Engineering Data

How to Determine the Proper Cylinder Size

Refer to the chart below which gives the values of push and pull developed by Airoyal cylinders at various operating pressure; These are theoretical force values, which are always reduced by such factors as cylinder friction, pressure drop, back pressure, friction of the workload, line losses, etc. For this reason it is suggested that an adequate factor of safety be incorporated in to the cylinder selection either through the use of the next larger bore cylinder or by using a higher operating pressure, On single-acting cylinders it must be remembered that the force required to compress the return spring detracts from the force output of the cylinder.

Cylinder Ratings

• Airoyal “A” cylinders are suitable for air service to 150 psi
• Airoyal “H” cylinders are suitable for oil service to 750 psi
• Airoyal “HP” cylinders are suitable for oil service to 2000 psi
• Airoyal “SHP* cylinders are suitable for oil service to 3000 psi

Cushions

Adjustable cushions are a standard option for all bores of hydraulic cylinders and most air cylinders. Though available, we do not recommend cushions on air cylinders of 5/8” and 1” bore or air cylinders with oversize rods because of their relative ineffectiveness. These may be had on either the rod end, the blind end or on both ends. “Opposite hand” position available on special order.

Flow Controls

Adjustable flow controls are similar to cushions but are effective through the complete stroke.

Mounting

All square rod-end heads are drilled with six holes for universal mounting. Upon request, however, these heads may be secured with only the side or the end mounting holes. When side mounting holes are used, be sure that the base upon which the cylinder is to be mounted is sufficiently flat, that even before being tightened down, there is no rocking motion, and that the structure is of such rigidity that there will be no *give’ when the cylinder is operating under load.

Stroke Lengths

Airoyal double-acting cylinders are available in stroke lengths up to 120 inches. However, great care must be taken, when using a long stroke cylinder, to prevent the rod from buckling due to column action or from sagging due to its own weight. Except in those applications where the rods are in constant tension, all long stroke cylinders should be furnished with over-sized rods and possibly “Stop Tubes.”

Stop Tubes

Stop tubes are placed internally between the piston and the rod end to provide greater distance between bearing surfaces, thus decreasing side-bearing loads.

Find the illustration of the cylinder in question and calculate the distance from the center-line of mounting holes to the centerline of the load, with the rod extended.

If this distance is more than 40″, a stop tube should be used. (1” stop tube for each 10” increment, or part thereof, is recommended.)

Reference the length of the stop tube, and then the length of the effective stroke.

Ex: SPH311 1 x 25 (eff.)
SP= 5” stop tube

Thus, this cylinder will have a 30” stroke that is limited to 5” by the internal stop tube.

There Are No Minimum Strokes

When the sum of the constant (ex: “A” on page 6 for Models 310 and 340) plus the stroke is less than the minimum dimension for that model and bore, an internal spacer will be furnished to limit the stroke to the value requested.

The 1-3/8” diameter rod has an area approximately one-half of that of a 2” bore cylinder and thus finds additional use in regenerative circuits. Except for the 1-3/8” (2:1) rod, which is noted in the dimension charts (pages 4 and 5), oversized rods have no effect on cylinder dimensions.

Ports

Oversize ports, or two ports per end, are available for extra-high-velocity applications. Ports may be obtained in positions other than those shown, at additional cost in each case, as may SAE ports

Magnetic Pistons

All of our cylinders can be supplied with magnetic pistons and reed or hall effect switches. Cylinder length will change slightly, please contact us for additional information