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).
Testing and modifying a Lucas Governor due to sluggish performance and susceptibility to contact lever pressure.
| Identifier | ExFiles\Box 168\3\ img221 | |
| Date | 11th July 1939 | |
| To By c. to Da.{Bernard Day - Chassis Design} c. to By/RD. c. to Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/RC{R. Childs}/JH.11.7.39. re Lucas Governor to DB.{Donald Bastow - Suspensions}2327. On a previous test of this type of governor (see Rm{William Robotham - Chief Engineer}/RC.{R. Childs}9 JH.20.4.39) it was found that the unit was sluggish in getting off the mark, and we proved by removing the governor weight retaining springs that the fault could only be eliminated by modification of the weights and linkage. It was then found that the governor characteristic was to an appreciable extent, dependant on the amount of pressure exerted on the cam by the contact fingers. By exerting pressure on the contact fingers by hand while the distributor is running, it is possible to retard the ignition by 9 degrees. Subjecting the Delco-Remy and R.R. type governors to the same conditions resulted in a retardation of 4 degrees and 2 degrees respectively. The Lucas expert agreed that a modification was necessary and has since submitted a unit in which the weight linkage has been modified. We find that this modified unit is still sluggish in getting off the mark, the lowest speed at which automatic advance commences is 260 distributor r.p.m. Both the R.R. type and Delco-Remy type get away at 120 distributor r.p.m. which is the figure requested by Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} With a contact pressure of 16 oz. the Lucas governor is 2 degrees late, reducing this pressure to 12 oz. decreases this figure to 1 degree. Using the R.R. contact breaker we cannot go below 15 oz. without running into flinging troubles at high speed. The attached curves show the result of reducing the contact pressure to 12 oz. From the above it is evident that the Lucas governor is still too susceptible to contact lever pressure and further modification is necessary. we can carry on with the existing Lucas governors by making allowances for the sluggishness, when timing the engine, - - | ||