Although M-3 offers both single and dual systems, the dual system is recommended on doors weighing 120# or more. The dual-spring system offers greater flexibility when balancing a ramp door. Safety is another key issue. Since both springs are mounted on a common shaft, if one should happen to break the second spring is still loaded. This will not keep the door from falling but will slow the rate for descent.
A description of our standard dual spring system follows:
- Standard tube length for 8’ and 102” trailers is 96”. Tube length for 7’ wide trailers is 81” and 5’ wide and 6’ wide trailers are provided with a 66” tube and a single spring.
- Standard dual spring weight is 160# for 8’ wide and 102” wide trailers. We recommend 120# dual spring systems for 7’ wide trailers and a single 80# spring for 5’ wide and 6’ wide trailers.
- All systems are provided with 5” diameter cable spools unless additional height is required. At this point we will go to a 6” diameter spool to allow for more cable. Please call for quotation on systems requiring additional height.
- We also stock 185#. 205# and 250# dual spring systems. Prices quoted above are for systems to 205#. 250# and above require a special quotation.
- For orders of 25 or more, systems will be crated at no additional charge for LTL shipments. Please specify your choice of carriers.
- For orders of less than 25, the spring systems (to 205#) will be packaged two per box and shipped UPS. Two spring systems (to 205#) can fit in each box. Spring systems over 205# are shipped one per box.
*Door weight is established by simply lowering a finished door onto a bathroom scale before any lifting mechanism is installed. We refer to this as “springing weight”. By weighing a finished door we can more accurately balance the door.