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).
Correspondence regarding the design and inspection of 3 Phase Brake Magnets.
| Identifier | Morton\M6\ img096 | |
| Date | 12th November 1927 | |
| GM.121127.GC. 12th November 1927. F.H.Royce Esq., "ElmsteadHenry Royce's home in West Wittering" West WitteringHenry Royce's home town, Nr. Chichester. Dear Sir, We enclose herewith for your inspection, two further drawings of 3 Phase Brake Magnets. The first drawing No. B.154 is developed on the lines of your letters of the 3rd inst; and 5th inst; and embodies:- (a). 3" dia Dashpot. (b). Articulated connection to moving core. (c). Tight fitting coils intended to be pressed into case with oversized dummy of moving core. (d). Channel support holding top core and coils. (e). Holding together of case by 4 long studs. (f). Solid head to dashpot plunger. (g). Modification to terminals using bakelite base instead of bakelite or bakelite covered rods. (h). Insulated bolts for holding moving core. There are several features which I do not care for, the most important being:- (c). Tight fitting coils. Whilst I agree with your method for a large mass production of brake magnets, and particularly if we had only one voltage to deal with, then we could stock cases complete and in the event of coils roasting out, send a complete new top case with coils. Unfortunately, we shall not be able to consider only one voltage, and therefore we must use coils which can easily be taken out of the case and replaced even by customer at times, and without special pressing tools and dummy core. (f). I think Solid Head to Dashpot Plunger a mistake, and I think it rather hampers the fitting of the piston as we are bound to put the bulky bottom plate of brake magnet on before securing piston in position. We shall have to drill a 3/8" dia hole to attach to moving core, and the 3/8" dia pin can hold the top casting as well as the side plates. There is also the question of guides and a careful examination of other makes, all show that the moving core is not closely guided. Each moving leg has a total of 1/8 of an inch clearance, i.e. 1/16th clear on all sides, the chief object of these pressings being to ensure the moving core not rubbing actually on the coils. | ||