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).
Letter from General Motors Corporation discussing harmonic balancers and engine design.
| Identifier | ExFiles\Box 25\3\ Scan219 | |
| Date | 10th December 1926 | |
| GENERAL MOTORS CORPORATION. 224 West 57th Street, NEW YORK. December 10, 1926. Commander W. Briggs, Rolls-Royce Ltd., 14-15 Conduit Street. Dear Commander: I received yours of November 25th only a few days after writing you - partially on the same subject of the harmonic balancer. You raise a number of points in your letter which are very interesting and deserve a more complete answer than I can personally give. I am, therefore, asking Mr. C. E.{Mr Elliott - Chief Engineer} Summers, who developed this device in our Research Division, to give you a complete answer. In general, I am satisfied that the harmonic balancer operates by setting up counter impulses at the speeds of the natural torsional periods of the crankshaft in question. Originally, I had a good deal of suspicion that friction was largely concerned in the operation but as the application of the device has developed from one model to another it has become apparent to me that the amount of friction and friction surface available is far too small to do what is done in the Lanchester type of damper. It is an interesting fact that a wide range of engine design is possible in motor car work, using the six-cylinder vertical type - in which not more than one critical period has to be considered. As a matter of fact, it is quite possible to design a very satisfactory engine of moderate speed type in which no critical period is of serious account and which can therefore be operated successfully without any damping device at all. The Pontiac engine of the General Motors line is a sample of the latter type of design. I believe that the ability to work out designs in this way is considerably due to the damping effect of pistons and connecting rods. Most engines of this latter type of design, if crowded a very little more by attempts to increase the horsepower at high engine speed, will reach into a very serious torsional period which can only be corrected by the use of some damping device. CONT: | ||