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 explanation of a central-point chassis lubrication system, its components, and operation.
| Identifier | ExFiles\Box 72\1\ scan0061 | |
| Date | 1st March 1925 guessed | |
| 2 CENTRAL-POINT CHASSIS LUBRICATION oil during the pressure period, which lasts for about 1 min. Distribution of the oil is controlled without the use of mechanism or moving parts, hence the equipment requires no attention whatever except for replenishing the oil supply at intervals of not less than 2 months and in some cases longer. To understand this distribution, assume for a moment that the line is solidly full, with all outlets tightly sealed. If the line is connected to a source of pressure, the oil will be at a uniform pressure throughout, since no flow occurs. Now if each outlet is opened the smallest conceivable amount, so that oil oozes out very slowly, a very slow movement of oil through the piping will take place. This condition is not very different from that in which the openings were closed and the pressure conditions throughout the line will not be greatly different. There will, however, be a small variation in pressure from point to point, caused by pressure being used up in producing the flow. It will be understood readily that the pressure losses will be small if this rate of flow is kept down so that the pressure at the more remote points will not differ greatly from the pressure at the source of supply. The outlets emit oil so slowly that the pressure variation in the line is well within 10 per cent of the average pressure, which, for the purposes of distribution, may be considered as being substantially uniform pressure throughout the system. FIG. 2.—DRIP-PLUGS or CONTROL OUTLETS. The One at the Left is Used at the End of an Oil Line and the One at the Right at an Intermediate Point of the Line, Like an Electric Light Bulb in a Simple-Wire Electrical System. Oil Passes From the Top Down Through an Axial Hole, 0.008 in. in Diameter, in the Plug in Which is Fitted a Steel Pin from 0.002 to 0.007 in. Smaller in Diameter Than the Hole, so that the Pin is a Meter-Relief-Valve-Ferrule With Soft Material That is Impervious to Oil. The Valve is Held against its Seat by a Phosphor-Bronze Spring and Prevents Leakage When the System is Not under Pressure. Cars designed for use of the system require very little piping, and mechanical front-wheel brakes, together with the wheel bearings and all attached steering mechanism, are readily oiled through internal channels. ENTIRELY apart from the engineering principles and details discussed herein, an oiling system whereby all parts of an automobile chassis requiring lubrication are supplied simultaneously with oil from a central point by pressure has a human interest in its appeal to the car-owner, who now either has to do a more or less dirty and irksome job of lubricating at frequent intervals or spend time and money to have it done for him. An advertisement that appeared recently in current periodicals showed the outline of a chassis and 58 points that required lubrication by hand, whereas Fig. 1 shows another chassis with 64 places supplied with oil by a central lubricating system. This system has been in successful use on several cars for a considerable period. Two of these cars have been run 25,000 miles and all have gone 15,000 miles or more, all without squeaks or showing appreciable wear; in fact, a well-designed self-oiled chassis must be run a great mileage before any wear can be detected. The illustrations presented herewith were taken to make the oil piping and its connections prominent but the impression should not be gathered that the apparatus is rather noticeable on the car. On the contrary, it is so inconspicuous that a self-oiled car is recognized chiefly by the absence of the usual oil-cups or grease-gun connections. Moreover, all parts of the system are well protected against damage by rough usage or collision. SYSTEM NORMALLY NOT UNDER PRESSURE Referring to Fig. 1, copper tubing of 3/16-in. diameter is used throughout for the pipe line, which is kept full of oil. Normally the oil is not under pressure, but when the lubricator is operated the oil in the entire line is subjected to a pressure somewhat in excess of 50 lb. and the control outlets emit predetermined quantities of DRIP-PLUGS CONTROL OIL FLOW The construction of a control outlet, known as a drip-plug, is shown at the left in Fig. 2. This fitting is threaded at its lower end directly into a bearing, the FIG. 3—CENTRAL LUBRICATOR OR OIL RESERVOIR This Is Mounted on the Dash under the Engine Hood with Its Outlet Connected to the Chassis Lubrication Oil Line. A Spring-Actuated Pump, Supported by a Stamped Bracket, Passes Through the Dash to the Base of the Lubricator. CENTRAL-POINT CHASSIS LUBRICATION 7 gravity through an internal tubular connection to the rear joint. Oil is supplied to the first joint by a drip-plug feeding the inside of a stationary annular lip, which in this case is pressed into the speedometer-drive gear-housing, whence it drips into an annular trough that revolves with the joint. Bearings of the brake linkage can be lubricated from a single source, in the way shown in Fig. 10. A stud is pressed into the lower end of the brake-operating lever, which is fed from the adjacent bearing, and oil from the stud flows through the hollow pull-rod and feeds a similar stud pressed into its lower end. A pipe brazed on the brake-stand lever conveys oil to the two lower pins. The joints are adjustable to take up side-shake, overlapping flanges exclude dust and the oil has a general tendency to wash dirt away, thus leaving the passages unobstructed. When a car is designed originally to take this system, only a little piping is required to distribute oil to all lubrication points. Oil flows to the rear axle through a torque-arm line which is connected to the pipe line on the side-member by a bridge of seamless tubing. A drip-plug lubricates the ball joint at the front end of the torque-arm and also its hinged support. A hollow spring-bridge is composed of two short helical coils of hard brass tubing, threaded over suitable studs, and the various motions of the front end of the torque-arm are accommodated chiefly by axial deflection of the two coils. The unsupported portion of this bridge is so light that it cannot be set into vibration. INGENIOUS LUBRICATION OF FRONT BRAKES Drip-plugs toward the front of the car feed mechanical front brakes and parts associated with them, incidentally dispensing with the need of a separate oil line to the front axle. Fig. 11 shows the construction by which the oiling of front brakes is accomplished. Oil from the drip-plug on the frame passes through the ball end of the brake-operating shaft, lubricating the ball surface on its way, and thence through the other half of the operating shaft, lubricating the telescopic joint between the two. Thence the path of oil to the camshaft bearing is through the universal-joint by suitably drilled passages, the joint being constructed to be dirt-excluding, with horizontal and vertical bolts alike. The camshaft bearing drains into a collecting pocket, whence the oil is finally distributed to the ball studs of the steering-rod and tie-rod arms. It is almost impossible for oil to reach the braking surfaces but, even if it did, minute quantities of such oil would have no effect on braking action. Once the oil supply is brought to the upper part of each knuckle, it can then be distributed to all of the adjacent bearings, which are really part of the knuckle, so that an oil line on the front axle is not needed. This use of the brake-operating shaft as an oil bridge does not greatly alter the conventional construction. | ||