SUBFRAME REINFORCEMENT | WHAT IS IT AND WHY DO YOU NEED IT?
A roll-off subframe is an engineered frame design that is used to be compatible with roll-off trucks. There are different subframe styles available, a Standard Subframe or an ISO Subframe, allowing you to choose your own roll-off solution. While an ISO Subframe is designed to be used with an ISO/Land Sea/Shipping container, a Standard Subframe is commonly used to replace an existing frame design on a roll-off container or to convert equipment to be compatible with a roll-off system. Due to the different applications, the subframes have different builds. The ISO Subframe is manufactured as a standalone frame that locks the shipping container using ISO lock mechanisms located on the four corners of the frame. The Standard Subframe is a frame that requires reinforcement to the container or piece of equipment that it is paired with. Let’s focus more on the build of a Standard Subframe and the reinforcement needed to ensure safe operation.
A Standard Subframe is manufactured with 2” x 6” tubing long rails and comes in lengths ranging from 8-22’ long. Both subframes can be set up with a cable, hooklift, or combo style hookup, as well as the option to have the frame arrive raw steel, primed, or painted. On a hooklift style hookup for a subframe, the entire weight of the load is being lifted at a single location, the hook, to be hoisted on the hooklift truck. The A-Frame will need to be reinforced to the container or piece of equipment.
According to the Merriam-Webster dictionary, reinforcement is defined as “the action of strengthening or encouraging something,” and further explained as “something designed to provide additional strength (as in a weak area).” The most common reinforcement for a subframe would be to weld the frame to the container. Like what you would see when looking at hooklift roll-off container, there are four places for the frame to be welded in order to have a strong and secure reinforcement on a hooklift subframe:
A 36” hooklift subframe differs due to the height of the frame. Because of this, you will need to weld the top of the small hook box to the bulkhead cross tube on the container. A bulkhead cross tube appears on a container when the bulkhead is taller than the A-Frame. If there isn’t a bulkhead cross tube or bulkhead posts on a container, adjustments may need to be made to reinforce the A-Frame.
If you are not looking for a permanent reinforcement, some users choose to use a bolt-on solution. Custom plates can be made that allows you to bolt both the subframe and the container or piece of equipment. This plates will most likely be made by a local fabrication shop or in the users shop as they are not supplied by the subframe manufacturer.
If at any time the A-Frame of the subframe will not be reinforced or supported, it will need to be communicated to the manufacturer. This way, they will know to make accommodations to the subframe.
The reinforcement of a hooklift subframe to the container or equipment is a necessity for proper and safe operation. Failure to do so can result in damage and injury. Be sure to follow the four reinforcement locations or make the accommodations for best results.