A Hydro-mechanical Gearbox P ATENT No. 787,082 shows a twospeed epicyclic
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gear in which ratios between the speeds are provided by a hydraulic gear of the swashplate type. (J. Weaving, D. Stuart and The Austin Motor Co., Ltd., Longbridge Works, Birmingham.)
The input member carries an internal ring-gear (1) which meshes with one set of planetary pinions and through them a sunwheel (2). The planet carrier is common to two sets of pinions, the other set being shown at 3. The planet carrier also forms the output member, being, fi:e.d to the shaft 4.
The sunwheel (2) drives, via a tubular shaft, one of the swashplate drums (5), whilst the sunwheel (6) is attached through an inner tubular shaft to the other swashplate drum (7). A plate clutch (8), hydraulically operated, can be engaged tO give a straight-through drive.'
The intermediate ratios are obtained by varying the angle of inclination of the swashplates, and the torque is transmitted partly by the epicyclic gear and partly by the hydraulic mechanism. By suitable choice of inclination angle, reverse can also be obtained.
In the position shown, a straightthrough drive is hydraulically established by fluid lock, but if the -clutch were engaged the drive would continue and Ole hydraulic system would then be unloaded.
A SEMI-TRAILER COUPLING
PATENT No. 786,529 refers to semitrailer combinations in which the semi-trailer is fitted with a retractable
undercarriage to support it when standing alone. An improved design disclosed in the patent renders it impossible for the temporary support to be accidentally collapsed when in use. (J. Brockhouse and Co., Ltd,, Victoria Works, Hill Top, West Bromwich.)
The drawing shows the combination in the act of coupling. When the tractor is reversed, it forces its ramps (I) under the rollers (2) and so lifts the support wheels from the ground. The wheels are mounted in a frame supported by slotted connections
(3). During the early part of the movement the slots allow the wheel frame to descend slightly, an action which lifts support struts (4) out of sockets (5). Until this has been done, the
787.082 whole linkage is positively locked.
Continued movement brings a roller (6) on to a hornplate (7), thus causing the linkage to fold up into the travelling position.
PREVENTING HYDRAULIC CAVITATION
PATENT No. 786,064 shows a modification to a hydraulically powered steering sYstem, the aim of which is to prevent cavitation in the liquid circuit. By maintaining a slight pressure at all times. severe pressure-drops across the control equipment are unlikely to create cavitation. (Bendix Aviation Corp., South Bend, Indiana, U.S.A.).
MIXED FUELS IN OIL ENGINES
TO feed an oil engine with a very weak petrol-air mixture which is itself too weak to self-ignite, but which will fire readily when the main heavy fuel charge is injected, may have advantages; however, it calls for the complication of a two-fuel supply system. A scheme in which the two fuels can be initially mixed and separate themselves automatically is shown in patent No. 787,671 (Esso Research and Engineering Company, Elizabeth, New Jersey, U.S.A.)
The drawing shows diagrammatically the principle of the separating device which is located in the engine intake. The incoming air enters at the top and first passes over a jet (I) which is fed with the mixed fuel. The mixture falls on to a vaporizing unit (2) which is kept at a temperature of 150°-200° C. during running.
The lighter fraction of the fuel is vaporized and carried away by the air stream, but the heavier part drips into a well (3) from which the injection pump draws its supply. A preferred mixture is 80 per cent. oil fuel and 20 per cent. petrol or other volatile oil.
COUPLING HITCH FOR TRACTORS
OVERLOADED tractors meeting an excessive drawbar pull have been known to lift about their back axle as a pivot. To prevent this, patent No. 785,756 shows a coupling hitch in which increasing drawbar pull applies a proportionately heavier downward load to the tractor. (Wharton Engineers (Elstree). Ltd.. Watford Road, Elstree, Herts.)
AN OIL-COOLED PISTON
A DESIGN for a piston having an oilZ.-I cooled inner surface forms the subject of patent No. 786,985. The oil is supplied from the lubricating system of the engine and reaches the piston via the gudgeon-pin assembly. (Ricardo and Co. Engineers (1927), Ltd., 21 Suffolk Street, I.ondon, S.W.].)
An annular tray (1) is attached to the underside of the crown portion and is extended to form a baffle (2). In operation, oil is ejected from a jet (3) in the connecting rod and lies partly in the annulus and partly against the roof of the chamber because of the rapid accelerations of. the piston.
The acceleration forces are large compared with gravity so that the scheme will work effectively whether the cylinders be vertical or horizontal.
CONSTANT-HEIGHT SUSPENSION. DATENT No. 784,021 comes from Regie Nationale Des Usines Renault, 8-10 Avenue Emile Zola, Billancourt, Seine, France, and deals with a suspeniion system that keeps the height of the vehicle constant. A feeler arm measures the relative axle height and not only brings corrective mechanism into action, but also indicates the state of the suspension to the driver by means of a dial.