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).
Article on lubrication, detailing types of oil and grease for engines, chassis parts, and gearboxes.
| Identifier | ExFiles\Box 145\3\ scan0015 | |
| Date | 13th February 1934 | |
| Reprinted from The Motor February 13, 1934. LUBRICATION The Most Vital Part of Car Maintenance Types of Oil and Grease available for Engines, Chassis Parts and the Easy-change Gearboxes BY THE TECHNICAL EDITOR Image Labels and Captions: Left Diagram: A modern forced-feed engine lubrication system, showing the gear-type pump which delivers oil through pipes and passages to the bearings. The surplus is thrown off to serve the pistons and cylinder bores. Labels: DRIVE FROM CAMSHAFT, GUDGEON PIN, BIG END, CRANKPIN, JOURNAL, MAIN BEARING, PRESSURE GAUGE, MAIN GALLERY PIPE, GEAR-TYPE PUMP. Right-side Diagrams: (Below) The latest Vokes oil-filter. Labels: PERFORATED CONTAINER, CLOTH BAG, OIL ENTRY PIPE. (Right) Another type of oil - filter, the Auto-Klean strainer. (Left) The A.C. cloth - bag type of oil-filter. An oil-wetted air-filter (the Smith). Main Text: UNDER ideal conditions of lubrication the working parts of a mechanism would show no signs of wear; metal-to-metal contact would be eliminated once and for all. Conversely, it is broadly true that under practical conditions the degree of wear which occurs is a measure of the imperfections of the oil and/or the lubrication system employed. The car owner has no control over the design of the various systems by which the working parts of the chassis are fed with oils and greases. He can, however, ensure that every component shall receive not only an adequate supply, but also a lubricant best suited to the duties which it has to perform. Many Types of Lubricant The problem of ensuring correct lubrication is complicated by the fact that the modern car requires many different types of oil and grease if it is to give the best possible service. Thus, in many cases the three major components—engine, gearbox and back axle—each requires a different grade of oil, while yet another oil is needed to replenish the shock absorbers. Then again, the grease best suited to the universal joints differs from those which are recommended for other parts, such as the steering gear, the wheel-hub bearings, the water pump, spring shackles, etc. To this lengthy list may be added special oils for running-in and upper cylinder lubrication, penetrating oils for springs, a light spindle oil for the magneto or distributor, etc. It is the purpose of this article to give a brief survey of chassis lubrication as an aid to the owner-driver who is baffled by the wide selection of oils and greases available for these purposes. In addition to making a suitable choice, the car owner should know enough about the systems employed for serving the various parts with lubricant to maintain them in an efficient working condition. There is no doubt that by proper attention to these points the life of a car can be very greatly prolonged. Viscosity and Temperature Dealing first in general terms with the oils available, it is most important to remember that the “thickness” or “body” of a fluid—technically called its viscosity—varies to a very marked extent in accordance with temperature conditions. Viscosity is determined by allowing a definite quantity of oil (50 c.c.) to flow through a fixed orifice and measuring (in seconds) the time required. The device employed is called the Redwood Viscometer. This matter of viscosity is so important—and yet so frequently misunderstood—that a few figures may help to show the very big influence which temperature exerts. It is quite common for an engine oil, for example, to be ten times as viscous at a normal atmospheric temperature (70 degrees F.{Mr Friese}) as at the temperature which usually obtains in the sump of an engine (140 degrees F.{Mr Friese}). Thus the figures might be 2,400 seconds and 240 seconds respectively, while in the bearings themselves, at a temperature of 200 degrees F.{Mr Friese}, the viscosity might drop still further to about 80 seconds. In other words, such an oil will run through a bearing, under hot working conditions, just 30 times as readily as is the case when the engine is cold. Free Running When Cold Concerns engaged in the refining and blending of lubricants have attained great success during recent years in improving the viscosity characteristics of their products. It will be obvious that, provided an oil is sufficiently thick at the normal working temperature in a bearing, it is a very definite advantage that it should thicken up to as small an extent as possible when cold. Whether used in the engine, gearbox or back axle, such an oil will enable the parts to run more freely when the car is started in the morning, so reducing friction and loss of power. When a film of oil is separating the surface of a rotating shaft from the bearing in which it is carried, the relative motion shears the film; one may imagine a series of layers in the oil slipping one over another. We are, of course, dealing with microscopic dimensions, the thickness of with petrol and treated with a fresh supply of a light oil of the correct type. For many years the only filter employed in the lubrication system consisted of a metal gauze through which the oil passed on its way to the pump or to the bearings. Such filters can only remove relatively large particles, allowing fine abrasive grit to pass through without hindrance. Latterly far more efficient types of filter have been introduced which are capable of removing very fine grit. Some of these devices can be cleaned periodically, while others must be replaced entirely at the end of a set period of running—usually about 10,000 miles. In the most efficient systems the filter is placed in the main circuit so that all the oil delivered by the pump passes through it. Another plan is to place the filter on a by-pass circuit so that it takes only a proportion of the oil which is in circulation. In any case, it is up to the owner to look after the filtering device in view of its importance to efficient lubrication. LUBRICATION—VITAL TO CAR MAINTENANCE—Contd. Minor Chassis Parts THE motorcar manufacturers have made considerable progress during the past few years in the direction of reducing the number of minor parts requiring lubrication. For example, spring shackles are frequently fitted with rubber bushes needing no oil. An opposite tendency is noticeable for the road springs themselves; gaiters packed with grease were generally employed not long ago, whereas to-day the usual practice is to leave the plates uncovered and to lubricate them periodically with the penetrating oils now generally available at service depots. These oils are capable of entering between the leaves by capillary action and are usually mixed with colloidal graphite. Another method is to employ a device for separating the leaves and inserting grease. Then there is the new Woodhead spring in which channels for lubricant are formed in the leaves. High-quality greases are available for other parts, such as steering connections, where the small amount of movement and heavy pressure is apt to squeeze out an ordinary lubricant, leaving the surface dry. The kind of grease employed for any specific part is always worth special consideration, some being more tenacious (and more proof against water) than are others. Graphited greases are available for heavily loaded bearings. In cars where grease-gun nipples are grouped at convenient points and are connected to the various bearings by copper pipes, a heavy grease should on no account be employed, because this will not flow with sufficient freedom. A solidified oil, or a heavy gear oil, is usually recommended. For wheel hubs, on the other hand, a fairly heavy grease will “stay put,” whereas a thinner lubricant will run out when warmed up. Special greases are also available for the water-pump bushes. These lubricants have a high melting point, and can withstand boiling water. One-shot systems of lubrication, used on the more expensive types of car, greatly facilitate the lubrication of minor bearings. These may be automatic in action or a pump may be fitted for operation by the driver. Occasional inspection is desirable to make sure that each bearing is receiving its proper share of oil. These one-shot systems always incorporate metering devices, which, fitted adjacent to each bearing, regulate the amount of lubricant delivered through the pipe in question. For consistent results it is advisable to stick to one well-known grade of oil in the system. Lubrication Service Stations AS mentioned earlier in this feature, many different kinds of oil and grease are often required for the efficient lubrication of the modern motorcar. Consequently, it is small wonder that the owner-driver who has little time to spare is unable to devote the attention necessary to the maintenance of his car. In order to meet these conditions efficient lubricating service stations have sprung up in all parts of the country, where really sound service can be obtained. The owner-driver has only to take his car into one of these appointed stations, give instructions as to what jobs he wants carried out, and he can rest assured that they will be done rapidly and that the requisite grade of oil or grease will be employed. There are now something like 5,000 stations of this nature appointed throughout this country by the Tecalemit and Wakefield concerns, each of which is clearly indicated by a sign, the former bearing the Tecalemit plaque in red, white and blue, and the latter carrying the Castrol Lubrequipment flag. Motorists are rapidly becoming service-minded, which accounts for the increasing popularity of these service stations where, in addition to lubrication, other matters, such as brake adjustments, battery inspection, washing and so on, can receive attention. From the lubrication point of view, whilst at Castrol depots only lubricants of this name are employed, the Tecalemit depots can supply any particular brand that the motorist may demand. High-pressure equipment is used in each case to deliver grease to the bearings, ensuring that old, stiff lubricant and any dirt are forced out and are replaced by a new charge; further, in view of the fact that a hoist or pit is used, the operator can work under the car and can reach all the inaccessible nipples which might normally be overlooked by the owner-driver. For the lubrication of the springs a spray gun is used, from which device a penetrating oil can also be delivered to the underparts of the body and chassis to assist in the complete elimination of those rattles and squeaks which so frequently are impossible to locate and eradicate. The sump, gearbox and back axle can be drained, flushed out and refilled with the appropriate lubricant or, if topping up only is necessary, this can be done with ease and rapidity by piping oil with oil under light pressure from the main drum. Footer: Temple Press Ltd., 5-15, Rosebery Avenue, E.C.1. | ||