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).
Journal article discussing engine vibration, crankcase deflection, and various types of resilient rubber mountings for vehicles.
| Identifier | ExFiles\Box 126\4\ scan0142 | |
| Date | 1st April 1934 | |
| 140 S.A.E. JOURNAL (Transactions) ance, and still others must be eliminated at the source. We will deal with that portion of range roughness that can be affected by mountings. Three years ago, during a study of crankcase deflection on the dynamometer under fairly high brake mean effective pressure, we found by actual timing and measurement at high engine speeds that the plan view or transverse deflection of the case was in the form of an “O.G.” curve at the front bearing. This particular engine had a “bump” usually associated with high brake mean effective pressure. A metal mounting was installed at the front end that provided transverse freedom but restricted the up-and-down movement. This mounting eliminated the sharp O.G. in the case and the “bump”. This same bracket was installed in a 1931 car which had metal mountings, with very gratifying results. Transverse freedom was determined to be vital for range smoothness. This is a fact that has been brought home to us in many ways since, and we will endeavor to support this by other data. The General Motors Research Laboratory has developed a simple means of photographically recording movements of mechanical units under operation. Fig. 3 is an optical indicator which consists of a concave mirror mounted so as to have relatively unrestrained tilt in two directions. This corresponds to horizontal and vertical movement. A shutter mechanism electrically controlled was placed between the source of light and the mirror, which reflected a spot of light on a screen or film as desired. Two crankshaft revo- COMPONENTS OF A TORQUE Fig. 5—Illustrations Showing That the Angle between the Polar Axis and the Source of Vibration Causes a Couple about the Vertical Axis Through the Center of Gravity Fig. 4—Diagrams Indicating Actual Paths of Light Beams Moving with the Engine Vol. 34, No. 4 RESILIENT MOUNTINGS 145 Master Chevrolet Side-Support Designed to allow a universal motion in a plane parallel to the faces of the mount, controlled to close-rate limits, with a minimum deflection in a vertical plane, also controlled to close-rate limits. Construction: Two malleable-iron castings vulcanized in rubber. Chevrolet and Pontiac Transmission Support Designed to allow maximum side-deflection with no fore-and-aft movement, and small vertical movement. Construction: Rubber vulcanized to steel stampings. Tubular bushings inserted after molding. Standard and Commercial Chevrolet Side-Support Designed to cushion engine, replacing motor mounting bracket without change to adjacent members, allowing a restricted rocking motion and a minimum deflection in a vertical plane. Construction: Rubber boots assembled to the legs of a steel forging, enclosed in a steel stamping to which a steel-rubber retainer is projection welded. Chevrolet Passenger Front-Support Designed to allow a definitely controlled swinging movement within close-rate limits, with restricted vertical deflection. Construction: Malleable-iron casting and steel shell vulcanized in rubber. Chevrolet Commercial Front-Support Designed to allow a definitely controlled swinging movement within close-rate limits, with restricted vertical deflection. Construction: Two malleable-iron castings and steel shell vulcanized in rubber. Fig. 11–A Series of Inland Mfg. Co. Mountings April, 1934 | ||