FAQ

Piston rod column failure (buckling) can occur if the rod diameter is not sized to match the stroke and load. The manufacturer should be consulted for application assistance.Column strength considerations: Standard size rods are recommended for use in cylinder applications where column strength, rod sag, or rate of cylinder return do not require an oversize rod. Being more flexible, standard rods absorb shock loads and minimize bearing loads caused by misalignments. For long push stroke cylinders, an oversize rod may be required to prevent column failure and rod bending. Total cylinder length when extended is considered in column strength.

It’s a sudden, large, and unstable lateral deflection. It can be associated with only a small increase in compressive load above a critical level, known as the buckling load. The corresponding stress can be far less than the yield strength of the rod material.

Hydraulic cylinder drift is caused by internal leaks in the cylinder across the piston. The fluid physically moves from one side of the piston to the other which creates an uneven balance and causes the cylinder to move or “drift”.

Mis-staging is a telescopic cylinder extending or retracting in the wrong sequence. When the cylinder tries to correct its sequence, rapid movement and violent slamming between moving stages can occur.

Generally, no. Speed is a factor of flow. You need more flow to make things move faster.

A telescoping cylinder is a cylinder employing several pistons which telescope into each other. This cylinder is used when a relatively long working stroke is needed for a short cylinder length. Telescopic cylinders are used in a variety of applications that require the use of a long cylinder in a space-constrained environment.

Telescopic hydraulic cylinders, sometimes called multi-stage cylinders, are a type of linear actuator consisting of a series of tubular rods called sleeves. The sleeves (usually 2 to 6) sequentially decrease in diameter and are nested inside of each other.Once hydraulic pressure is introduced to the cylinder, the largest sleeve is extended first. Once the largest sleeve has reached its maximum stroke, the next sleeve begins to extend. This process continues until the cylinder reaches its last stage, called the plunger.There are three common types of telescopic cylinders: Single-acting, Double-acting, and a combination of single and double-acting.

Double ActingA cylinder in which fluid force can be applied in either direction to the moveable element. These cylinders are also classified as differential cylinders because of their unequal exposed areas during extend and retract. The difference in effective area is caused by the area of the rod that reduces the piston area during retraction. Extension is slower than retraction because more fluid is required to fill the piston side of the cylinder. However, more force can be generated on extension because of greater effective area. On retraction, the same amount of pump flow will retract the cylinder faster because of the reduced fluid volume displaced by the rod. Less force, however, can be generated due to less effective area.Single ActingA cylinder in which hydraulic energy can produce thrust or motion in only one direction. Once the pressure is released, the load (can be spring or gravity returned) on the cylinder retracts the rod. The inactive end is sometimes vented to atmosphere through a breather/filter or vented to reservoir below the oil level.

Pneumatic cylinders rarely provide much more than a hundred pounds per square inch of pressure to the piston, whereas hydraulic cylinders are capable of anywhere from 1500 to 10,000 psi, which can be ten to hundred times the force of a pneumatic cylinder.

A ram-type cylinder is a cylinder in which a cross-sectional area of a piston rod is more than one-half a cross-sectional area of a piston head. In many cylinders of this type, the rod and piston heads have equal areas. A ram-type actuating cylinder is used mainly for push functions rather than pull.

A hydraulic cylinder is made up of 7 main components:Cylinder Barrel (Main, Body). The barrel is the cylindrical body of the cylinder. The barrel guides the piston and provides a sealing surface for the piston seal. The barrel is also the structural part of the cylinder that holds the ends in place.Cylinder Cap (Back End, Blind End, Blind Head, Rear End). A cylinder end closure which completely covers the bore area (opposite the rod end).Cylinder Head (Packing Gland, Stuffing Box, Head End, Front End, Front Face, Rod End). The head gland or stuffing box is a cylinder component that serves more than one purpose. It retains the static and dynamic seals at the head end of the cylinder, it seals off at the end of the cylinders, it is the support or guide for the rod and it is the mechanical stop to keep the piston from falling out of the cylinder barrel.Piston. The piston is a cylinder component that has multiple purposes. The piston retains the primary seal from the extend side of the cylinder and the retract side of the cylinder. It is the component that moves back and forth from the hydraulic oil. The piston is the mechanical means of connecting and moving the rod in and out of the cylinder as well as serves as a guide for one end of the piston rod.Piston Rod. The rod is also known as the cylinder shaft, plunger or ram. It is the round device that moves in and out of the cylinder. The piston rod can be solid or hollow. The rod is usually plated, or heat treated to provide better wear and corrosion resistance.Ports. Cylinder ports are the means in which the cylinder is able to have fluid lines or conduits connected. O-ring Boss (SAE) Port is a port that has straight or parallel threads as well as an O-ring to seal the threads. Pipe port threads are tapered threads that count on interference between the male and female threads to do the sealing. 4-Bolt Flange Port is a port that counts on 4 bolts to hold to two halves together. This type uses an O-ring to do the sealing. BSP is a British Standard Pipe Thread.Seals.Static seals keep the joint pressure tight.Rod wiper / scraper is provided to remove and prevent foreign material from entering the bearing and seal area.Rod seals hold pressure in the cylinder by preventing fluid from leaking out.Piston seals prevent pressurized fluid from leaking across the piston as the system pressure pushes the piston and rod assembly down the cylinder bore.

The function of hydraulic cylinder is to provide linear motion. It converts the fluid energy into mechanical energy (linear movement). Cylinders are broken down into two main categories: pneumatic and hydraulic. Pneumatic cylinders can be operated by several types of gases, however, compressed air is by far the most common. Hydraulic cylinders can be operated with a very large range of fluids. By far the most common is petroleum based hydraulic fluid. Fire-resistant fluids are also common, they may be synthetic, or water based.

A hydraulic cylinder is a device which converts fluid power into linear mechanical force and motion proportional to the effective cross-sectional area of the piston. Their output force, or motion, is in a straight line. Their work applications may include pushing, pulling, tilting, and pressing. Cylinder type and design are based on specific applications. Cylinders usually consist of a movable element such as a piston and piston rod, plunger or ram, operating within a cylindrical bore. Common types of cylinders include double-acting, single-acting, and telescoping.

The three most common hydraulic cylinder configurations are piston hydraulic cylinders, telescopic hydraulic cylinders and plunger hydraulic cylinders. Each cylinder design varies by the type of application as below: Piston hydraulic cylinders are the most common on the market and can be designed with welding (welded hydraulic cylinders) or without (tie-rod hydraulic cylinders). Also, any piston cylinder can be suitable for single and double acting applications. Telescopic hydraulic cylinders consist of a minimum of two stages or more and able to provide an extremely long cylinder stroke (travel distance) from a compact collapsed length of the cylinder body. Just like piston cylinders, telescopic cylinders can be single and double acting.Plunger hydraulic cylinders do not have piston. Therefore, plunger cylinders require a larger size of the hydraulic rod in order to create the same amount of force compared to piston cylinders. Also, plunger cylinders are suited only for single acting applications.For all types of cylinders, the crucial measurements include cylinder stroke, bore diameter and rod diameter. Stroke lengths vary from less than an inch to several feet or more. Bore diameters can range anywhere from an inch up to more than 24 inches, and rod diameters range from 0.5 inch to more than 20 inches. In practice, however, the choice of stroke, bore and rod dimensions may be limited by environmental, application or design conditions. For example, space may be too limited for the needed cylinder stroke length. For tie-rod cylinders, increasing the size of the bore also means increasing the number of tie rods needed to retain stability. Increasing the diameter of the bore or piston rod is an ideal way to compensate for higher loads, but space considerations may not allow this, in which case multiple cylinders may be required.