AN A.E.C. TRACTOR-LORRY IMPROVEMENT.
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A Résumé of Recently Published Patents.
AN INTERESTING invention in connection with a six-wheeled vehicle of the tractor-trailer type is discloged in specification No. 213,990, by the Associated Equipment CO., Ltd., and H. K. Thomas. One object is to prevent overturning when the vehicle as travelling round corners, and this is effected by limiting the angle through which the one portion of the combination can turn
With respect to the other. Another object is to improve the control which the driver has over a machine of this type when it is being driven backwards. This object is achieved by arranging that. the two parts of the vehicle can be locked to one another in such a manner that the angle between them. is maintained unaltered..
One application of this invention is described and illustrated in the above.
ii-ened specification. The patentees, however, point out that several modifications might be introduced without departing from the principle involved, which is itself the subject of the patent. In the arrangement described the traner carries a portion of a curved rack. the Centre of curvature, being the king which connects the tractor to the trailer, and about which, of course, all angular movement between these two takes place. This rack gears with an idle pinion which is mounted on the tractor, The number of teeth on the rack is limited, so that, in turning, When -the pinion on the tractor reaches the last tooth on the rack, all further steering or angular movement in that direction is prevented, and in that way is the limitation of the steering effected.
A transverse lever, pivoted to one side-member of the tractor frame, and Carrying, at its centre; serrations designed to be capable of engagement with teeth of the pinion already mentioned, is controlled by the driver, so that he may cause such engagement to be brought about when, if reversing, he Wishes to prevent further angular movement between tractor and trailer_
Other Patents of Interest.
AN IMPROVED arrangement of the 'Sentinel combined differential gear and crankshaft is described, in specification No. 213,988, by S. E. Alley and Woodvine. It is designed to allow' the provision of better bearings. Prior tothe invention of this construction, the main bearings for the shaft have been divided, part serving as support for the crankshaft sleeves and part for the differential shafts: Experience has shown that ther,e are drawbacks to tbia arrangement, inasmuch as, owing to the variation speed rotation as between' one shaft and the other, the. wear of the bearings was uneven. Now the sleeve ' is to be carried right, through, being joianalled in the bearings for the whole of its length, whilst the differential shaft is supported in bushes inside the . sleeve.
A further feature of this invention isthat the sleeve itself is prolonged. and actually extends beyond the bearing, serving to support, the, driving sprocket which is bored oat to fit over it.
THE SENTINEL differential locking
gear, which • was an interesting feature of last year's Commercial Motor Exhibition, is now described in the form of a patent, in specification No, 213,993, by S. E. Alley. The full references which the gear had, in the course of our special Show Numbers, makes it unneeeesaxy for us to deal with the construction now at any great length. We would, however, remind our readers that this differential gear, which is built up into the crankshaft of the engine, embodies an automatically slipping friction brake, which is so designed that it can be adjusted so that, until a certain predetermined tendency for differential action is exceeded, it will peeve* such action;. that is to say, small differences in the resistance to drive, as between one sprocket wheel and the other, will not produce any differential effect, but, when that difference is really serious, as
when the vehicle is turning a corner, then the friction exerted by the brake will be overcome and differential action will occur.
IN SPECIFICATION No. 214,956
there is described a method of equipping the well-known Eagle two-wheeled trailer so that it can be used to equal advantage either for horse or motor haulage. In this particular trailer it may be remembered the weight distribution is such that the bulk of it lies in front of the axle, thus ensuring that additional adhesive effect is imparted, to the tractor. A single castor wheel is provided to support the trailer when it is necessary for it to stand alone. In the present invention this castor wheel is mounted on a nut-and-screw gear, so that the frame may be raised or lowered on the wheel, either in, order to facilitate coupling the trailer to, or -uncoupling it from, the tractor, or in order to modify its height for convenience of horse haulage. When the trailer is coupled to FE tractor this castor Wheel is withdrawn entirely from contact with the road.
CONSIDERABLE expenditure on springs is apparently not involved in the suspension system which is de scribed in specification No. 284,680, by L. M. Baines. Each axle is attached by ball joints to the end of the horizontal and longer arms of a pair of bell-crank levers. The depending arms of these levers are attached to transverse compensating bars which are tied stogether by an adjustable rod. Spriggs are disposed between the upper surfaces of the bell-crank levers and the frames of the chassis, and a feature of the arrangement is that a blow felt by one wheel is transmitted and divided amongst, all four sets of springs. "
SPECIFICATION No 214,086, by C. Clench and the Aster . Engineering Co., Ltd., deals with an interesting type of servo brake. A pair of expanding brake shoes is operated by a relay lever, which is coupled to an operating shoe brought into contact with the drum by operation of the ordinary brake pedal or hand lever. Frictional contact
with the brake drum by this operating shoe causes the arm to rotate through an angle that varies according to the speed Of rotation of the dram' and applies the brakes with greater or lesser effect accordingly.
ANOTHER invention connected with motorcar suspensions is described in specification No. 188,673, by H. Johnsen. The device is intended to serve as shock absorber, and automatically to stiffen the main spring when it is subjected to excessive loads. A bracket is .clipped on to the spring, at a convenient point, say about one-third the distance from the eye to the centre in the case of
a semi-elliptic spring. The connection to the frame is replaced by a lever, attached to the spring and to the frame, and prolonged to receive the end of a .rod which is designed to slide in the aforesaid bracket. The movement of this rod is restrained by a coil spring, butting, at one end, against the bracket, and at' the other against a nut in the rod, which affords means of adjustment. of the tension of the spring. As the load comes on the spring, and it, flattens and lengthens, the resistance of the coil spring operates in part to take some of the shock and in Dart to stiffen the main Spring.