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Hydraulic Cylinders

Hydraulic Cylinders

Hydraulic cylinders, which are also refered to as linear hydraulic motors, are actually mechanical actuators that are used to give a unidirectional force through a unidirectional stroke. Meaning a push or pull in one direction at a time. They have many applications in the mining industry, in construction equipment, civil engineering and manufacturing machinery.

How Cylinders Work

Hydraulic cylinders are powered with pressurised hydraulic fluid, usually oil but can be water, brake fluid or even compressed air. Hang on, that would make it an air cylinder. Forget that, we’re talking about hydraulic cylinders here. The hydraulic cylinder consists of a cylinder barrel or tube, in which a piston connected to a piston rod moves back and forth. The bottom of the tube is closed in with a cap, usually welded in but can be bolted, and the top of the tube has a cap with a hole in it, usually called a head or gland, through which the rod runs. The piston has seals to hold the pressurised fluid in the top or the bottom of the cylinder tube and sometimes has wear rings to hold it straight and take the sideways pressure off the seals. The piston divides the inside of the cylinder into two chambers, the bottom chamber (cap end) and the piston rod side chamber (rod end or head end).

Things to Lookout For

Remember, when designing a system which uses a hydraulic cylinder that the pressure exerted on the cap end of the piston is proportionally larger than the pressure exerted on the rod end of the piston. This is because the surface area of the whole piston is more than the surface area of the piston on the rod side because the cross sectional area of the rod has to be subtracted. For example, if you have a 3” piston with a 2” rod, then the piston area is 7 inch² but, on the rod end, the cross sectional area of the rod, which is 3 inch², will have to be subtracted to give you 4 inch² piston area. The formula for the force being exerted on the piston is F = P * A, where F is the pounds force, P is the fluid pressure in PSI and A is the area of the piston in inch². Therefore: using a pressure of 2000PSI the force on each side of the piston is... So the rod is pushed out with almost twice the force of what it is drawn back into the cylinder with. This must be taken into account when designing a system and when testing a cylinder for piston seal leakage. Pressure intensification is what results from blocking the rod end fluid supply for any reason. This may be done under controlled situations to test the cylinder. Go here for details on pressure intensification. Central Queensland Hydraulics is not tied to any one manufacturer, so we can supply, service and repair cylinders for any and all applications. We have the technology to perform complete overhauls of any type of cylinder. At Central Queensland Hydraulics we can also source new agricultural and industrial cylinders from many manufacturers. Or, we can supply a comprehensive range of purpose built cylinders to suit your application. Remember, at Central Qld Hydraulics, we take any old cylinders that are preserved well, replace their damaged parts to make them go on doing their outstanding work as new cylinders.
cyl1 cyl2 cyl3 excavator Force on piston end Force on rod end Checkout our Surplus Cylinder stock

CENTRAL QUEENSLAND HYDRAULICS

As well as selling new parts and components, we also service and rebuild all the products we sell. We have a comprehensive spare parts and exchange parts service. And all work is guaranteed.
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All types of hydraulic tooling. Hydraulic cylinders of all shapes and sizes. Hydraulic fittings and hoses.
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Home Products Filtration Service & Repairs Hire Distributorships Quality & Safety Profile Contact Us headerline Flare
Copyright © 2013, Central Queensland Hydraulics Pty.Ltd. - Contact our Webmaster
Oil drop

Hydraulic Cylinders

Hydraulic Cylinders

Hydraulic cylinders, which are also refered to as linear hydraulic motors, are actually mechanical actuators that are used to give a unidirectional force through a unidirectional stroke. Meaning a push or pull in one direction at a time. They have many applications in the mining industry, in construction equipment, civil engineering and manufacturing machinery.

How Cylinders Work

Hydraulic cylinders are powered with pressurised hydraulic fluid, usually oil but can be water, brake fluid or even compressed air. Hang on, that would make it an air cylinder. Forget that, we’re talking about hydraulic cylinders here. The hydraulic cylinder consists of a cylinder barrel or tube, in which a piston connected to a piston rod moves back and forth. The bottom of the tube is closed in with a cap, usually welded in but can be bolted, and the top of the tube has a cap with a hole in it, usually called a head or gland, through which the rod runs. The piston has seals to hold the pressurised fluid in the top or the bottom of the cylinder tube and sometimes has wear rings to hold it straight and take the sideways pressure off the seals. The piston divides the inside of the cylinder into two chambers, the bottom chamber (cap end) and the piston rod side chamber (rod end or head end).

Things to Lookout For

Remember, when designing a system which uses a hydraulic cylinder that the pressure exerted on the cap end of the piston is proportionally larger than the pressure exerted on the rod end of the piston. This is because the surface area of the whole piston is more than the surface area of the piston on the rod side because the cross sectional area of the rod has to be subtracted. For example, if you have a 3” piston with a 2” rod, then the piston area is 7 inch² but, on the rod end, the cross sectional area of the rod, which is 3 inch², will have to be subtracted to give you 4 inch² piston area. The formula for the force being exerted on the piston is F = P * A, where F is the pounds force, P is the fluid pressure in PSI and A is the area of the piston in inch². Therefore: using a pressure of 2000PSI the force on each side of the piston is... So the rod is pushed out with almost twice the force of what it is drawn back into the cylinder with. This must be taken into account when designing a system and when testing a cylinder for piston seal leakage. Pressure intensification is what results from blocking the rod end fluid supply for any reason. This may be done under controlled situations to test the cylinder. Go here for details on pressure intensification. Central Queensland Hydraulics is not tied to any one manufacturer, so we can supply, service and repair cylinders for any and all applications. We have the technology to perform complete overhauls of any type of cylinder. At Central Queensland Hydraulics we can also source new agricultural and industrial cylinders from many manufacturers. Or, we can supply a comprehensive range of purpose built cylinders to suit your application. Remember, at Central Qld Hydraulics, we take any old cylinders that are preserved well, replace their damaged parts to make them go on doing their outstanding work as new cylinders.
cyl1 cyl2 cyl3 excavator Force on piston end Force on rod end Checkout our Surplus Cylinder stock