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).
Report discussing chassis and body interferences concerning crossmembers, hangers, and wheel housing clearance.
| Identifier | ExFiles\Box 14\8\ Scan292 | |
| Date | 23th June 1930 guessed | |
| - 3 - (a) We have to have a body crossmember - i.e. heelboard - at this location and by supporting the body off a crossmember rather than the sill will relieve the sill of torsional loads that a bracket on one side of the sill would apply. (b) This represents the furthest back that we are likely to require for the heelboard. (c) This reduces the overhang of the rear end to a minimum and from an inspection of SK-403 brings this maximum B.M. to the magnitude as the maximum reached further forward. We come now to the question of interferences. 1. Step Hanger - An inspection of DL-89 shows how the rear step hanger is impossible with any construction of this nature and sufficiently explains our reasons for asking for this to be changed as we did in our Btn-3 of June 11th. 2. Rear Spring Front Hanger - This would foul any sill deeper than 5-1/2". This is the point B on SK-403 which tells us that here the sill depth must not be cut down to less than 85% of the maximum. We are trying to work out a revised form of this hanger bracket as sketched in pencil in such a way we can still keep the maximum depth of sill at this point. I will let you have something on this later. On SK-402 we have taken a body of max. overhang at the rear. The effect of a shorter body will be to reduce the bending moment at the rear support and the point "A" of zero B.M. will move back toward s the point of support, and to increase the load at "B". On account of the movement of this point of low stress with body lengths it is not advisable to take full advantage of it and we think it is desirable to maintain the full depth of sill right up to the rear spring front hanger. (Handwritten note: max down due 13/7) 3. Wheel Housing Clearance. DL-89 is drawn up with a 60" track axle, maintaining the springs centered as at present. We have held the 21-1/4" dimension for clearance at the top of the brake drum housing. The axle is drawn in pivoted about the center of the opposite wheel, as I believe is still standard practice, and is deflected upward until one of the spring clip nuts strikes the frame. - In fact as drawn it shows about .250 interference and yet we still have a clearance of 1.300 from the brake drum cover plate to the housing. This certainly seems excessive, but since so many stabs have been made at this job, by Derby, we must accept it, as essential. This then suggests to us at once that the lateral suspension of the axle is entirely too flexible - either in side bending of the springs or torsion of the rear end of the frame, and would suggest that some investigation of this trouble might enable us to get more lateral stiffness and cut down this excessive clearance with a corresponding gain in the width of the rear seat. - continued - | ||