How the INA Shift Force Simulator is Helping to Develop the Perfect Gear Change

No two vehicles have an identical gear shift. For instance, a short shift travel is preferred in a sports vehicle, while a reduced level of shifting force is regarded as comfortable in a luxury limousine. There are hardly any vehicle test reports that don¡¯t make a reference to shift quality, and motoring journalists like to use adjectives such as ¡°firm¡±, ¡°notchy¡± or ¡°sloppy¡± to describe the feel of the gear shift, which plays an important role in the character of vehicles with manual transmissions. The technical background is complex. Gears are difficult or easy to engage or the engagement of a gear (feedback through the lever) is felt more or less strongly depending on specific force curves in the gear shift unit. The perceived force is produced mainly by a shift detent rolling over a multidimensional contour. The geometry of the contour can be freely selected within certain limits (lift, curvature). The gear shift lever is guided precisely by the shift gate, which enables the lever to be moved within the shift pattern at any time. This results in the driver feeling varying degrees of resistance on the gear shift knob when changing gears. The optimization of the gear shift in the vehicle on the basis of a qualitative force curve is no easy task even for experts. Specialists often find it difficult to estimate exactly what effect modifications to the level of shifting force and shift travel will have on the gear shift feeling in the vehicle. In many cases, the only solution is the costly and time consuming design of suitable prototypes of the gear shift unit. Engineers working at Schaeffler KG for the INA brand have been dealing with this problem for many years. They have developed the INA shift force simulator, a tool which significantly reduces the time required for optimizing shift quality and saves the need for costly prototypes. Once the customer has selected a number of potential force curves, the shift force simulator is programmed with these and the shift gate data. The shift force simulator is designed like a proper vehicle with vehicle seat, pedals, mock-up steering wheel and gear shift knob so that the customer can test almost any desired and calculated force curve directly and realistically as if in the vehicle. It is normally possible to reduce the numerous potential force curves to one or two options thanks to the simulator. The software, which is linked to a CAD program, uses the selected force curves to firstly calculate the appropriate contours ¨C these are then designed as prototypes for final appraisal. There are many benefits which pay off for the customer. Quantifiable advantages such as savings in time and development costs make the INA shift force simulator the ideal tool for optimizing the feel of the gear shift .