NO-BACK DEVICE AND METHOD FOR DETERMINING THE APPARENT OPERATIONAL INTEGRITY OF A NO-BACK DEVICE

摘要

This invention provides an improvement in a no-back device (20) having a ball screw (21 ) connected to a variable load of reversible polarity (± L) and having a portion penetrating a housing (24). The device includes a braking mechanism (29) acting between the housing and the ball screw for producing a force that resists movement of the ball screw in the direction of an 'aiding' load, but does not substantially resist movement of the ball screw in the direction of an 'opposing' load. The improvement broadly includes: a first spring (43) acting between the housing and the braking mechanism for exerting a first preload force (Fl ) on the braking mechanism for simulating the application of an external load on the ball screw in one of the directions; whereby the apparent operational integrity of the no-back device may be checked when no external load is applied to the ball screw.