The relief valve is a device, usually in a high-low circuit used. The circuit is sometimes referred to as a fast approach, slow feed circuit. The valve is also in a system where a large flow is needed at a lower pressure, and then used later, is a very low flow at a higher pressure is required.

Usually two pumps are plumbed in parallel used in such a circuit.
A fixed displacement pump, the volume provides for low pressure, high flow mode, while a small pump provides the low-flow with the higher pressure. Both pumps have a flow in the low-pressure, high-flow mode. The purpose of the use of two pumps draw energy from the engines to save long term, if only to maintain the function of the hydraulic system at a constant maximum pressure with little or no flow.

If the system cylinders are rapidly expanding at low pressure to send (no pressure relief valve setting), two pumps in its entirety in the cylinder.
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When the cylinder enough to encounter mechanical resistance of the system, the introduction of the relief valve under pressure to be piloted high pump flow directed into the tank through the pressure relief valve. In contrast to a pressure relief valve, reducing the pressure operated valve on the flow is minimal. Therefore, the pressure relief valve no danger to the heating problem. The volume of the smaller pump can not escape to the tank through the relief valve through the check valve in the system. The presence of the valve makes the chart symbol for relief valve differs from a typical pressure relief valve.

When the cylinder further against the resistance (system pressure) is higher than the relief valve setting, the movement is slower than the volume of the small pump to move. In many cases, the cylinder to a halt if the machine is active margins of an assembly machine or system unique. At this point, open the main valve and the maximum (or terminals) pressure. If you’re a safety valve is to be pressure compensated to a maximum pressure limitation of the smaller pump with variable displacement / strain.

In many systems, the large volume, designed to pump pump. The small pump is often used as the pump, since they often used only on a printing system to offer support if the cylinders are used in a terminal mode called. The small pump will only supply enough volume to make the cylinder for an internal leak in the system.

What you need to
A wiper seal
Oil pan
One of the candles and jack
engine oil
new oil filter
Changing the oil pump
New oil pan gasket
Keys
Screwdriver
rags or towels

Simple Hydraulic Pump

Step 1 – Prepare the vehicle
First, park your vehicle at the ground level. So be sure to set the parking brake.

Step two – Raise vehicle
Use the jack to lift the vehicle, then it is placed under the car jack so you can safely work under the vehicle.

Step 3 – Engine Oil Drain
Place a plastic container in the sump of the vehicle. Then remove the drain plug and allow oil to flow into the container. Set the engine oil of the old, and remember to put the recycling center after completing the work.

Step 4 – Remove the oil pan
Remove the screws holding the oil pan in place and remove the oil pan of the vehicle. Be careful not to damage the plate to remove them.

Step 5 – Remove the Oil Pump
First, locate the pump oil. On most cars, will be behind the engine. There should have a hose and a filter that are related to a reduction of the sump pump to suck oil. In most cases, there will be only one or two bolts used to hold it in place. Then, remove screws and fix old pump oil aside.

Step 6 – Install the new oil pump
Use the bolt (s) was withdrawn from the old oil pump install the new one. Make sure to apply sufficient torque when tightening bolts.

Step 7 – Install a new pan gasket
Before you can install the new pan gasket, you must delete the old one. Use the scraper to scrape the old gasket. Then, use glue to stick the new gasket on the oil pan gasket. Allow the seal to dry for at least an hour before reinstalling the oil pan.

Step 8 – Replace the drain plug
Tighten the drain plug and tighten the rear.

Step 9 – Replace the oil filter
While you’re under the vehicle, go ahead and replace the oil filter as well. Turn counterclockwise old oil filter and replace it with a new one.

Step 10 – Lower the vehicle
Remove the candles and lower the vehicle.

Step 11-Add new engine Oil
Remove the oil filler cap on top of your car engine and fill the engine with engine oil. Visit the owner’s manual for the number of gallons you’ll need to add.

This is part of the (waste valve) spring a bridge bet. This spring, it is to use another. But there are several ways such as a weight the press itself. ”
This can often leave off the water valve open. Or the ball (ball valve), but the ball valves are made more difficult. Depending on which way we would like.

- Check equipment. Hydraulic systems installed in more appropriate placements available for use as filters, pumps, pressure limit valve, directional control valves, cylinders, pipe joint, gas, pipeline and etc..

2. Refueling.

- Make sure the tank room was already clean and free from impurities other waste materials.

- Fuel oil as guides or qualified as a specification to fill the tank without telling than the highest rating.

- In the case of tank capacity does not tell level. The fuel quantity required.

- The fuel should be added via a specific device for a filter is installed.

3. The starting system

- Open the valve closed – open the oil suction pipe in the first case of the installation in it.

- Adjust the valve to limit pressure in the open position flows into the oil tank room at low pressure. Or near zero

- Check the direction of rotation of the pump with the correct direction of rotation of the powered device. (Electric motors, engines), the pump is starting to follow most carefully. Especially lubricating oil, usually based on hydraulic pump that uses the c starting first often in the worst condition. Due to lack of flow of oil Therefore necessary to add fuel to fully pump before starting pump first, and for pump adjusts the flow rate was (Variable Displacement) should start walking at low pressure will best part of starting electric motors, it should be done by using triggered moment to ensure that the oil shock occurred. Distinguishable from the sound of the pump has changed. If the pump does not work to stop sending oil pump hire immediately. To prevent damage inspection of the oil viscosity. More typical oil filter and remove the jam Pump see nothing inside the pump to speed up work will be to check the oil level is higher than said low limit.

4. Punching the air.

- Due to air in the system resulting in wear and high interfere with other, so it is necessary to chase air from the system out after the start operation by the chase through the exit tube fittings in the open that the highest position of the system. We can observe that the exhausted air from the system. Based on the oil that flows out continuously at the open pipe. No oil in tank foam No sound system disorders. And equipment work. (Cylinder or motor – Hydraulic A) is functioning correctly.

5. And the pressure for use.

- Set pressure limit valve (Relief Valve) or pressure compensation valve (Pressure Compensating Valve) in the pump flow rate was adjusted. To control the maximum pressure of the system to suit the work load. Based on internal pressure on the pressure gauge. Which generally come from areas of origin. The pressure read at the source should be greater than the pressure that occurs destination (Pressure work that occurs when cylinder or motor Hydraulic acrylic work driving or driving load is) not much, or may say that should set the pressure at the source rather than the pressure drop across arising from the flow of oil at the source end นั่นเอง in practice to ensure that While the cylinders or hydraulic motors driving a loaded work. Limit pressure valve or valve pressure compensation. Must be open so that the adjustment is considered appropriate.

6. The accumulated power control pressure tank. (Accumulator).

- Tank pressure should be controlled to successfully accumulate energy in the first week of operation and in case of no leakage If the control can work as usual every year I check once a year to check the gauge pressure of the hydraulic system, a collection tank connected to power directly The compression test fuel tank to accumulate energy and then gradually release the gas pump stops the accumulation of power cylinder pressure under control. Observation of the pressure gauge. Indicator will fall to zero as soon as the pressure in the tank to accumulate energy before compression pressure before compression pressure reading from the first position the needle will fall to zero.

1. Flow. The need for oil.

2. The pressure being used.

3. Size electric motors. Or engine driving the pump.

Suppose to 200 bar maximum pressure cylinder size ID 100 mm. Speed of movement of the cylinder was 3 cm / sec.

A = 10 x 10 x 0.785 = 78.5 cm2.

V = 3 cm / sec.

Q = V x A = 3 cm / sec x 78.5 cm2 = 235.5 cm3 / sec = 14.13 L / min.

Rotate pump drive motor speed 1450 rpm. Therefore, pump size should be 9.7 cc / rev.

Hydraulic cylinder repair

Now that we know how a hydraulic cylinder, we can delve into the reasons why falls overlook. Here are some common problems that can break a hydraulic cylinder or cause a malfunction. I will discuss possible solutions that can help rebuild or repair the hydraulic cylinder. Reading instruction manuals for equipment supplied by manufacturers carefully before proceeding.

First Problem : rod hydraulic cylinder piston is broken or bent!

Bent rods are a common cause of joint failure. Bending cylinder bars can be caused by the rod diameter or insufficient material strength, cylinder mounting bad deal or a combination. Once the rod bends, the excessive burden is placed on the seal resulting in premature failure of the joint. The permissible load for a cylinder rod in an existing application can be checked using the Euler formula. A detailed explanation of how to do this is contained in the hydraulic industry control.

Solution: If the coverage, you see the twisted cylinder or barrel of the bottle is broken, there is nothing more or less you can do. It is time to replace the cylinder. Forging a new stretcher or ironing, the piston rod is beyond your capabilities. So if this is the case, repairing the hydraulic cylinder is not possible.

Second Problem: The seal of the hydraulic cylinder is broken!

Solution: If the shaft seal is broken can be replaced. However, the opening of the entire cylinder assembly is needed. Let’s see how we go about it. Get a diagram hydraulic cylinder, if possible, because it will help to reassembly. These cards you get equipment manufacturers and can also make an impression. You can order a repair kit for your standard hydraulic cylinder which is driven by production companies. It contains parts of cylinder seals and other parts based on the number and type of cylinders in the car.

The assembly of the cylinder varies with the type of machine. Locate the first seal. Most are located around the shaft at one end. The rotor shaft entrance is accessible by unscrewing the cover on that side. Then loosen the ducts that carry the fluid in the chamber capable of releasing the pressure. This will allow you to remove the tree that otherwise can not be removed due to hydraulic pressure. Handle with care the trees and be careful not to scratch it. Unplug the piston shaft and replace the seal with parts from a repair kit. Make sure the gasket is correctly aligned. Oil all the parties after the installation and back together in exactly the reverse order.

Third Problem : Inflated Tubes
Ballooning of the cylinder tube is usually caused by insufficient wall thickness and / or resistance materials for pressure cylinder operation. Once the tube balloons, correct tolerance between the piston and the tube wall is lost and high pressure fluid bypasses the seal. This high velocity fluid can erode the seal and localized overheating caused by the pressure drop through the piston reduces the length of the seal.

Cylinder Hydraulic System Diagram (Click Here to See Detail)

Four Problem: The segments are damaged!

Solution: If the piston rings are damaged, they can also be replaced by disassembling the same procedure regarding the above problem. The piston rings must be removed and replaced with great care. Scraper rings and cylinder before putting it all together.

If you have a multiple cylinder, things are more complicated. It is best to consult a qualified technician before continuing. I hope this article gave you an idea of how to rebuild a hydraulic cylinder with ease. I always remember one rule while you are solving mechanical problems, not without a reason to take some action. In addition, the assembly studies and etiological framework of the car before going to repair. Repair of hydraulic cylinders may be a good learning experience for those who like the design of the machine.