MTS Series 244 Actuators - Manual (Page 50)

Spiral Washers
The optional Model 601 Spiral Washers are typically used to provide fatigue-resistant connections between
elements of the force train and to minimize the effects of backlash. If the operating procedure requires changing
of preloaded force train elements such as the load cell or grips, the spiral washers must be readjusted.
The spiral washers are placed over the connector studs at each connection, and adjusted to place a constant
preload on the stud.
When cyclic loads below the tensile force level of the preload are applied to the connections, the load is
distributed between the surfaces of the spiral washers and the stud in a ratio of the relative stiffness of the
parts. The spiral washers have a large surface area and therefore greater stiffness. They react to most of the
load and keep the stress in the stud below its fatigue run out level. In addition to providing fatigue-resistant
connections, the spiral washers also minimize the possibility of backlash due to loose-fitting or worn stud
threads.
Force Train Components
Description Item
Compliant Material 1
Load Cell 2
50 Series 244 Actuators Product Information
Installation