From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Page discussing the cushioning qualities and installation of foamed latex in passenger car seats.
| Identifier | ExFiles\Box 132\3\ scan0230 | |
| Date | 9th January 1939 guessed | |
| - 3 - If a diaphragm or fabric support is used, the insulator is eliminated and the balance of the space is filled with the skeleton supporting frame. In all types of installations, the base coring of the foamed latex may be varied or eliminated to give additional support at localized points. Present passenger car installations are of two general types. The last mentioned combination type being used in regular seats and the reduced thickness all foamed latex cushions being used where space restrictions are severe. In this discussion, reference to detail dimensions or design of both the foamed latex cushion and the seat in general are intentionally avoided because of the wide variance in individual requirements. Actual service results in many fields indicate continued and increased usage of this material. No prediction on the future design trend is made but it is toward a better understanding in future development that the properties and possibilities of the material are discussed. Cushioning Qualities Of first consideration in seating are the actual cushioning qualities of the resilient units. With the reduction in car body accelerations resulting from improved chassis suspensions, probably the most important factor in comfortable travel is the ability of the cushion to conform to the contours of the human body and eliminate excessive unit pressures. Foamed latex has the ability to take relatively large local deflections and has the permanent resiliency common to all high grade rubber products. The use of foamed latex not only tends to reduce the spread between minimum and maximum unit pressures on the body but also the average unit pressure. This reduction is possible for several reasons. The material has a permanent molded shape and structure. The surface is resilient and distributes the load uniformly over the entire contact area. The original molded softness can better be retained after trimming because preloading at assembly to offset packing down in service is not necessary. This latter quality allows for an actual increase in contact area. Proof of these statements may be found in the following test results. A contoured form was depressed by a constant load into the surface of two cushions of approximately the same thickness and the area of contact measured. The contact surface of the foamed latex cushion was approximately 25% greater than that of a production cushion in which foamed latex was not used. Tests to check the actual surface pressures on the same two types of cushion constructions have been previously reported by Elden (1). A small rubber pressure bag containing electrical contacts was placed between the passenger and the cushion surface. Measurements were taken at three locations, - at the point of maximum loading directly under the trunk of the body, at the middle of the thigh, and at the front edge of the seat. The results for a typical set of cushions showed that both the variation in pressure at the different locations and the average of the three points measured were reduced approximately 50% in the case of the foamed latex cushion. | ||