In earlier years, hydraulic systems were used as a means for removing the stress from structural members of bridges for effecting repairs and also for replacing beams. As many as four or five bulky low-pressure hand pumps and jacking ram setups were used to relieve stress in the beams that needed replacement. Labor costs were high and there were no accurate means of recording the pressures.
In recent times, modem hydraulic systems have been designed, with capacities to locate several 100 tons rams on the bridge structure. Only one portable pump is used to actuate all the rams by the use of a special manifold, thereby simplifying the operation and making it easier to remove the stress from the members that need replacement.