Double end threaded rod, sometimes referred to as U bol […]
Double end threaded rod, sometimes referred to as U bolt rod, is purchased from a manufacturer in order to bend U bolts. These U bolts may be bent in house by heavy duty truck repair shops, sometimes referred to as spring shops. They bend U bolts to size in order to fasten leaf springs onto trucks ranging from tractor trailers to dump trucks and snow plows. U bolt benders are commercially available, though some are not strong enough to bend 1-1/4" diameter rods, which are commonly used on larger Class 8 trucks.
Threaded rod is commonly sold in grade 5 when the diameter of the rod is 9/16" or below, and Grade 8 when the diameter of the rod is 5/8" or above. The threaded rods are normally sold in two inch length increments in order to end up with U bolts with 1" leg length differences. Threaded rod is manufactured with fine thread on each end, normally 6" in length. Lengths under 24" commonly have 3" of fine thread.
The rods have the thread rolled onto them in order to produce a stronger thread fit than would be found in cut threaded manufacturing processes. Cut threading removes metal and has less surface area in contact with the inside of the mating nut. Roll threading moves the metal, not removing it, and creates more contact with the mating nut. Normal industry practice involves chamfering each end of larger diameter rods to facilitate starting the nuts easily during final installation. In general, you will find chamfers on rods 9/16" and below.
If there is too much thread on a short rod, the rod may break when it is bent. This is especially true when the bend is over a square die, as the force applied to the corner is more than the rod can handle. You may find square bent U bolts break, but this is usually the error of the operator. Many places will bend a square U bolt in two operations as opposed to one, alleviating this problem. Normally, you will not find a round bent U bolt break, unless the elasticity of the steel is too low. Elasticity is what allows the steel to stretch as it is drawn around the bend.
Many smaller shops will merely order their din975.net threaded rod with springs and other hardware from distributors. While this may be easier, it is always more cost effective to buy the rods direct from the manufacturer. Even if this requires buying more threaded rods often, the cost savings and factory direct availability normally outweighs any inconvenience.