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Two New Agricultural Motors.

15th June 1911, Page 3
15th June 1911
Page 3
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Page 3, 15th June 1911 — Two New Agricultural Motors.
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The Daimler Co. Builds Two New Machines, which are Complete Departures from Previous Productions of the Famous Coventry Works.

After 15 years of experience in the manufacture of petrol engines, and over five years in the design and construction of the Daimler road trains for goods and passenger transport, the whole of the resources of the gigantic Daimler works at Coventry have been con-.

centrated on the production of two new types of agricultural tractors ; examples of these, in both the large and the small sizes, will be prominent features of the Daimler Co.'s exhibit at the Royal Agricultural Society's Show at Norwich:

The smaller of these new models is a 30 h.p. tractor, which is capable of much useful work, but the centre of attraction on the Daimler stand will certainly be the larger vehicle, and it is to this model that the following description applies. So far as external appearance goes, the larger Daimler tractor does not differ radically from the generallyaccepted design of steam road locomotives. There are, however, many distinctive features which place this tractor in a class by itself, and there is ample evidence throughout that the design has been the work of skilled engineers. The power plant consists of a six-cylinder petrol engine of the Daimler slide-valve type. It is claimed that the experience of the past three years. in the case of pleasure cars of all sizes, and in the more-severe omnibus and road-train branches, has shown, in a conclusive manner, that the Daimler type of engine is absolutely reliable, and that it retains its power to the fullest degree, without any fall mg-off, even after several years of hard work. For an agricultural tractor, working very frequently at continuous full load, this quality is of great importance.

The larger of the two tractors has a 100 lLp. Knight-Daimler engine, which has been specially designed for heavy service, and the results of most-stringent tests have proved the soundness of its construction. The various details—pistons, connecting rods, crankshaft and bear ings—all follow the best accepted practice, and the only engine feature to which special attention need be drawn is the automatic lubrication arrangement, which is right out of the driver's control, and which needs no attention except the replenishment of the oil supply at regular interval s---every week or so. Lubrication is afforded by a pump delivering oil to troughs placed benealh each connecting-rod big-end ; a tell-tale on the dashboard indicates the working of the pump. A centrifugal governor controls the engine and, the spring for

the governor being placed outside, it may easily be adjusted by a thumb-screw. The situation ot the engine, at the rear of the tractor, behind the main driving wheels, is ttie most accessible that could possibly be arranged, and all the accessories—magneto, carburetter, and the like– can be reached without trouble. This important feature of accessibility is wed in evidence throughout the whole of the design.

The method of power transmission to the driving wheels is particularly interesting. The engine flywheel contains a metal-to-metal cone clutch, which is operated by a pedal on the driver's platform, and, in front of this clutch, a double universal joint is provided, both for the purpose of compensating for any flexure of the frame when travelling over rough roads, and of permitting the engine to be easily removed if this should prove necessary at any time. The universal coupling leads to the gearbox, which provides a second, or indirect, forward speed and a reverse, in addition to the low speed, or normal direct forward drive. The indirect forward drive is provided for use when the tractor is hauling loads along the level, and the speed under these conditions will approximate to four miles an hour. The direct, or ploughing, speed is about 24 miles an hour, when the engine is running at its normal r.p.m. In front of the very small change-speed gearbox, there. isa large worm gear, which transmits the power, at a greatlyreduced speed of rotation, to the main transverse shaft ; this shaft is provided at. its ends with small spur

gear-wheels, which mesh with large gear-wheels that are bolted to the main driving wheels ; thus, the power is transmitted as directly as possible from the engine.

Inside the driven worm-wheel is placed the differential mechanism ; a simple locking device, actuated by a small and aceessibly-placed lever, puts the differential-gear out of action when the tractor is climbing steep hills or travelling over soft ground.

It will thus be seen that, in the Daimler tractors, long trains of spur and bevel gearing are avoided, and the solution is found by dividing the reduction (on direct drive) into two stages : the first of these is by worm and worm-wheel from the engine ; the second is by the finaldrive spur-wheels to the road wheels. As the total reduction is 114 to 1, it is evident that a moreefficient method of mechanical transmission could hardly be obtained.

The forward portion of the tractor frame is occupied by the fuel and water tanks, and by the radiator. The fuel tank is placed right in front, and behind this is situated a funnel, or chimney, up which the exhaust is blown, in steam-locomotive fashion, so that a draught may be induced through the radiator_ In addition to this induced draught, a large fan impels air through the radiator tubes, the air escaping up the chimney together with the exha,ust gases, No difficulty, we

are assured, has been experienced in keeping the water cool under the most-adverse conditions, and the consumption of water has been found to he practically negligible-less than a gallon a day.

The road wheels, steering gear, and other general details follow accepted steam-tractor practice ; they, therefore, need not be fully described here.

Concerning the control gear, this is neatly arranged on a dashboard in front of the driver. The choice of gear—normal, fast forward, or reverse—is effected by a side lever, which is used in conjunction with the clutch pedal that disconnects the engine, and, thereafter, all variation in speed is effected by a movement of the throttle lever. The other fittings within the driver's view and reach are merely the oil and pressure gauges, which indicate that the lubrication and petrol supplies are working.

This tractor is intended to haul a 21-furrow plough, such as is used in the Colonies and foreign countries, where extensive mechanical ploughing may economically be effected. The smaller tractor is intended for the use of the small farmer, and is stated to be capable of hauling a seven-furrow plough.

The engine of the smaller tractor is placed at the front of the vehicle and behind a circular radiator, This engine is also built on the DaimlerKnight principle: it has four cylinders, and gives 20 b.h.p. at 1,000 a p.m. The lubrication is ante

inatie, and is carried out by a multiple-plunger oil pump, which is driven by the engine and supplies oil to a trough beneath each connecting-rod big-end. The carburetter is of the usual Daimler plug type, and needs no adjustment after leaving the works ; it has no springcontrolled or other automatic parts to get. out of order. Ignition is effected by the Bosch dual-ignition system. A centrifugal pump circulates the cooling water, whilst a fan, belt-driven from the front of the engine, induces a good air draught through the radiator. The Petrol tank. which is placed beneath the driver's seat, has a capacity of :10 gallons, and supplies fuel to the earburetter under pressure.

The drive is transmitted from the engine through a leather-faced cone clutch to the gearbox, which is bolted directly to the worm ease. The gears are case-hardened, and give three speeds forward and a reverse. The forward sneeds consist of a Ploughing sneed (on direct drive) of 2+ to qmiles per hour, and two other speeds, of four and seven miles per hour, respectively. for haulage or road work. All the shafts run on ball bearings. A shaft, which is mounted parallel to the nrimary gear-shaft and is driven therefrom by snipg.earing, is connected to a pulley for threshing or other purposes, and this pulley is plmeed at the rear of the tractor_ The ease-hardened steel worm engages at the ton with a phosphorbronze worm-wheel, which encircles a bevel-type differential cage. As in the ease of the large tractor_ this

gear can be effectually locked by means of a lever at the side of the ease. The brake drum in attached to the end of the worm-shaft, and ho final drive to the road wheels is transmitted by spur pinions on the cross-shaft, which mesh with the spur rings bolted to the wheels. The frame is in two parts. It consists of : a main frame carrying the engine, petrol tank, body and front axle ; a subsidiary frame, outside and underneath the main frame and attached to it at the front end by links, which carries the worm case and rear axle, Guide blocks, pressed on the axle, work in horn blocks which are bolted to the main frame and rest on coiled springs which are suspended from the axle by links. The springing of the front axle is of the common tractor type. Bevel gear transmits the motion from the steering rod to a worm and sector on the axle. The wagon body can be tipped by the rotation of a handwheel at the rear.

In conclusion, it should be mentioned that, in addition to ploughhaulage and general tractor work, both these Daimler tractors are capable of performing any kind of harvesting operation, or of driving fixed and portable machinery by means of a belt.

Taken throughout, the Daimler tractors, both large and small, are excellent examples of British engineering construction, and they should certainly prove to be centres of keen attraction at the forthcoming show. We shall make further reference to both machines, after examination of their interesting features.

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Locations: Coventry, Norwich

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