The present invention is a hill holder device for a vehicle manual transmission. This includes a selectable bidirectional clutch which is coupled to the output shaft of the transmission box. The selectable bidirectional clutch has an inner race secured to the output shaft of the transmission, and an outer race secured to the vehicle transmission case. More particularly the present invention relates to a mechanism that prevents the vehicle rolling back in an ascending grade, after the braking.

The direction selecting mechanism consists of forward, neutral and reverse mode. The present subject matter describes a hill holder device for an automotive vehicle that includes a selectable bidirectional clutch. The purpose of the present invention is to prevent the backward motion of the vehicle when it attains zero velocity while travelling in an ascending grade. Another purpose of the present invention is to prevent the forward movement of a vehicle in a descending grade when it was supposed to move in reverse direction. The present invention avoids the discomfort for the driver while accelerating the manual transmission vehicle from rest when parked in an ascending grade. The present invention includes an electronic control system which will automate the selection of modes namely forward, neutral and reverse mode. In the electronic control system, the different operating parameters were measured by the different sensors and they are given as input signals for the Electronic Control Unit (ECU) which will process the signal and the processed output signal is given to the actuator i.e. the stepper motor, which will change the appropriate mode of the hill holder device.

When the hill holder shifting lever is operated in the forward mode, it causes the release cage to have a helical movement about the axis of the shaft. The helical movement of the release cage causes the plurality of rollers to cause wedging action between the inner and outer race. Thus the rotation of the shaft is prevented in one direction and thereby preventing the backward motion of the vehicle. Similarly when the hill holder shifting lever is operated in reverse mode, the vice versa of the above operation takes place and the forward motion of the vehicle is prevented when the vehicle is stopped in a descending grade. When the hill holder lever is operated to the neutral mode, the hill holder mechanism become inactive and provides free movement of the vehicle is both directions. Latching action is provided by the Spring and Ball arrangement.

According to the inclination of the vehicle and the position of the gear shifting lever, the sensors measures the corresponding signals, process the measured signal and actuates the stepper motor for the purpose of changing the mode. The mode of the hill holder mechanism can be automatically selected without the drivers aid. In case of any emergency, the mode selecting mechanism can be switched off by the switch provided in the ECU. This switching off of the mechanism causes the hill holder shifting lever to shift to the neutral mode.