Processes and apparatus for collection and delivery of voice messages. The cover includes a cover body and a packing member. Depending on how the steering vectors are defined, beam-steering or beam-forming can be achieved for each subband. A similar operation effect can be obtained alternatively by making a thickness of the spacer thinner in portions facing the intermediate cylinder bores and thicker in portions facing the end-portion cylinder bores. The linear trend of topsoil resistance pressure change with depth and the torque on the soil engaging implement are then used to determine both measured and predicted mechanical soil resistance to penetration applied to the point and the difference between the two values serves as an input for tillage depth adjustment. These signals, such as electronicelectricopticwireless signals, travel between the cab and the brake management equipment to apply and release the brakes, and may be much more compact and more easily routed or transmitted through a vehicle than conventional airhydraulic lines.