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).
Technical report on camwheel machining, gear tolerances, and an investigation into gear distortion on a Bentley engine.
| Identifier | ExFiles\Box 136\1\ scan0179 | |
| Date | 3rd February 1936 | |
| contd- -2- Sft{Mr Swift}/Set1/NA{Mr Nadin}3.2.36. On the question of machining and gearcutting the camwheel, revisions ensuring fine limits being given to the side of the wheel, are being done to the list of operations. These revisions will unquestionably be to the good of the job, but it would be wrong if any impression is conveyed that this gear is generated in a careless or inefficient manner because after being placed upon an arbor it is clamped between plates. It should be pointed out that the centre bore location is not fixed, the parallel portion of the arbor being allowed to float so that the action of clamping brings the wheel into a natural position on the plates. The bringing of the gears and other parts to much closer limits will of course be welcomed, but it should be stressed also that the actual fitting of the cam wheel on to the camshaft is of the utmost importance. The limits of .002 permitted does not only apply to the camwheel itself, but it must not be more than this when fitted to the engine. We have, a few hours ago received a large bore Bentley engine from the Experimental Department with a request to quieten the gears. Following our usual practice, we clocked the camwheel immediately with the Starrett Indicator. We found the wheel to be running out of truth .008. Upon taking it off we found the cause not to be original distortion of the wheel, but that burrs were present within the bore. Near the key-way the metal was raised in two places as if in the operation of placing the wheel in position, the metal had been caught with the key and torn, the wheel in consequence being pulled out of truth on being fixed on end of camshaft. The wheel may be inspected in Mr. Goodall's Department. Whilst on the matter of the camwheel we would suggest that a .050 parallel portion be given at the small end of taper bore to avoid stress on the wheel if unduly pulled up. Regarding the condition of the Lapping Machines it should be appreciated that they are constantly employed every minute of the working week, running in gears to meet the production of 25 and more sets per week, besides those for Repair and Experimental. | ||