AN EIGHT-CYLINDER SIX-WHEELED CHASSIS.
Page 67
Page 68
If you've noticed an error in this article please click here to report it so we can fix it.
A Complete Description of a Miesse -Design, in Which a Number of Interesting Features is Included.
IN recent issues attention has been drawn to the great progress which te being made in Belgium with the establishment of motorbus services, not only in the large towns, but in the country districti. The demand lot public-seeice vehicles has, in fact, grown to such Cu extent that several of the Belgian motor manufacturers are DOW mainly devoting, their energies to the construction of vehicles for this class of work. Amongst them is the Miesse Co., of 8.8, Rue cles Goujous, Curegbem, Brussels, which, in addition to having supplied a large number of four-Cylinder buses for service in Belgium and Holland, last year produced the first omnibus with an eight-eylindered engine.
As we have already recorded, the Miesse . Co. has already advanced a stage farther in its motorbus development work by producing an eight-cylinder six-wheel chassis, of which we are this week able to give a description. The engine, which is rated at 35-100 is of what has come to -be known as the straighteight type, and the cylinders, which are in a single casting with the upper half of the crankcase, have a bore and 'stroke of S5 mm l and 130 mm. respectively. The valves are located overhead and directly actuated off an overhead camshaft driven from the crankshaft by a vertical spindle and spiral-bevel gearing. A pump circulates oil to the crankshaft bearings, to the connecting rod big and little ends, and to the overhead-valve gear.
Ignition is effected by the Bosch combined lighting and ignition dynamo, with a distributor vertically mounted
on the near side of the engine. A Bosch electric engine starter is also provided. Two carburetters are fitted on the off side of the engine, one -for each set of four cylinders, the gas leads to each of the cylinders being embodied in the casting, The compactness of the eight-cylindered engine may he judged from the fact that the bonnet length is only 4 ft., or but 17 ins. more than that on the maker's chassis with a four-cylindered engine.
The clutch, which, together with the three-speed gearbox, is embodied as a unit with the engine, is of the multidry-disc variety. . A two-piece pro'idler shaft is used, the rear end of the forward section being supported by a ball joint housed in one of the chassis cress-members. The rear half of the shaft is connected by oil-retaining universal joints at both front and rear ; the oil supply can be conveniently replenished from the sides of the vehicle. The final drive of each of the two live axles is by under-type worm gearing, the two worm-carrying spindles being connected by a short double-jointed extension of the main propeller shaft.
The rear wheel supporting system adopted by the Miesse Co. is one ot the interesting details of the new chassis. As will be seen from one of our illustrations, it comprises on each side a series of three inverted minielliptic springs connected to a pivotal shaft supported in a tubular frame cross-member centrally located between the two driving axles. Two of the springs are located above and one below the pivot. Thus the springs can osclllate about their centres—which are • • fitted with "Silent Bloc" bearings— without causing the springs to twist or to be otherwise distorted.
As a result of this arrangement, it is claimed that when travelling over rough roads, each of the three springs is only compressed to half the height of the obstacle encountered by the wheel, and that the springing of the vehicle is improved to the extent of four times that provided by the ordinary method. Moreover, all liability to skidding, with consequent tyre wear, is obviated.
Another feature of interest is that the chassis is provided with internalexpanding brakes on each side of the six road wheels. The brake drums have a diameter of 16 ins. and are 2.4 ins, wide. The front-wheel brakes are of a 811ecial design so far as the brake-shoe control mechanism is concerned, the cams being operated not by the usual turn shaft but by a pitch chain. Unfortunately, we are not able to give full details of the arrangement, which, we understand, is being made the subject of a patent. The six wheels arc of the steel disc detachable type, and are shown with large pneumatic tyres of 1,025 mm. by 185 ram. dimensions.
In view of the length of the vehicle, special attention has been devoted to the production of a specially strong chassis frame, the pressed-steel sidemembers being not only of considerable depth but also very wide. Moreover, in addition to the two end and three intermediate cross-members, the central position of the chassis is braced by a cross-member, the central portion of which provides the support for the divided propeller shaft.
It will be noted, toe, that the low loading level—the top of the frame, is only 24i ius, above the ground—has been obtained without any unusual shaping of the main members. Indeed, except for a slight upward bend to provide the necessary clearance for the back-axle casings they are perfectly horizontal, the work of body fitting being thus greatly facilitated. It will also be noticed that to afford a wide steering lock, the frame members , are brought inwards at the forward end to a considerable degree.
Special attention has been devoted to the accessibility of the chief, chassis components in order to facilitate and reduce the cost of maintenance and re
pairs. Thus, the .Miesse Co. claims that, without having to dismantle the engine or to remove it from the chassis, a connecting rod or piston can be detached within an hour by removing the
bottom half of the crankcase. The cylinder heads are detaChable and can be decarbonized and their valve seatings ground in less than half a day, whilst the camshaft can be detached in 30 minutes. It is passible to dismantle the dutch or to remove the gearbox in the same time, after which any of the change-speed gearwheels can be renewed within an hour.
So far as the back axles are. con!corned, it is claimed that the crown wheels and differential can be removed within an hour, it being only necessary to remove the hub caps, withdraw the axle shafts and remove the central covers of the axle casings, when the whole gearing can be removed for inspection or repair.
In order to increase the passengercarrying space, the steering gear is mounted at the extreme forward end of the chassis, so that the driver, whose cab -is entirely enclosed, is seated at one side of the engine. This arrangement has necessitated some modification in the layout of the usual clutch and foot-brake control mechanism and in the change-speed control, the hand lever for the latter being connected with the gearbox selectors by a shaft which runs longitudinaliy instead of transversely to the frame.
The new chassis is being made in two lengths of wheelbase, 12 ft. 9 ins. and 17 ft. 9 ins., the former being shown in the accompanying illustrations. The track is 6 ft. 3 ins, and the width over the axle caps 7 ft. 3 ins.
The distance between the springs on the two sides of the vehicle is 4 ft. 3 ins. In the has illustrated the available body space is 22 ft. 11 ins., whilst the overall length of the vehicle is 28 ft. 5 ins.
The first bus or coach—a 45-seater vehicle—was recently supplied to the S.A_T.A.L. Co., of Brussels. which has been uSing it on tourists' service between the Belgian capital and the pleasure resorts of the hilly Ardennes district. It may be mentioned that the new six-wheeled chassis is being adopted for use as a goods-carrying unit, capable of dealing with loads up to 7 tons.