Pneumatic And Hydraulic Equipment Page 1103

PIVOTED CENTERLINE MOUNTS If the machine member moved by the piston rod travels in a curvilinear path, a pivot mount cylinder is the obvious choice. Pivotal mounts are available with the pivot points at the head (TF Mount), at the cap (TR & C Mounts), or centrally located at some position between the head and the cap (T mount). In most cases, a layout of the rod end path will determine the best pivot mounting style to be used. In general, pivot mounted cylinders with the pivot points near the head (TF and T mounts) can use smaller diameter rods without the danger of buckling than similar cylinders with the pivot points at the cap. This can be verified by consulting our column strength chart. There are times when a fixed mounting style might be indicated by an application but a pivot mount is selected to compensate for any misalignment that might occur if the misalignment is in one plane. Where misalignment can occur in multiple planes, the cylinder should be equipped with Sheffer UNI-LIGN accessories or with Spherical Bearings. TRUNNION MOUNTS Pillow blocks of ample size and rigidity should be provided and should be mounted as close to the head or (cap) as possible. Bearing should be provided for the full length of the trunnion pin. Pins are intended for shear loads only, not bending loads. SELF-ALIGNING MOUNTS should NOT BE USED TO SUPPORT THE TRUNNIONS SINCE BENDING forces can also be set up (See Fig.C.) Lubrication should be provided to the pins. An intermediate trunnion (T mount) can be located at any position between the head and cap (within limitations) at the time of cylinder manufacture, but cannot be easily changed once produced. The trunnion location (dimension XI) must be specified on the order. CLEVIS MOUNT All Clevis mount cylinders need provision on both ends for pivoting in one direction. A clevis pin of proper length and of sufficient diameter to withstand the maximum shear load generated by the cylinder at rated operating pressure is provided. Should a rod end accessory such as a rod eye or rod clevis be desired, select one with a pin size (or pin hole) with the same diameter as the clevis pin. You can then specify a rod end thread to match the accessory. Selecting the accessory on the basis of the rod end thread normally supplied can result in an expensive and unsightly mismatch, especially when the cylinder has a large oversize or 2:1 diameter rod. FIXED NON-CENTERLINE MOUNTS Cylinders with non-centerline styles of mounts tend to sway when under load. Relatively short fixed, non-centerline mounted cylinders can subject mounting bolts to large tension forces which, when combined with shear forces, can over stress standard bolts. High tensile cap screws are recommended. See Figure D. The rigidity of the machine should be considered when using cylinders with a non-centerline mount since stronger machine members are often required to resist bending moments. See Figure E. Fixed mounted cylinders should be held in place by keying or pinning. Cylinders with integral key mounts may be used where a keyway can be milled in a machine member. This type of arrangement takes up shear loads and provides accurate alignment of the cylinder. Shear keys should be placed at the proper end of the cylinder: at the head, if major loads are in thrust or at the cap if major loads are in tension. See Figure F. Only one end of the cylinder should be keyed. Dowel pins can be used instead of keys to help take shear loads and to obtain alignment. The side lug mount has room for dowel pins in the lugs. Cylinders may be pinned together at either end but NOT AT BOTH ENDS. TRUNNION FRONT STYLE TF TRUNNION REAR STYLE TR INTERMEDIATE TRUNNION STYLE T CLEVIS STYLE C SIDE FLUSH STYLE SF FIGURE D SIDE LUG STYLE SL END LUG STYLE EL FIGURE C SELF ALIGNING BEARINGS SHOULD NOT BE USED. FIGURE E FIGURE F CYLINDER KEYED FOR MAJOR LOADS IN THRUST. KEY ENGINEERING-MOUNTING INFORMATION S H E F E R Sheffer cylinders JHF Catalog [ Volume 7 ] (314) 427-0600 800-444-0522 (FAX) 314-427-3502 www. j hf.com 1103 Prices Subject to Change Without Notice John Henry Foster pneumatic and hydraulic equipment

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