| 摘要 |
A modular sub-frame comprises an upper portion, a lower portion and an intermediate shock absorbing member. The upper portion is a steel fabrication for mounting to the chassis and the lower portion is a light-weight metal, e.g., aluminum, casting or castings for mounting to the steering components, whereby these two portions are separated by a vibration-dampening bushing. The lower portion of the modular sub-frame may be formed as a one-piece cast member or a multi-piece casting design where the casting members are jointed by bolts or other fastening means. In the multi-piece casting design, the front and rear bulkhead castings are the same identical part as are the top longitudinal members to provide interchangeability among the various components. By splitting the sub-frame into two parts, the top part can be isolated from the bottom part to reduce noise transmission from the sub-frame to the chassis, while maintaining the necessary rigid positioning of the suspension control arms and steering system. Also, the top part of the sub-frame can be readily revised to adapt to various chassis configurations without having to revise the bottom part of the sub-frame. With this invention, the lower half of the sub-frame can be highly tooled for low cost and improved dimensional reliability. The upper half of the sub-frame can be tooled with a lower volume manufacturing process to save on capital investment. The design of this invention adds flexibility for various chassis configurations while maintaining a constant suspension mounting framework.
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