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).
Steering and brake mechanism issues on the Springfield Chassis.
| Identifier | WestWitteringFiles\Q\July1927-September1927\ Scan044 | |
| Date | 8th August 1927 | |
| COPY. FROM R.{Sir Henry Royce} C.c. to BJ. WCR. HS.{Lord Ernest Hives - Chair} DY.{F R Danby} DA.{Bernard Day - Chassis Design} [all crossed out] RECEIVED AUG 10 1927 [stamp] ORIGINAL [stamp] R1/M8.8.27. [Handwritten:] X3682 X8430 X8991 X8420 X240. X3692 re. SPRINGFIELD CHASSIS. OY's visit, and the remarks of Springfield require some explanation. (1) STEERING. [Handwritten: X3682] It would appear that most of the trouble with steering comes about through the introduction of the large low pressure tyres. This, coupled with the naturally heavy load on the front wheels of a large car, demand a good deal of force to twist the wheels while the car is standing. We believe that with such heavy cars some of the steering gears will not make any attempt to change the angle of the road wheels. In changing the dia. of the worm from 1.8 to 1.6 so little alteration is made to the steering that we cannot believe it could be appreciated, and it is probable that the variation is due to the better bedding of the nut, and other things outside the dia. of the worm. However, so as not to be an obstructionist I agree to the modification. It should be remembered that if it is necessary to twist the wheels about while the car is stationary the load on the front of the car should be reduced to the minimum, and the tyres kept rather higher in pressure. For instance, on my own car the spare wheel is at the rear, and the front tyres (6.75 dia.) are kept at 30 lbs. per sq. in. in which case the 1.8 worm gives the best steering that I have ever used. My recommendation therefore is to do everything possible to reduce the load on the front road wheels, to keep the tyre pressure slightly higher, and not expect the wheels to move when the treads are badly worn, or on a road having a very adhesive surface. It is now realised that in the hands of certain people the steering wheel is dragged and held in one direction until the oil film gives way and sticking occurs. In other people's hands this phenomenon would not occur. With the quicker pitch worm the steering gear relieves itself of the pressure by running back between each effort of moving the road wheels. In our latest suggested experiments we are reducing the load on the worm and increasing the area of the surface for a given force to the road wheels. The result of these experiments will follow, but in the meantime my impression is that there is little to complain of in the .720 mechanism, the chief thing being the wish to move the wheels while stationary, and the combination of a very large tyre at low air pressure, having a long road contact, and too much weight on the front wheels. (2) BRAKE MECHANISM. [Handwritten: X8420] Regarding the clanking in the brake mechanism, the only shock we know of is one occurring when the brakes are suddenly applied, and the servo is made to act powerfully and suddenly on the brakes. This appears to have been (1) | ||