Reliability in a finished product can only be ensured when the designer has taken care to achieve the optimum solution to the sum of the needs of a particular set of circumstances. To follow this design philosophy, the designer must determine the function of the product, the length of time it will be required to operate correctly, and the amount of maintenance which is acceptable. When the necessary knowledge and information have been obtained from all available sources, then it is time to translate this concept into a product design.The engineering drawing is the message which communicates a reliable design to the production department so that it may be converted into a reliable product. The key to successful design is collaboration among as many designers as possible to maximize the amount of information and the number of ideas available, with one “manager of design” to coordinate their activities. This manager of design must be of the highest personal integrity since component reliability is impossible without personal reliability. Top designers should be encouraged to remain in designing.There are many examples of good and bad approaches to the design problem. Some historical examples offer insights into design practices, and a very fine example of cooperation and coordination of design efforts is given in the casting used in the British Leyland Range Rover gearbox.