Door Height – It is also helpful to know the distance from the top of the door to the end of the open door. This is an easy check to be sure the cable will be long enough. Standard cable lengths are 150”. Lengths of 110”, 125”, and 174” are also available and can be substituted in any standard system. Standard M-3 drums require 13” of cable to remain on the drum when the door is open. This is a safety precaution that ensures that the cable does not disconnect from the drum.
Header Width – Width of available headroom inside of the trailer. This determines the length of tube in the spring assist.
Frame material of trailer – Spring assist systems are built with either steel or aluminum weld brackets that attach to the header above the door frame.
Ramp door hinge style – M-3 spring assist systems are designed to be used on doors with pipe-style hinges attaching the ramp door to the trailer frame. Spring-type hinges should not be used with M-3 spring assists as they alter the physics of the door, and you will not achieve satisfactory lift.
Please use the following site RampDoorSprings.com to help us size your system. Fill in the relevant information and send it to us. We will respond with a system that will meet your needs.