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).
Comparative analysis of axle designs, focusing on half-floating axles and referencing models from Ford, Rover, Aston Martin, Bentley, and Lagonda.
| Identifier | ExFiles\Box 7\3\ X 602 Axle Rear-page23 | |
| Date | 24th September 1936 | |
| -2- We consider the most important innovation required in R.R. axle design the elimination of slack, with particular reference to the wheel drivers. This can be achieved with a saving in cost by adopting a half floating axle. The Ford V-8 3/4 floating axle is the simplest and cheapest example of this, weighing 120 lbs., excluding brake mechanism. They have no trouble from the taper and always remove a brake drum by splitting the taper in preference to removing the drum from its spigot by undoing a row of nuts. They are able to have the half shaft bevel solid with the shaft in a differential of small dimensions by taking the cornering thrust on the plain steel bearing between the bevel and the differential housing. In the other direction the thrust is conveyed to the other side by the half shafts butted on the differential pinion spider. They claim this latter feature to be entirely satisfactory. Rovers maintain that it is difficult to adjust, whereas Aston Martins say that considerable wear of the abutting ends takes place. Bentleys overcame the trouble by fitting hardened washers in the shaft ends. In view of our own troubles with wear of the diff. washers, we do not recommend adopting either of these features. Ford, like Rolls-Royce, has a cast centre box and detachable half tubes. Those tubes are of great interest. They are taper tubes of good material seam-welded and then electrically butt-welded to the forgings. The cost per car is 9/10d. material and 30 minutes labour. We intend to prove on the bump whether this is strong enough for our requirements. As regards half floating construction; about 90% of American cars have axles of this type. We do not think we need fear a half shaft failure. Rovers, with 1.7 overhang, as they told H.{Arthur M. Hanbury - Head Complaints}, have had failures at the thread beyond the bearing and at the taper keyway. They now use an electrically upset end onto which the wheels are fixed direct. This necessitates taking the cornering thrust on the diff. spider. We think the Rover material must have been inferior. All the old type Bentley cars had half floating axles 44 m/m.{Mr Moon / Mr Moore} under the bearing, and only one failure in bending has ever occurred on an 8-litre, after 82,000 miles. The overhang on these axles is very small. They have never had any trouble with the taper for the hub. Lagonda on their 2 1/2 litre have a 40 m/m.{Mr Moon / Mr Moore} half shaft with 2 1/2" overhang. | ||