Cylinders allow hydraulic hydraulic cylinder systems to apply linear motion and push without mechanical gears or levers by transferring the pressure from liquid through a piston to the idea of operation.
Hydraulic cylinders are at work in both industrial applications (hydraulic presses, cranes, forges, packing machines), and cellular applications (agricultural machines, construction equipment, marine equipment). And, in comparison to pneumatic, mechanical or electrical systems, hydraulics can be simpler, more durable, and offer greater power. For example, a hydraulic pump offers about ten times the energy density of a power motor of similar size. Hydraulic cylinders are also available in an impressive array of scales to meet an array of application needs.
Choosing the right cylinder meant for an application is crucial to attaining maximum overall performance and reliability. Which means considering several parameters. Fortunately, a variety of cylinder types, mounting techniques and “rules of thumb” are available to greatly help.
The three the majority of common cylinder configurations are tie-rod, welded and ram styles. Tie-rod cylinders make use of high-strength threaded metal tie-rods, typically on the outside of the cylinder housing, to provide additional balance. Welded cylinders feature a heavy-duty welded cylinder housing with a barrel welded directly to the end caps, and require no tie rods. Ram cylinders are just what they sound like-the cylinder pushes directly ahead using high pressure. Ram cylinders are used in heavy-duty applications and more often than not push loads instead of pull.
For all types of cylinders, the key measurements include stroke, bore diameter and rod diameter. Stroke lengths vary from less than an ” to several feet or even more. Bore diameters can range from an inch up to more than 24 in., and piston rod diameters range between 0.5 in. to more than 20 in. In practice, however, the decision of stroke, bore and rod dimensions may be tied to environmental or design circumstances. For example, space could be as well limited for the perfect stroke length. For tie-rod cylinders, raising how big is the bore does mean increasing the number of tie rods had a need to retain stability. Raising the diameter of the bore or piston rod is an ideal way to pay for higher loads, but space factors may not enable this, in which particular case multiple cylinders may be required.
Cylinder mounting methods
Mounting methods also play an essential role in cylinder overall performance. Generally, fixed mounts on the centerline of the cylinder are best for straight line force transfer and avoiding wear. Common types of installation include:
Flange mounts-Very strong and rigid, but possess little tolerance for misalignment. Specialists recommend cap end mounts for thrust loads and rod end mounts where major loading puts the piston rod in stress.
Side-mounted cylinders-Easy to install and service, however the mounts create a turning moment as the cylinder applies force to a load, increasing wear and tear. In order to avoid this, specify a stroke at least as long as the bore size for side mount cylinders (weighty loading can make short stroke, large bore cylinders unstable). Part mounts need to be well aligned and the strain supported and guided.
Centerline lug mounts -Absorb forces on the centerline, but require dowel pins to secure the lugs to prevent movement in higher pressures or under shock circumstances.
Pivot mounts -Absorb force on the cylinder centerline and let the cylinder change alignment in one plane. Common types include clevises, trunnion mounts and spherical bearings. Because these mounts allow a cylinder to pivot, they must be used with rod-end attachments that also pivot. Clevis mounts can be used in any orientation and are generally recommended for brief strokes and little- to medium-bore cylinders.
Operating conditions-Cylinders must match a specific application with regards to the quantity of pressure (psi), power exerted, space requirements imposed by machine design, etc. But knowing the working requirements is only half the task. Cylinders must withstand high temperature ranges, humidity and also salt water for marine hydraulic systems. Wherever temperatures typically rise to a lot more than 300° F, regular Buna-N nitrile rubber seals may fail-choose cylinders with Viton synthetic rubber seals rather. When in question, assume operating conditions will be more tough than they appear initially.
Fluid type-Most hydraulics use a kind of mineral essential oil, but applications involving synthetic liquids, such as for example phosphate esters, require Viton seals. Once again, Buna-N seals may not be adequate to handle synthetic fluid hydraulics. Polyurethane is also incompatible with high water-based fluids such as for example water glycol.
Seals -This is just about the most vulnerable facet of a hydraulic program. Proper seals can reduce friction and put on, lengthening service life, while the wrong kind of seal can result in downtime and maintenance nightmares.
Cylinder materials -The type of metallic used for cylinder mind, base and bearing could make a big change. Most cylinders make use of SAE 660 bronze for rod bearings and medium-grade carbon metal for heads and bases, which is adequate for most applications. But more powerful materials, such as for example 65-45-12 ductile iron for rod bearings, can provide a big performance advantage for tough industrial tasks. The kind of piston rod material can be essential in wet or high-humidity environments (e.g., marine hydraulics) where17-4PH stainless may be stronger than the regular case-hardened carbon metal with chrome plating utilized for most piston rods.