Fixed mounts that do not absorb force on the cylinder centerline comprise the third group of mountings to consider. They include side lug, side tapped, end lug, and endangle mounts. Cylinders in this group mount on one side or edge of the head and cap and, as a result, the mounting plane is not through the cylinder centerline.

For this reason, side-mounted cylinders produce a turning moment as the cylinder applies force to the load. If the cylinder is not well secured to the machine, this turning moment will side-load the gland and piston. Large-bore, short-stroke cylinders tend to sway on their mountings, especially side, end lug, and angle mounts. A general rule to avoid these side-loading conditions is to select a stroke length equal to at least 1.5 times the bore diameter.

Of all the side-mount styles, the side lug is the most reliable because mounting lugs are welded to the head and cap to form an integral unit at each end. Side-tapped mounts are popular in applications where cylinders must be packed side by side into a confined space with minimum center-to-center distances. Another narrow sidemount style is the end-lug mount which has lugs threaded to the tie rods. Thus the end lugs hold the cylinder together and act as a means of mounting. Because the end lugs are subject to compound stresses, this mounting style should only be used in light-duty applications.

Also, consider design of the machine frame used to support these cylinders, because stronger members are frequently required to resist bending moments for heavy loads and high-shock conditions. Side-mounted cylinders should be held in place with a key or pins to prevent shifting. A shear key or thrust key can be ordered for most cylinders in this group. Obviously, a keyway must be milled in the machine member to use this mount. The key and keyway provide accurate alignment and take up the shear load.

Side-lug mounts can accept dowel pins to secure the cylinder to the machine member. Pin both sides of the mount but not both ends. Varying pressure and temperature during operation can cause the cylinder to change length slightly. Therefore, it must be free to expand and contract.

Install the pins after the cylinder has been properly aligned. Locate the key or pins to take advantage of the cylinder’s elasticity. For shock loads in tension, locate the key or pin at the rod end. For shock loads in thrust, locate the key or pin at the cap end of the cylinder.

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