2010).
1188:McNeil, Ian (1990).
1172:References and notes
685:Control valves on a
546:without compensators
498:
445:
437:Load-sensing systems
432:Load-sensing systems
365:Closed loop circuits
316:Open center circuits
278:Hydraulic power pack
159:used extensively in
1708:Hydraulic machinery
1222:Hounshell, David A.
761:Pressure regulators
296:Hydraulic cylinders
292:Passive components
284:Transmission lines
257:hydraulic cylinders
155:for metal forging.
100:hydraulic cylinders
39:Resistance training
1392:www.flowtech.co.uk
1373:2021-10-23 at the
1300:Bruus, H. (2007).
887:a system's fluid.
845:Hydraulic cylinder
783:provide a logical
690:
660:Radial piston pump
613:
517:
482:
353:Open loop circuits
350:
274:Active components
231:Hydraulic circuits
77:Hydraulic machines
74:
66:
54:
52:hydraulic circuit.
1695:
1694:
1570:Open-channel flow
1328:978-0-521-11903-0
1286:978-0-262-08198-6
1239:978-0-8018-2975-8
1207:978-0-415-14792-7
1146:Hydraulic analogy
995:Seal (mechanical)
962:and suitable for
919:hydraulic systems
649:Axial piston pump
535:) x sum of flow.
479:
466:
451:
309:hydraulic circuit
111:pneumatic systems
86:to perform work.
16:(Redirected from
1730:
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1331:. Archived from
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1278:
1268:
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1041:quick disconnect
831:Auxiliary valves
812:Cartridge valves
526:
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253:hydraulic motors
96:hydraulic motors
21:
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1698:
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1670:Public networks
1665:
1584:
1574:Manning formula
1533:
1519:Hydraulic fluid
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1375:Wayback Machine
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1161:Hydraulic press
1134:Hydraulic brake
1100:
997:
991:
935:
915:
896:
894:Hydraulic fluid
881:
869:
850:Hydraulic motor
841:
824:Hydraulic fuses
768:Sequence valves
677:
616:Hydraulic pumps
601:
596:
541:
534:
504:
496:
495:
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459:
443:
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367:
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287:Hydraulic hoses
249:hydraulic pumps
245:hydraulic fluid
233:
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145:hydraulic press
138:
113:, are based on
92:hydraulic fluid
42:
35:
28:
23:
22:
15:
12:
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5:
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1445:External links
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1065:Flare fittings
1062:
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1044:
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1034:
1031:
1030:, for example.
1012:
993:Main article:
990:
987:
960:non-galvanized
934:
931:
914:
911:
898:Also known as
895:
892:
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877:
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780:Shuttle valves
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675:Control valves
673:
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599:Hydraulic pump
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379:Disadvantages:
373:applications.
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261:circuit theory
232:
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215:Pump and motor
213:
209:hydraulic jack
192:
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187:
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178:
175:
149:Henry Maudslay
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104:control valves
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1335:on 2020-11-24
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743:off the shelf
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623:power density
621:Pumps have a
619:
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610:
609:exploded view
605:
598:
593:
591:
589:
588:Bosch Rexroth
584:
578:
571:
568:
565:Load sensing
564:
561:
558:Load sensing
557:
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551:Load sensing
550:
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544:Load sensing
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146:
143:patented the
142:
141:Joseph Bramah
135:
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58:
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46:
40:
33:
19:
1656:Rescue tools
1621:Drive system
1595:
1589:Technologies
1451:
1419:. Retrieved
1415:
1406:
1395:. Retrieved
1391:
1382:
1363:
1354:
1348:
1337:. Retrieved
1333:the original
1317:
1310:
1301:
1295:
1274:
1225:
1216:
1191:
1166:Pascal's law
1085:
1046:
1040:
1024:pipe threads
1006:
1002:
998:
983:
969:
968:
947:
946:
937:
936:
923:
916:
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889:
884:Accumulators
882:
879:Accumulators
874:
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830:
822:
815:
811:
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798:
792:Check valves
790:
778:
767:
759:
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742:
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727:
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687:scissor lift
678:
665:
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614:
582:
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529:
494:The average
493:
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370:Closed-loop:
369:
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269:
234:
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204:
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165:
157:
153:steam hammer
139:
123:
115:Pascal's law
108:
76:
75:
49:
1601:Accumulator
1524:Fluid power
1109:Brake fluid
1016:O-ring boss
721:three point
627:elastomeric
375:Advantages:
324:open center
84:fluid power
50:open center
1723:Hydraulics
1702:Categories
1687:Manchester
1514:Hydraulics
1500:Hydraulics
1421:2024-06-01
1397:2024-06-01
1339:2020-01-04
1256:1104810110
1156:Sidelifter
1129:Hydraulics
970:Hydraulic
956:Black pipe
948:Hydraulic
938:Hydraulic
926:cavitation
819:functions.
653:swashplate
594:Components
573:developed.
450:Power loss
396:inch pedal
358:Open-loop:
32:Hydraulics
1677:Liverpool
1596:Machinery
1090:(41
1071:Face seal
1061:in place.
1028:face seal
907:lubricate
867:Reservoir
839:Actuators
802:cylinder.
787:function.
732:solenoids
717:clearance
699:cast iron
643:Vane pump
637:Gear pump
583:up-stream
502:Δ
470:⋅
457:Δ
203: = π
126:actuators
62:excavator
48:A simple
1626:Manifold
1616:Cylinder
1538:Modeling
1507:Concepts
1371:Archived
1248:83016269
1224:(1984),
1114:Fluidics
1098:See also
773:recloser
425:unloaded
415:standard
305:filtered
241:pressure
186:Examples
161:Bessemer
130:machines
1611:Circuit
964:welding
913:Filters
656:versa).
136:History
1682:London
1437:
1325:
1283:
1254:
1246:
1236:
1204:
1080:Swaged
1059:o-ring
978:swaged
861:Brakes
413:(CP),
237:liquid
119:liquid
81:liquid
1641:Press
1631:Motor
1606:Brake
1022:, or
940:tubes
728:pilot
703:steel
265:pumps
1661:Seal
1646:Pump
1435:ISBN
1323:ISBN
1281:ISBN
1252:OCLC
1244:LCCN
1234:ISBN
1202:ISBN
972:hose
950:pipe
736:seal
320:tank
171:ASME
98:and
79:use
1651:Ram
1198:961
1092:MPa
1088:psi
1026:to
1020:JIC
1018:to
958:is
701:or
607:An
478:tot
197:lbf
60:An
1704::
1414:.
1390:.
1263:^
1250:,
1242:,
1232:,
1200:.
1180:^
1039:A
966:.
785:or
671:.
533:LS
465:LS
423:,
255:,
173:.
1576:)
1572:(
1492:e
1485:t
1478:v
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1400:.
1357:.
1342:.
1304:.
1289:.
1210:.
775:.
586:(
530:p
513:S
510:L
506:p
474:Q
461:p
454:=
205:r
201:S
41:.
34:.
20:)
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