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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.

Cushion/Flow Control Location DiagramFlow 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

NET
AREA
OPERATING PRESSURE - PSI DISPLACEMENT
BORE ROD ACTION 50 100 150 500 750 1000 1500 2000 3000 Gal/In Cu Ft./In
5/8 5/16 PUSH .307 15 31 46 154 231 307 461 614 921 .0013 .0011
PULL .230 12 23 35 115 173 230 345 460 690 .0010 .0009
5/8 3/8 PUSH .307 15 31 46 154 231 307 461 614 921 .0013 .0011
PULL .196 10 20 29 98 147 196 294 392 588 .0009 .0007
1 1/2 PUSH .785 39 79 118 393 589 785 1178 1570 2355 .0034 .0029
PULL .589 29 59 88 295 442 589 884 1178 1767 .0026 .0022
1 5/8 PUSH .785 39 79 118 393 589 785 1178 1570 2355 .0034 .0029
PULL .479 24 48 72 240 360 479 719 958 1437 .0021 .0018
1 3/4 PUSH .785 39 79 118 393 589 785 1178 1570 2355 .0034 .0029
PULL .343 17 34 51 170 257 340 510 686 1029 .0015 .0013
1-1/2 5/8 PUSH 1.767 88 177 265 884 1326 1767 2651 3534 5301 .0077 .0066
PULL 1.460 73 146 219 730 1095 1460 2190 2920 4380 .0063 .0055
1-1/2 3/4 PUSH 1.767 88 177 265 884 1326 1767 2651 3534 5301 .0077 .0066
PULL 1.325 66 133 199 663 994 1325 1988 2650 3975 .0057 .0049
1-1/2 1 PUSH 1.767 88 177 265 884 1326 1767 2651 3534 5301 .0077 .0066
PULL .982 49 98 147 491 737 982 1473 1964 2946 .0043 .0037
2 3/4 PUSH 3.142 157 314 471 1571 2357 3142 4713 6284 9426 .0136 .0117
PULL 2.700 135 270 405 1350 2025 2700 4050 5400 8100 .0117 .0101
2 1 PUSH 3.142 157 314 471 1571 2357 3142 4713 6284 9426 .0136 .0117
PULL 2.356 118 236 353 1178 1767 2356 3534 4712 7068 .0102 .0088
2 1-3/8 PUSH 3.142 157 314 471 1571 2357 3142 4713 6284 9426 .0136 .0117
PULL 1.657 83 166 249 829 1243 1657 2486 3314 4971 .0072 .0062

Notes

Values of push and pull output are theoretical and are based upon the formula; developed force(push or pull) in pounds = net or effective piston area (sq. in) x operating pressure (PSI).

To determine the force at a pressure not shown in the chart add the values of push or pull for two or more pressures that equal the desired operating pressure.

Net areas given are in square inches and represent full bore areas, for push directions and annulus areas (bore area minus rod area) for pull directions. The displacement in gallons per inch represents the oil required to move the piston through one inch of stroke in one direction.

To determine the required oil delivery in GPM, multiply the gallons per inch x the desired piston speed in inches per minute.

The displacement in cubic feet per inch represents the FREE AIR required to move the piston through an inch of stroke in one direction, based upon an operating pressure of 80 PSI. the free air requirements at other pressures = the figures shown x (operating pressures + 14.7) ÷ 94.7.

To determine the required free air delivery in CFM, multiply the cubic feet per inch by the desired piston speed in inches per minute.