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).
Stresscoat Lacquer test performed on a Phantom III wheel rim to investigate stresses produced by tyre inflation.
| Identifier | ExFiles\Box 96\4\ scan0173 | |
| Date | 29th June 1939 | |
| 356 To By from HPS{Horace Percy Smith - Experimental Factory Mgr}/B1. c. to Rm.{William Robotham - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to E/SGH.{Sir Stanley Hooker} PHANTOM III WHEEL RIM TEST. Stresscoat Lacquer Test. This test was carried out on a G.83717 rim, fitted with a 7" x 18" Dunlop Fort tyre, to instructions By.6/G.1.6.39, in order to investigate the nature of the stresses produced in the rim of a Phantom III wheel by inflating the tyre. Accordingly, with the tyre deflated, the rim of the wheel was thoroughly cleaned in various places round its circumference, the enamel being carefully removed. These parts were then polished and coated with stresscoat lacquers 668 and 669. At the time of coating, the temperature of the room was 15ºC and the humidity 75%. From the chart accompanying the lacquers it was observed that the correct lacquer specified for these conditions was 669. Two specially shaped strips of rolled aluminium were also given thin coatings of lacquers 668 and 669. The wheel and the strips were then left to dry for about 16 hours under identical conditions. On inspection after this period had elapsed, it was seen that both the lacquers had crazed considerably on the rim and on the strips. This was probably due to the fact that the atmospheric conditions could not be kept within the specified limits during the drying period. The rim and the strips were then cleaned, repolished and given two coatings of lacquers 666 and 667, again being left to dry for about 16 hours. No crazing at all took place. The tyre was then pumped up to the normal pressure of 35 lb./sq. in., the lacquer being inspected at intervals. No cracks were observed up to this stage. However, on increasing the pressure to 40 lb./sq. in., circumferential cracks were faintly discernible in the radius marked "A" (BL.2357 Sheets 1 & 2), whilst at 55 lb./sq. in. there was a definite full crack pattern in this area. The pressure was increased up to 100 lb./sq. in. as quickly as possible to avoid difficulties due to the plastic flow of the lacquer, but no further cracks appeared. continued. | ||