These mechanisms often create a right angle change in direction; this is the case in helicopters and rotary mowers. Each gearbox is built for a specific purpose, which means there is a specific gear ratio; and this ratio supplies the required level of force for that task and is fixed. The only adjustment that can be made after the gearbox is constructed is one that slows an increase in shaft speed and a corresponding torque reduction.
Gearboxes are constructed using a variety of materials, most often steel-based metals. The most common materials include brass, aluminum, stainless steel and iron. Some kinds and shapes of gears, such as spur gears may be made from less durable materials such as nylon and polycarbonate. The type of material used for the gearbox is directly related to its performance. More durable materials are able to resist the power of stronger motors and offer larger reduction in torque. Less durable materials work best with lower power motors.
Teeth alignment also has implications in regard to suitable applications. Gearboxes with straight teeth are employed in low-speed applications while those with helical teeth can be relied on in high-speed applications due to their strength and the fact that they offer more efficiency in terms of torque reduction.
Wind turbines are good examples of large scale gearboxes. The rotation of the turbine is very slow, and with a large amount of torque. The power is translated into the electricity generator, which has lower torque and much faster rotational speed. Wind turbines contain several gears and stages, so the generator can offer consistent output regardless of fluctuation in the turbine’s rate of rotation. Another obvious application of a gearbox is their role in automobiles. There are three main kinds of transmissions- manual, automatic, and continuously variable.