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).
Detailed description of the central-point chassis lubrication system, its components, operation, and an analogy to a single-wire electrical system.
| Identifier | ExFiles\Box 72\1\ scan0063 | |
| Date | 15th October 1925 guessed | |
| 4 CENTRAL-POINT CHASSIS LUBRICATION FIG. 8—CONSTRUCTION OF DIRT-EXCLUDING SPRING-SHACKLE Lateral Travel of Dirt Is Prevented by Overlapping Parts of Splits, Links and Bushings and by Felt Ring-Washers, as Shown at the Ends. The Two Bolts Are Identical and Interchangeable. At the Right Is a Tension Shackle in Which Oil Is Fed to the Top Bolt without the Use of Flexible Connections or Extra Parts. A Drip-Plug Is Formed integrally in the Link by Drilling a Long Hole and Inserting a Pin a Few Thousandths of an Inch Smaller. A Groove around the Lower-Bolt Bushing Conveys Oil to the Top or Loaded Surface of the Lower Bolt, Whence It Flows through Continuous Oil-Tight Ducts to the Upper Bolt, Which Has a Groove at the Top for Exit of the Oil. ing to which it is applied or of the location of the bearing on the car. The drip-plug shown at the left in Fig. 2 is used as the terminal of a line, as at the ends of the frame, but when it is desired to carry the line past the point to be oiled, a drip-plug in the form shown at the right in Fig. 2 is used. In this the flow-controlling elements are in the stem of the T and oil flows freely through the head of the T to the line beyond. Such T drip-plugs are mounted on spring-shackles and in various accessories on an engine that are lubricated readily from a single line using this type of plug. CONSTRUCTION OF LUBRICATOR AND PUMP Fig. 3 shows the lubricator, mounted on the engine side of the dash, with its single outlet connected to the chassis lubrication oil line. A spring-actuated pump, supported rigidly by a stamped bracket, extends through the dash so that its handle is in a convenient operating position, as shown in the drawing in section of the lubricator and pump assembly in Fig. 4. Oil poured into the filler-opening at the top passes through a fine-mesh gauze bag into the upper compartment of the tank, then filters through the dense felt diaphragm at the bottom of the tank and fills the spaces below, while any air beneath the felt escapes through two vent tubes. A pair of drilled holes, shown in dotted lines, communicate between the valve-chamber and the pump or gun cylinder, and when the piston is pulled out its full stroke about a tablespoonful of filtered oil is drawn from the chamber into the gun cylinder. Upon releasing the handle, the spring pushes the piston down and the backward flow of oil around the inlet-valve closes the valve. As the chassis oil line is solidly full of oil, the oil pressure instantly rises to its full value and persists throughout the stroke. A spring of great free length and under strong initial-compression is used, hence the oil pressure remains constant throughout the stroke within 10 per cent of its mean value. At the lower end of the piston is a self-aligning extension which seats tightly at the end of the stroke on a leather washer, sealing the inlet from the gun and also the outlet from the gun to the line. FIG. 7—METHOD OF OIL DISTRIBUTION TO KNUCKLE AND STEERING CONNECTIONS WITHOUT USE OF SWIVELS The Oil Pipes Are Short, Protected and Concealed by the Wheel When It is in Place. Oil is Conveyed from the Ball Stud on the Wheel Knuckle to the Ball Stud on the Steering-Gear Lever through the Drag-Link. All Ordinary Assemblies and Adjustments can be Carried on without Regard to the Oiling System and the Mere Assembling of the Parts Forms the Proper Oil Ducts. The piston will ordinarily descend in about 1 min. During this time a small amount of oil might leak up past the leather piston-cups and eventually accumulate but to avoid this four holes are drilled in the gun just above the upper end of the stroke to furnish a drain for such oil into a sleeve surrounding the lower part of the cylinder and thence to the engine side of the dash. HOW AIR IS ELIMINATED FROM THE SYSTEM It is obvious that high and uniform line-pressure contributes to uniform predetermined distribution and makes negligible any small commercial variations in the valve-opening pressure of the drip-plugs. Such line pressure, which is attained readily when the line is solidly 5 CENTRAL-POINT CHASSIS LUBRICATION filled with incompressible oil, is affected unfavorably by appreciable quantities of air in the line; therefore the apparatus is arranged to avoid the introduction of air, even when the tank is empty. In this condition there is no longer enough oil to close the inlet-valve; consequently no pressure can be developed and, as the inlet-valve remains open all the while, the piston can merely draw up a charge of air from the valve chamber and return it promptly thereto, without forcing either oil or air into the line. Incidentally, the rapid descent of the piston gives the driver notice that the lubricator tank needs filling. When the gun is used to fill an empty line, the first stroke of the piston discharges oil into the line but the bore of the line is so small that air and oil will not pass each other, the air beyond the oil is compressed slightly. There would be a tendency for the gun and part of this oil back out of the line the next time the handle is pulled were it not for a loosely-fitting ball-check valve in the gun outlet which serves only to impede such return flow and plays no role in the normal operation of the system. As more and more oil enters the line, the air beyond is compressed into the ends of the line whence it readily escapes through the various drip-plugs, which offer little resistance to the exit of air. Therefore, to remove the air completely and fill the lines solidly with oil when new and the lubricator are empty, it is only necessary to fill the lubricator with oil and operate the handle 10 or 15 times. From this it will be seen that if a section of pipe is replaced at any time, thus introducing a long bubble of air, a few strokes of the gun will cause this air to escape through the nearest drip-plugs and the line will resume its normal oil-filled condition. The line can be disconnected from any drip-plug, or a section of pipe replaced, without material loss of oil, because the gun piston seals the inlet to the line at the end of its stroke and the relief valves in the drip-plugs prevent reverse flow through them, so that air cannot enter the line at any point and it is plain that oil will not run out anywhere if the line is opened. It may be pertinent to remark, since this lubricating system uses oil, that oil appears to be the best lubricant for chassis wearing-surfaces when it is applied at sufficiently short intervals. Grease squeezes out from the wearing surfaces under load and does not flow back, whereas an oil-film, if broken, is at once restored and creeps by capillarity to whatever parts are in wearing contact. FIG. 9—A METHOD OF OILING BOTH UNIVERSAL-JOINTS Oil Is Admitted through the Drip-Plug at the Lower Rear of the Transmission Box and a Stationary Annular Lip, Whence it Drips into an Annular Trough That Revolves with the Joint. When the Joint Stops Revolving in the Position Shown, a Small Quantity of Oil Runs by Gravity through an Internal Tubular Connection to the Rear Universal-Joint LIKE SINGLE-WIRE ELECTRICAL SYSTEM An analogy exists between the system here described and the single-wire system of electrical energy distribution. The high-resistance drip-plugs correspond to the high-resistance incandescent lamps and the low-resistance pipe line corresponds to the low-resistance copper wire. A lamp can be placed in the electric circuit at any desired point merely by running an appropriate wire from the main lead to the lamp and thence to ground. Similarly with the oil system, a drip-plug can be located anywhere on the chassis and merely connected to the nearest oil-lead with the shortest convenient tubing. The constant pressure of the oil system while the piston is descending is analogous to the constant voltage of the electric system, and the function of the gun as a generator of oil pressure is like that of the generator that generates and maintains the electrical pressure. The only considerable difference in the analogy between the two systems is that the high-resistance filaments in the lamps operate at such a high temperature that their life is limited, whereas the drip-plugs, not being subjected to any destructive effects, do not wear out in use. This analogy may help to show to those who are familiar with voltage drop in electrical circuits that the distribution of oil is not affected by temperature so long as the oil remains fluid, and as to this, oil that remains fluid at a temperature as low as —20 deg. fahr. may be had for especially cold climates. Although the viscosity of lubricating oil varies enormously with temperature and may be 10 times greater in cold weather than on a hot day, the distribution of the oil nevertheless always remains the same, because the resistances of the various parts of the system bear a fixed relation to one another. Regardless of temperature, the operator pulls out the FIG. 10—SINGLE-SOURCE LUBRICATION OF BRAKE LINKAGE The Brake-Operating Lever Is Fed from an Adjacent Bearing and Oil Flows through the Hollow Pull-Rod and is Led from the Lower End through the Pipe on the Brake-Band Lever to the Two Lower Brake-Band-Lever Pins. Joints in the Rods and Levers Are Adjustable To Take Up Side-Shake and Overlapping Flanges Exclude Dust. | ||