hydraulic cylinders?

Question

anyone know where to find information about bridge? must got sketch or picture of how it work or built and also it mechanical parts. thank.

Answer 1

You want details about Hydraulic Cylinders or Bridge?

Hydraulic cylinders are pressurized by hydraulic pressure and get their power for the hydraulic fluid under pressure. They transform the oil's energy to linear work. A Hydraulic cylinders works in a hydraulic system and is the motor side of this system. The generator side of the oil hydraulic system is the pump, that brings a fixed or regulated oilflow into the system. The hydraulic cylinder initiates the pressure of the oil, which can never be larger than the pressure that is asked by the load. The cylinder consists out of a cylinder barrel, in which a piston connected to a piston rod is moving. The barrel is closed by the cylinder bottom at the bottom side and by the cylinder head at the side where the piston rod comes out of the cylinder. Mounting bracket or clevisses are mounted to the cylinder bottom as well as the piston rod. The piston has sliding rings and seals. The piston divides the inside of the cylinder in two chambers, the bottom chamber and the piston rod side chamber. By pumping hydraulic oil to the bottom side of the hydraulic cylinder, the piston rod starts moving out. The piston pushes the oil in the other chamber back to the reservoir. If we assume that the oil pressure int the piston rod chamber is zero, the pressure in the cylinder is now Force/Piston area. If the oil is pumped into the piston rod side chamber and the oil from the piston area flows back to the reservoir without pressure, the pressure in the piston rod area chamber is Load/(piston area - piston rod area). In such a way the hydraulic cylinder can push and pull.


[edit] Parts of a hydraulic cylinder
A hydraulic cylinder consists out of following parts:

Cylinder barrel
Cylinder bottom
Cylinder head
Piston
Cylinder bottom connection
Piston rod connection
(some times) Feet for mounting of the barrel
The cylinder barrel is mostly a seamless thick walled forged pipe that must be machined internally. The cylinder barrel is ground and/or honed internally. In most hydraulic cylinders, the barrel and the bottom are welded together. This can damage the inside of the barrel. Therefore it is better to have a screwed or flanged connection. In that case also the barrelpipe can be maintained and/or repaired in future. The cylinder head is sometimes connected to the barrel with a sort of a simple lock (for simple cylinders). In general however the connection is screwed or flanged. Flange connections are the best, but also the most expensive. A flange has to be welded to the pipe before machining. The advantage is that the connection is bolted and always simple to remove. For larger cylinder sizes, the disconnection of a screw with a diameter of 300 to 600 mm is a big problem as well as the alignment during mounting. A hydraulic cylinder should be used for pushing and pulling and no bending moments should be transmitted to the cylinder. For this reason the ideal connection of a hydraulic cylinder is a single clevis with a ball bearing.


[edit] Piston rod protection
The piston rod of a hydraulic cylinder is sometimes inside and sometimes outside the barrel (and the oil). The surface of the rod should be smooth and hard for the sealings and the slide rings, but should at the same time be resistant to corrosion. Often a Chromium layer is used. The problem with chromium however is that Chromium is porous. Whem Chlorium ions enter the layer, this is the beginning of the end. So in harsh marine environment the steel is often foreseen with a nickle layer and subsequently with a Chromium layer. Often 60(Ni)-40(Cr)micron to 150-100 microns were used. Sometimes stainless steel rods are used. High quality stainless steel (AISI 316) is expensive but mostly not strong enough. Stainless steel AISI 431 is often used, but this steel is not very good corrosion resistant. The problem with the chemical Nickle and Chromium layers is that the production process gives environment problems. For this reason a ceramic coating was developed. In the early days, this rod protection seems to be the ideal protection; later on it was proven that the layer also was porous. Especially the last five years other layers are used that have better properties. Especially in the harsh offshore world, it is important that the quality of the cylinders is excellent. In case of a calamity, the loss of production and the dismounting and mounting costs are normally much higher than a new cylinder.


[edit] Special hydraulic cylinders
Telescopic cylinder

The length of a hydraulic cylinder is the total of the stroke, the thickness of the piston, the thickness of bottom and head and the length of the connections. Often this length does not fit in the machine. In that case the pistonrod is also used as a piston barrel and a second pistonrod is used. This kind of cylinders are called "telescopic cylinders" If we call a normal cylinder "one stroke", telescopic cylinders can be two, three, four, five and even six stroke. In general telescopic cylinders are much more expensive that normal cylinders. Most telescopic cylinders are single acting (push). Double acting telescopic cylinders must be specially designed and manufactured.

Plunger cylinder

A hydraulic cylinder without a piston or with a piston without seals is called a plunger cylinder. A plunger cylinder can only be used as a pushing cylinder; the maximum Force is pistonrod area * pressure. This means that a piston cylinder in general has a relatively thick pistonrod.

Differential cylinder

A differential cylinder acts like a normal cylinder when pulling. If the cylinder however has to push, the oil from the pistonrod side of the cylinder is not going to tank, but goes to the bottomside of the cylinder. In such a way, the cylinder goes much faster, but the maximum force the cylinder can give is like a plungercylinder.

Answer 2

A Hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke.

Answer 3

I think a hydraulic cylinder comprises of a round and hollow barrel, cylinder, and a cylinder bar. The cylinder that is put inside the barrel is associated with the cylinder bar. The chamber base, and the barrel head, shuts the base and the leader of the barrel separately. The barrel head is the side from where the cylinder bar leaves the chamber.