Manual transmission pedal modules consist of an accelerator pedal, brake pedal and clutch pedal. The pedals, i.e. the entirety of the pedals in a vehicle, enable the driver to accelerate, decelerate and change gears. Automatic transmissions do not require a clutch device. The position of the accelerator pedal determines the opening of the throttle and thus the fuel-air mixture and the power output. Instead of a mechanical connection, the accelerator pedal and throttle valve are now connected via sensors and the control unit. When the brake pedal is depressed, a force is applied that moves the brake cylinder hydraulically, and the incipient friction of the brake disc and brake pads brakes the vehicle. The clutch pedal separates the frictional connection between the engine shaft and the transmission shaft and enables a gear change. Gear selector levers are used to select the gear ratio of motor and commercial vehicles. Changing the direction of travel or neutral can also be selected. Initially purely mechanical connections between gear selectors developed into purely electrical connections via the vehicle's CAN bus in modern vehicles. As an alternative to the gear lever in the centre console, steering wheel gearsticks were mounted on the steering column. Mechanical gear selectors, as used from the 1940s to the 1970s, are also used in a further development as electronic shift paddles in manually shiftable automatic transmissions. Other names for gear selector levers are gear selector lever, manual gear selector lever, gear lever, gear stick, gear lever or gear selector switch.