Abstract: A vibration isolation arrangement, for example for supporting a stretcher in an ambulance, comprises a lever (16) which extends between a base structure (6) and a support frame (4). The lever (16) can pivot about a fulcrum (30) and is acted upon by a spring (28). The fulcrum (30) is displaceable by an actuator (32) along a guide (34). Such displacement not only varies the stress of the spring (28), but also alters the moment arm (h) between the spring (28) and the fulcrum (30). When raising the support frame (4) to a predetermined level, the mechanism automatically adapts to the load on the support frame (4) to provide a constant natural frequency for the system, regardless of the weight of the patent being carried.