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 chassis lubrication methods, comparing oil and grease, with illustrations of various oiling systems.
| Identifier | ExFiles\Box 76\4\ scan0142 | |
| Date | 28th February 1918 | |
| AUTOMOTIVE INDUSTRIES THE AUTOMOBILE Page 441 [Image Caption: Oil cups on spring bolts and steering connections of Kissel car] the oil, even if the oil is dirty or if dirt enters the brackets and cups when being filled. Under the action of vibration and the movement of the lubricated surfaces the oil feeds slowly and regularly whenever the machine is in motion, but stops when the machine stops. This renders every bit of bearing surface continuously effective and prevents wear, squeaks, rattles and rust. The same oil used in the engine can be used in cups or brackets. This insures a good lubricant, and one which is light or heavy as the weather is cold or hot. So little oil is used that the expense is very small—less than grease when grease is applied as often and as carefully as it should be. The cups and pockets can be easily and quickly filled, and it is not a messy job; they can also be cleaned with gasoline and a squirt gun. Control of the Feed The main disadvantage is that at some points the oil is apt to feed more freely than necessary and coat the surrounding parts, unless care is taken to get wicks of the proper material and properly fit them in the holes. Rapid feed would be particularly objectionable from a passenger car standpoint, but care in design and fitting will obviate this. Cotton wicks and wicks loose in the drilled holes feed quite fast. Felt wicks, especially when snugly fitted, reduce the feed. If a very fast feed is desired a couple of fine wires, twisted and used as a wick, will give a surplus of oil at the expense of more frequent filling of the cup or pocket. [Image Caption: Oil cup on Packard governor housing] Where there is a great deal of vibration, as on axles, the rate of feed is accelerated. This is also the case where there is a great deal of motion between the lubricated surfaces, as is often the case with front spring bolts. The location of the final outlet hole to the bearing surfaces, too, has an influence on the feed, which is slower when this hole opens on the load side of the pin than it does when it opens on the free side. [Image Caption: Oil cup on Packard brake comshaft raised to convenient height] Feeding Oil by Wicks Objection has been made to feeding oil by wicks in cold weather, on account of the increased viscosity of the oil. It is true that the flow will be reduced if some means is not taken to offset very severe weather; but the system lends itself remarkably well to this condition, as the oil can be thinned down with kerosene. If engine oil is used at the chassis points, lighter oils are commonly used in cold weather, anyway. The lubrication afforded by grease in very cold weather is almost negligible, because it is almost impossible to force the grease to the bearing surfaces. In all trials of the magazine system that have come to the writer’s notice, its reliability, efficiency and durability have been well proven. The upkeep cost is practically nil. Operating cost and attention are reduced to a minimum. The first cost of brackets is somewhat greater, but there is a saving on fittings, so that the net cost is a little more than the old grease cup system of lubrication. For trucks the increased cost is not important, compared with the advantages secured. This should also hold for passenger cars, but up to the present the writer knows of no applications in this field. The improvement and modification of the details of design will obviate objection to this system as a production proposition, for it is toward simplicity and not complication, and it is susceptible of considerable development as to detail. The magazine system is applicable to the front axle, spring bolts and shackles, steering gear, starting crank, fan, pedal details, etc., and it lends itself to what might be called series lubrication—the seepage or surplus oil from one bearing being led to another and thence to a [Image Caption: A series feed from a wick oiler. Oil is supplied to the thrust bearing, the screw and nut, the trunnions and rocker shaft of the Ross steering gear, and the slight leakage is conveyed by a spiral channel on the steering arm to the ball joint. A branch feeds the pedal shaft bearings and the leakage goes down to the clutch release lever and oils its clevis] Page 442 [Image Caption: Upper right-hand corner—Oil spring bolts on Franklin car, filled with waste. Below—Oil cups on steering knuckle and spring bolts of Premier] [Image Caption: Oil cups with spring-retained caps on spring bolts of new Nash car] dictments. It is a splendid dirt carrier, and the methods of handling it expose it to dirt at every turn. We are all familiar with the open grease pail in garages, and with the dirty grease paddle which is scraped over the edge of the pail. We all know of dirty fingers lending their share to the contents of the refilled grease cup, which often catches no small portion of the dirt accumulated on the outside edges of the cup or its stud. Another important consideration in the use of grease is that most greases are full of inert matter, which makes them more or less stiff and heavy, but which has a negative qualification as a lubricant. The heavy body of grease is commonly thought to give them greater capacity for maintaining a lubricating film between the wearing surfaces, but this is not so, for in almost every case the stiffer the grease the poorer its lubricating value and its load-sustaining qualities, the inert filler acting as much in the nature of an abrasive as a lubricant. Grease does not readily spread itself in a film over the surfaces, especially if it is applied when they are loaded or when cold. This offsets the apparent advantage of being able to force grease out of the cups, for it often juts out at the opposite end of a bearing without actually spreading over that bearing, the appearance of the grease being a misleading sign that the bearing is properly lubricated. If all parts of a bearing are not lubricated the dry parts will soon accumulate dirt or inert matter and start a cutting action. When very cold it is almost impossible to force grease through small drilled holes and channels. It is therefore difficult to know when a grease-filled bearing is even getting the lubrication designed for it. Grease on painted surfaces is hard to remove in washing a car. Oil the Best Lubricant Oil, as a lubricant, has great advantages over grease, but it is not always as cleanly and its proper application to chassis bearings has required more painstaking design than has usually been given to it. These things have militated against its use, especially on passenger cars, but the advantages that follow are appealing more and more to designers and to users. Oil will maintain as heavy a bearing load as grease, and with less friction. Oil fed to one properly located point in a bearing will soon spread over the entire bearing surface. Oil will flow through a very small hole, and it can be conducted a considerable distance by means of capillary attraction and surface tension. Oil will carry much less dirt than grease, and it is not nearly so much exposed to dirt when in bulk or when being applied. Oil contains no inert matter to clog holes and channels. The oil used in the engine can be used in the chassis oilers, eliminating the necessity for carrying two kinds of lubricant. Oil is more easily applied than grease. A flow of clean oil tends to clear a bearing of any dirt which it may contain, and a bearing arranged for oil lubrication can be flushed and cleaned with gasoline or kerosene. Oil for Chassis Lubrication Up to a few years ago grease was almost universally used for chassis lubrication. In 1912 the writer had oil cups installed on some of the GMC trucks, and in 1913 designed and built an experimental truck on which oil was used at almost every point. This truck is still operating on the original pins and bushings, which show only a trace of wear. More recently we have seen a slow but steady increase in the use of oil, which seems now to have gained a very fair headway on both trucks and passenger cars. The severe service to which motor trucks have been put has proven the advantages of oil over grease, and it is in truck design that the greatest progress has been made in the use of oil. The court of last resort on the reliability, and hence the desirability of almost all features of chassis design, is the repair shop—our service stations and garages. It is here in particular that lubrication failures are noticed and the most reliable [Image Caption: Magazine wick feed shackle and shackle bracket as used on Fageol truck] | ||