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).
Explaining the theory and fundamental principles of Hartford Shock Absorbers.
| Identifier | ExFiles\Box 51\4\ Scan033 | |
| Date | 10th February 1922 guessed | |
| 3. Theory:- In the following short description dealing with theory and action of Shock Absorbers, all technical calculations and unnecessary formula have been avoided to explain the general fundamental principles of the action of the Hartford Shock Absorbers. Consider any spring, figure 1, loaded with a weight "W". Call the position which the spring assumes under this weight the neutral position. Assume that as the spring moves down or up, there is no friction, either against the surrounding air or between the leaves or other parts of the spring. Suppose that the spring is compressed a certain amount and then released. What happens?. When the spring was compressed, energy was stored in the spring, and when the spring is released, it moves back to the neutral position. All the energy that was originally stored in the spring is converted into energy of motion of the weight, - that is, the weight has momentum and will carry the spring past the neutral position until all the energy of motion of the weight is used in stretching the spring. The spring will then move the weight back to the neutral position, and the weight will fly past the neutral position, due to its momentum. Note that no energy can be lost since we are assuming that there is no friction, and when the spring gets back to its original compressed position, it has just as much energy stored in it as when it was compressed originally. This oscillation, or up and down movement of the spring, will persist for ever, providing no energy is taken away from the spring in any way. But no such frictionless spring is possible. An automobile spring consisting of many leaves, rubbing on each other, has considerable friction, and when your car goes over a bump in the road, the up and down motion does not keep up for ever, but is soon overcome by friction. The energy stored in the spring before the oscillation of the spring, will stop. Imagine a pencil attached to the body of an automobile, so that the pencil will trace a line on a gigantic sheet of paper as the car is driven over a perfectly smooth road in which there is one bump. In order to formulate a simple case, we will assume that the bump is a permanent change of level, as shown exaggerated in figure 2. Taking the impossible case where there is no friction, the pencil would draw the curve representing the motion of the car body, shown in figure 3. Take the case of a car not equipped with shock absorbers, where the spring oscillation is overcome by the friction in the springs themselves, - the curve would be as shown in figure 4. Note that the height of peak "A" is somewhat reduced from its heighth in the former case, and that the oscillation rapidly dies out. By increasing the friction that the springs must work against, the rate at which the oscillation dies out, can be increased as desired, - figure 5. Cont'd. {John DeLooze - Company Secretary} | ||