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).
Complaints and findings related to 20 HP dynamos from four different chassis.
| Identifier | ExFiles\Box 57\2\ Scan100 | |
| Date | 18th August 1927 | |
| To EY. from EFC. c. Mr. Brock. X578300 EFC4/T18.8.27. 20 HP. DYNAMOS. - COMPLAINTS. No.114 Ex Chassis 57.S8. This is a 29 segment machine of a comparatively early type with an early brush setting of 120°, giving rather too large an output. The micas were noted to be flush with the top of the segments. The control brush had been sparking badly. We attribute the running of the solder to the combination of the two facts - control brush position, and flush micas. The control brush is now tight in its holder and may have helped the failure of the machine by being so before failure occurred. No.156 Ex Chassis 53-S9. This is a 29 segment machine. Apparently the control brush has been moved outside to increase the output, as the angle is 116°, the control brush carrier having been cut away to enable this to be done. <strikethrough>This would sufficiently account for the running of the solder.</strikethrough> This, and the fact that the mica is not very well undercut, will account for the running of the solder. No.299.Ex Chassis 49-G4. This is a 29 segment machine. To all appearances the control brush has been moved since the machine left these Works. Its present angle is 113° which would give far too large an output for satisfactory working, resulting in the throwing of the solder. The commutator is black and some of the segments are burnt, though the micas are duly undercut. No.497 Ex Chassis GA.21. This is a 29 segment machine. The commutator solder is not thrown on this machine. We have run this machine and it has charged satisfactorily, but we noticed that the motion of the armature was opposed by some frictional resistance which apparently is due to end thrust. The appearance of the commutator and brush holder and <handwritten>bearing</handwritten> bracket on this machine is that some foreign metallic body has become lodged to make contact with these items, and arcing has taken place and caused the brush holder to be burnt. In addition to this, the machine has been dis-assembled outside, because we have noted that the commutator end bearing retaining ring has been put in the wrong way round. It would appear to us that the failure of this machine is entirely the customer's concern. We return the machines to EY. EFC. | ||