For a hundred years the House of Hope Presbyterian Church has formed part of the St Paul's Historic Hill District in Minnesota, and its neo-gothic facade is a familiar landmark to residents. In 2011, caretakers discovered blocks of limestone high above the streets that were crumbling away, threatening to bring decorative columns and gargoyles falling down, and so engineers turned to modern spring technology for the solution.
Two decorative pinnacles and a latticed stone parapet were in danger, and the engineers at first thought that the area's variable climate cycles of heating and freezing may have directly affected the soft limestone used within the church's facade. However, the damage proved to be too severe for this to be the explanation.
The problem lay within the structure. The limestone was anchored with long steel tension rods, as much as 26 feet in length, which acted as vertical vices rather than using smaller bolts and cornice pieces. As steel expands and contracts at a much higher rate than limestone, the tension rods had crushed the stone every winter, and in summer they had become loose enough to leave the pinnacles vulnerable to strong winds.
The edifice had to be rebuilt with a new support structure that would last, and which would allow for expansion and contraction with the changing weather. To do this, engineers employed disc springs to give the tension rods room to contract in the cold winters, and to maintain holding pressure in the hot summers. The principal engineer called this solution unique; and now that the project is complete the repair is expected to last another century.
Disc springs are more commonly used in automobile mechanisms, such as clutch and brake equipment, but they have been used in various machines for over 150 years. However this may well represent the first time that they have been used in this particular way.
European Springs & Pressings Ltd applaud and encourage such innovative use of spring technology, and our team of experts are able to advise on the development of specialist springs for a wide range of applications within any industry. From materials to design, and even manufacture, whether you need a standard spring or a specialist solution contact us at for more information.