SOME CHANGE-SPEED , GEARS.
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A Résumé of Recently Published Patents.
AHYDRAULIC change-speed gear of the familiar awashplate type is described in specification No. 167,168, by H. D. Williams. Although the principle of operation of the device presents' no features of novelty, there are so many interesting practical points about the detail construction of the gear as to make its study well worth while. As a matter of fact, the inventor, in the earlier paragraphs of the specification, states that his primary object is to improve the construction of such mechanisms so that they may be run at higher speeds, and be used for the transmission of greater powers, than has hitherto been practicable. Amongst the means by which he hopes to attain this end are: The abolition of universal joint connections between the pistons of the pump or motor cylinders and the awash-plates; the embodi
ment of lubricating means, the employment of which will obviate the necessity for running the whole of the mechanism in a bath of oil, the said lubricating means being supplemented by a replenishing device which will maintain the quantity of oil •within the pumps and motors, and between them, at a maximum, and the use of ball bearings for the piston rods, to reduce friction between them and the cylinder walls.
Most of these features are, as might have been expected, interrelated and interdependent.. For example, universal joints between the pistons and awash-plates are eliminated by making the piston rods serve only as push rods, so that is positive connection between rod and plate is thus not required. That this may be effective under all conditions of working, as, for example, when the pump piston is traversing a suction stroke, use is made of the replenishing device, which is a small, supplementary pump located in a sump, to maintain the pressure of oil within the pump and motor cylinders always at such a figure thatitowill overcome the friction and inertia of the pistons,push rods and ball bearings. Interesting, also, is the curious construction of the two awash-plates.
This condition—that the piston rods are always in compression—allows of an interesting construction of the piston and rods, in that there is no positive connection between the two. In the interior of the piston a hardened push-button is located, on which the sounded end of the piston rod bears. The piston rod itself; as has already been stated, is supported within the cylinder in ball hearings, and the whole construction has the merit of relieving the cylinder walls from any side thrust whatever.
Other Patents of Interest.
Specification No 181,310, by G. C. de Courval, describes an ingenious use of an cpicyclie gear as a means of regulating the
ratio of the transmission gearing. A substantial cone is mounted on the driving shaft, and in contact with it, one on inch side, are two friction wheels. The driving shaft is continued.beylond the end of the cone, and supports the star piece of a differential gear. On the ends of the shafts which carry
B46 the friction wheels are gearwheels, which are in engagement with a pinion which is integral with one of the sun wheels of the differential gear, the other being keyed to the driven shaft. The main drive, it will be understood, particularly if reference be made to one of our illustrations, is via the star piece of the gear, the planetary pinions, and the sunwheel on the driven shaft, whilst the ratio of the gearing is controlled by the speed of the other sunwheol, Which is geared to the fric tion wheels. The speed of the latter is variable by moving them along the conical drum, hence the means of varying the ratio of the main gear.
The change-speed gear which is the subject of specification e, No. 181,683, by A. Brunel, is of a, different order altogether The driving shaft. carries a disc, which supports, in ball bearings, equally spaced round its middle cir cumference, a number of spindles, on which are carried planetary discs, which themselves drive planetary pinions by means of frictioh ratchet devices. The movement of the planetary discs, however, is controlled by a peculiar double eccentric device. Each disc has a pro jecting pin, eccentrically disposed. All these pins work in a circular groove, which is cut in another eccentric, the eccentricity of which is manually con trolled. The ratchet-driven planetary pinions are in engagement with a pinion on the driven shaft, through which the power is transmitted. Varying the eccentricity of the disc in which the groove is cut alters the rotational velocity of the planetary discs, and controls the speed ratio accordingly. . . N. Schreiber shows, in specification No. 189,167, how a three-wheeled ma chine may be given that stability when cornering which is afforded to the twowheeled single-track machine by the rider leaning to the side to which lie is turning. The side-by-side wheels are mounted on stub axles su.pported in vertical levers which form part of the parallel motion framework, a central member of which is a-part of the frame of the machine. Thus, as the driver leans, the machine can lean with him as though only two wheels we:43 fitted, A two-stroke engine with horizontally opposed cylinders, of which there may be two, four, six, eight, and so on, is de scribed in specification No. 168,066, the patentee being C. H. Whitoombe. A vortical pump, OD pumps, disposed above the crankshaft., is used to effect the preliminary compression of the charge. The feature of the crankcase which is described in specification No. 179,530, by M. J. B. Barbaron, is the reduction to a minimum of. the aluminium used. Steel pressings are used for covers, and the same pressings are utilized as supports for the case in the chassis frame.
The application of a double-inverted type of Hooks joint to the mechanism of a bent-wheel-driven chassis is described in specification N.o. 189,22E3, the patentee being G. Barker.