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 from 'The Motor' magazine describing the Lentz Hydraulic Transmission Gear.
| Identifier | ExFiles\Box 136\4\ scan0002 | |
| Date | 14th November 1911 | |
| The Motor 734 14th November, 1911. THE LENTZ HYDRAULIC TRANSMISSION GEAR. An Old Idea Incorporated in a New and Particularly Ingenious Way. IN all probability it will not be an exaggeration to say that ever since the inception of the automobile movement, the one problem which has engaged the attention of most of our cleverest engineers and inventors has been in reference to the transmission of the power of the engine to the road wheels. A recital of the various methods adopted would cover numerous pages in THE MOTOR, even with but the briefest details, and Dr. Lentz (although the production which we are about to describe is highly ingenious and cleverly arranged) cannot claim actual novelty for his system. Many of our readers of the old brigade, by which term we mean those whose associations with motoring matters extend back anywhere in the regions of eight or ten years ago, will remember that there was quite a run on hydraulic transmission gears, especially in Germany, and also several at later dates, in this country, but none of them has ever risen to any very great heights. It is never safe to prophesy that such-and-such an invention will or will not be successful, but, after a careful examination of the principles embodied and the construction of the new Lentz transmission, one comes to the conclusion (if, perhaps, against one's primarily conceived opinion on the subject) that the plan is at least feasible; whilst those people whose knowledge of mechanical matters extends into steam practice, will recognize in the name of Dr. Lentz an authority who would not incorporate such a thing as a slip drive and claim a proportionate increase of power for the production—a state of affairs which has occurred several times in the past. From the illustration, it will be seen that the construction is of a fairly substantial character, and also that the transmission gear is quite compact, whilst it must be remembered that it takes the place primarily of the clutch, and, in the second place, of the gear-box and brake; also of the differential gear and the bevel or worm drive, as the case may be. It will be seen, therefore, that a sweeping claim for simplicity may be advanced with justification on behalf of the new mechanism. The primary criticism of it would appear, on the face of it, to be on the question of weight, but, excepting on light cars, it is intended to be mounted with a dead axle and a cardan (à la{L. A. Archer} De Dion) drive. The main casting has two large cylindrical borings at right angles the one to the other, and also three subsidiary ones, all of the said borings being adapted to receive packed cover plates. On the front portion there is on top a large cylindrical boring, in which is mounted a combination of three concentric-eccentric-pin-operated fan-bladed pumps. The technical drawings reproduced are shown as simply as possible, as a description of the mechanism is not very easy to convey in every-day parlance and without a complete set of technical drawings. Bear in mind, however, for a moment, the three pumps in this central casing, all of which are mounted on a continuation of the tailshaft. To the right and left-hand lower side of this said trio of pumps, ports are cast, which, by means of a distributor valve, may be put into communication with the back portion of the gear or disconnected from it. Looking at the drawing of the actual transmission gear in the back axle, with its four pump vanes, let the reader picture to himself for a moment that three sets of apparatus, quite similar to this, constitute the three pumps just referred to; that is to say, as the tailshaft is revolved, the fan blades are drawn in and out with a varying degree of eccentricity, according, of course, to the variations in the combined concentric and eccentric cam curve in the face plate, which controls the movement. It will be seen in another sketch of this triplicated pump that the orifices vary in size, and through this fact the five different forward speeds are obtained. Let us assume for a moment that the engine, and therefore the tailshaft and these pumps, are revolving, but that by means of the valve gear no connection between the forward cylindrical casing and the casing which ordinarily would contain the differential gear, is possible, owing to the ports being covered. Also imagine that the whole apparatus is filled with oil, and in order to ensure that the whole of the casing shall have a free air vent, holes are provided on the top, through which the air may escape when the oil. Image 1 text (on component): LENTZ-GETRIEBE D.R.P.a Image 1 caption: A complete transmission unit built on Dr. Hugo Lentz's system, which is a very clever adaptation of well-known hydraulic transmission principles. The mechanism illustrated above replaces the ordinary gearbox, brakes, differential gear, and worm (or bevel) gear, etc. Image 2 caption: A plan view of a chassis fitted with Dr. Lentz's transmission, from which illustration it will be seen that the general construction of a chassis is undoubtedly simplified to a large extent. Of the three rods shown the centre one is the tailshaft, and the other two connect the distributor valves to the change-speed lever. | ||