| Motivated by the present problem of wheel separations from tractor-trailers on Ontario's highways due to wheel stud failure, a study of current wheel stud tightening practices was carried out. In place of the present industry standard of torque wrench tightening, an alternative technique known as angle-torque tightening was investigated. The technique is based on stud tightening by turning its nut a fixed angle from an initial 'snug' position. Unlike torque wrench tightening, stud pre-load produced by angle-torque tightening is not influenced by the degree of friction between studs, nuts and clamped members.;Although the experimental results are promising, practical application of the angle-torque technique on the shop floor is not yet feasible. Before successful practice of the technique is possible, repeatable procedures for attaining proper stud seating in the wheel hub and for determining the 'zero-point' of nut rotation must be developed.;For testing, a load cell was designed to measure pre-load in single studs tensioned via nut tightening. Using the load-cell, experiments were conducted to determine the variation of pre-load induced when practicing each tightening method on studs with various surface conditions. Results indicate that the angle-torque method can reduce the standard deviation of pre-load by 39% compared to torque wrench tightening. |
