A HYDRAULICALLY OPERATED BRAKE,
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A Resume of Recently Published Patent Specifications.
0 F. EDGE. assignee of Etablissements -de Dion Bouton, 0' a French company, in specification No. 239,475, describes a means for operating a brake or clutch by hydraulic pressure. As with most of the more modern applications of hydraulic pressure to such purposes the pres.sure exerted on the hydraulic piston is in exact relation to the pressure exerted by the. driver on his pedal or on his hand lever. We have recognized the importance of this relation of Mechanical power to man power from the first introduction of this class of bralm-operating mechanism, and have impressed upon designers the importance of a driver being able to " feel" how hard he is applying his brake.
.. The main features of the invention resembie designs that have gone before, as there is a geared pump which is continually revolving, and is driven, we suppose, by means of a connection to the transmission behind the gearbox, which supplies a continuous stream of oil which passes from the pump through the control valve an back to the tank; so long as the aperture of the. control valve is not constricted. Should this apertare be partly closed, the pressure in the pipe which leads to the cylinder, which operates the brake or clutch, is raised, the rise in pressure being in exact relation to the effort exerted in closing the control valve against the pressure of the passing flow of oil.
A spring is provided in the brake-operating cylinder to cause it to return to its position where the brakes are off, so that until the pressure of the oil rises to a prearranged degree no movement of the piston will take place. A spring is also provided to keep the control valve open, so that no pressure can be exerted on the brake-operating piston unless the control valve is partly or wholly closed.
The only part of this specification which ,appears to he novel to us is the form of control valve, as by means of its special shape and that of its orifice, any desired degree of gradual action can be obtained_ •
The invention is said to be applicable to brakes and clutches, but no mention :s made in the specification as to the means fOr driving the oil pump. If-it be driven from the transmission behind the gearbox, it is hard to see how the clutch can be opeated while the vehicle is standing still, whilst, on the other hand, if the pump be driven from the engine it is 'not easy to see how the brake can be relied upon to act should the engine stop and the. driver by any chance get into neutral.
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A Tractor-trailer Combination.
A TRACTOR-TRAILER combination forms the subject
. of the specification of Leonard Dewing, No. 253,568. The object of the invention is to throw a certain proportion of the weight of the trailer on to the tractor so as to increase its adhesion to the ground. The invention is said to he particularly suitable to tractors of the Fordson type, and, where such tractors are employed, the drawbar is so formed that it is attached to a fitting below the front axle of the trailer so as to lie in 'a horizontal line. Two springs are fixed to the trailer by means of a hinged support. One end of each spring is anchored to the turntable of the trailer, whilst the other ends bear on the drawbar near its centre. These springs are nearer together than those which support the axle, so that they afe close to the drawbar when viewed from above. A screw is provided to raise a nut which is provided with trunnions to which are connected links or shackles to take the pressure of the springs. It will be seen, also, that the drawbar is trussed so as to give it strength to hear the load.
In action, when the drawbar is coupled up, the screw can be adjusted to allow a proportion of the weight of the trailer to bear on the drawbar and,. in so doing, to bear on the trailer. The links connecting the ends of the springs to the trunnions are intended to allow for relative Movement of the tractor and trailer caused by uneven roads, as they can swing forward and backward to allow of the play of the springs. A hand brake f...r the trailer is also shown.
Bodies for Carrying Food. .
mi.AND T. BOl3SON, LTD.. AND F. W. ROB SON, in specification No. 253,628, describe a construction of body which is particularly suitable for the carrying of goods that rest on trays, such as food, etc.
The sides of the body are built of upright members which are let in flush with the lower horizontal members so that the panels which form the external part of the body can lie fiat on the vertical mem!):As. The rails that form the supports for the trays are firmly attached to the vertical members so that they make a very rigid structure on which to secure the external panels.
There is little doubt thA such a body would form a strong and convenient body for the class of goods to be carried, but there does not appear to he much that is new *in the method of construction as disclosed.