Hydraulic circuits

"A hydraulic circuit is a system comprising an interconnected set of discrete components that transport liquid. 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 pressure (as in hydraulic amplifiers).
... hydraulic circuit theory works best when the elements (passive component such as pipes or transmission lines or active components such as power packs or pumps) 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." [Hydraulic circuit. Wikipedia]
The engineering drawing example "Hydraulic circuits" was redrawn using ConceptDraw PRO diagramming and vector drawing software from the Wikimedia Commons file: Hydraulic circuits.png.
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The engineering drawing example "Hydraulic circuits" is included in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.

"Directional control valves route the fluid to the desired actuator. They usually consist of a spool inside a cast iron or steel housing. The spool slides to different positions in the housing, and intersecting grooves and channels route the fluid based on the spool's position.
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 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.
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.
Tolerances are very tight in order to handle the high pressure and avoid leaking, spools typically have a clearance with the housing of less than a thousandth of an inch (25 µm). The valve block will be mounted to the machine's frame with a three point pattern to avoid distorting the valve block and jamming the valve's sensitive components.
The spool position may be actuated by mechanical levers, hydraulic pilot pressure, or solenoids which push the spool left or right. A seal allows part of the spool to protrude outside the housing, where it is accessible to the actuator.
The main valve block is usually a stack of off the shelf 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." [Hydraulic machinery. Wikipedia]
The Mac template "Hydraulic 4-ported 3-position valve" for the ConceptDraw PRO diagramming and vector drawing software is included in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.
www.conceptdraw.com/ solution-park/ engineering-mechanical

A simple hydraulic schematic showing apparatus for testing the strength of a hydraulic hose splice.
Water enters through normally closed solenoid valve (1) and passes through intake flow meter (2) to high pressure pump (4). Intake water pressure is monitored by pressure gauge (3). The hose to be tested connects between pump (4) and normally open solenoid activated drain valve (7). To test the hose, pump drive motor (5) is turned on, the solenoid of drain valve (7) is activated, closing the valve, and the pump is run to pressurize the hose. Test pressure is monitored by gauge (6). When the test is complete or the hose fails, the solenoid of drain valve (7) is deactivated, opening valve and discharging water, depressurizing the system. All components are operated electrically by a remote control circuit so that the operator may perform the test from a protected location, monitoring it with a camera and video monitor.
This hydraulic schematic example was redrawn using ConceptDraw PRO diagramming and vector drawing software from the Wikimedia Commons file: Hydraulic schematic.jpg.
[commons.wikimedia.org/ wiki/ File:Hydraulic_ schematic.jpg]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
[creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
The hydraulic schematic example "Apparatus for testing the strength of a hydraulic hose splice" is included in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.