Heavy duty load brakes hold vehicles firmly in position once they have been raised. Brakes set automatically and are released only when power is applied to raise or lower the lifts. Redundant wedge locks ensure fail-safe operation. The wedge locks are independent of the lifting mechanisms and engage directly with the columns.

must be considered when specifying mobile lifting systems. Tires are designed for highway use and may not be equal in capacity to some available models of mobile column lifts. Load limits for the Interstate highway system which were set in 1975 are 20,000 pounds per single axle and 34,000 pounds per tandem. Some states allow 22,400 pounds per single axles on their state owned roads. While these load limits have remained unchanged, the capacity of standard mobile lifts has increased from its original 12,000 pounds per column to 16,000 pounds, and today several models rated at 18,000 pounds per column are available. This progression to higher capacities has been fueled by the notion that fewer columns can be used to lift heavy vehicles.

While nearly all of these new super capacity mobile lifts are ALI certified indicating they can handle their rated load, there is no corresponding certification for the tires. This is a particularly important when considering 18,000 pound capacity columns. A fully loaded tandem axle vehicle with a gross rear weight of 34,000 pounds could be lifted by a four column set of these lifts. The resulting load on each rear tire engaged by the lifts would be 17,000 pounds. By comparison, if 16,000 pound capacity columns were used, six columns would be required and the resulting load per tire would be reduced to 8,500 pounds. Whether tires are capable of supporting 17,000 pound loads is beyond the scope of this article. The issue herein is that the margin of safety for personnel who work beneath vehicles with heavily loaded tires is unknown and should be seriously considered.