With a design style that manages to create an extension spring function out of a compression spring, Drawbar Springs have a number of specific benefits. These apply in situations where - perhaps for safety reasons – the load must be supported even if the spring fails, for example, on a garden swing seat. Equally, the design protects against spring deformation in situations where a sequence of connections is being made when one or two springs will for a short time carry excessive forces until the installation is complete, for example, a swimming pool cover.
Drawbar Springs are assemblies in which the main spring will compress as the drawbars extend under an applied load. They are often capable of withstanding loads far in excess of the compression spring closing force and should be considered in applications where a positive stop of overload protection is required. Because of the Drawbar Spring’s characteristic as an extension spring with a fixed stop, potential overstretching is eliminated.
When a regular extension spring will undergo many cycles of deflection that will result in failure, compression springs fitted with a drawbar can be used to reduce the chance of catastrophic failure. These drawbar compression springs have the same properties as an extension spring and perform the same functions but with a fail-safe feature.
Lee Spring Drawbar Springs are suitable for use in many applications such as: supporting a porch swing/garden swing seat, attaching a tarpaulin or a pool cover, tethering a boat, tensioning fences or gates.
There are a wide range of material possibilities including carbon steels, alloy steels, stainless steel 17-7, 301, 302* and 316, carbon steel, phosphor bronze, hastelloy, inconel 600, 718 and x750, beryllium copper, elgiloy. Likewise, a matching selection of surface treatments such as: zinc plating which offers corrosion resistance, nickel plating for good corrosion resistance and good conductivity, black oxide, shot peening to reduce stress or fatigue, powder coating to give corrosion resistance and colour coding. Electro gold plating is also available to offer conductivity if used in electrical applications.