Hydraulic cylinders help in the linear motion of a hydraulic machine parts. The market is expected to grow with the hydraulic equipment market growth.
Cylinders allow hydraulic systems to apply linear motion and force without mechanical gears or levers by transferring the pressure from fluid through a piston to the point of operation. Hydraulic cylinders are used for creating mechanical force in a linear motion. The mechanical force generated is proportional to the combined factors of both the piston area and the pressure applied to that piston area. Hydraulic cylinders are used in various construction, mining and material handling machinery applications operating booms, arms, lifts, platforms, buckets, and platens. They can push, pull and lift loads of any description, and the mobile machinery industry relies nearly exclusively on hydraulic cylinders for linear motion. Hydraulic cylinders are the most effective and efficient method of pushing, pulling, lifting and lowering. There are many types of cylinders for various applications in construction equipment such as: backhoe-stick cylinder, boom cylinders, dipper cylinders, bucket cylinders, lift cylinders, tilt cylinders, arm cylinders, crowd cylinder, angle cylinders, etc.
A hydraulic cylinder is a tube capped at either end with a rod sticking out of one side. Attached to the rod, interior to the cylinder is a piston. The piston separates the internal rod side from the internal cap side of the cylinder. Fluid is forced into either side of the cylinder to extend or retract the piston rod. The piston rod is attached to the part of the machine requiring motion. Literally any application requiring linear application of force is an excellent use of a hydraulic cylinder, and no other method of linear motion is strong and efficient as a cylinder is. Hydraulic cylinders can extend with force ranging from a couple thousand pounds up to thousands of tonnes.
Double-acting and single-acting
Differential cylinders are normally double-acting as they are powered in retraction as well as extension. A differential cylinder can be powered in just one direction, if required, which is called single-acting. A single-acting cylinder is manufactured in various forms, and normally when a differential cylinder is used as single acting, it will have a breather at the non-powered port to avoid trapped air. Single-acting cylinders are sometimes spring loaded, and are important if the mass of the load isn't enough to push the fluid back through valves alone. Springs can be added to either the cap or rod end of a cylinder, enabling spring-extend or spring-retract functions, respectively.
Single-acting cylinders can also be rams, which are cylinders consisting of just a rod in a tube. Pressure pushes the ram up or out, but often requires energy to retract. This energy can come from the mass of the load, but sometimes is generated from springs or other devices that are part of the machine itself, rather than inside the cylinder.
Cylinders are created with various manufacturing techniques, but the two most common types are tie-rod and welded-tube. A tie-rod cylinder uses cast or machined ends, a common tube between them, and then tie rods to pull the cap end towards the rod end.
The type of metal used for cylinder head, base and bearing can make a significant difference. Most cylinders use SAE 660 bronze for rod bearings and medium-grade carbon steel for heads and bases, which is adequate for most applications. But stronger materials, such as 65-45-12 ductile iron for rod bearings, can provide a sizable performance advantage for tough industrial tasks. The type of piston rod material can be important in wet or high-humidity environments where 17-4PH stainless steel may be more durable than the standard case-hardened carbon steel with chrome plating used for most piston rods.
Selection and application Selecting the right cylinder for an application is critical to attaining maximum performance and reliability. That means taking into consideration several parameters.
It's also important to consider operating conditions. Cylinders must match a specific application in terms of the amount of pressure, the force exerted, and space requirements imposed by the machinery's design. Cylinders must be able to withstand extreme high or low temperatures for some designs.
A major challenge in the area of construction is posed by the frequent load changes that the machine has to go through. Hydraulic cylinders need to be manufactured keeping in mind that the machine has to withstand all these conditions.
For mining applications, hydraulic cylinders have to cope with high static and dynamic forces. Steel and metals of special features need to be used to have sturdiness and durability for the cylinders to match and withstand the demanding working conditions in mines. Mining equipment is exposed to heavy vibrations and impact loads. Therefore, leading manufacturers have developed shock absorbers for the front and rear axle, especially for heavy machines such as dump trucks.