The limiting constraint in designing and fabricating these big ton spring supports was to maintain an overall height less than 15-3/4" and still allow the load table to travel downward during operation. Whereas a standard PT&P size 2-190 variable springs would have been sufficient to hold the load specified, the coil alone was taller than the space available at site. For this reason, a "big ton" design was implemented which utilized six smaller coils (2-130 size) working in parallel to produce the required load-carrying capability and spring rate.

All of the frame/housing components were made from carbon steel and supplied with an HDG finish. The travel stop rods were made of A-193 Gr. B7 material and were painted red. The slide plates sitting atop the load flange were made of polished A-304 stainless steel.

Both "big ton" assemblies are 30" wide by 30" deep by 15-3/4" tall. Overall spring rate is 3,600 lb/in. and each weighed approximately 1,460 pounds. The installed (cold) load = 14,800 lbs. and the operating (hot) load = 16,075 lbs. Movement from cold to hot = 0.354" down.

Tested in the load cell to insure proper operation throughout the entire working range of the coils, the "big tons" were then set to the cold (installed) load as specified.